著者

WATANABE Wataru

出版者

Japan Society for Bioscience, Biotechnology, and Agrochemistry

雑誌

Bulletin of the Agricultural Chemical Society of Japan (ISSN:03758397)

巻号頁・発行日

vol.22, no.4, pp.255-261, 1958

被引用文献数

1

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(1) When samples containing <i>E. coli</i> irradiated with gamma-ray were incubated at 37°C or 25°C, no difference on the survival of the strain was observed in both cases and the same survival was also recognized in case of the preserving procedure carried out in an icebox for 24 hours prior to incubation at 37°C.<br> (2) Prior to gamma-ray irradiatien, when the strains incubated at 37°C for 24 hours were preserved in an ice-box at 0°C for a period as long as 23 days, no difference on gamma-ray resistivity of the strain was found. However, the survival obtained from the strain stocked at room temperature, 18°C, for a period as long as 24 days was higher than that of the strain stocked for a shorter period.<br> (3) There was no difference on survival of <i>E. coli</i> at the concentration of 10² cell/ml caused by gamma-ray irradiation, when the medium also contained heat sterilized cells of the same strain at the concentration of 10⁷ cell/ml.<br> (4) No difference on survival of <i>E. coli</i> was caused by gamma-ray irradiation, when the medium contained glucose, lactose or fructose in the amount of 8%.<br> (5) The survival obtained from the medium at the pH value of 6.4 adjusted with HCL was almost identical with that of the pH 7.0 medium. However, when the pH value of the medium decreased to 6.1, survival obtained from the medium was higher than that in the medium of pH 7.0 or 6.4.<br> (6) When tartaric acid, citric acid or succuic acid was added to each medium, the survival-ratios obtained from the medium containing one kind of the chemicals were higher than that of the normal medium containing no organic acid. In these cases, tendencies of such protective effects as previously mentioned were more distinct than in the case of the medium containing HCL at the same pH value, 6.1.

著者

SU Yuan-Chi YAMADA Koichi

出版者

Japan Society for Bioscience, Biotechnology, and Agrochemistry

雑誌

Bulletin of the Agricultural Chemical Society of Japan (ISSN:03758397)

巻号頁・発行日

vol.24, no.2, pp.140-146, 1960

被引用文献数

2

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(1) With regard to the constituents of the fermentation medium, various nitrogen sources, glucose and their optimum concentrations, as well as the additive influences of various growth substances and metals, were examined.<br> Solely considering its worth in industrial application, urea seems to be a satisfactory nitrogen source. Its optimum concentration in the medium containing 5% of glucose was found to lie between 0.67 to 0.9%. The growth of cells should be suppressed when the initial con-centration of glucose exceeds 12.5%; therefore a level of 10% gives a better result. Data show-ed that addition of meat and bran extracts gave an increment of about 26% in acid yield.<br> (2) As for the fermentation condition, after experiments on the incubation temperature, pH and the influence of oxygen supply, etc., reveal that the aerobic condition is favorable for cell growth and accumulation of L-glutamic acid. An oxygen supply around 5 × 10^-6 of K_d is desirable. The optimum incubation temperature was found to lie at 30°C.<br> A reasonable quantity of L-glutamic acid will be produced if the culture is kept neutral or preferably slightly alkaline by feeding a proper amount of urea aqueous solution throughout in-cubation.<br> (3) As a conclusion of the above experimental results, the yield of L-glutamic acid reached 45%, on basis of glucose supplied after 30 hours' in-cubation.<br> (4) By-products such as alanine, α-ketoglutaric acid, pyruvic acid and succinic acid were found at the same time, in the fermentation of L-glu-tamic acid employing <i>Brevibactcrium divaricatum</i> nov. sp.<br> By observing the time of formation, the kind and the amount of these by-products it was presumed that the L-glutamic acid formation with this strain most probably proceeds from glucose to pyruvic acid, and then to α-ketoglu-taric acid via Krebs TCA Cycle. L-Guutamic acid could be considered to be formed from α-keto-glutaric acid. The reductive amination reaction of α-ketoglutaric acid is assumed to be the main pathway of L-glutamic acid synthesis.