JPH0310680A - Composition for culture medium - Google Patents

Abstract

PURPOSE:To provide the subject composition having excellent high pressure stability such as flow resistance and decomposition resistance and having improved stability at high temperature (>=80 deg.C) by adding curdlan as a medium agent to a gel medium for thermophilic bacteria. CONSTITUTION:At least curdlan is added as a medium agent to a gel medium for thermopholic bacteria to provide the objective composition. The curdlan in the medium is preferably >=10wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved culture medium composition that is stable at high temperatures. More specifically, the present invention relates to a gel medium composition suitable for culturing thermophilic bacteria.

(Prior art and its problems) Conventionally, an agar gel medium has been used as a gel medium for culturing bacterial cells. For example, Experimental Biology Course Volume 8, 5
The agar gel medium is explained in detail on page 8. Since this agar gel exhibits a good gel state in the temperature range of 10°C to 30'C, it is a suitable medium for general bacterial cells that are cultured at around room temperature. Materials for gel media other than agar include natural polymer compounds such as konjac powder, carrageenan, locust bean gum,
Gelatin, albumin, collagen or synthetic polymer compounds such as polyacrylamide, polyhydroxyacrylate, ethylene-maleic acid copolymer, PV
I can give you things like A. In recent years, food hygiene management,
Culture of thermophilic bacteria has become necessary in fields such as research on pathogenic bacteria, and there is a need for improved medium compositions suitable for culturing thermophilic bacteria that are stable even at high temperatures.

Thermophilic bacteria refers to bacteria that normally grow at temperatures above 55°C, such as Themusthemophilus;
us), Clostridium (Clostridiu)
m), Lactobacillus
), Streptomyces
), STEP CO SO
Those belonging to various genera such as Streptococcus have been widely discovered. The following conditions are required for culture medium compositions for culturing these thermophilic bacteria.

After the medium composition has gelled, it must maintain a stable gel state within the culture temperature range of thermophilic bacteria. However, the gel state of the agar medium described above may become unstable or break down at the culture temperature of thermophilic bacteria, so a particularly high culture temperature of 80°C or higher is required. Furthermore, the gel composition for a medium made of carboxyalkylcellulose and polyvalent metal salts shown in JP-A-62+119136 forms a stable gel state even at high temperatures; Although it is suitable as a gel medium for thermophilic bacteria, since metal salts are used for gelation, metals may affect the growth of bacteria, which is not preferable.

(Means for Solving the Problems) The present invention was developed as a result of extensive research into a culture medium composition that forms a stable gel even at high temperatures and does not contain substances that inhibit the growth of bacterial cells. Reached. That is, the present inventor discovered that curdlan is effective as a gel for a culture medium of thermophilic bacteria, and solved the above problem by providing a composition for a culture medium using the curdlan. below,
The culture medium composition of the present invention will be specifically explained.

The composition for a medium for thermophilic bacteria used in the present invention is composed of a gel base material made of a mixture of curdlan and other medium materials, substances required by the bacterial cells, and water. The culture medium can be obtained by heating a liquid in which the gel base material and the substances required by bacterial cells, etc. are dissolved or become cloudy in water to a temperature of 100°C or higher, taking into consideration sterilization, and then cooling it. I can do it. The ratio of gel base material in the turbid liquid varies depending on the hardness of the gel produced, but is 0.05
~20% by weight is preferred. Substances required by microbial cells vary depending on the type of microbial cell, but include, for example, amino acids, nucleic acids, vitamins, inorganic salts, sugars, and other substances necessary for the microbial cell to be cultured. The required amount of the required substance also differs depending on the type of bacterial cell.

Curdlan is a natural polysaccharide glucan consisting only of 13-1.3 glycosidic bonds, such as Alcaligenes (Alc
It can be obtained from the culture solution of a natural variety of A. aligenes or the culture solution of a variety of Agrobacter (Physical and Chemistry Dictionary, 4th edition, p. 243). When agar was used as the gel base material, the agar gel became fluid in just a few minutes when kept in a water bath at 80°C, but when using curdlan alone, curdlan gel did not become fluid under the same conditions. It was able to maintain its original shape for a long time. In addition, in the case of curdlan/agar mixed gel, if the curdlan ratio is 10% or more, it is 8.
It was found that it remained stable in a hot water bath at 0°C. In addition, cell production was observed using a medium containing curdlan or a mixture of curdlan and agar as a gel base, but no difference was observed in the growth state compared to an agar medium.

(Effects of the Invention) The gel prepared from the medium composition provided by the present invention has higher high-pressure stability such as fluidity and disintegration than the agar medium commonly used even in a hot water bath, and has a temperature of 80°C or higher. The gel state does not change even if it is kept in a hot water bath. Since microbial cells can be inoculated into the culture medium composition of the present invention and cultured, it can be used as a normal culture medium. It is particularly suitable as a medium for thermophilic bacteria that need to be cultured at a higher temperature range.

The present invention will be explained in detail below. However, the symbol % indicates weight %.

(Example) Curdlan (Wako Pure Chemical, for biochemistry) and agar (Wako Pure Chemical,
(for bacterial culture medium) were mixed in the proportions shown in the table below. Add an appropriate amount of bacterial cell-required substances to this mixture, and stir in purified water. This turbid liquid is heated and cooled while stirring with a glass rod to obtain a gel. The components of this gel composition are 3% curdlan and a mixture of curdlan and agar, 0.95% glucose, and 0.05% ammonium sulfate. To evaluate the high temperature stability of these gels, we placed a 2g metal ball on top of the gel and placed it in a hot water bath at 80°C, and then measured the time it took for the gel to flow or collapse and the metal ball to fall. It was measured. The results are shown in the table below.

A mixture of curdrant agar is less stable than curdlan alone, but if the mixing ratio is 10% by weight or more, it has sufficient stability as a gel medium.

This gel composition contains Escherichia coli (Escherichia coliforms).
When the cells were inoculated with E. coli and observed, they were successfully cultured.

*) Time taken for the metal ball to fall after placing a 2g metal ball on the gel and placing it in a hot water bath at 80°C

Claims (1)

[Scope of Claims] 1. A composition for a medium containing at least curdlan as a medium agent in a gel medium for thermophilic bacteria. 2. The medium composition according to claim 1, wherein the medium contains 10% by weight or more of curdlan.