Method for sterilizing spore-forming bacteria

Abstract

To provide a sterilization method that allows simple sterilization of spore-forming bacteria while suppressing degradation of an object to be sterilized.SOLUTION: A method for sterilizing spore-forming bacteria, using an aqueous solution (X1) containing (A1) component: a specific anionic surfactant, and (B1) component: a specific acid, or an aqueous solution (X2) containing (A2) component: alkylbenzenesulfonic acid, wherein the aqueous solutions (X1) and (X2) may contain (C) component: hypochlorite, a content of the (A1) component is 0.001 to 1 mass%, a content of the (B1) component is 0.001 to 5 mass%, a content of the (A2) component is 0.002 to 6 mass%, a content of the (C) component is 0 to 0.001 mass% in terms of effective chlorine concentration, a pH of the aqueous solutions (X1) and (X2) at 25°C is 1.5 or more and less than 5, and the aqueous solution (X1) or (X2) is heated to 50 to 100°C and brought into contact with spore-forming bacteria to sterilize the spore-forming bacteria.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for sterilizing spore-forming bacteria. [Background technology]

[0002] Microorganisms adhere to and multiply on manufacturing equipment used to produce food and cosmetics, kitchen utensils, pipes, water tanks, etc., so sterilization treatments are carried out to improve hygiene. As a sterilization method, for example, Patent Document 1 describes the use of a spray containing ethanol, an organic acid, and a nonionic surfactant, and Patent Document 2 describes the use of a powder composition containing an organic acid and a surfactant.

[0003] However, the methods described in Patent Documents 1 and 2 are insufficient in sterilizing effects against spore-forming bacteria that are highly heat-resistant and drug-resistant. Furthermore, when washing textile products such as hospital linens and hand towels, spore-forming bacteria may remain even after washing. Residual spore-forming bacteria on the object to be sterilized may not only deteriorate the quality of the product but also cause infectious diseases. Steam sterilization, which involves heating to 100°C or higher using an autoclave, is a known method for sterilizing the spores of spore-forming bacteria (hereinafter also referred to as the "killing method"). However, the range of use of this method is limited because the objects to be sterilized using steam sterilization must be pressure-resistant and heat-resistant.

[0004] As an alternative to heat steam sterilization, methods using chemicals have been proposed. For example, Patent Document 3 describes a germination method using an aqueous solution containing an organic acid, polyoxyethylene sodium lauryl sulfate, and sodium hypochlorite, with a pH of 5 to 6.5. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-40889 [Patent Document 2] Special Publication No. 2003-524425 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-288018 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the sterilization method described in Patent Document 3 requires careful handling of the chemicals, and there is also the concern that the chemicals may deteriorate the object to be sterilized. An object of the present invention is to provide a sterilization method that can easily sterilize spore-forming bacteria while suppressing deterioration of an object to be sterilized. [Means for solving the problem]

[0007] The present invention has the following aspects. [1] A method for sterilizing spore-forming bacteria using an aqueous solution (X1) containing component (A1) and component (B1), The aqueous solution (X1) may contain a component (C), The component (A1) is one or more anionic surfactants selected from alkyl sulfates, alkylbenzene sulfonates, alkanesulfonates, and olefin sulfonates, The component (B1) is at least one selected from organic acids and inorganic acids, The component (C) is a hypochlorite, the content of the component (A1) is 0.001 to 1 mass%, the content of the component (B1) is 0.001 to 5 mass%, and the content of the component (C) is 0 to 0.001 mass% in terms of an available chlorine concentration, relative to the total mass of the aqueous solution (X1); The pH of the aqueous solution (X1) at 25°C is 1.5 or more and less than 5, A method for sterilizing spore-forming bacteria, comprising heating the aqueous solution (X1) to 50 to 100°C and bringing the aqueous solution into contact with the spore-forming bacteria to sterilize the spore-forming bacteria. [2] The method for sterilizing spore-forming bacteria according to [1] above, wherein the mass ratio of the component (B1) / the component (A1) is 1 to 500. [3] A method for sterilizing spore-forming bacteria using an aqueous solution (X2) containing component (A2), The aqueous solution (X2) may contain a component (C), The component (A2) is an alkylbenzenesulfonic acid, The component (C) is a hypochlorite, the content of the component (A2) is 0.002 to 6 mass% and the content of the component (C) is 0 to 0.001 mass% in terms of available chlorine concentration, relative to the total mass of the aqueous solution (X2); The pH of the aqueous solution (X2) at 25°C is 1.5 or more and less than 5, A method for sterilizing spore-forming bacteria, comprising heating the aqueous solution (X2) to 50 to 100°C and bringing the aqueous solution into contact with the spore-forming bacteria to sterilize the spore-forming bacteria. [4] The method for sterilizing spore-forming bacteria according to any one of [1] to [3] above, wherein the spore-forming bacteria is at least one species selected from the group consisting of Bacillus subtilis and Bacillus cereus. [Effects of the Invention]

[0008] According to the sterilization method of the present invention, spore-forming bacteria can be easily sterilized while suppressing deterioration of the object to be sterilized. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following embodiments and can be implemented with various modifications within the scope of the gist thereof. In this specification and claims, a numerical range expressed as "to" means a numerical range that includes the numbers before and after "to" as the lower and upper limits. For example, A to B is equivalent to A or more and B or less. In addition, in this specification, sterilization of spores of spore-forming bacteria is also referred to as "spore killing," and a method for sterilizing spores of spore-forming bacteria is also referred to as a "spore killing method."

[0010] The object to be sterilized in the sterilization method of the present invention is not particularly limited as long as it is an object, equipment, facility, etc. in which spore-forming bacteria can exist. Specific examples include items such as tableware and cooking utensils; various items and equipment in facilities that mainly handle food, such as kitchens of restaurants and the like, various items and equipment in food factories, and the back-of-house areas of supermarkets; various items and equipment in medical settings; various items and equipment in cosmetic manufacturing factories; and textile products. Deterioration of the object to be sterilized includes, for example, corrosion of metal components of the object to be sterilized, such as kitchen utensils, food and cosmetic manufacturing equipment, washing machines, etc., due to the metal corrosiveness of the chemicals; deterioration of the quality of textile products, etc. In this specification, the inhibition of deterioration of the object to be sterilized due to metal corrosiveness is also referred to as "metal corrosion prevention."

[0011] Spore-forming bacteria to be killed in the sterilization method of the present invention are bacteria that form spores, such as bacteria of the genera Bacillus, Clostridium, Geobacillus, Paenibacillus, Amphibacillus, Sporosarcina, Aeribacillus, Alicyclobacillus, and Sporolactobacillus. Among these, the sterilization method of the present invention is effective against bacteria belonging to the genera Bacillus and Clostridium, and is more effective against bacteria belonging to the genus Bacillus.

[0012] Examples of species of the genus Bacillus include Bacillus subtilis, Bacillus cereus, Bacillus amyloliquefaciens, Bacillus anthratis, Bacillus megaterium, Bacillus brevis, Bacillus circulans, Bacillus flexus, Bacillus halmapalus, Bacillus halodurans, Bacillus licheniformis, and Bacillus thuringenesis. Among these, the sterilization method of the present invention is effective against Bacillus subtilis and Bacillus cereus.

[0013] Examples of species of the genus Clostridium include Clostridium botulinum, Clostridium difficile, Clostridium perfringens, and Clostridium tetani. Examples of Geobacillus species include Geobacillus stearothermophilus.

[0014] First Embodiment The sterilization method in the first embodiment of the present invention uses the aqueous solution (X1) shown below (hereinafter also referred to as "sterilizing liquid (X1)").

[0015] [Sterilizing liquid (X1)] The sterilizing solution (X1) contains the following components (A1) and (B1), and water. The sterilizing solution (X1) may further contain the component (C) shown below in addition to the component (A1), the component (B1), and water. The sterilizing solution (X1) may further contain, in addition to the components (A1), (B1) and water, any optional components other than the components (A1), (B1), (C) and water, as long as the invention is not impaired.

[0016] "Component (A1)" The component (A1) is one or more anionic surfactants selected from alkyl sulfates, alkylbenzenesulfonates, alkanesulfonates, and olefinsulfonates. The disinfectant solution (X1) contains the component (A1), and when used with the component (B1) described below, it has a sprout-killing effect.

[0017] Examples of salt forms of component (A1) include alkali metal salts such as sodium salts and potassium salts; alkaline earth metal salts such as magnesium salts and calcium salts; and alkanolamine salts such as monoethanolamine salts (monoethanolammonium salts), diethanolamine salts (diethanolammonium salts), and triethanolamine salts (triethanolammonium salts). Of these, alkali metal salts are preferred, sodium salts and potassium salts are more preferred, and sodium salts are even more preferred. The component (A1) may be used alone or in combination of two or more. As the component (A1), from the viewpoint of having a higher sprouticidal effect, alkyl sulfates, alkyl benzene sulfonates, and alkyl sulfonates are preferred, alkyl sulfates and alkyl benzene sulfonates are more preferred, and alkyl sulfates are even more preferred.

[0018] In the alkyl sulfate, the number of carbon atoms in the alkyl group is preferably 10 to 14. As the alkyl sulfate, lauryl sulfate is preferred, and sodium lauryl sulfate is more preferred.

[0019] In the alkylbenzenesulfonate, the alkyl group bonded to the benzene ring preferably has 8 to 24 carbon atoms, more preferably 8 to 16 carbon atoms, and even more preferably 10 to 14 carbon atoms. The alkyl group bonded to the benzene ring may be linear or branched, but is preferably linear. That is, the alkylbenzenesulfonate is preferably linear alkylbenzenesulfonate.

[0020] In the alkanesulfonate, the number of carbon atoms is preferably 8 to 24, more preferably 10 to 20, and even more preferably 14 to 17. The alkane sulfonic acid is preferably a secondary alkane sulfonate. The olefin sulfonate is preferably an α-olefin sulfonate. In the α-olefin sulfonate, the alkyl group preferably has 8 to 24 carbon atoms, more preferably 10 to 20 carbon atoms, and even more preferably 14 to 17 carbon atoms.

[0021] The content of the component (A1) is 0.001 to 1 mass% relative to the total mass of the disinfectant solution (X1), preferably 0.005 to 1 mass%, more preferably 0.01 to 1 mass%, and even more preferably 0.1 to 1 mass%. When the content of the component (A1) is equal to or greater than the lower limit, a sufficient germination effect can be obtained. Even if the content of the component (A1) exceeds the upper limit, the effect of the component (A1) reaches a plateau.

[0022] "(B1) Component" The component (B1) is at least one selected from organic acids and inorganic acids. The inclusion of component (B1) in the disinfectant solution (X1) lowers the pH of the disinfectant solution (X1), and when used in combination with component (A1), a germination effect is obtained. The component (B1) may be used alone or in appropriate combination of two or more types. As the component (B1), only an inorganic acid may be used, only an organic acid may be used, or an inorganic acid and an organic acid may be used in combination. The dissociation constant (pKa) of the organic acid is preferably 4.8 or less, more preferably 3.7 or less. The dissociation constant (pKa) of the inorganic acid is preferably 3.0 or less, more preferably 2.2 or less.

[0023] In this specification, pKa refers to the pKa at 25°C, and for acids with multiple pKa values, it refers to the lowest pKa. For example, phosphoric acid is a trivalent acid and has pKa1, pKa2, and pKa3. For example, in the present invention, the pKa of phosphoric acid is pKa1 = 2.2 (25°C). The pKa values ​​are those listed in the Basic Chemistry Handbook, 3rd Revised Edition, edited by the Chemical Society of Japan (published by Maruzen Co., Ltd.). The pKa can also be determined by preparing an aqueous solution with an ionic strength of 0.1 mol / L using ultrapure water substituted with nitrogen at 25°C, and measuring this aqueous solution using a potentiometric titrator such as COM-2500 (manufactured by Hiranuma Sangyo Co., Ltd.) or AT-510 (manufactured by Kyoto Electronics Manufacturing Co., Ltd.).

[0024] Examples of organic acids include citric acid (pKa=2.90) and its hydrate, malic acid (pKa=3.23) and its hydrate, lactic acid (pKa=3.64) and its hydrate, tartaric acid (pKa=2.87 and its hydrate), fumaric acid (pKa=3.07) and its hydrate, succinic acid (pKa=3.99) and its hydrate, acetic acid (pKa=4.76) and its hydrate, and adipic acid. Examples of such hydrates include carboxylic acid (pKa=4.26) and its hydrate, phthalic acid (pKa=2.75) and its hydrate, itaconic acid (pKa=3.85) and its hydrate, glycine (pKa=2.91) and its hydrate, salicylic acid (pKa=2.78) and its hydrate, ascorbic acid (pKa=4.04) and its hydrate, and linear alkylbenzenesulfonic acid and its hydrate. Examples of inorganic acids include hydrochloric acid (pKa=-5.9) and its hydrates, sulfuric acid (pKa=-3.29) and its hydrates, phosphoric acid (pKa=2.2) and its hydrates, nitric acid (pKa=-1.43) and its hydrates, and boric acid (pKa=9.24) and its hydrates.

[0025] As the component (B1), from the viewpoint of further enhancing metal corrosion prevention properties and facilitating the preparation of the disinfectant composition (U1) described below, phosphoric acid and its hydrates, and organic acids and their hydrates are preferred, phosphoric acid and its hydrates, citric acid and its hydrates, malic acid and its hydrates, lactic acid and its hydrates, and linear alkylbenzenesulfonic acid and its hydrates are more preferred, phosphoric acid and its hydrates, citric acid and its hydrates, malic acid and its hydrates, and lactic acid and its hydrates are even more preferred, phosphoric acid and its hydrates, and citric acid and its hydrates are particularly preferred, and citric acid and its hydrates are most preferred.

[0026] The content of component (B1) is 0.001 to 5% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.1 to 1% by mass, relative to the total mass of the sterilizing solution (X1). When the content of component (B1) is equal to or greater than the lower limit, the sterilization method of the present invention can achieve a germination effect when used with component (A1). When the content of component (B1) exceeds the upper limit, the effect of component (B1) reaches a plateau.

[0027] In the disinfectant solution (X1), the mass ratio of the (B1) component to the (A1) component, expressed as (B1) component / (A1) component (hereinafter also referred to as the "B1 / A1 ratio"), is preferably 1 to 500, more preferably 1 to 20. When the B1 / A1 ratio is equal to or greater than the above lower limit, the pH is stable and a sufficient germination effect can be obtained. When the B1 / A1 ratio exceeds the above upper limit, the effect of (B1) reaches a plateau.

[0028] The total content of the components (A1) and (B1) is preferably 0.02 to 6% by mass, more preferably 0.1 to 1% by mass, based on the total mass of the sterilizing solution (X1). A sufficient germination effect can be obtained when the total content of the components (A1) and (B1) is equal to or greater than the lower limit. Even if the total content of the components (A1) and (B1) exceeds the upper limit, the effect of the components (A1) and (B1) reaches a plateau.

[0029] "(C) Component" Component (C) is a hypochlorite. The germicidal effect can be further enhanced by the inclusion of component (C) in the germicidal solution (X1).

[0030] Examples of salt forms of component (C) include alkali metal salts such as sodium salts and potassium salts; alkaline earth metal salts such as magnesium salts and calcium salts; and alkanolamine salts such as monoethanolamine salts (monoethanolammonium salts), diethanolamine salts (diethanolammonium salts), and triethanolamine salts (triethanolammonium salts). Of these, alkali metal salts are preferred, sodium salts and potassium salts are more preferred, and sodium salts are even more preferred.

[0031] The content of the component (C) optionally contained in the sterilizing solution (X1) is 0.001% by mass or less, preferably 0% by mass, of the total mass of the sterilizing solution (X1) in terms of available chlorine concentration. That is, it is preferable that the sterilizing solution (X1) does not contain the component (C). When the content of the component (C) is within the above range, spore-forming bacteria can be easily sterilized while suppressing deterioration of the object to be sterilized. In this specification, hypochlorous acid (HClO) and hypochlorite ion (ClO ― ), and chlorine (Cl2) are collectively called "available chlorine," and the concentration of available chlorine in an aqueous solution is also called "available chlorine concentration."

[0032] The available chlorine concentration in the sterilizing solution (X1) is preferably 0.001% by mass or less, more preferably 0% by mass, based on the total mass of the sterilizing solution (X1).

[0033] "water" Examples of water include sterilized water, distilled water, ion-exchanged water, ultrapure water, and tap water. Among these, sterilized water, ultrapure water, ion-exchanged water, and distilled water are preferred from the viewpoint of not interfering with sterilization, and sterilized water is more preferred. The water content is preferably 90.0 to 99.99% by mass, more preferably 94.0 to 99.98% by mass, and even more preferably 99.97 to 99.98% by mass, based on the total mass of the sterilizing solution (X1). When the water content is equal to or greater than the lower limit, the components (A1), (B1), and (C) can be dissolved. When the water content is equal to or less than the upper limit, the sterilizing solution (X1) can contain the necessary amounts of the components (A1), (B1), and (C).

[0034] "Optional ingredients" The optional components are not particularly limited as long as they are components used in disinfectants, and examples thereof include surfactants other than component (A1) (hereinafter also referred to as "optional surfactants"), organic solvents (hereinafter also referred to as "component (D)"), hydrogen peroxide, colorants, antifoaming agents, fragrances, etc.

[0035] (Optional surfactant) Examples of optional surfactants include anionic surfactants other than component (A1), cationic surfactants, and nonionic surfactant preparations. Examples of anionic surfactants other than component (A1) include alkyl ether sulfates or salts thereof, alkenyl ether sulfates or salts thereof, and higher fatty acids or salts thereof. Higher fatty acids are saturated fatty acids having 8 to 24 carbon atoms and unsaturated fatty acids having 8 to 24 carbon atoms. Examples of higher fatty acids or salts thereof include single fatty acids or salts thereof such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, hydroxystearic acid, oleic acid, and behenic acid; mixed fatty acids or salts thereof such as coconut fatty acid and beef tallow fatty acid; and the like. Examples of salt forms of higher fatty acids include alkali metal salts such as sodium salts and potassium salts; alkaline earth metal salts such as magnesium salts and calcium salts; and alkanolamine salts such as monoethanolamine salts (monoethanolammonium salts), diethanolamine salts (diethanolammonium salts), and triethanolamine salts (triethanolammonium salts). Among these, alkali metal salts are preferred, sodium salts and potassium salts are more preferred, and sodium salts are even more preferred. The higher fatty acid or salt thereof may be used alone or in combination of two or more. Examples of cationic surfactants include didecyl dimethyl ammonium chloride, didecyl dimethyl ammonium methosulfate, distearyl dimethyl ammonium chloride, dioctyl dimethyl ammonium chloride, distearyl dihydroxyethyl ammonium chloride, di-tallow alkyl dimethyl ammonium chloride, di(stearoyloxyethyl) dimethyl ammonium chloride, di(oleoyloxyethyl) dimethyl ammonium chloride, di(palmitoyloxyethyl) dimethyl ammonium methosulfate, di(stearoyloxyisopropyl) dimethyl ammonium chloride, di(oleoyloxyisopropyl) dimethyl ammonium chloride, di(oleoyloxybutyl) dimethyl ammonium chloride, di(stearoyloxyethyl) methyl hydroxyethyl ammonium methosulfate, and tri(stearoyloxyethyl) methyl methosulfate. The "tallow alkyl" group has 14 to 18 carbon atoms. The cationic surfactant may be used alone or in appropriate combination of two or more kinds. Examples of nonionic surfactants include polyoxyalkylene alkyl ethers and alkyl polyglycosides. The nonionic surfactants may be used singly or in appropriate combination of two or more.

[0036] The content of the optional surfactant is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and even more preferably substantially free of the optional surfactant, relative to the total mass of the sterilizing solution (X1). In this specification, "substantially free of the optional surfactant" means that the optional surfactant is not intentionally blended, except for those that are unintentionally contained.

[0037] ((D) component) (X1) can be prepared, for example, by diluting the disinfectant composition (U1) described below. The disinfectant solution (X1) containing (D) is obtained by diluting the disinfectant composition (U1) containing (D). When the disinfectant composition (U1) contains the component (D), the liquid stability of the disinfectant composition (U1) when stored at low temperatures (for example, 10°C or lower) (hereinafter also referred to as "low-temperature stability") can be improved. The component (D) is preferably a water-soluble base, and examples thereof include monohydric alcohols having 1 to 6 carbon atoms, such as ethanol and methanol, and polyhydric alcohols, such as ethylene glycol, propylene glycol, and glycerin. Among these, from the viewpoint of easy preparation of the disinfectant composition (U1), ethanol, ethylene glycol and diethylene glycol are preferred, and ethanol is more preferred. The component (D) may be used alone or in appropriate combination of two or more types.

[0038] The content of component (D) is preferably 0.01 to 5 mass%, more preferably 0.02 to 0.2 mass%, and even more preferably 0.02 to 0.1 mass%, relative to the total mass of the sterilizing solution (X1). When the content of component (D) is equal to or greater than the above-mentioned lower limit, the stability of the sterilizing composition (U1) can be improved. When the content of component (D) is equal to or less than the above-mentioned upper limit, component (D) does not affect the germination effect of the sterilizing solution (X1).

[0039] (hydrogen peroxide) When the disinfectant solution (X1) contains hydrogen peroxide, the germicidal effect of the components (A1) and (B1) can be further enhanced. The content of hydrogen peroxide is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.1 to 3% by mass, relative to the total mass of the sterilizing solution (X1). When the content of hydrogen peroxide is equal to or greater than the lower limit, the effect of hydrogen peroxide can be fully exerted. When the content of hydrogen peroxide exceeds the upper limit, the effect of hydrogen peroxide reaches a plateau.

[0040] (dye) The dye is preferably a base that changes color when the pH of the solution at 25°C increases to 5 or higher. Examples include bromophenol blue (pKa = 3.85), bromocresol green (pKa = 4.76), and methyl red (pKa = 5.00), which are used as pH indicators with a dissociation constant (pKa) of 3.0 to 5.0 at 25°C. Other dyes besides these pH indicators include anthocyanin dyes such as red radish dye and red cabbage dye, cochineal dye, and flavonoids. When the sterilizing solution (X1) contains such a pigment, the color of the sterilizing solution (X1) changes when the pH of the sterilizing solution (X1) becomes 5.0 or higher during germination by the sterilization method of the present invention, making it easy to visually grasp the change in pH. Note that if the pH value of the sterilizing solution (X1) changes to 5.0 or higher, the pH can be lowered by adding component (B1) to the sterilizing solution (X1). The dyes may be used singly or in appropriate combination of two or more. As the pigment, bromophenol blue and anthocyanin pigment are preferred, and bromophenol blue is more preferred.

[0041] The content of the dye is preferably 0.0001 to 0.5% by mass, more preferably 0.001 to 0.05% by mass, and even more preferably 0.001 to 0.01% by mass, relative to the total mass of the sterilizing solution (X1). If the content of the dye is equal to or greater than the lower limit, the change in color tone of the sterilizing solution (X1) can be adequately grasped. If the content of the dye exceeds the upper limit, the effect of the dye reaches a plateau.

[0042] (Antifoaming agent) When the sterilizing solution (X1) contains the component (C), as the pH of the sterilizing solution (X1) decreases, chlorine gas tends to be generated more easily, and the sterilizing solution becomes more likely to foam. By including an antifoaming agent in the sterilizing solution (X1), foaming of the sterilizing solution (X1) can be suppressed. The antifoaming agent is not particularly limited, and any of the general antifoaming agents used in conventional disinfectants can be used. The antifoaming agent is not particularly limited and may be an oil type, a compound type, a self-emulsifying compound type, a powder type, or the like. Examples include dispersions or emulsions of polyorganosiloxane oils or resins such as polydimethylsiloxane, and combinations of polyorganosiloxanes in which polyorganosiloxanes are chemically adsorbed or melted onto silica and silica particles. The antifoaming agent may be used alone or in a suitable combination of two or more kinds. The content of the antifoaming agent is preferably 0.00001 to 0.1 mass% relative to the total mass of the sterilizing solution (X1), more preferably 0.0001 to 0.01 mass%, and even more preferably 0.001 to 0.01 mass%. When the content of the antifoaming agent is equal to or greater than the above lower limit, foaming of the sterilizing solution (X1) can be sufficiently suppressed. When the content of the antifoaming agent is equal to or less than the above upper limit, foaming of the sterilizing solution (X1) can be suppressed without an excessive amount.

[0043] (fragrance) The fragrance may be a fragrance raw material alone or a fragrance composition comprising a fragrance raw material, a fragrance solvent, a fragrance stabilizer, etc. Alternatively, a capsule fragrance in which a fragrance is encapsulated may be blended. The fragrance may be used alone or in combination of two or more kinds. The content of the fragrance is preferably 0.0001 to 0.1% by mass, more preferably 0.0001 to 0.01% by mass, and even more preferably 0.001% by mass, relative to the total mass of the sterilizing solution (X1). If the fragrance is at or above the lower limit, the fragrance can be felt. If the fragrance exceeds the upper limit, the effect of the fragrance will plateau.

[0044] The total content of all components contained in the sterilizing liquid (X1) is 100% by mass.

[0045] "pH" The lower limit of the pH of the sterilizing solution (X1) at 25°C is 1.5 or more, preferably 2 or more, and more preferably 2.1 or more. If the pH of the sterilizing solution (X1) at 25°C is the above-mentioned lower limit or more, deterioration of the object to be sterilized can be suppressed. The upper limit of the pH of the sterilizing solution (X1) at 25°C is less than 5, preferably 4 or less, and more preferably 3.3 or less. If the pH of the sterilizing solution (X1) at 25°C is the above upper limit or less, the sterilizing solution (X1) will exhibit a sufficient germination effect. The lower and upper limits of the pH of the sterilizing solution (X1) at 25° C. can be combined in any way. For example, the lower and upper limits of the pH of the sterilizing solution (X1) at 25° C. are 1.5 or more and less than 5, preferably 2 to 4, and more preferably 2.1 to 3.3. The pH (25°C) of the liquid detergent composition is a value measured by a method in accordance with JIS Z 8802:2011 "pH measurement method."

[0046] "Manufacturing method" The sterilizing liquid (X1) can be produced by a conventionally known method for producing a liquid composition. The sterilizing solution (X1) can be produced, for example, by dissolving each component in a portion of water and adding the remainder of the water to make the total amount 100% by mass. Alternatively, the disinfectant composition (U1) shown below can also be prepared by diluting it. The dilution ratio of the disinfectant solution (X1) (volume of water / disinfectant composition (U1)) is preferably 10 to 2000 times, more preferably 100 to 500 times, from the viewpoints of obtaining the minimum concentration of each component required for the disinfectant solution (X1) to exhibit a germicidal effect and ensuring the stability of the disinfectant solution (X1) even if the concentration of each component in the composition increases.

[0047] [Fungicide composition (U1)] The fungicide composition (U1) contains the component (A1) and the component (B1). The fungicide composition (U1) may further contain a component (C) in addition to the components (A1) and (B1). The fungicide composition (U1) may further contain water in addition to the components (A1) and (B1). The fungicide composition (U1) may further contain, in addition to the components (A1) and (B1), optional components other than the components (A1), (B1), and (C), as necessary, within the scope of the present invention.

[0048] The content of the component (A1) is preferably 1 to 20 mass% and more preferably 5 to 10 mass% based on the total mass of the disinfectant composition (U1). If the content of the component (A1) is equal to or greater than the above lower limit, the dilution rate during use increases, and the total mass of the disinfectant composition (U1) required to prepare the disinfectant solution (X1) can be reduced. If the content of the component (A1) is equal to or less than the above upper limit, the disinfectant composition (U1) can be easily prepared and the low-temperature stability of the disinfectant composition (U1) can be improved.

[0049] The content of the component (B1) is preferably 10 to 70% by mass, more preferably 10 to 45% by mass, and even more preferably 10 to 40% by mass, based on the total mass of the disinfectant composition (U1). If the content of the component (B1) is equal to or greater than the above-mentioned lower limit, the dilution rate during use increases, and the total mass of the disinfectant composition (U1) required to prepare the disinfectant solution (X1) can be reduced. If the content of the component (B1) is equal to or less than the above-mentioned upper limit, the disinfectant composition (U1) can be easily prepared.

[0050] The content of the component (C) optionally contained in the disinfectant composition (U1) is preferably 1 mass% or less, more preferably 0.25 mass% or less, and even more preferably 0 mass% in terms of available chlorine concentration relative to the total mass of the disinfectant composition (U1). That is, the disinfectant composition (U1) preferably does not contain the component (C). When the content of the component (C) is not more than the above upper limit, the disinfectant composition (U1) can be easily handled.

[0051] The concentration of available chlorine in the disinfectant composition (U1) is preferably 1% by mass or less, more preferably 0.25% by mass or less, and even more preferably 0% by mass, based on the total mass of the disinfectant composition (U1).

[0052] The content of the optional surfactant is preferably 10% by mass or less, more preferably 1% by mass or less, based on the total mass of the disinfectant composition (U1), and even more preferably substantially none.

[0053] The content of component (D) is preferably 5 to 60 mass%, more preferably 5 to 50 mass%, and even more preferably 5 to 40 mass%, relative to the total mass of the disinfectant composition (U1). When the content of component (D) is at least the above lower limit, the low-temperature stability of the disinfectant composition (U1) can be improved. When the content of component (D) is at most the above upper limit, the total mass of the disinfectant composition (U1) required to prepare the disinfectant solution (X1) can be reduced.

[0054] The total content of components (A1), (B1), (C), and (D) is preferably 10% by mass or more, more preferably 50% by mass or more, and even more preferably 97% by mass or more, based on the total mass of the fungicide composition (U1). The total content of components (A1), (B1), (C), and (D) may be 100% by mass, based on the total mass of the fungicide composition (U1). When the total content of components (A1), (B1), (C), and (D) is within the above range, the water content in the fungicide composition (U1) is reduced, thereby suppressing hydrolysis of component (A1) (especially sodium lauryl sulfate).

[0055] The content of hydrogen peroxide is preferably 0.1 to 25% by mass, more preferably 1 to 20% by mass, and even more preferably 3 to 15% by mass, based on the total mass of the disinfectant composition (U1). When the content of hydrogen peroxide is equal to or greater than the above lower limit, the effect of hydrogen peroxide can be fully exerted. When the content of hydrogen peroxide is equal to or less than the above upper limit, it is easy to incorporate hydrogen peroxide into the disinfectant composition (U1).

[0056] The content of the dye is preferably 0.001 to 5 mass%, more preferably 0.005 to 1 mass%, and even more preferably 0.01 to 0.5 mass%, relative to the total mass of the disinfectant composition (U1). If the content of the dye is equal to or greater than the lower limit, it is possible to grasp the change in color tone of the disinfectant solution (X1) obtained by diluting the disinfectant composition (U1) even if the pH of the disinfectant solution (X1) changes to 5 or higher. If the content of the dye exceeds the upper limit, the effect of the dye reaches a plateau.

[0057] The content of the antifoaming agent is preferably 0.0001% by mass to 1% by mass, more preferably 0.001% by mass to 0.1% by mass, based on the total mass of the disinfectant composition (U1). When the content of the antifoaming agent is equal to or greater than the above lower limit, foaming of the disinfectant composition (U1) can be sufficiently suppressed. When the content of the antifoaming agent is equal to or less than the above upper limit, low-temperature stability of the disinfectant composition (U1) can be improved.

[0058] The content of the fragrance is preferably 0.001 to 5% by mass, more preferably 0.01 to 1% by mass, and even more preferably 0.1 to 1% by mass, based on the total mass of the fungicide composition (U1). If the content of the fragrance is equal to or greater than the lower limit, the fragrance can be felt. If the content of the fragrance exceeds the upper limit, the effect of the fragrance will plateau.

[0059] The water content is preferably 90% by mass or less, more preferably 50% by mass or less, and even more preferably 3% by mass or less, based on the total mass of the disinfectant composition (U1). Furthermore, the water content may be 0% based on the total mass of the disinfectant composition (U1). When the water content is equal to or less than the upper limit, hydrolysis of the (A1) component (especially sodium lauryl sulfate) can be suppressed.

[0060] The total content of all components contained in the fungicide composition (U1) is 100% by mass.

[0061] "Manufacturing method" The fungicide composition (U1) can be produced by a conventionally known method for producing a liquid composition. The fungicide composition (U1) can be produced, for example, by dissolving the components other than component (D) in a portion of component (D), and adding the remainder of component (D) to make the total amount 100% by mass. Alternatively, each component may be dissolved in a portion of water, and the remainder of the water may be added to make the total amount 100% by mass.

[0062] [How to use] In the sterilization method in the first embodiment, a sterilizing liquid (X1) heated to the temperature shown below is brought into contact with spore-forming bacteria to exert a germination effect. The lower limit of the temperature of the heated sterilizing liquid (X1) is 50° C. or higher, preferably 60° C. or higher. If the temperature of the sterilizing liquid (X1) is the above lower limit or higher, a sufficient germination effect can be obtained. The upper limit of the temperature of the heated sterilizing liquid (X1) is not more than 100° C., and preferably not more than 80° C. If the temperature of the sterilizing liquid (X1) is not more than the above upper limit, germination can be easily performed without requiring equipment with high heating capacity (for example, an autoclave), and the range of use of the sterilization method in the first embodiment can be expanded. The lower limit and upper limit of the temperature of the heated sterilizing liquid (X1) can be arbitrarily combined. For example, the temperature of the sterilizing liquid (X1) is 50 to 100°C, preferably 60 to 80°C.

[0063] The lower limit of the contact time between the spore-forming bacteria and the heated sterilizing solution (X1) is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more. If the contact time is equal to or longer than the above lower limit, the sterilizing effect of the sterilization method in the first embodiment can be further improved. The upper limit of the contact time between the spore-forming bacteria and the heated sterilizing solution (X1) is preferably 24 hours or less, more preferably 12 hours or less, even more preferably 6 hours or less, particularly preferably 3 hours or less, and even particularly preferably 60 minutes or less. If the contact time is equal to or less than the above upper limit, the energy required to heat the sterilizing solution (X1) can be further reduced, and the range of applicable objects to be sterilized can be expanded.

[0064] The lower and upper limits of the contact time between the spore-forming bacteria and the heated sterilizing solution (X1) can be arbitrarily combined. For example, the contact time is preferably 1 minute to 24 hours, more preferably 5 minutes to 12 hours, even more preferably 5 minutes to 6 hours, and particularly preferably 10 to 60 minutes.

[0065] An example of a method for contacting spore-forming bacteria with a heated sterilizing solution (X1) is to add the heated sterilizing solution (X1) to a washing machine and wash or rinse the object to be sterilized (in-laundry sterilization method). In the in-laundry sterilization method, examples of the object to be sterilized include a washing machine and items to be washed, such as textile products. Alternatively, there may be mentioned a method of immersing the object to be sterilized in heated sterilizing liquid (X1) (immersion method), a method of spraying heated sterilizing liquid (X1) onto the object to be sterilized with a spray or the like, and the like. Specifically, methods include disassembling the washing machine and individually immersing the pipes, valves, etc., or spraying them with a spray, etc. Furthermore, dishwashers and manufacturing equipment for food and cosmetics, etc. can also be sterilized in the same way as washing machines.

[0066] With regard to the pH of the sterilizing solution (X1), if the pH range of the sterilizing solution (X1) at 25°C is 1.5 or more and less than 5, the pH of the heated sterilizing solution (X1) can also be maintained at 1.5 or more and less than 5. Therefore, the above sterilization method can easily sterilize spore-forming bacteria while suppressing deterioration of the object to be sterilized.

[0067] [Action and effect] The sterilization method in the first embodiment can easily kill germs while suppressing deterioration of the object to be sterilized. The effect of the present invention is not certain, but is presumed as follows. By using the component (A1) in the sterilization method of the first embodiment, spore-forming bacteria can be killed. This is thought to be because the protein denaturing effect of the component (A1) acts on spore-forming bacteria. Furthermore, by using the component (B1) in the sterilization method of the first embodiment, the pH of the sterilizing solution (X1) tends to fall within the above range, thereby enhancing the germination effect of the component (A1). This is thought to be because the component (B1) lowers the pH of the sterilizing solution (X1), thereby increasing the adsorption of the component (A1) to spore-forming bacteria and enhancing the protein denaturing effect of the component (A1). The sterilizing effect can be enhanced by increasing the temperature of the sterilizing solution (X1) at the time of contact with spore-forming bacteria to above the above lower limit. This is thought to be because the increase in temperature destabilizes the three-dimensional structure of proteins and increases the reactivity of chemical reactions, thereby enhancing the protein denaturing effect. The sterilizing solution (X1) used in the first embodiment does not contain the component (C) or contains the component (C) within the above range, thereby suppressing deterioration of the object to be sterilized and making the sterilizing solution (X1) easy to handle. Furthermore, since the temperature of the heated sterilizing solution (X1) is below the above upper limit, no equipment with high heating capacity, such as an autoclave, is required. Therefore, the sterilization method in the first embodiment allows for simple sterilization.

[0068] Second Embodiment The sterilization method in the second embodiment of the present invention uses the aqueous solution (X2) (hereinafter also referred to as "sterilizing liquid (X2)") shown below.

[0069] [Sterilizing liquid (X2)] The sterilizing solution (X2) contains the following component (A2) and water. The sterilizing solution (X2) may further contain, in addition to the component (A2) and water, a component (C). In the second embodiment, the water and the component (C) are the same as those in the first embodiment. The sterilizing solution (X1) may, in addition to the component (A2) and water, optionally contain any other component other than the component (A2), the component (C), and water, as long as it does not impair the scope of the present invention.

[0070] "(A2) Component" The component (A2) is an alkylbenzenesulfonic acid. The disinfectant solution (X2) contains the component (A2), which provides a germicidal effect. In the alkylbenzenesulfonic acid, the alkyl group bonded to the benzene ring preferably has 8 to 24 carbon atoms, more preferably 8 to 16 carbon atoms, and even more preferably 10 to 14 carbon atoms. The alkyl group bonded to the benzene ring may be linear or branched, but is preferably linear, i.e., the alkylbenzenesulfonic acid is preferably linear alkylbenzenesulfonic acid.

[0071] The content of component (A2) is 0.002 to 6 mass% relative to the total mass of the disinfectant solution (X2), preferably 0.015 to 6 mass%, more preferably 0.02 to 2 mass%, even more preferably 0.03 to 1.5 mass%, and particularly preferably 0.1 to 0.5 mass%. A sufficient germination effect can be obtained when the content of component (A2) is equal to or greater than the above-mentioned lower limit. Even if the content of component (A2) exceeds the above-mentioned upper limit, the effect of component (A2) reaches a plateau.

[0072] The content of the component (C) optionally contained in the sterilizing solution (X2) is 0.001% by mass or less, preferably 0% by mass, of the total mass of the sterilizing solution (X2) in terms of available chlorine concentration. That is, it is preferable that the sterilizing solution (X2) does not contain the component (C). If the content of the component (C) is within the above range, spore-forming bacteria can be easily sterilized while suppressing deterioration of the object to be sterilized.

[0073] The available chlorine concentration in the sterilizing liquid (X2) is preferably 0.001% by mass or less, more preferably 0% by mass, based on the total mass of the sterilizing liquid (X2).

[0074] The water content is preferably 90.0 to 99.98% by mass, more preferably 94.0 to 99.98% by mass, and even more preferably 99.0 to 99.98% by mass, based on the total mass of the sterilizing solution (X2). When the water content is equal to or greater than the lower limit, the components (A2), (B2), and (C) can be dissolved. When the water content is equal to or less than the upper limit, the sterilizing solution (X2) can contain the required amounts of the components (A2), (B2), and (C).

[0075] "Optional ingredients" The optional components are not particularly limited as long as they are components used in disinfectants. For example, in addition to the same components as the optional components of the sterilizing solution (X1) of the first embodiment, the optional components include component (A1) and the component (B2) shown below. Note that the component (A1) and optional surfactant in the sterilizing solution (X2) are the same as the component (A1) and optional surfactant in the sterilizing solution (X1), respectively.

[0076] ((B2) component) The component (B2) is an organic acid or an inorganic acid other than the component (A2). Except for the component (A2), the preferred types of organic acids and inorganic acids and the reasons why they are preferred are the same as the preferred types of component (B1) and the reasons why they are preferred described in the first embodiment.

[0077] When the sterilizing solution (X2) contains the component (A1), the total content of the components (A1) and (A2) is preferably 0.002 to 6 mass%, more preferably 0.015 to 6 mass%, even more preferably 0.02 to 2 mass%, particularly preferably 0.03 to 1.5 mass%, and even more particularly preferably 0.1 to 0.5 mass%, relative to the total mass of the sterilizing solution (X2).

[0078] When the sterilizing solution (X2) contains the component (B2), the total content of the components (A2) and (B2) is preferably 0.002 to 6 mass%, more preferably 0.015 to 6 mass%, even more preferably 0.02 to 2 mass%, particularly preferably 0.03 to 1.5 mass%, and even more particularly preferably 0.1 to 0.5 mass%, relative to the total mass of the sterilizing solution (X2).

[0079] When the sterilizing solution (X2) simultaneously contains the component (A1) and the component (B2), the total content of the component (A1), the component (A2), and the component (B2) is preferably 0.002 to 6 mass%, more preferably 0.015 to 6 mass%, even more preferably 0.02 to 2 mass%, particularly preferably 0.03 to 1.5 mass%, and even particularly preferably 0.1 to 0.5 mass%, relative to the total mass of the sterilizing solution (X2).

[0080] The preferred ranges of the contents of the optional surfactant, component (D), hydrogen peroxide, colorant, antifoaming agent, and fragrance in the sterilizing liquid (X2) and the reasons for these preferred ranges are the same as the preferred ranges of the contents of the optional surfactant, component (D), hydrogen peroxide, colorant, antifoaming agent, and fragrance in the sterilizing liquid (X1) in the first embodiment and the reasons for these preferred ranges, respectively.

[0081] The total content of all components contained in the sterilizing liquid (X2) is 100% by mass.

[0082] The pH of the sterilizing solution (X2) at 25° C. is 1.5 or higher, preferably 2 or higher, and more preferably 2.1 or higher. If the pH of the sterilizing solution (X2) at 25° C. is equal to or higher than the above lower limit, deterioration of the object to be sterilized can be suppressed. The pH of the sterilizing solution (X2) at 25°C is less than 5, preferably 4 or less, and more preferably 3.3 or less. If the pH of the sterilizing solution (X2) at 25°C is the above upper limit or less, the sterilizing solution (X2) can obtain a germination effect. The lower and upper limits of the pH of the sterilizing solution (X1) at 25° C. can be combined in any way. For example, the lower and upper limits of the pH of the sterilizing solution (X1) at 25° C. are 1.5 or more and less than 5, preferably 2 to 4, and more preferably 2.1 to 3.3.

[0083] "Manufacturing method" The sterilizing liquid (X2) can be produced by a conventionally known method for producing a liquid composition. The sterilizing solution (X2) can be produced, for example, by dissolving each component in a portion of water and adding the remainder of the water to make the total amount 100% by mass. Alternatively, the disinfectant composition (U2) shown below can also be prepared by diluting it. The dilution ratio of the disinfectant solution (X2) (volume of water / disinfectant composition (U2)) is preferably 100 to 5000 times, more preferably 200 to 1000 times, from the viewpoints of obtaining the minimum concentration of each component required for the disinfectant solution (X2) to exhibit a germicidal effect, and ensuring the stability of the disinfectant solution (X2) even if the concentration of each component in the composition increases.

[0084] [Fungicide composition (U2)] The fungicide composition (U2) contains the component (A2). The fungicide composition (U2) may further contain a component (C) in addition to the component (A2). The fungicide composition (U1) may further contain water in addition to the component (A2). The fungicide composition (U2) may further contain, in addition to the component (A2), optional components other than the component (A2), the component (C), and water, as needed, within the scope of the present invention.

[0085] The content of the component (A2) is preferably 1 to 99% by mass, more preferably 1 to 50% by mass, and even more preferably 3 to 30% by mass, based on the total mass of the disinfectant composition (U2). If the content of the component (A2) is equal to or greater than the above-mentioned lower limit, the dilution rate during use increases, and the total mass of the disinfectant composition (U2) required to prepare the disinfectant solution (X2) can be reduced. If the content of the component (A2) is equal to or less than the above-mentioned upper limit, the disinfectant composition (U2) can be easily prepared, and the low-temperature stability of the disinfectant composition (U2) can be improved.

[0086] The preferred ranges of the content and effective chlorine concentration of the component (C) optionally contained in the disinfectant composition (U2), and the reasons for these preferred ranges, are the same as the preferred ranges of the content and effective chlorine concentration of the component (C) optionally contained in the disinfectant composition (U1), and the reasons for these preferred ranges.

[0087] When the fungicide composition (U2) contains (A1), the total content of the components (A1) and (A2) is preferably 0.01 to 10 mass%, more preferably 0.1 to 3 mass%, and even more preferably 0.1 to 1 mass%, based on the total mass of the fungicide composition (U2).

[0088] When the fungicide composition (U2) contains (B2), the total content of the components (A2) and (B2) is preferably 0.1 to 40 mass%, more preferably 1 to 20 mass%, and even more preferably 3 to 10 mass%, based on the total mass of the fungicide composition (U2).

[0089] When the fungicide composition (U2) contains the components (A1) and (B2), the total content of the components (A1), (A2) and (B2) is preferably 1 to 99 mass%, more preferably 5 to 99 mass%, and even more preferably 10 to 60 mass%, based on the total mass of the fungicide composition (U2).

[0090] The preferred ranges of the contents of the optional surfactant, component (D), hydrogen peroxide, colorant, antifoaming agent, and fragrance in the disinfectant composition (U2) and the reasons for these preferred ranges are the same as the preferred ranges of the contents of the optional surfactant, component (D), hydrogen peroxide, colorant, antifoaming agent, and fragrance in the disinfectant composition (U1) in the first embodiment and the reasons for these preferred ranges, respectively.

[0091] When the disinfectant composition (U2) contains the component (A1), the total content of the components (A1), (A2), (B2), (C), and (D) is preferably 10% by mass or more, more preferably 50% by mass or more, and even more preferably 97% by mass or more, based on the total mass of the disinfectant composition (U2). The total content of the components (A1), (A2), (B2), (C), and (D) may be 100% by mass, based on the total mass of the disinfectant composition (U2). When the total content of the components (A1), (A2), (B2), (C), and (D) is within the above range, the water content in the disinfectant composition (U2) is reduced, thereby suppressing hydrolysis of the component (A1) (especially sodium lauryl sulfate).

[0092] When the disinfectant composition (U2) contains the component (A1), the water content is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, based on the total mass of the disinfectant composition (U2). The water content may be 0% based on the total mass of the disinfectant composition (U2). When the water content is less than the above upper limit, hydrolysis of the component (A1) (especially sodium lauryl sulfate) can be suppressed.

[0093] When the fungicide composition (U2) does not contain the component (A1), the total content of the components (A2), (B2), (C) and (D) is preferably 1 mass% or more, more preferably 5 mass% or more, and even more preferably 10 mass% or more, based on the total mass of the fungicide composition (U2).

[0094] When the disinfectant composition (U2) does not contain the component (A1), the water content is preferably 95% by mass or less, more preferably 80% by mass or less, and even more preferably 50% by mass or less, based on the total mass of the disinfectant composition (U2). The water content may be 0% by mass based on the total mass of the disinfectant composition (U1).

[0095] The total content of all components contained in the fungicide composition (U2) is 100% by mass.

[0096] "Manufacturing method" The fungicide composition (U2) can be produced by a conventionally known method for producing a liquid composition. The fungicide composition (U2) can be produced, for example, by dissolving the components other than component (D) in a portion of component (D) and adding the remainder of component (D) to make the total amount 100% by mass, or by dissolving the components in a portion of water and adding the remainder of the water to make the total amount 100% by mass.

[0097] [How to use] In the sterilization method in the second embodiment, the sterilizing liquid (X2) heated to the temperature shown below is brought into contact with spore-forming bacteria to exert a germination effect. The temperature of the heated sterilizing liquid (X2) and the reasons for the preferred temperature are the same as those for the temperature of the heated sterilizing liquid (X1) in the sterilization method of the first embodiment and the reasons for the preferred temperature. The preferred contact time between the spore-forming bacteria and the heated sterilizing liquid (X2) and the reasons for the preferred contact time are the same as the preferred contact time between the spore-forming bacteria and the sterilizing liquid (X1) in the first embodiment and the reasons for the preferred contact time.

[0098] The method for bringing the sterilizing liquid (X2) into contact with the spore-forming bacteria is the same as the method for bringing the sterilizing liquid (X1) into contact with the spore-forming bacteria in the first embodiment.

[0099] With regard to the pH of the sterilizing solution (X2), if the pH range of the sterilizing solution (X2) at 25°C is 1.5 or more and less than 5, the pH of the heated sterilizing solution (X2) can also be maintained at 1.5 or more and less than 5. Therefore, the above sterilization method can easily sterilize spore-forming bacteria while suppressing deterioration of the object to be sterilized.

[0100] [Action and effect] The sterilization method according to the second embodiment can easily kill spore-forming bacteria while suppressing deterioration of the object to be sterilized. Moreover, since the number of types of components essential to the composition of the sterilizing solution (X2) is fewer than that of the sterilizing solution (X1), the sterilization method according to the second embodiment can be said to be even easier to kill spore-forming bacteria than the first embodiment. The effect of the present invention is not certain, but is presumed as follows. The use of component (A2) in the sterilization method of the second embodiment can sterilize spore-forming bacteria. This is thought to be because the protein-denaturing effect of component (A2) acts on spore-forming bacteria. Furthermore, even without the need for component (B1) in the first embodiment, component (A2) makes it easier for the pH of the sterilizing solution (X2) to fall within the above range, which is thought to increase the adsorption of component (A2) to spore-forming bacteria and enhance the protein-denaturing effect of component (A2). By increasing the temperature of the sterilizing solution (X2) at the time of contact with spore-forming bacteria to above the lower limit, the sterilizing effect can be enhanced. This is thought to be because the increase in temperature destabilizes the three-dimensional structure of proteins and increases the reactivity of chemical reactions, thereby enhancing the protein denaturing effect. The sterilizing solution (X2) used in the second embodiment does not contain the component (C) or contains the component (C) within the above range, thereby suppressing deterioration of the object to be sterilized and making the sterilizing solution (X2) easy to handle. Furthermore, since the temperature of the heated sterilizing solution (X2) is below the above upper limit, equipment with high heating capacity such as an autoclave is not required. Therefore, the sterilization method in the second embodiment can easily kill germs. [Example]

[0101] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following descriptions. The amounts of components used in each example are pure amounts unless otherwise specified.

[0102] "Raw materials used" The compound shown below was used as the component (A1). A1-1: Sodium lauryl sulfate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). A1-2: Sodium linear alkylbenzene sulfonate (manufactured by Fujifilm Wako Pure Chemical Industries, a compound with a molecular weight of 340-350). A1-3: Sodium lauryl sulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0103] The compound shown below was used as component (A2). A2-1: Linear alkylbenzene sulfonic acid (manufactured by Lion Specialty Chemicals Co., Ltd., trade name "Lipon (registered trademark) LH-200", a mixture of linear alkyls with 12 to 14 carbon atoms).

[0104] The compound shown below was used as a comparative product (component (A')) for components (A1) and (A2). A'-1: Sodium polyoxyethylene lauryl ether sulfate (manufactured by Lion Specialty Chemicals Co., Ltd., trade name "Sunol LMT-1430", a compound with 3 moles of oxyethylene groups added). A'-2: Decaglycerin laurate (manufactured by Riken Vitamin Co., Ltd., trade name "Poem (registered trademark) J-0021").

[0105] The following compound was used as component (B1). B1-1: Citric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). · B1-2: Malic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). · B1-3: Lactic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). · B1-4: Phosphoric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). B1-5: Sulfuric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "1 mol / L sulfuric acid").

[0106] The compound shown below was used as component (B2). B2-1: Citric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0107] The following compounds were used as component (C). C-1: Sodium hypochlorite (manufactured by Nippon Garlic Co., Ltd., a compound with an effective chlorine concentration of 12% by mass).

[0108] The compounds shown below were used as optional components and water. ((D) component) D-1: Ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). D-2: Ethylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). D-3: Propylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). (water) Sterile water (water filtered using Merck's Milli-Q (registered trademark) filter, then autoclaved at 121°C for 20 minutes)

[0109] (pH measurement method) Each sample solution at 25°C was added to a 100 mL beaker, and the pH was measured using a pH meter (manufactured by Horiba Ltd., trade name "pH meter D-51").

[0110] (Preparation of spore suspension) Agar plates were prepared using 1 L of tryptic soy agar medium containing 1 L of 0.01 N hydrochloric acid containing 2.5 g of manganese chloride tetrahydrate, 25 g of magnesium sulfate heptahydrate, and 30 mg of iron(II) sulfate heptahydrate, and 1 L of 0.01 N hydrochloric acid containing 15 g of calcium chloride dihydrate. Bacillus subtilis NBRC3134 was inoculated and cultured at 37°C for 10 days. A portion of the grown colonies was suspended in sterile water and observed under a microscope to confirm the presence of spores. Sterile water was then added dropwise to the agar plate and stirred with a conical rod. The suspension was then placed in a centrifuge tube and centrifuged (5,000 rpm, 5 minutes, 4°C) to remove the supernatant. The precipitate was then suspended in sterile water and incubated at 80°C for 30 minutes to kill vegetative cells. After that, the addition of sterilized water and centrifugation were repeated twice in the same manner, and finally sterilized water was added to suspend the precipitate, thereby preparing a bacterial solution containing viable spores (hereinafter also referred to as "spore solution"). As other spore-forming bacteria, Bacillus cereus NBRC15305 or Geobacillus stearothermophilus NBRC13737 was used. They were cultured in the same manner as Bacillus subtilis NBRC3134, except that the culture temperature was 37°C for Bacillus cereus NBRC15305 and 55°C for Geobacillus stearothermophilus NBRC13737, and spore suspensions of each spore-forming bacterium were prepared.

[0111] <Evaluation> (Evaluation of sprout killing effect) Five milliliters of sterilizing solution was added to a sterile test tube and incubated at the temperatures shown in Tables 1–5. 0.005 mL of spore suspension from each spore-forming bacterium was added, and the spore-forming bacterium was allowed to come into contact with the sterilizing solution for a set period of time. After incubation, the solution was serially diluted 10-fold with SCDLPB (Soybean Casein Digest Broth Medium with Lecithin and Polysorbate-80), and the diluted solution was poured into SCDLPA (Soybean Casein Digest Agar Medium with Lecithin and Polysorbate-80). The solution was then incubated for two days at the same temperature as when the spore suspension was prepared to allow colonies to grow. The number of colonies was counted to determine the number of grown bacteria after incubation. The value was calculated using the formula below, and the spore-killing effect was evaluated using the following criteria. (formula) (Logarithm of the number of colonies when bacterial solution is added to sterilized water at room temperature (25°C)) - (Logarithm of the number of colonies after the reaction for each sample) (Evaluation criteria) ◎: The formula value became 5 or more within 10 minutes of reaction. O: The formula value became 5 or more within 30 minutes of reaction, more than 10 minutes. △: The formula value became 5 or more within 30 to 60 minutes of reaction. ×: The numerical value of the formula after 60 minutes of reaction was 1 or less.

[0112] (Evaluation of metal corrosion resistance) 20 mL of sterilizing solution was added to each 100 mL beaker, and a portion of a 2 mm x 50 mm x 50 mm stainless steel plate (SUS304, manufactured by Standard Test Piece Co., Ltd.) was inserted therein. In this state, the top of the beaker was covered with plastic wrap and kept warm in a thermostatic bath at 60°C for 2 hours, after which the stainless steel plate was removed and washed with distilled water. The same procedure was repeated a total of three times, and the appearance was observed and evaluated based on the following evaluation criteria. In this evaluation method, metal corrosion prevention is evaluated at the waterline portion (i.e., the boundary between the sterilizing solution and air) and the portion above it, where a noticeable change in color tone indicating metal corrosion is observed. (Evaluation criteria) ○: No change was observed in the stainless steel plate. △: A slight change in color tone was observed at the waterline of the stainless steel plate. ×: A change in color tone was observed over almost the entire surface of the stainless steel plate above the waterline.

[0113] (Evaluation of low temperature stability) The disinfectant composition was placed in a test tube, kept at about 70°C to dissolve, and then stored at 4°C for one day, after which the presence or absence of precipitation was observed. In this evaluation method, the evaluation was made based on the following evaluation criteria. (Evaluation criteria) ○: No precipitation was observed. ×: Precipitation was observed.

[0114] "Examples 1 to 18, Comparative Examples 1 to 7, 9" According to the compositions shown in Tables 1 to 3, component (A1) or component (A2), component (B1), component (C), and optional components were mixed to prepare the sterilizing solution for each example, and the pH was measured by the method described above. The prepared disinfectant solution was used to evaluate its germination effect and metal corrosion prevention effect. The results are shown in Tables 1 to 3.

[0115] "Comparative Example 8" A portion of the sterilized water was mixed with the components (A1) and (B1) according to the composition of Comparative Example 8 shown in Table 3. After mixing, an appropriate amount of 1N NaOH was added as a pH adjuster so that the pH at 25°C would be the value shown in Comparative Example 8 in Table 3, and the remaining sterilized water was added so that the total amount was 100% by mass to prepare a sterilizing solution, and the pH was measured by the method described above. The prepared disinfectant solution was used to evaluate its germination effect and metal corrosion prevention effect. The results are shown in Table 3.

[0116] "Comparative Example 10" In Comparative Example 10 shown in Table 3, sterilizing water alone was used instead of the sterilizing solution to evaluate the germicidal effect and metal corrosion prevention properties. The results are shown in Table 3.

[0117] "Examples 19 to 34" According to the compositions shown in Tables 4 and 5, component (A1) or component (A2), component (B1), component (B2), component (C), and optional components were mixed to prepare the fungicide compositions of each example. The prepared fungicide compositions were evaluated for low temperature stability, and the results are shown in Tables 5 and 6. For Examples 19 to 31, 33, and 34, the disinfectant compositions prepared by the above-mentioned method were diluted with sterilized water so that the content of component (A1) was 0.01% by mass to prepare disinfectant solutions. For Example 32, the disinfectant composition prepared by the method described above was diluted with sterilized water so that the content of component (A2) was 0.05% by mass to prepare a disinfectant solution. The sprout-killing effect of the prepared disinfectant solution was evaluated, and the results are shown in Tables 4 and 5. In the evaluation of the sprout-killing effect in Examples 19 to 34, a sterilizing solution heated to 80°C was used.

[0118] [Table 1]

[0119] [Table 2]

[0120] [Table 3]

[0121] [Table 4]

[0122] [Table 5]

[0123] The blending amounts in Tables 1 to 5 are pure content equivalents. Components without blending amounts listed in the tables were not blended. The "appropriate amount" of pH adjuster content listed in Table 3 is the amount required to achieve the pH of Comparative Example 8. The "balance" of sterilized water content in the table is the amount required to make the sterilizing solution and sterilant composition 100% by mass. In Tables 1 to 5, the "B1 / A1 ratio" is the mass ratio expressed as component (B1) / component (A1). The evaluation results of the sporicidal effect shown in Tables 1 to 5 are the results obtained when Bacillus subtilis NBRC3134 was used as the spore-forming bacterium.

[0124] As is clear from Tables 1, 2, 4, and 5, the sterilization methods using the sterilizing solutions of each Example exhibited a germination effect. Furthermore, as is clear from Tables 1 and 2, the sterilization methods using the sterilizing solutions of Examples 1 to 18 exhibited excellent metal corrosion prevention properties. On the other hand, as is clear from Table 3, the sterilization methods using the sterilizing solutions of Comparative Examples 1 and 2, which did not contain the components (A2) and (B1), were inferior in sprout killing effect. The sterilization methods using the sterilizing solutions of Comparative Examples 3 and 4, which did not contain the components (A1) and (A2), were inferior in sprout killing effect. The sterilization methods using the sterilizing solutions of Comparative Examples 5 and 6, which contained component (A') instead of components (A1) and (A2), were inferior in sprout killing effect. The sterilization method of Comparative Example 7, which used a sterilizing solution heated to 40°C, was inferior in sprout killing effect. The sterilization method of Comparative Example 8, which used a sterilizing solution with a pH of 6.0, was inferior in sprout killing effect. The sterilization method of Comparative Example 9, which used a sterilizing solution containing sodium hypochlorite in an amount of 0.01 mass % in terms of available chlorine, was inferior in metal corrosion prevention properties. The sterilization method of Comparative Example 10, in which sterilized water was used instead of the sterilizing solution, was inferior in sprout killing effect. As is clear from Tables 4 and 5, the fungicide compositions of Examples 16 to 29 were excellent in low-temperature stability. On the other hand, the fungicide compositions of Examples 30 and 31, which did not contain component (D), were inferior in low-temperature stability. The sporicidal effects shown in Tables 1 to 5 were similar when the spore liquid of each spore-forming bacterium was used.

[0125] From the above results, it was confirmed that by applying the present invention, spore-forming bacteria can be easily sterilized while suppressing deterioration of the object to be sterilized.

Claims

1. A method for sterilizing spore-forming bacteria using an aqueous solution (X1) containing component (A1) and component (B1), comprising: The aqueous solution (X1) may contain a component (C), The component (A1) is one or more anionic surfactants selected from alkyl sulfates, alkylbenzene sulfonates, alkanesulfonates, and olefin sulfonates, The component (B1) is at least one selected from organic acids and inorganic acids, The component (C) is a hypochlorite, the content of the component (A1) is 0.001 to 1 mass%, the content of the component (B1) is 0.001 to 5 mass%, and the content of the component (C) is 0 to 0.001 mass%, expressed as an available chlorine concentration, relative to the total mass of the aqueous solution (X1); The pH of the aqueous solution (X1) at 25°C is 1.5 or more and less than 5, A method for sterilizing spore-forming bacteria, comprising heating the aqueous solution (X1) to 50 to 100°C and bringing the aqueous solution into contact with the spore-forming bacteria to sterilize the spore-forming bacteria.

2. The method for sterilizing spore-forming bacteria according to claim 1, wherein the mass ratio of the component (B1) to the component (A1) is 1 to 500.

3. A method for sterilizing spore-forming bacteria using an aqueous solution (X2) containing component (A2), comprising: The aqueous solution (X2) may contain a component (C), The component (A2) is an alkylbenzenesulfonic acid, The component (C) is a hypochlorite, the content of the component (A2) is 0.002 to 6 mass% relative to the total mass of the aqueous solution (X2), and the content of the component (C) is 0 to 0.001 mass% in terms of an available chlorine concentration, The pH of the aqueous solution (X2) at 25°C is 1.5 or more and less than 5, The method for sterilizing spore-forming bacteria comprises heating the aqueous solution (X2) to 50 to 100°C and bringing the aqueous solution into contact with the spore-forming bacteria to sterilize the spore-forming bacteria.

4. The method for sterilizing spore-forming bacteria according to any one of claims 1 to 3, wherein the spore-forming bacteria is at least one selected from the group consisting of Bacillus subtilis and Bacillus cereus.

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