JP2011000045A - Medium for detecting lactic acid bacterium and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medium for detecting lactic acid bacteria, which accurately and efficiently decides the presence or absence of lactic acid bacteria in a check sample and is widely usable for examinations and production process examinations of general foods, beverages, water, etc., and a method for detecting lactic acid bacteria, using the medium.SOLUTION: The medium for detecting lactic acid bacteria contains an enzyme substrate to be hydrolyzed by β-galactosidase, a microorganism growth inhibitor other than lactic acid bacteria and a pH adjustor for adjusting the pH to 5.0-6.5. The method for detecting lactic acid bacteria includes using the medium.

Description

  The present invention relates to a medium for detecting lactic acid bacteria capable of determining the presence or absence of lactic acid bacteria in a test sample visually or under fluorescence, and a method for detecting lactic acid bacteria using the same.

Lactic acid bacteria have long been used in many food processing such as miso, soy sauce, sake, wine, yogurt, cheese, lactic acid bacteria beverages, pickles, fermented sausages, fermented tea, and unfamiliar. In addition, the health function of lactic acid bacteria has been elucidated, and foods for specified health use using probiotic lactic acid bacteria are establishing a new food market.
However, lactic acid bacteria utilized as useful bacteria mainly in the food processing field, on the other hand, cause various deterioration such as acidity, acid odor, and production of neto. For example, roasted moromi in which the taste in sake brewing is soured, fires in which bottled products are spoiled, unpleasant taste and turbidity of unheated beer, acidity in fish paste products and low-salt pickles, etc. Is the cause. Lactic acid bacteria are involved in processing stages and product quality abnormalities in meat products such as ham and wiener sausages and processed foods such as side dishes, hamburgers and fried foods.
Moreover, since many foods and beverages using lactic acid bacteria are manufactured reflecting the health food boom, there is a possibility that such lactic acid bacteria may be mixed into other foods, alcoholic beverages, and the like during the production line.

  Lactic acid bacteria rarely cause health hazards, but the deterioration of foods caused by lactic acid bacteria is not desirable for quality control, and if not discovered early, there is a large economic loss, and its control is important for food processing manufacturers. It is a difficult task. In order to prevent food quality abnormalities caused by lactic acid bacteria in various foods, not just meat products, priority is given to eliminating lactic acid bacteria, resulting in the elimination of many pathogenic bacteria, other harmful bacteria, and bacteria other than the intended ones. Is also connected. In addition, the inspection of lactic acid bacteria in such cases is part of the quality control of mass-produced products at the manufacturer, so that not only the operation is simple, but the results are obtained quickly and the judgment is easy. It is necessary.

From these facts, the following detection media for lactic acid bacteria are known.
(A) BCP-added plate count agar medium It is described in an official method for measuring the number of bacteria (see Non-Patent Document 1). Taking advantage of the fact that BCP changes from purple to yellow when it becomes acidic due to lactic acid production, colonies that grow yellow around the agar medium are measured as lactic acid bacteria.
(B) MRS agar medium, BL agar medium These two culture media are both described in the official method as a method for measuring the number of bacteria (see Non-Patent Document 1). Although effective for the growth of lactic acid bacteria, there is no selectivity, and microorganisms other than lactic acid bacteria grow actively.
(C) APT agar A medium developed for lactic acid bacteria (see Non-Patent Document 2), which contains glucose 10 g / L.
(D) APT agar + BCP
It is the culture medium (refer nonpatent literature 3) which added BCP which is a pH indicator to APT agar.
(E) LBS agar medium It has been reported that the selectivity of Lactobacillus is higher than the tomato juice medium that was developed as a selective medium for Lactobacillus and has been used before (see Non-Patent Document 4). Agar plates are cultured at 35 ° C. in a carbon dioxide atmosphere.

  Furthermore, as a detection medium for lactic acid bacteria and a method for detecting lactic acid bacteria using the same, for example, culture is performed in a detection liquid medium for lactic acid bacteria having a pH of 6.2 ± 0.2, and the culture solution is removed to obtain bacterial cells. By adding a fluorescent substance (acridine orange-10-dodecyl bromide) and measuring the viable cell count by fluorescence intensity (see Patent Document 1), or by adding a whiskey distillation residue to an existing medium such as Modified NBB medium, Detection of beer lactic acid bacteria that are harmful to beer brewing, with the addition of cytidine, thymidine, and fermented wort as a growth-promoting substance for lactic acid bacteria (see Patent Document 2) A culture medium for bacterial count measurement (see Patent Document 3) has been proposed.

  Further, as a selective detection method of a lactic acid bacterium using a medium that selectively detects a specific lactic acid bacterium, for example, propionic acid or a salt thereof is used in addition to oligosaccharide, and Bifidobacterium and lactic acid bacterium are used. As a growth promoter in a selective / viable cell count medium (see Patent Document 4) for preferential growth of Bifidobacteria from among the substances containing selenium and measuring the number of bacteria A medium for selective detection and bacterial count measurement of lactic acid bacteria belonging to the genus Bifidobacterium containing lithium chloride and galactose (see Patent Document 5), and for culturing lactic acid bacteria belonging to the genus Bifidobacterium containing oligosaccharides Agar medium for selection / viability count measurement (see Patent Document 6) and liquid selection medium for culturing lactic acid bacteria belonging to the genus Bifidobacterium using a pH indicator (Patent Document 7) Irradiation) has been proposed.

  However, there is a need for a medium that can accurately and easily detect lactic acid bacteria in a wide range of test samples such as foods and beverages, and a detection method using the medium.

Food Sanitation Inspection Guidelines Microorganisms, supervised by the Ministry of Health, Labor and Welfare, 2004 Shaepe, M. E. and Fryer, T.F., Laboratory Practice, June, 1965 Compendium of methods for the microbiological examination of foods, Second editon, Marvin L. Speck, Editor, 1984 Rogosa, Mitchell and Wiseman, J. Bacteriol, 62; 132, 1951

Japanese Patent Laid-Open No. 6-113887 Japanese Patent Laid-Open No. 03-91493 Japanese Patent Laid-Open No. 03-130071 Japanese Patent Laid-Open No. 11-28098 JP-A-6-343491 JP-A-4-20283 Japanese Patent Laid-Open No. 7-99995

  The present invention uses a lactic acid bacteria detection medium that can accurately and efficiently be used for the presence or absence of lactic acid bacteria in a test sample, and that can be widely used for inspection of general foods, beverages, water, etc. and manufacturing process inspections, and this medium. The present invention relates to providing a method for detecting lactic acid bacteria.

  As a result of studying various lactic acid bacteria detection media in view of such circumstances, the present inventor has often found that bacteria other than lactic acid bacteria grow or that it is difficult to visually distinguish lactic acid bacteria. By adding three components to the medium, an enzyme substrate that is degraded by β-galactosidase, a microbial growth inhibitor other than lactic acid bacteria (particularly aminoglycoside antibiotics), and a pH adjuster that adjusts the pH to 5.0 to 6.5. The presence of lactic acid bacteria because the enzyme (β-galactosidase) is specifically produced at the stage of growth of lactic acid bacteria present in food, beverages, and other specimens, and this reacts with the enzyme substrate to color the settlement and its surroundings. Can be confirmed quickly and easily, and aminoglycoside antibiotics can suppress the growth of microorganisms other than lactic acid bacteria such as coliforms that produce β-galactosidase. Since the kill, it can be detected accurately and efficiently lactic acid bacteria, moreover, common foods and beverages, found that it is also widely used in inspection and manufacturing process inspection, such as water, has led to the completion of the present invention.

That is, the present invention provides a medium for detecting lactic acid bacteria comprising an enzyme substrate that is degraded by β-galactosidase, a microbial growth inhibitor other than lactic acid bacteria, and a pH adjuster that adjusts the pH to 5.0 to 6.5. .
In addition, the present invention provides a method for detecting lactic acid bacteria, which comprises inoculating a subject with the lactic acid detection medium and then culturing, and determining the color of the colony visually or under fluorescence.

  According to the lactic acid bacteria detection medium of the present invention and the method for detecting lactic acid bacteria using the same, when lactic acid bacteria are present in the subject, the lactic acid bacteria are selectively grown and colored so that they can be recognized visually or under fluorescence. Therefore, the presence of lactic acid bacteria can be confirmed accurately, efficiently and simply. In addition, the present invention can be widely used for inspection of general foods, beverages, water, etc. in which various microorganisms exist and manufacturing process inspection.

The target lactic acid bacteria to be detected in the present invention is a general term for bacteria that ferment sugar and produce a large amount of lactic acid. This lactic acid bacterium is classified into Lactobacillus genus, Pediococcus genus, Tetragenococcus genus, Carnobacterium genus, Vagococcus genus, Leuconostoc genus, Weissella genus, Oenococcus genus, Streptococcus genus, Enterococcus genus, Lactococcus genus, Enterococcus genus, Bifidobacterium genus, etc. About two hundred and ten types of lactic acid bacteria have been reported.
Among these, Lactobacillus genus (e.g. Lactobacillus acidophilus, Lactobacillus delbrueckii subsp.bulgaricus, Lactobacillus delbrueckii subsp. (Eg Streptococcus thermophilus); Lactococcus genus (eg Lactococcus lactis subsp. Cremoris etc.); Enterococcus genus (eg Enterococcus faecalis, Enterococcus faecium etc); Pediococcus genus (eg Pediococcus acidilactici, Pediococcus pencoscus (For example, Leuconostoc mesenteroides subsp. Mesentedoides, Leuconostoc citreum, Leuconostoc mesenteroide subsp. Dextranicum, etc.); entium etc.) is preferred. Among these, the genus Lactobacillus and the genus Leuconostoc are more preferable, and the genus Lactobacillus is particularly preferable.

The enzyme substrate decomposed by β-galactosidase used in the medium of the present invention is a coloring substance (color) that reacts with an enzyme (β-galactosidase) specifically produced at the stage where lactic acid bacteria develop and can be recognized visually or in the presence of fluorescence. There is no particular limitation as long as it is a chromogenic enzyme substrate from which a base compound and a fluorescent compound are produced. As the chromogenic enzyme substrate, 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (also referred to as “X-β-Gal” or “X-β-gal”, blue), 5 -Bromo-6-chloro-3-indoxyl-β-D-galactopyranoside (MAGENTA-β-galactopyranoside, magenta), 5-bromo-6-chloro-3-indolyl-β-D- Galactopyranoside (red purple), 6-chloro-3-indolyl-β-D-galactopyranoside (pink) and orthonitrophenyl-β-D-galactopyranoside (also referred to as “ONPG”, yellow) One or more selected from the above are mentioned, and X-β-Gal that can easily recognize a colored colony is particularly preferable.
The content of the enzyme substrate in the medium is not particularly limited, but is preferably 0.015 to 1.5% by mass in the medium.

The microorganisms other than lactic acid bacteria (hereinafter, also referred to as “other microorganisms”) used in the culture medium of the present invention have a weak growth inhibitory action against lactic acid bacteria, and preferably have a growth inhibitory action against other microorganisms. What can adjust the growth of these microorganisms by adjusting the content of the growth inhibitory substance is desirable.
Examples of the growth inhibitor include aminoglycoside antibiotics (for example, kanamycins such as kanamycin and bekanamycin; streptomycin; gentamicin; tobramycin; amikacin; dibekacin; arbekacin) and the like.
Among the aminoglycoside antibiotics, kanamycin antibiotics are particularly preferable because they inhibit the growth of coliforms that decompose X-β-Gal and the like and hardly inhibit the growth of lactic acid bacteria.
The content of the microbial growth inhibitor other than lactic acid bacteria is 0.001 to 0.2% by mass, more 0.001 to 0.04% by mass, further 0.003 to 0.02% by mass, and even more 0 in the medium. It is preferably 0.004 to 0.0095% by mass, more preferably 0.0045 to 0.009% by mass, and especially 0.005 to 0.009% by mass inhibits the growth of other microorganisms. However, it is preferable because lactic acid bacteria can grow. In the case of selectively detecting the genus Lactobacillus, the genus Lactobacillus has a small inhibitory effect on growth by kanamycin antibiotics, and is preferably 0.0045 to 0.04% by mass in the medium.

  The pH adjuster used in the medium of the present invention is preferably one that can adjust the pH of the medium at the time of inoculation with lactic acid bacteria to 5.0 to 6.5, more preferably 5.0 to 6.2, Although 5.0 to 5.9 can be used together with the growth inhibitory substance, the lactic acid bacteria can grow well and can inhibit the growth of many other microorganisms (particularly coliforms). This is preferable because it facilitates detection. Examples of components used in the pH adjuster include organic acid salts such as oxalic acid, acetic acid, fumaric acid, malic acid, lactic acid, gluconic acid, and tartaric acid, carbonates such as sodium carbonate and sodium hydrogen carbonate, phosphoric acid, hydrochloric acid, and the like. One or more selected from inorganic salts such as sulfuric acid, hydroxides such as sodium hydroxide, ammonia or aqueous ammonia, citrate amines, lower alkanolamines, basic amino acids such as arginine and lysine It is done.

The medium of the present invention can be obtained by a general production method by blending optional components such as a carbon source, a nitrogen source, minerals and vitamins in addition to the above essential components.
For example, the carbon source is one or more selected from fructose, lactose, saccharose, etc .; the nitrogen source is one or more selected from proteolysate, yeast extract, fish extract, etc .: As this mineral source Is one or more selected from copper, zinc, magnesium, cobalt and the like: Examples of vitamins include one or more selected from nicotinic acid, pantothenate, biotin, riboflavin, folic acid and the like.
The basal medium containing these carbon sources may be a known basal medium for detecting lactic acid bacteria, such as MRS medium, BL medium, APT medium, APT + BCP medium, and LBS medium as described in Patent Documents 1 to 5. These medium compositions may be changed as appropriate.

The basal medium preferably contains a lactic acid bacteria growth promoting component.
As this lactic acid bacteria growth promoting component, barley shochu distillation residue (see Japanese Patent No. 3527661), calcium salt (see Japanese Patent No. 2673333), buttermilk (see Japanese Patent Laid-Open No. 2000-102380), whiskey distillation residue (see JP-A-03-91493), cytidine and thymidine, fermented wort (see JP-A-03-130071), sake lees extract (see JP-A-3-172171), citrate or malic acid Salt (see JP-A-57-102184), L-cysteine (see JP-A-54-143585), free base (adenine, cytosine, guanine, thymine, uracil and inosine), ribonucleoside (adenosine, cytidine) , Guanosine, uridine) and deoxyribonucleoside (2'-deoxyadenosine, 2'-deoxysi) Gin, 2′-deoxyguanosine, 2′-deoxyuridine and thymidine) (see JP 2000-279166), Gal- (Gal) n-Glc (n = 1 to 4) oligosaccharides, propionic acid or Examples thereof include one or more selected from salts thereof (see JP-A-11-28098 and JP-A-4-20283), lithium chloride and galactose (see JP-A-6-343491).

Further, the medium of the present invention may contain solidifying components such as gelatin, agar, and carrageenan in order to obtain a solid or semi-solid medium.
Moreover, you may use fibrous liquid absorption raw materials, such as a fibrous water absorbing sheet, which make a culture medium of this invention absorb a liquid culture medium. Examples of the fibers include natural fibers derived from plants, animals and the like, chemical fibers derived from chemical synthesis, glass fibers, and the like, and nonwoven fabrics in which the fibers are formed into a sheet shape are preferable.

  As a method for preparing the culture medium of the present invention, for example, after adding purified water or the like to each of the above-mentioned medium composition components, mixing and stirring, sterilizing with an autoclave or the like, dispensing this into a sterilized petri dish, etc., and cooling or allowing to cool Method: A method in which ethanol, purified water, or the like is added to each medium component described above, mixed and stirred, and then dispensed into a container containing a fibrous liquid absorbent material, followed by sterilization by gamma irradiation.

  In the method for detecting lactic acid bacteria of the present invention, the lactic acid bacteria detection medium obtained above is inoculated with a subject, cultured under predetermined conditions, and the color of the formed colony is confirmed visually or in the presence of fluorescence. Then, the presence or absence of lactic acid bacteria is determined.

Although it does not specifically limit as a test object, Test samples, such as a foodstuff, a drink, a river, seawater, are mentioned. This test sample may be cultivated as it is or after concentrating or diluting it and inoculating the medium of the present invention. At this time, it is preferable to dilute the test sample about 10 ⁻² to 10 ⁻¹⁰ times at the time of inoculation from the viewpoint of the number of settlements.
Further, the inoculation method is not particularly limited, but a flat plate smearing method and an image smearing method are preferable.

The culture conditions may be any of anaerobic culture, aerobic culture, or carbon dioxide gas culture, and the atmosphere at this time may be any of air, nitrogen gas, argon gas, helium gas, and carbon dioxide gas. Among these, from the viewpoint of growth of lactic acid bacteria, carbon dioxide gas culture under an atmosphere of carbon dioxide gas is particularly preferable.
Moreover, although culture | cultivation temperature is not specifically limited, 25-42 degreeC which is the temperature suitable for growth of lactic acid bacteria, especially 30-40 degreeC is preferable.
The number of days for cultivation is not particularly limited, but is preferably 24 to 96 hours, particularly 40 to 72 hours.

The color of the lactic acid bacteria colonies (including their surroundings) formed in the medium varies depending on the chromogenic enzyme substrate to be used. In the case of X-β-Gal, the color tone is light blue to blue and blue-green. In this case, the color tone of yellow is determined to be a colony of lactic acid bacteria based on the presence of such a color tone. On the other hand, if the color tone is not found, it is determined not to be a colony of lactic acid bacteria. In this way, the presence or absence of lactic acid bacteria in the sample and the number of settlements are determined.
Here, under fluorescence is meant to include visual observation under illumination of a fluorescent lamp. For example, even when detection (absorbance measurement) is performed at a specific wavelength (380 to 570 nm) in the case of X-β-Gal. Good. In the case of absorbance measurement, since the number of bacterial cells and the absorbance are proportional, it may be determined that the higher the absorbance, the more lactic acid bacteria are present, or the amount of lactic acid bacteria present may be quantified in comparison with a standard. On the other hand, if the absorbance is almost the same as that of the control (no subject added), it may be determined that lactic acid bacteria are not present.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
After preparing an MRS agar medium (Difco) (pH 6.5), X-β-gal (Biosynth) was added to the medium so as to be 0.15% by mass to obtain a test medium.
After preparing a blood agar medium (tryptosoya agar medium (Nissui Pharmaceutical) as a basic medium and 5% horse defibrillated blood (Kohjin Bio) added), the one without X-β-gal is called “blood agar” Using.
20 kinds of lactic acid bacteria as shown in Table 1 were inoculated into this, and aerobic culture (in an atmosphere of about 21% oxygen and about 78% nitrogen) or anaerobic culture (5% hydrogen, 37 ° C or 25 ° C) Under an atmosphere of 10% carbon dioxide and 85% nitrogen), the color and colony diameter (mm) of the colonies formed at this time were measured. The results are shown in Table 1.
As shown in Table 1, it is recognized that many lactic acid bacteria form blue colonies in the test medium, and various lactic acid bacteria can be detected by using an enzyme substrate that is degraded by β-galactosidase. Admitted.

Example 2
After preparing MRS agar medium (Difco) (pH 6.5), X-β-gal (Biosynth) was added to the medium so as to be 0.15% by mass, and kanamycin 0-100 mg / ml was added in the medium. , 0 to 0.15 mass% (0.15, 0.075, 0.0375, 0.0188, 0.0094, 0.0047, 0 mass%) to obtain a test medium.
After preparing a blood agar medium (tryptosoya agar medium (Nissui Pharmaceutical) as a basic medium and 5% horse defibrinated blood added), the one without X-β-gal and kanamycin was used as “blood agar” .
11 types of lactic acid bacteria as shown in Table 2 and strains other than 6 types of lactic acid bacteria were identified as microplanters (Hidemasa Odaka et al., J. Jpn. Soc. Clin. Microbiol., 10 (1), 6-17, 2000), and aerobic culture (in an atmosphere of about 21% oxygen and about 78% nitrogen) was performed for 48 hours, and its growth was judged. The results are shown in Table 2.
As shown in Table 2, when the concentration of kanamycin is higher than a certain concentration (especially 0.0047% by mass) in the medium, lactic acid bacteria grow, but bacteria other than lactic acid bacteria (especially E. coli and Enterobacter sp.) Growth can be suppressed. In particular, in the genus Lactobacillus, growth was observed even when the concentration of kanamycin in the medium was high.

Example 3
After preparing MRS agar medium (Difco) (pH 6.5), X-β-gal (Biosynth) is added to the medium so as to be 0.15% by mass, and kanamycin is 0.0086% by mass in the medium. As described above, this was used as “main medium”.
In the same manner as above, X-β-gal was added to the MRS agar medium, but kanamycin was not added as the “reference medium”. The blood agar medium (tryptosoya agar medium (Nissui Pharmaceutical) was used as the basic medium) After preparation of fiber blood (5% added), the product without X-β-gal was used as “blood agar”.
4 kinds of lactic acid bacteria and 4 kinds of coliform bacteria shown in Table 3 were inoculated by the MISULA method (literature; MILESA,. A, et al., 1938. J. Hyg., Cu d., 38, p732.) Then, carbon dioxide gas culture was performed at 35 ° C. for 48 hours, and the number of colonies, color, and colony diameter (mm) were measured. The results are shown in Table 3.
As shown in Table 3, it was confirmed that by adding a kanamycin concentration of 0.0086% by mass in the medium, the growth of lactic acid bacteria was not suppressed, and the growth of bacteria other than lactic acid bacteria such as coliforms was suppressed.

Example 4
Peptone 10g, meat extract 10g, yeast extract 5g, glucose 20g ammonium citrate 2g, sodium acetate 5g, magnesium sulfate heptahydrate 0.1g, manganese sulfate 0.05g, dipotassium hydrogen phosphate 2g, xanthan gum 30g, X-β-gal 0.1 g and kanamycin 6 mg were added to 1000 ml of ethanol containing 1 g of hydroxypropylcellulose to prepare a suspension. 1 ml of this ethanol suspension was dispensed into a container (50 mm) containing a cotton-like sheet (50 mm), and then dried and capped to prepare a simple medium. The medium was hermetically packaged in an aluminum wrapping material with a desiccant, and then sterilized by gamma irradiation with a surface dose of 10 to 20 kGy. Four types of lactic acid bacteria and four types of coliform bacteria were prepared in the same manner as in Example 3, and 1 ml each of this simple medium (pH 6.5, X-β-Gal 0.15 mass%, kanamycin 0.0086 mass in the medium). %), Followed by carbon dioxide culture at 37 ° C. for 48 hours (5% carbon dioxide, 15% oxygen, nitrogen 80% atmosphere), and the number of bacteria and color were measured. The results are shown in Table 4.
As shown in Table 4, even in a simple medium, many lactic acid bacteria form blue colonies with X-β-gal, and kanamycin has no effect on the growth of lactic acid bacteria. It was observed that the growth of

Example 5
After preparing MRS agar medium (Difco), X-β-gal (biosynth) was added to 0.01 mass% (0.1 g / L) in the medium, and kanamycin was added in the medium at 6 × 10 ^{− 3} % by mass was added, and oxalic acid and sodium carbonate were further added so that the pH in the medium was 5.0, 5.7, 6.4, 6.8, 7.0, 7.2, and used as a test medium.
After adjusting the MRS agar medium (Difco) (pH 6.5), a medium to which X-β-gal and kanamycin were not added was used as a “reference medium”.
After preparing a blood agar medium (tryptosoya agar medium (Nissui Pharmaceutical) as a basic medium, 5% horse defibrinated blood (Kohjin Bio) added), the one without X-β-gal and kanamycin is added. Was used.
This strain was inoculated with 19 types of lactic acid bacteria and strains other than 80 types of lactic acid bacteria using a microplanter, and cultured at 37 ° C for 48 hours with carbon dioxide gas (5% carbon dioxide, 15% oxygen, nitrogen 80%). Was measured. The results are shown in Table 5.
As shown in Table 5, the selectivity to bacteria other than lactic acid bacteria (especially coliforms) is strong in a medium of pH 5.0 to 6.4 containing a microbial growth inhibitor (0.006% by mass in the medium). Was recognized.

Example 6
The growth of Leuconostoc dextranicum JCM9700, Streptococcus thermophilus ATCC14485, and Bifidobacterium pseudolongum JCM1205 was measured in the same manner as in Example 5 except that “pH 6.4” was used. Growth was recognized as “+”, “+”, and “W”, respectively.

Example 7
The lactic acid bacteria Lactobacillus acidophilus ATCC19992, Lactobacillus bulgaricus ATCC11842 and Escherichia coli ATCC8739, Enterobacter are the same as in Example 5 except that “pH” is “pH6.4” and “kanamycin” is “gentamicin”. Growth was measured for sp.CCJC13024. Growth was recognized as “+” and “+” for lactic acid bacteria, respectively, and growth was not recognized as “−” and “−” for coliforms, respectively.

  Therefore, when the method for detecting lactic acid bacteria and the culture medium for detecting lactic acid bacteria of the present invention are used, in many lactic acid bacteria, the entire range where the enzyme (β-galactosidase) produced by lactic acid bacteria is colored, and colonies of lactic acid bacteria become clear, Similarly, it has been clarified that the growth of the coliform group to be colored can be suppressed by antibiotics, and the presence or absence of lactic acid bacteria in the test sample can be accurately and efficiently determined visually or under fluorescence.

Claims (6)

  A medium for detecting lactic acid bacteria, comprising an enzyme substrate that is degraded by β-galactosidase, a microbial growth inhibitor other than lactic acid bacteria, and a pH adjuster that adjusts the pH to 5.0 to 6.5.   The enzyme substrate which is degraded by β-galactosidase is 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside or orthonitrophenyl-β-D-galactopyranoside. Medium for detecting lactic acid bacteria.   The medium for detecting lactic acid bacteria according to claim 1 or 2, wherein the microbial growth inhibitor is an aminoglycoside antibiotic.   The medium for detecting lactic acid bacteria according to claim 3, wherein the aminoglycoside antibiotic is a kanamycin antibiotic.   The medium for detecting lactic acid bacteria according to any one of claims 1 to 4, further comprising a lactic acid bacteria growth promoting component.   A method for detecting lactic acid bacteria, comprising inoculating a test sample on the lactic acid detection medium according to claim 1 and then culturing, and determining the color of the colony visually or under fluorescence.