An antimicrobial composition

Abstract

The present invention relates to an antimicrobial composition. It more particularly relates to an anti-fungal composition that is also additionally seen to provide antibacterial and biofilms inhibiting efficacy. This is achieved through a composition that comprises a rhamnolipid surfactant in addition to a primary anionic surfactant and a secondary amphoteric surfactant at specific ratios along with the inclusion of two types of organic acids.

Description

[0001] AN ANTIMICROBIAL COMPOSITION

[0002] Field of the Invention

[0003] The present invention relates to an antimicrobial composition. It more particularly relates to an anti-fungal composition. It also relates to a composition which in many cases also delivers antibacterial and / or biofilms inhibiting efficacy. It more particularly relates to delivering hygiene in the kitchen including hard surfaces therein like floors, table tops, and utensils and soft surfaces of kitchen implements like mops and sponges.

[0004] Background of the Invention

[0005] Most people prefer to live in areas where the floors, table tops, kitchen surfaces, utensils, bathrooms and toilets are clean and well disinfected. Such surfaces are generally cleaned using compositions that contain surfactants. Certain antimicrobial agents may also be included in such compositions to disinfect the surfaces to make them free of harmful microorganisms like bacteria or virus. People also prefer fabrics that they use like clothes, bedsheets and other upholstery to be clean and smelling good and free of such germs.

[0006] The present inventors noticed that compositions known in the art are good in delivering desired anti-bacterial efficacy but lack in delivering antifungal efficacy. A representative fungus which is difficult to inactivate on inanimate surfaces is Aspergillus Brasiliensis. The present inventors therefore took it upon themselves to solve the problem of providing high antifungal efficacy with a combination of ingredients that have a history of safe use in home care products. After extensive experimentation in this area using conventionally safe ingredients, they hit upon a surprising finding that a combination of a rhamnolipid surfactant in addition to a primary anionic surfactant and a secondary amphoteric surfactant at specific ratios along with the inclusion of two types of organic acids (one aliphatic and one aromatic organic acid) one is able to get excellent antifungal efficacy. They also surprisingly found that in addition to antifungal benefits, many of these composition may also deliver antibacterial and / or biofilms inhibiting efficacy. In many cases, the antibacterial efficacy is seen to be good against both gram positive as well as gram negative bacteria.

[0007] It is thus an object of the present invention to provide for an antifungal composition using a combination of ingredients that have a history of safe use in home care products. Summary of the Invention

[0008] The present invention relates to an antimicrobial composition comprising

[0009] (a) 3 to 30 wt% of a surfactant system comprising

[0010] (i) a primary anionic surfactant;

[0011] (ii) a secondary amphoteric surfactant selected from one or both of alkyl amidopropyl betaine surfactant and amine oxide surfactant;

[0012] (iii) 0.25 to 5 wt% rhamnolipid surfactant;

[0013] (b) 0.05 to 3.0 wt% an aliphatic organic acid selected from one or more of citric acid, lactic acid, sorbic acid, glycolic acid, and tartaric acid; or salts thereof; and

[0014] (c) 0.05 to 1.5 wt% of aromatic organic acid selected from one or more of benzoic acid, salicylic acid, anisic acid or salts thereof; wherein the weight ratio of the primary anionic surfactant to the secondary amphoteric surfactant is between 1.5:1 to 20: 1 ; wherein the composition has a pH in the range of 2 to 4.

[0015] Detailed description of the invention

[0016] For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of” or "composed of'. Thus, the term "comprising" is meant not to be limiting to any subsequently stated elements, but rather to optionally also encompass nonspecified elements of major or minor functional importance. In other words, the listed steps or options need not be exhaustive. Whenever the words "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Except in the examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and / or use are to be understood as modified by the word "about". Unless specified otherwise, numerical ranges expressed in the format "x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "x to y", it is understood that all ranges combining the different endpoints are also contemplated. Unless specified otherwise, amounts as used herein are expressed in percentage by weight based on total weight of the composition and is abbreviated as “wt%”. Throughout this description, the term disinfection refers to reduction of the number of viable microorganisms in a given medium or on a given surface. Typically, disinfection involves the destruction or inactivation of the microorganisms. Both animate and inanimate media and surfaces are contemplated, although inanimate surfaces are preferred.

[0017] The term " antimicrobial " refers to a compound capable of killing, inhibiting the growth of or controlling the growth of microorganisms at a locus; antimicrobials include bactericides, fungicides and algaecides. The term "microorganism" includes, for example, fungi (such as yeast and mould), bacteria and algae. However, since the object of the present invention is to inhibit growth of fungus the term ‘antimicrobial especially refers to inhibition or killing of fungus.

[0018] The compositions of the present invention are preferred for non-therapeutic use, and more particularly preferred for use in cleaning surfaces, preferably wherein the surface is a hard surface and more preferably for use in cleaning applications such as cleaning kitchen, bathroom and floor surfaces. They may also be used for cleaning fabrics.

[0019] The composition of the invention is especially useful for delivering a dishwash composition, especially one which is used for washing dishes by hand. The composition ensures delivery of antimicrobial efficacy to the dishes and other surfaces cleaned in the kitchen. It also delivers good efficacy against germs accumulating on dishwash and other cleaning implements used in the kitchen like sponges, scrubs, and mops.

[0020] The composition of the invention comprises a surfactant system comprising total amount of 3 to 30 %, preferably 3 to 20 %, more preferably 3 to 15%, further more preferably 3 to 12 % surfactants, by total weight of the composition. Three types of surfactants are present in the surfactant system. It includes a primary surfactant which is an anionic surfactant. The anionic surfactant is preferably selected from one or more of an alkyl ether sulphate surfactant, an alkyl sulphate surfactant and an alkyl benzene sulphonate surfactant. The primary anionic surfactant is preferably included in 2 to 20 wt%, preferably 2 to 9 wt%, more preferably 2 to 7%, further more preferably 2 to 6% of the total weight of the composition. Rhamnolipid surfactant is also generally classed as an anionic surfactant. Hence to be clear and unambiguous, by ‘the primary anionic surfactant’ as per this invention is meant any anionic surfactant other than rhamnolipid surfactant.

[0021] The anionic surfactant is preferably an alkyl sulphate surfactant. The alkyl sulphate surfactant for inclusion in the composition of the invention preferably has 10 to 18 carbon atoms, more preferably 10 to 12 carbon atoms. The surfactant has a counterion which is an alkali metal such as sodium or potassium; or an ammoniacal counterion such as monoethanolamine, (MEA) diethanolamine (DEA) or triethanolamine (TEA). Preferably it is sodium or potassium, most preferably it is sodium. The most preferred surfactant of this class for inclusion in the composition of the invention is sodium lauryl sulphate. The alkyl sulphate surfactant preferably is included in 0.1 to 5%, preferably 0.2 to 4% by weight of the composition.

[0022] The anionic surfactant is preferably an alkyl ether sulphate surfactant. The alkyl ether sulphate surfactant for inclusion in the composition of the invention preferably has 10 to 18 carbon atoms, more preferably 10 to 12 carbon atoms. The alkyl ether sulphate surfactant preferably has one to ten ethylene oxide or propylene oxide units per molecule, preferably one to three ethylene oxide units per molecule. The surfactant has a counterion which is an alkali metal such as sodium or potassium; or an ammoniacal counterion such as monoethanolamine, (MEA) diethanolamine (DEA) or triethanolamine (TEA). Preferably it is sodium or potassium, most preferably it is sodium. The most preferred surfactant of this class for inclusion in the composition is sodium laureth sulphate 1 EO. The alkyl ether sulphate surfactant is preferably included in 0.1 to 5%, more preferably 0.2 to 4% by weight of the composition.

[0023] Another class of anionic surfactant that may preferably be included is of the alkylbenzene sulfonates type, particularly linear alkylbenzene sulfonates (LAS) with an alkyl chain length of from 10 to 18 carbon atoms.

[0024] The composition as per the invention comprises a secondary surfactant which is an amphoteric surfactant. The amphoteric surfactant is selected from one or both of alkyl amidopropyl betaine surfactant and amine oxide surfactant. Thus, either of the above two type of amphoteric surfactants may be used or the composition could comprise a mixture of the two. Preferred alkyl amidopropyl betaine is cocoamido propyl betaine. The amine oxide may be any one of the C8 - C18 alkyl amine n-oxide (which is broadly referred to an amine oxide). The preferred amine oxide is one or both of lauramine oxide or lauryl / myristyl amido propyl amine oxide. The more preferred amine oxide is lauramine oxide.

[0025] Preferably, the total composition preferably comprises 1 to 20 wt%, more preferably 1 to 10 wt%, further more preferably 1 to 5 wt%, even further more preferably 1 to 3% of amphoteric surfactant.

[0026] It is preferred that the weight ratio of the primary anionic surfactant to the secondary amphoteric surfactant is between 1.5:1 to 20:1, more preferably between 1.5: 1 to 5: 1. The composition of the invention comprises a rhamnolipid. Rhamnolipids are a class of glycolipid. They are constructed of rhamnose combined with beta-hydroxy fatty acids. Rhamnose is a sugar. Fatty acids are ubiquitous in animals and plants.

[0027] Rhamnolipids are discussed in Applied Microbiology and Biotechnology (2010) 86:1323- 1336 by E. Deziel et al. Rhamnolipids are produced by Glycosurf, AGAE Technologies and Urumqi Unite Bio-Technology Co., Ltd. Rhamnolipids may be produced by strains of the bacteria Pseudomonas aeruginosa. Rhamnolipids may also be produced by a recombinant cell of Pseudomonas putida where the recombinant cell comprises increased activity of at least one of the enzymes a / P hydrolase, rhamnosyltransferase I or rhamnosyl-transferase II compared to the wild-type of the cell.

[0028] There are two major groups of rhamnolipids; mono-rhamnolipids and di-rhamnolipids. Monorhamnolipids have a single rhamnose sugar ring. A typical mono-rhamnolipid produced by P. aeruginosa is L-rhamnosyl-p-hydroxydecanoyl-p-hydroxydecanoate (RhaCwCw). It may be referred to as Rha-Cw-Cw, with a formula of C26H48O9. Monorhamnolipids have a single rhamnose sugar ring.

[0029] The IUPAC Name is 3-[3-[(2R,3R,4R,5R,6S)-3,4,5-trihydroxy-6-methyloxan-2- yl]oxydecanoyloxy]decanoic acid.

[0030] Di-rhamnolipids have two rhamnose sugar rings. A typical di-rhamnolipid is L-rhamnosyl-L- rhamnosyl-p-hydroxydecanoyl-p-hydroxydecanoate (Rha2C Cio). It may be referred to as Rha- Rha-C- -C-10, with a formula of C32H58O13.

[0031] The IUPAC name is 3-[3-[4,5-dihydroxy-6-methyl-3-(3,4, 5-tri hydroxy-6-methyloxan-2- yl)oxyoxan-2-yl]oxydecanoyloxy]decanoic acid.

[0032] In practice, a variety of other minor components with different alkyl chain length combinations, depending upon carbon source and bacterial strain, exist in combination with the above more common rhamnolipids. The ratio of mono-rhamnolipid and di-rhamnolipid may be controlled by the production method. Some bacteria only produce monorhamnolipid, see US5767090: Example 1 , some enzymes can convert mono-rhamnolipid to di-rhamnolipid. In various publications mono-rhamnolipids have the notation Rha-, which may be abbreviated as Rh or RL2. Similarly, di-rhamnolipids have the notation Rha-Rha or Rh-Rh or RL1. For historical reasons "rhamnolipid 2" is a mono-rhamnolipid and "rhamnolipid 1 "is a di-rhamnolipid. This leads to some ambiguity in the usage or "RL1 " and "RL2" in the literature.

[0033] Throughout this patent specification, we use the terms mono- and di-rhamnolipid in order to avoid this possible confusion. However, if abbreviations are used R1 is mono-rhamnolipid and R2 is di- rhamnolipid. For more information on the confusion of terminology in the prior art, see the introduction to US 4814272.

[0034] The following rhamnolipids have been detected as produced by the following bacteria: (C12:1 , C14:1 indicates fatty acyl chains with double bonds).

[0035] Rhamnolipids produced by P. aeruginosa (mono-rhamnolipids):

[0036] Rha-C8-C10, Rha-C10-C8, Rha-C10-C10, Rha-C10-C12, Rha-C10-C12:1 , Rha-C12-C10, Rha- C12:1-C10

[0037] Rhamnolipids produced by P. aeruginosa (di-rhamnolipids):

[0038] Rha-Rha-C8-C10, Rha-Rha-C8-C12:1 , Rha-Rha-C10-C8, Rha-Rha-C10-C10, Rha-Rha-C10- C12:1 , Rha-Rha-C-10-C-12, Rha-Rha-C-12-C-10, Rha-Rha-C-12:1-C-12, Rha-Rha-C10-C14:1

[0039] Rhamnolipids produced by P. aeruginosa (unidentified as either mono- or di-rhamnolipids): C8- C8, C8-C10, C10-C8, C8-C12:1 , C12:1-C8, C10-C10, C12-C10, C12:1-C10 C12-C12, C12:1- C12, C14-C10, C14:1-C10, C14-C14.

[0040] Rhamnolipids produced by P. chlororaphis (mono-rhamnolipids only):

[0041] Rha-C10-C8, Rha-C10-C10, Rha-C12-C10, Rha-C12:1-C10, Rha-C12-C12, Rha-C12:1- C12, Rha-C14-C10. Rha-C- 14:1-010.

[0042] Rhamnolipids produced by Burkholdera pseudomallei (di-rhamnolipids only): Rha-Rha-C14-C14.

[0043] Rhamnolipids produced by Burkholdera (Pseudomonas) plantarii (di-rhamnolipids only): Rha-Rha-C14-C14. There are over 100 strains of P. aeruginosa on file at the American Type Culture Collection (ATCC). There are also a number of strains that are only available to manufacturers of commercial Rhamnolipids. Additionally, there are probably thousands of strains isolated by various research institutions around the world. Some work has gone into typing them into groups. Each strain has different characteristics including how much rhamnolipid is produced, which types of rhamnolipids are produced, what it metabolizes, and conditions in which it grows. Only a small percentage of the strains have been extensively studied.

[0044] Through evaluation and selection, strains of P. aeruginosa can be isolated to produce rhamnolipids at higher concentrations and more efficiently. Strains can also be selected to produce less byproduct and to metabolize different feedstock or pollutants. This production is greatly affected by the environment in which the bacterium is grown.

[0045] A typical di-rhamnolipid is L-rhamnosyl-L-rhamnosyl-p-hydroxydecanoyl-p-hydroxydecanoate (Rha2CioC with a formula of C32H58O13).

[0046] In practice a variety of other minor components with different alkyl chain length combinations, depending upon carbon source and bacterial strain, exist in combination with the above more common rhamnolipids. The ratio of mono-rhamnolipid and di-rhamnolipid may be controlled by the production method. Some bacteria only produce monorhamnolipid, see US6767090: Example 1 , some enzymes can convert mono-rhamnolipid to di-rhamnolipid.

[0047] Preferably the rhamnolipid is selected from:

[0048] Rhamnolipids produced by P. aeruginosa (mono-rhamnolipids):

[0049] Rha-C8-C10, Rha-C10-C8, Rha-C10-C10, Rha-C10-C12, Rha-C10-C12:1 , Rha-C12-C10, Rha- C12:1-C10

[0050] Rhamnolipids produced by P. chlororaphis (mono-rhamnolipids only):

[0051] Rha-C10-C8, Rha-C10-C10, Rha-C12-C10, Rha-C12:1-C10, Rha-C12-C12, Rha-C12:1- C12, Rha-C14-C10, Rha-C14:1-C10.

[0052] Mono-rhamnolipids may also be produced from P.putida by introduction of genes rhIA and rhIB from Psuedomonas aeruginosa [Cha et al. in Bioresour Technol. 2008. 99(7):2192-9]

[0053] Rhamnolipids produced by P. aeruginosa (di-rhamnolipids): Rha-Rha-C8-C10, Rha-Rha-C8-C12:1 , Rha-Rha-C10-C8, Rha-Rha-C10-C10, Rha-RhaC10- C12:1 , Rha-Rha-C10-C12, Rha-Rha-C12-C10, Rha-Rha-C12:1-C12, Rha-Rha-C10- C14:1 Rhamnolipids produced by Burkholdera pseudomallei (di-rhamnolipids only):

[0054] Rha-Rha-C14-C14.

[0055] Rhamnolipids produced by Burkholdera (Pseudomonas) plantarii (di-rhamnolipids only):

[0056] Rha-Rha-C14-C14.

[0057] Rhamnolipids produced by P. aeruginosa which are initially unidentified as either mono- or di-rhamnolipids:

[0058] C8-C8, C8-C10, C10-C8, C8-C12:1 , C12:1-C8, C10-C10, C12-C10, C12:1-C10, C12-C12, C12:1-C12, C14-C10, C14:1-C10, C14-C14.

[0059] Preferably the Rhamnolipid is L-rhamnosyl-(3-hydroxydecanoyl-p-hydroxydecanoate (RhaC Cio with a formula of C26H48O9).

[0060] Preferably, the rhamnolipid comprises at least 50 wt.% di-rhamnolipid, more preferably at least 60 wt.% di-rhamnolipid, even more preferably 70 wt.% di-rhamnolipid, most preferably at least 80 wt.% di-rhamnolipid.

[0061] Preferably the rhamnolipid is a di-rhamnolipid of formula: Rha2C8-i2Cs-i2. The preferred alkyl chain length is from Cs to C12. The alkyl chain may be saturated or unsaturated. The most preferred di-rhamnolipid is an example of a di-rhamnolipid of formula: Rha2C8-i2Cs-i2, known as Rhamnolipid R2 herein, and can be supplied from Evonik. The composition comprises rhamnolipid in 0.25 to 5%, preferably 0.25 to 4.5% and most preferably 0.5 to 3%, by weight of the composition.

[0062] The composition comprises two types of organic acid i.e. an aliphatic organic acid and an aromatic organic acid. The aliphatic organic acid is selected from one or more of citric acid, lactic acid, sorbic acid, glycolic acid, and tartaric acid. It is preferably selected from one or both of citric and lactic acid. Aliphatic organic acid is included in 0.05 to 3.0 wt%, preferably 0.2 to 3.0 wt%, more preferably 0.3 to 3 wt%, further more preferably 0.4 to 3 wt%, and most preferably 0.5 to 3 wt% of the total composition.

[0063] The aromatic organic acid is selected from one or more of benzoic acid, salicylic acid, anisic acid or salts thereof. It is preferably sodium benzoate. The aromatic organic acid is included in 0.05 to 1.5 wt%, preferably 0.1 to 1.0 wt% of the total composition. The composition of the invention is preferably in liquid form. Liquid composition of the invention generally comprise 70 to 90 wt% water. The pH of the composition is preferably in the range of 2 to 4, more preferably in the range of 3.0 to 3.9, further more preferably in the range of 3.4 to 3.9. The formulation is homogenized and the pH of the formulation is directly measured using a precalibrated pH meter at a temperature of 25 °C.

[0064] The composition may optionally comprise other ingredients, such as fragrance, colour, chelating agents, salts and preservatives.

[0065] The composition of the invention is preferably used for home care applications. A "home care product" is a product for the treatment, cleaning, caring or conditioning of the home or any of its contents. The foregoing includes, but is not limited to, compositions, products, or combinations thereof relating to or having use or application in the treatment, cleaning, cleansing, caring or conditioning of surfaces, furniture and atmosphere of the home and household contents, such as clothes, fabrics and / or cloth fibres and the manufacture of all of the foregoing products.

[0066] Preferably, the composition used in the present invention is used to clean a hard surface, more preferably wherein the hard surface is a kitchen, bathroom or floor surface. Typically, such hard surfaces are surfaces that require frequent cleaning and preferably also sanitisation and / or disinfection. Such surfaces may be found in many household or industrial environments, and may include kitchen and bathroom surfaces, tabletops, floors, walls, windows, utensils, cutlery, and crockery. Such surfaces may be made from many different materials, including for instance plastics, wood, metal, ceramics, glass, concrete, marble, and painted surfaces. The composition may be applied to the surface by any suitable means known to the skilled person. For instance, a suitable means may be pouring, dropping, spraying or wiping in case of liquid compositions.

[0067] The composition may be used as is, i.e. neat, preferably the composition is diluted with water before use. For example, if applied in a diluted form, the composition is diluted with water preferably in a ratio in the range of 1 :1 to 1 :1000, more preferably 1 :50 to 1 :500, even more preferably 1 :100 to 1 :300.

[0068] It may also be used for hand dishwash applications to clean utensils, cutlery, and crockery. The invention also ensures good antimicrobial efficacy on soft surfaces like those on cleaning implements like sponges, mops and scrubs. In such cases the composition may be used in diluted form with water. The dilution with water in such cases is preferably in the range of 1 :1 to 1 :100 and more preferably in a ratio of between 1 :1 to 1 :10.

[0069] In most hard surface cleaning application, the diluted solution is applied on to the desired surface by using a brush or a mop and allowing it to dry. One preferred method of applying the composition is through use of a spray pump. This is especially useful when cleaning vertical surfaces. In certain cases, the compositions after it is applied on to the desired surface, may be wiped off to a substantially dry condition using a dry cloth or wipe. In toilet cleaning applications, the composition is generally applied on to the toilet bowl, allowed to stay thereon for a few minutes, and then the toilet is flushed, preferably after brushing with a toilet brush.

[0070] Another preferred embodiment of the invention relates to compositions according to the invention for use as or incorporation in industrial and / or institutional products. More preferably, this embodiment of the invention relates to a composition according to the invention which is an industrial and / or an institutional product. Industrial and institutional products are for example products being marketed under professional brands, with non-limiting examples being products for industrial, institutional, janitorial, and medical cleaning, cleaning-in-place, food services, veterinary, and agricultural products.

[0071] Another aspect of the present invention relates to a method of providing anti-fungal benefit to a surface comprising the step of cleaning the surface with a composition of the invention preferably diluted with water.

[0072] Yet another aspect of the present invention relates to a method of providing antibacterial benefit against both gram positive as well as gram negative bacteria comprising the step of cleaning the surface with a composition of the invention preferably diluted with water.

[0073] Yet another aspect of the present invention relates to a method of preventing formation of biofilm on a surface and / or disrupting biofilm from a surface comprising the step of cleaning the surface with a composition of the invention preferably diluted with water.

[0074] Another aspect of the present invention relates to use of a composition of the present invention for providing anti-fungal benefit to a surface cleaned with the composition. Yet another aspect of the present invention relates to use of a composition as per the invention for providing antibacterial benefit against both gram positive as well as gram negative bacteria to a surface cleaned with the composition.

[0075] Yet another aspect of the present invention relates use of the composition as per the invention for preventing formation of biofilm on a surface and / or disrupting biofilm from a surface which has been cleaned with the composition of the invention.

[0076] Examples

[0077] Examples A, B, 1 : Antifungal benefit from use of the composition of the invention

[0078] Compositions as shown in Table - 1 were prepared and the antifungal efficacy was measured using the procedure as given below:

[0079] Sponges were cut into cubes (removing any scouring pad that may be glued to the sponge). Three replicates per test sample and a water control were used. Five cubes were weighed and the average weight was calculated. The sponges were immersed into water to ensure they were thoroughly wet through, then hand squeezed and weighed again. This then determines the vol of dilute product. The sponges were dried in an oven or incubator.

[0080] Products at 25% dilution in water of standard hardness (as in the EN1276) were prepared. Required volume of dilute product as determined above was added. 104spores / ml of A. brasiliensis in 50% Czapek Dox broth was prepared. 1ml of the prepared inoculum was dosed onto each sponge piece. The sponges were placed into a tray that contained damp absorbent material (e.g. a paper wipe) and this was cover with a bag. The samples were incubated for seven days. After seven days, 10ml of neutralizer was added, neutralised for 5 minutes, serially diluted, plated using malt extract agar and incubated for seven days. After seven days, the number of colonies were counted.

[0081] The quantification of the fungus with each of the test products are summarized in Table - 1.

[0082] Table - 1

[0083] The data in the Table -1 above indicates that the composition of the invention (Example -1) provides for vastly improved fungal inhibition as compared to the control sample and other compositions outside the invention (Examples A and B).

[0084] Example C-E, 1: Anti bacterial efficacy

[0085] Composition as per the invention (Example -1) was compared to a composition outside the invention (Example - C) for antibacterial efficacy as shown in table - 2 below. The Compositions C and 1 were adjusted to a pH of 3.5 (with additional HCI if required) while Compositions D was adjusted to pH of 5 and Composition E to pH of 5.5 with additional NaOH.

[0086] Table - 2

[0087] The immediate hygiene benefit and long term germ protection (long lasting hygiene - LLH) was measured for the above two compositions using the following procedure:

[0088] Immediate hygiene benefit was evaluated as per EN1276 protocol. To 1ml of 0.3% BSA, 1ml of bacterial culture containing 8 log / ml of bacteria was inoculated. After 2 minutes of contact time, 8ml of formulation diluted with 37.5FH hard water diluted at a ratio of 1 : 1 was added. After contact time of 5 minutes, neutralization was performed by adding 1 ml of above culture formulation mix to 9ml of 2X D / E neutralisation solution. After 5 minutes, the neutralised solution was serially diluted in 9ml of 2X D / E solution and 1ml from each dilution was plated by pour plate method using TSA. All the plates were incubated at 37°C for 24-48 hours and total bacterial count was determined. Log reduction was compared with the water control sample.

[0089] Long lasting hygiene benefit was evaluated by using commercially available synthetic sponge of size 7 x 9 x 4.5 cm which was cut into 6 pieces and used for determining the disinfection efficacy of the formulation. 1ml of soil (Low Soil: 0.3% BSA) and test microorgansim (108cfu / ml) mix in the ratio 1 :1 applied on the sponge and sponge was squeezed to distribute the microrganisms. After 2 minutes 4.5 ml of the mix containing 2.5 ml of 37.5 HW (as per EN 1276) and 2ml of product was applied on the sponge and squeezed to generate a foam. After contact time of 4-6 hours, 20 ml of 2X D / E neutraliser is added to the sponge (squeeze the sponge to distribute the neutralizer). After 5 minutes of neutalization conatct time, the neutarlised solution was serially diluted and plated on TSA by pour plate method.

[0090] The plates were incubated at 37°C for 48 hours. Microbial log reduction was determined by comparing the microbial reduction against water control sample.

[0091] The pass criteria was set as > 5 log reduction for immediate hygiene and > 3 log reduction for LLH. The data is summarised in Table - 3 below:

[0092] Table - 3

[0093] The data in the Table - 3 above indicates that composition as per the invention (Example -1) provides for vastly improved immediate and long term hygiene for many types of bacteria as compared to a composition outside the invention (Example - C). It is also further observed that the benefits of the invention are obtained only at lower pH in the range of 2 to 4 while such benefit is not obtained at higher pH (of say 5.0 and 5.5 as in Example D and E).

[0094] Example C, 1 : Bacterial biofilm inhibition:

[0095] Multi-species biofilm inhibition efficacy of Example -1 was measured in comparison with Example -C. The measurement was done using the following procedure:

[0096] Inhibition of multispecies biofilm on a solid surface over 48 -hours was done using P.aeruginosa, E.coli and S. epidermidis. All test bacteria were inoculated together and exposed to the formulation incubated. After 48 hours biomass of remaining biofilm was estimated by staining the biofilm and the remaining biomass was quantified by measuring the optical density.

[0097] The data is summarised in Table - 4 below:

[0098] Table - 4:

[0099] The data in the table above indicates that composition as per the invention (Example - 1) provides for vastly improved biofilm inhibition as compared to a composition outside the invention (Example - C).

Claims

Claims1. An antimicrobial composition comprising(a) 3 to 30 wt% of a surfactant system comprising(i) a primary anionic surfactant;(ii) a secondary amphoteric surfactant selected from one or both of alkyl amidopropyl betaine surfactant and amine oxide surfactant;(iii) 0.25 to 5 wt% rhamnolipid surfactant;(b) 0.05 to 3.0 wt% an aliphatic organic acid selected from one or more of citric acid, lactic acid, sorbic acid, glycolic acid, and tartaric acid; or salts thereof; and(c) 0.05 to 1.5 wt% of aromatic organic acid selected from one or more of benzoic acid, salicylic acid, anisic acid or salts thereof; wherein the weight ratio of the primary anionic surfactant to the secondary amphoteric surfactant is between 1.5:1 to 20:1 ; and wherein the composition has a pH in the range of 2 to 42. A composition as claimed in claim 1 wherein the primary anionic surfactant is selected from one or more of an alkyl ether sulphate surfactant, an alkyl sulphate surfactant and an alkyl benzene sulphonate surfactant.

3. A composition as claimed in claim 2 wherein the alkyl ether sulphate surfactant has 10 to 18 carbon atoms.

4. A composition as claimed in claims 2 or 3 wherein the alkyl ether sulphate surfactant has one to ten ethylene oxide or propylene oxide units per molecule, preferably one to three ethylene oxide units per molecule.

5. A composition as claimed in any one of the preceding claims 2 to 4 wherein the alkyl ether sulphate is sodium laureth sulphate 1 EO6. A composition as claimed in any one of the preceding claims comprising 2 to 20 wt% of the primary anionic surfactant.

7. A composition as claimed in any one of the preceding claims comprising 1 to 20 wt% of the secondary amphoteric surfactant.

8. A composition as claimed in any one of the preceding claims wherein the aliphatic organic acid is citric acid, lactic acid or mixture thereof.

9. A composition as claimed in any one of the preceding claims wherein the aromatic organic acid or salt thereof is sodium benzoate.

10. A composition as claimed in any one of the preceding claims wherein the alkyl amido propyl betaine is cocoamidopropyl betaine.

11. A composition as claimed in any one of the preceding claims comprising 70 to 90% water.

12. A composition as claimed in any one of the preceding claims having a pH in the range of 3.0 to 3.9.

13. Use of a composition as claimed in any one of the preceding claims for providing antifungal benefit to a surface cleaned with said composition.

14. Use of a composition as claimed in any one of the preceding claims 1 to 12 for providing anti-bacterial benefit against both gram positive as well as gram negative bacteria to a surface cleaned with said composition.

15. Use of a composition as claimed in any one of the preceding claims 1 to 12 for preventing formation of biofilm on a surface and / or disrupting biofilm from a surface which has been cleaned with said composition.

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