Method for Evaluating or Selecting Bluing Reducing Agent

Abstract

To provide a method for evaluating or selecting an agent for reducing dullness objectively and efficiently.SOLUTION: A method for evaluating or selecting a dullness reducer involves the step for measuring the proliferation of Aureimoas bacteria or the level of biofilm components produced by the Aureimoas bacteria in the presence of a test substance.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for evaluating or selecting a dullness reducing agent.

Background Art

[0002] In textile products such as clothing, towels, bedding, and stuffed toys, dullness occurs due to use and aging deterioration. Since dullness has a negative impact on comfort and satisfaction during use, there is a demand for treatment agents or techniques for reducing dullness.

[0003] One of the causes of dullness is bacteria that have grown on fibers. In Non-Patent Document 1, it was confirmed that when bacteria of the genus Micrococcus were cultured on a fabric, the fabric changed color to yellow and a biofilm-like structure was formed in the discolored area. In Patent Document 1, it was disclosed that when a fabric in which bacteria of the genus Brevundimonas sp., which is one of the causative bacteria of the bad odor of laundry, were pre-grown was washed with a detergent in the presence of DNase, soil adhesion to the fabric was prevented compared to the case in the absence of DNase, suggesting the relationship between Brevundimonas bacteria and fabric soil. However, the relationship between dullness and bacteria has not been sufficiently studied.

[0004] On the other hand, bacteria of the genus Aureimonas are aerobic Gram-negative bacteria belonging to the class Alphaproteobacteria. Currently, 17 species names are known, and there are detection examples from environments such as the leaves and bark of plants, the air, and the ocean (Non-Patent Document 2). However, there are no reports on the isolation of bacteria of the genus Aureimonas from textile products or their association with the dullness of textile products.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Literature

[0006]

Non-Patent Literature 1

Non-Patent Literature 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention relates to a method for evaluating or selecting a stain-reducing agent.

Means for Solving the Problems

[0008] The inventors focused on towels and conducted investigations. As a result of examining the relationship between the stain intensity of towels, the flora in towels, and the amount of biofilm components of bacteria present in towels, it was found that there was a significant correlation between the stain intensity and the proportion of the genus Aureimonas bacteria in the flora, the stain intensity and the amount of biofilm components, and the proportion of the genus Aureimonas bacteria and the amount of biofilm components, respectively. Therefore, it is considered that it is possible to evaluate or select a stain-reducing agent using the growth property of the genus Aureimonas bacteria or the amount of biofilm components produced by the genus Aureimonas bacteria as an index.

[0009] That is, the present invention relates to a method for evaluating or selecting a stain-reducing agent, including a step of measuring the growth property of the genus Aureimonas bacteria or the amount of biofilm components produced by the genus Aureimonas bacteria in the presence of a test substance.

Effects of the Invention

[0010] According to the method of the present invention, an agent for reducing dullness can be objectively and efficiently evaluated or selected.

Embodiments for Carrying Out the Invention

[0011] In the present invention, "dullness" refers to discoloration occurring in an inanimate object, specifically, a decrease in the value of whiteness (W). The W value can be measured with a color difference meter for the lightness (L* value) of the inanimate object and the chromaticity (a* value and b* value) representing hue and chroma, and can be calculated from the obtained values by the calculation formula described in Griesser, R. Appita J. 1996, 49(2): 105-112. Alternatively, the W value can also be calculated by the CIE W10 method described in JIS L 1916:2000 Method for Measuring Whiteness of Textile Products. In the present invention, the degree of change in the W value (Delta whiteness, Dw), which is the value obtained by subtracting the W value after discoloration from the W value before discoloration of the inanimate object, can be used as an index of dullness intensity.

[0012] "Reduction of dullness" refers to maintaining or improving the dullness of an inanimate object without worsening it, specifically, maintaining or improving (increasing) the whiteness of the inanimate object.

[0013] Examples of the "inanimate object" targeted for reducing dullness include inanimate articles having a soft or hard solid surface on which bacteria are present, may be present, or may adhere, in other words, a solid surface on which bacteria may form a biofilm. Examples of the soft or hard solid surface include, for example, a soft surface such as a textile product; hard surfaces in homes and business facilities such as countertops, sinks, dressing rooms, toilets, bathtubs, shower stalls, floors, windows, doorknobs, walls, drains, pipes, etc.; and hard surfaces of various utensils, tools, sundries, etc. such as kitchenware, furniture, telephones, toys, etc. Here, the textile product includes a fabric formed by weaving or knitting filament natural fibers, regenerated fibers, synthetic fibers, etc. into a thin and wide sheet-like form with a large number of fibers, and processed products of the fabric produced by sewing, heat bonding, etc. using such a fabric. Examples of the processed product of the fabric include, for example, clothing (e.g., underwear, shirts, sweaters, skirts, sweats, absorbent articles (disposable diapers, sanitary napkins, incontinence pads, panty liners, etc.)), towels, accessories (e.g., slippers, scarves, stoles, gloves, socks, etc.), medical supplies (e.g., supporters, masks, gauze, bandages, etc.), bedding (e.g., futons, mats, cushions, pillows, blankets, etc.), covers (e.g., futon covers, cushion covers, pillow covers, sheets, zabuton covers, toilet seat covers, etc.), toys (e.g., stuffed animals, etc.). In the present invention, the inanimate object targeted for reducing dullness is preferably a textile product.

[0014] In the present invention, the "biofilm" refers to a structure formed by a community of microorganisms such as bacteria attached to the solid surface of an inanimate object together with secretions.

[0015] As shown in the following examples, correlation analysis was performed on the fading strength of towels after repeated use, washing, and drying, the flora in the towels, and the amount of biofilm components present in the towels. As a result, the fading strength and the proportion of the presence of bacteria of the genus Aureimonas in the flora, the fading strength and the amount of biofilm components, and the proportion of the presence of bacteria of the genus Aureimonas and the amount of biofilm components were significantly and positively correlated with each other. In addition, the culture cloth cultured together with the bacteria of the genus Aureimonas had a higher fading strength as a result of the recontamination test than the control without the addition of the bacteria of the genus Aureimonas, and it was revealed that the presence of the bacteria of the genus Aureimonas increased the degree of recontamination of dirt and made it easier to fade. These results indicate that the control of the amount of biofilm components produced by the bacteria of the genus Aureimonas and the bacteria of the genus Aureimonas can be a target for reducing fading, and that it is possible to evaluate or select a fading reducing agent using the growth property of the bacteria of the genus Aureimonas or the amount of biofilm components produced by the bacteria of the genus Aureimonas as an index.

[0016] The method for evaluating or selecting a fading reducing agent of the present invention includes a step of measuring the growth property of the bacteria of the genus Aureimonas or the amount of biofilm components produced by the bacteria of the genus Aureimonas in the presence of a test substance.

[0017] In one embodiment, the method for evaluating or selecting a fading reducing agent of the present invention includes the following steps (1) to (4). (1) A step of bringing a test substance into contact with the bacteria of the genus Aureimonas (2) A step of holding the bacteria of the genus Aureimonas in (1) for a certain period under conditions where the bacteria of the genus Aureimonas can grow (3) A step of measuring the growth property of the bacteria of the genus Aureimonas held for the certain period in (2) (4) A step of evaluating or selecting, as a fading reducing agent, a test substance that suppresses the growth of the bacteria of the genus Aureimonas based on the results measured in (3)

[0018] In another embodiment, the method for evaluating or selecting a fading reducing agent of the present invention includes the following steps (5) to (8). (5) Step of bringing Aureomonas bacteria and a test substance into contact with a pre-sterilized solid surface (6) Step of holding the Aureomonas bacteria brought into contact with the solid surface in (5) for a certain period under conditions in which the Aureomonas bacteria can grow (7) Step of measuring the amount of biofilm components on the solid surface in (6) (8) Step of evaluating or selecting, based on the results measured in (7), a test substance that reduces the amount of biofilm components as a haze reducing agent

[0019] As the Aureimonas bacteria used in the method of the present invention, aerobic Gram-negative bacteria belonging to the genus Aureimonas of the class Alphaproteobacteria can be mentioned. Specifically, Aureimonas ureilytica, Aureimonas altamirensis, Aureimonas endophitica, Aureimonas ferruginea, Aureimonas flava, Aureimonas frigidaquae, Aureimonas galii, Aureimonas glaciei, Aureimonas glaciistagni, Aureimonas jatrophae, Aureimonas leprariae, Aureimonas mangrovi, Aureimonas phyllosphaerae, Aureimonas populi, Aureimonas psammosilenae, Aureimonas pseudogalii, Aureimonas rubiginis, etc. can be mentioned, and preferably Aureimonas ureilytica or Aureimonas altamirensis. These predetermined bacterial strains can be obtained from public microbial depositories. For example, Aureimonas ureilytica and Aureimonas altamirensis can be obtained from the NITE Biological Resource Center (NBRC), National Institute of Technology and Evaluation, as NBRC106430 and NBRC107774, respectively.

[0020] In step (1), the test substance is brought into contact with bacteria of the genus Aureimonas. As a means for bringing the test substance into contact with bacteria of the genus Aureimonas, any means known in the art may be used. For example, application, addition, dropping, spraying, atomization, etc. of the test substance to bacteria of the genus Aureimonas can be mentioned. As the bacteria of the genus Aureimonas, the bacterial cells, bacterial liquid, etc. of bacteria of the genus Aureimonas can be used, but from the viewpoint of operability, it is preferable to use the bacterial liquid of bacteria of the genus Aureimonas. As the bacterial liquid of bacteria of the genus Aureimonas, it is sufficient if it contains viable bacteria of bacteria of the genus Aureimonas, and a culture solution of bacteria of the genus Aureimonas containing viable bacteria of bacteria of the genus Aureimonas and a culture medium is preferable. The culture medium is not particularly limited as long as bacteria of the genus Aureimonas can grow, and for example, R2A liquid medium (Shiotani MS), SCD medium "Digo" (Shiotani MS) can be exemplified.

[0021] In step (5), bacteria of the genus Aureimonas and the test substance are brought into contact with a solid surface sterilized in advance. Examples of the solid surface include the soft or hard solid surfaces of the inanimate objects described above, and preferably the soft solid surface of a textile product. The order of contact is not particularly limited. The test substance may be brought into contact with bacteria of the genus Aureimonas and then these may be brought into contact with a solid surface sterilized in advance, or the test substance may be brought into contact with a solid surface sterilized in advance and then bacteria of the genus Aureimonas may be further brought into contact with the solid surface, or bacteria of the genus Aureimonas may be brought into contact with a solid surface sterilized in advance and then the test substance may be further brought into contact with the solid surface. As a means for bringing the test substance into contact with bacteria of the genus Aureimonas, any means known in the art may be used, and the same methods as in the case of step (1) can be mentioned. As a means for bringing bacteria of the genus Aureimonas and / or the test substance into contact with the solid surface, any means known in the art may be used, and for example, application, addition, dropping, spraying, atomization, etc. of bacteria of the genus Aureimonas and / or the test substance to the solid surface can be mentioned. As the bacteria of the genus Aureimonas, the bacterial cells, bacterial liquid, etc. of bacteria of the genus Aureimonas can be used, but from the viewpoint of operability, it is preferable to use the bacterial liquid of bacteria of the genus Aureimonas. The bacterial liquid and culture medium of bacteria of the genus Aureimonas are the same as those in the case of step (1).

[0022] The "test substance" is not particularly limited as long as it can be used as a dullness reducing agent. Examples include animals and plants, marine organisms, microorganisms, etc. and their extracts; natural components derived therefrom; synthetic compounds; and mixtures and compositions thereof, etc.

[0023] The amount of bacteria of the genus Aureomonas, as well as the concentration and amount of the test substance, may be appropriately set based on the growth phase of the bacteria of the genus Aureomonas, the form, chemical properties, cytotoxicity, etc. of the test substance. For example, adding a predetermined amount of the test substance diluted to an appropriate concentration to a predetermined amount of bacteria can be mentioned.

[0024] In step (2) or (6), the bacteria of the genus Aureomonas contacted with the test substance in step (1) or the bacteria of the genus Aureomonas contacted with the fixed surface in step (5) are held for a certain period under conditions where the bacteria of the genus Aureomonas can grow, and the bacteria of the genus Aureomonas are cultured. Here, "capable of growing" means "capable of proliferating". The conditions are not particularly limited as long as they are conditions under which the bacteria of the genus Aureomonas grow well. For example, it can be mentioned that the temperature is 4 to 40 °C, preferably 25 to 37 °C, and under aerobic conditions, preferably shaking culture. Since the growth rate of the bacteria of the genus Aureomonas may vary depending on the test substance, the holding period may be appropriately set in consideration of the form, chemical properties, cytotoxicity, etc. of the test substance. Usually, for example, it is 4 to 72 hours, preferably 8 to 48 hours. The container used for holding is not particularly limited as long as it does not affect the growth of the test substance and the bacteria of the genus Aureomonas, and ordinary glass bottles, glass tubes, centrifuge tubes, plastic containers, etc. can be used.

[0025] In step (3), the growth property of the Aureomonas bacteria retained in step (2) for a certain period is measured. Here, "growth property" refers to the number of bacteria capable of growth. The growth property of the Aureomonas bacteria retained for a certain period can be measured according to methods known in the art using the number of bacteria (concentration) of the Aureomonas bacteria as an index. Specifically, for example, it can be determined by the number of bacteria after retention or the difference or ratio of the number of bacteria before and after retention. As methods for measuring the number of bacteria, methods such as measuring the number of bacteria by spreading on a plate, measuring absorbance, measuring heat, measuring ATP, measuring impedance, and measuring the number of bacteria by real-time PCR can be used.

[0026] Next, in step (4), based on the results measured in step (3), a test substance that suppresses the growth of the Aureomonas bacteria is evaluated or selected as a reduction agent for blurring. Such evaluation or selection is performed, for example, by comparing a test substance contact group with a test substance non-contact group or a control substance contact group or before the test substance contact in the test substance contact group. Alternatively, the evaluation is performed by comparing the measurement results among test substances at various concentrations.

[0027] For example, in the test substance contact group, when the number of bacteria (concentration) of the Aureomonas bacteria after retention or the difference or ratio of the number of bacteria (concentration) of the Aureomonas bacteria before and after retention is less than that in the test substance non-contact group or the control substance contact group, the test substance is evaluated or selected as a reduction agent for blurring. In this case, it can be determined whether the number of bacteria of the Aureomonas bacteria after retention or the difference or ratio of the number of bacteria of the Aureomonas bacteria before and after retention in the test substance contact group is statistically significantly less than that in the test substance non-contact group or the control substance contact group. Alternatively, when the number of bacteria of the Aureomonas bacteria after retention or the difference or ratio of the number of bacteria of the Aureomonas bacteria before and after retention in the test substance non-contact group or the control substance contact group is set to 100%, it can be determined whether the number of bacteria of the Aureomonas bacteria after retention or the difference or ratio of the number of bacteria of the Aureomonas bacteria before and after retention in the test substance addition group is at a certain level or below, for example, 10% or below, preferably 1% or below. Alternatively, for example, in the test substance contact group, if the number of bacteria (concentration) of Aureomonas bacteria after retention is less than the number of bacteria (concentration) of Aureomonas bacteria before contact with the test substance in the test substance contact group, the test substance is evaluated or selected as a haze reducing agent. In this case, it can be determined based on whether the number of bacteria of Aureomonas bacteria after retention in the test substance contact group is significantly less than the number of bacteria of Aureomonas bacteria before contact with the test substance in the test substance contact group. Alternatively, when the number of bacteria of Aureomonas bacteria before contact with the test substance in the test substance contact group is taken as 100%, it can be determined based on whether the number of bacteria of Aureomonas bacteria after retention in the test substance contact group is below a certain level, for example, 10% or less, preferably 1% or less.

[0028] In step (7), the production amount of the biofilm constituent components on the solid surface retained in step (6) is measured. On the solid surface, since the biofilm is formed by Aureomonas bacteria derived from the bacterial solution, the measured amount of the biofilm constituent components is substantially the amount of the biofilm constituent components produced by Aureomonas bacteria. Examples of the biofilm constituent components generally include proteins, nucleic acids, polysaccharides, and the like. The production amount of the biofilm constituent components may be measured by means known in the art according to various components. For example, as an example of the method for measuring the protein amount, the Lowry method (O. Lowry et al. J. Biol. Chem., 1951, 193(1)) can be mentioned. As an example of the method for measuring the nucleic acid amount, a method of measuring using a commercially available kit such as Qubit (registered trademark) dsDNA HS Assay Kit (Thermo Fisher Scientific) can be mentioned. As an example of the method for measuring the polysaccharide amount, the phenol-sulfuric acid method (M. Dubois et al. Anal. Chem., 1956, 28(3)) can be mentioned.

[0029] Next, in step (8), based on the results measured in step (7), a test substance that reduces the amount of the biofilm constituent components is evaluated or selected as a haze reducing agent. Such evaluation or selection is performed, for example, by comparing a test substance contact group with a non-test substance contact group or a control substance contact group. Alternatively, the evaluation is performed by comparing measurement results among test substances at various concentrations.

[0030] For example, in the test substance contact group, if the amount of biofilm components is less than that in the non-test substance contact group or the control substance contact group, the test substance is evaluated or selected as a haze reducing agent. In this case, it can be determined whether the amount of biofilm components in the test substance contact group is statistically significantly less than that in the non-test substance contact group or the control substance contact group. Alternatively, when the amount of biofilm components in the non-test substance contact group or the control substance contact group is taken as 100%, it can be determined whether the amount of biofilm components in the test substance contact group is at a certain level or below, for example, 90% or below, preferably 50% or below, more preferably 10% or below.

[0031] The haze reducing agent thus obtained can be used not only by adding it to daily necessities such as laundry detergents for reducing haze, but also by blending it into cosmetics, quasi-drugs, pharmaceuticals, etc.

Example

[0032] Hereinafter, examples are shown to more specifically explain the present invention.

[0033] Example 1 Correlation among towel haze intensity, amount of biofilm components extracted from towel, and proportion of Aureimonas bacteria in flora Correlation analysis was performed on towel haze intensity, amount of biofilm components extracted from towel, and flora of towel.

[0034] (1) Analytical towel As the analysis target, a total of 78 towels that had been repeatedly used and washed for 2 to 6 months from a new state were used.

[0035] (2) Measurement of haze intensity The discoloration resistance of each towel was measured using a color difference meter. Specifically, the L*, a*, and b* values were measured for a 12-cm square cut-out towel piece. The whiteness was calculated from the obtained values (Griesser, R. Appita J. 1996, 49(2): 105-112), and the same towel piece in different regions was similarly measured three times, and the average value was taken as the Whiteness (W) value. Next, in order to represent how much the towel discolored relatively due to use and washing, the Delta whiteness (Dw) value was calculated according to the following formula. The Dw value of the towel represents the degree of discoloration that occurs through use, washing, and drying, that is, the discoloration resistance. (Equation 1) Dw = (W value of new towel) - (W value of used towel)

[0036] (3) Measurement of biofilm component amounts As the component amounts of the biofilm, the amounts of protein and nucleic acid were quantified. One 30-mg towel piece was cut out from a site that was thought to be frequently used in the collected towels, and for the fraction obtained by centrifuging the alkali-heated extract from the towel piece, the protein amount was measured by the Lowry method (O. Lowry et al. J. Biol. Chem., 1951, 193(1)), and the nucleic acid amount was measured using the Qubit (registered trademark) dsDNA HS Assay Kit (Thermo Fisher Scientific) according to the attached protocol.

[0037] (4) Microbiota analysis The microbiota analysis targeted the 16S rRNA of bacteria and was performed using a next-generation sequencer. Specifically, DNA extraction was carried out on a 1 cm square piece of the cut towel. Regarding the method of DNA extraction, the 1 cm square piece of the towel was further divided into four parts to make it 0.5 cm square, and each was placed in a 2 mL cryogenic disruption tube (Yasui Kikai) together with a metal cone (Yasui Kikai). It was frozen with liquid nitrogen and the operation of disrupting it at 2,000 rpm for 1 minute with a multi-bead shocker (Yasui Kikai) was repeated twice. 1 mL of buffer (10 mM EDTA, 1.0% (w / v) dodecyl sulfate, 10 mM Tris-HCl (pH 8.0)) was added to the disrupted tube and stirred vigorously. 500 μL of the supernatant containing disrupted fibers was collected from each of the four tubes and transferred to a single centrifuge tube. 700 μL of Phenol:Chloroform:Isoamyl alcohol (25:24:1, PCI) and zirconia beads (Zircoprep mini, Nippon Genetics) were added to the centrifuge tube and stirred vigorously for 5 minutes. After centrifuging the centrifuge tube at 8,000×g for 10 minutes at room temperature, 700 μL of the aqueous layer was transferred to a 1.5 mL centrifuge tube. 700 μL of PCI was added to the tube and stirred vigorously for 5 minutes. After centrifuging the tube at 12,000 rpm for 5 minutes at room temperature, 400 μL of the aqueous layer was transferred to a new 1.5 mL centrifuge tube. The genomic DNA purified according to the recommended protocol of Ethachinmate (Nippon Gene) was air-dried and then dissolved in 100 μL of TE buffer [pH 8.0] (Nippon Gene). The prepared genomic DNA was diluted 10-fold with TE buffer [pH 8.0] and then subjected to a PCR reaction. The nucleotide sequence amplified by PCR targeting the V3V4 region of the 16S rRNA gene in the extracted genomic DNA was analyzed using the next-generation sequencer MiSeq (Illumina). In the PCR reaction, the primers used were the Forward primer (341F: 5’-CCTACGGGNGGCWGCAG-3’ (SEQ ID NO: 1)) and the Reverse primer (805R_mod: 5’-GACTACHVGGGTATCTAAKCC-3’ (SEQ ID NO: 2)) synthesized by FASMAC Co., Ltd.The obtained data was analyzed using Qiime2 (E. Bolyen et al. Nat. Biotechnol., 2019, 37(8)) and then organized by Phyloseq (P. McMurdie et al. PLoS ONE, 2013, 8(4)) to clarify the abundance ratio of each bacterium.

[0038] (5) Correlation analysis of the musty intensity of the towel, the amount of biofilm components extracted from the towel, and the microbiota Correlation analysis of the musty intensity of the towel, the amount of biofilm components extracted from the towel, and bacteria (at the genus level) with an average abundance rate of 0.1% or more in the microbiota was performed by Pairwise Spearman’s correlation analysis. The Holm method was used for p-value correction.

[0039] (6) Results of the correlation analysis Table 1 shows the results of the correlation analysis of the abundance ratio of Aureimonas bacteria in the microbiota, the amount of biofilm components extracted from the towel, and the musty intensity of the towel. There was a significantly positive correlation between the abundance ratio of Aureimonas bacteria and the musty intensity of the towel, the abundance ratio of Aureimonas bacteria and the amount of biofilm components extracted from the towel, and the musty intensity of the towel and the amount of biofilm components extracted from the towel (q < 0.05).

[0040]

Table 1

[0041] Example 2 Recontamination of the mud by the Aureimonas bacteria culture cloth When Aureimonas bacteria were cultured on the cloth, it was confirmed whether the cloth was prone to becoming musty.

[0042] (1) Target strains Based on the results of the flora analysis in Example 1, the species were estimated from the DNA sequence information detected as the genus Aureimonas, and tests were conducted using Aureimonas ureilytica (NBRC106430) and Aureimonas altamirensis (NBRC107774).

[0043] (2) Preparation of bacterial solution Two species of bacteria belonging to the genus Aureimonas were cultured on R2A agar medium (Shiotani MS) at 30 °C for 24 hours. The colonies after culture were scraped off, suspended in R2A liquid medium (Shiotani MS), and the culture obtained by shaking culture at 30 °C, 200 rpm for 19 hours was used as the bacterial solution.

[0044] (3) Preparation of Aureimonas bacterial culture cloth A 3 cm square plain-woven cloth was placed in a sterilized test tube (φ22 mm) with a silicone stopper, and 10 mL of R2A liquid medium and 100 μL of the bacterial solution adjusted to OD600 = 0.3 were added, followed by shaking culture at 30 °C, 200 rpm for 24 hours. The plain-woven cloth was taken out and dried to obtain the Aureimonas bacterial culture cloth. Also, during the above operation, a control cloth was prepared by adding 100 μL of R2A liquid medium instead of the bacterial solution.

[0045] (4) Recontamination test on Aureimonas bacterial culture cloth In sterilized water with the hardness adjusted to 4°dH, Emulgen 108 (Polyoxyethylene(6) lauryl ether, Kao) was added to a final concentration of 200 ppm, and mud (Kanuma soil) was added to a final concentration of 250 ppm. The mixture was subjected to ultrasonic treatment for 1 hour and used as the recontamination solution. 10 mL of the recontamination solution and an Aureomonas bacterial culture cloth or a control cloth were placed in a UV-sterilized screw tube and shaken at 25 °C and 160 rpm for 30 minutes. 10 mL of 4°dH hard water was added to the screw tube from which the recontamination solution had been removed, and the operation of shaking at 25 °C and 160 rpm for 5 minutes was performed twice. The cloth was taken out of the screw tube, excess moisture was removed by sandwiching it with a clean paper towel, and then it was dried for 1 hour or more to obtain the recontaminated cloth. The whiteness of the recontaminated cloth was measured with a color difference meter, and the Dw value was calculated in the same manner as in Example 1(2).

[0046] (5) Results of the recontamination test Table 2 shows the results of the recontamination test. As a result of the Wilcoxon test, the Dw value of each Aureomonas bacterial culture cloth increased significantly compared to the control cloth. Therefore, it was shown that the cloth was likely to become dull in the presence of Aureomonas bacteria.

[0047]

Table 2

Claims

1. A method for evaluating or selecting a stain reducing agent, comprising the following steps (1) to (4). (1) A step of bringing a test substance into contact with a bacterium of the genus Aureimonas (2) A step of holding the Aureimonas bacterium of (1) for a certain period under conditions where the Aureimonas bacterium can grow (3) A step of measuring the growth property of the Aureimonas bacterium held for the certain period of (2) (4) A step of evaluating or selecting, as a stain reducing agent, a test substance that suppresses the growth of the Aureimonas bacterium based on the result measured in (3)

2. A method for evaluating or selecting a stain reducing agent, comprising the following steps (5) to (8). (5) A step of bringing a bacterium of the genus Aureimonas and a test substance into contact with a previously sterilized solid surface (6) A step of holding the Aureimonas bacterium brought into contact with the solid surface of (5) for a certain period under conditions where the Aureimonas bacterium can grow (7) A step of measuring the amount of biofilm components on the solid surface of (6) (8) A step of evaluating or selecting, as a stain reducing agent, a test substance that reduces the amount of biofilm components based on the result measured in (7)

3. The method according to claim 1 or 2, wherein the stain reducing agent is a stain maintaining or improving agent

4. The method according to claim 1 or 2, wherein the stain reducing agent is a whiteness maintaining or improving agent

5. The method according to claim 1 or 2, wherein the stain reducing agent is a stain reducing agent for textile products

6. The method according to claim 1 or 2, wherein the Aureimonas bacterium is Aureimonas ureilytica or Aureimonas altamirensis

7. The method according to claim 5, wherein the Aureimonas bacterium is Aureimonas ureilytica or Aureimonas altamirensis

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