1. Lysine accumulation by various auxotrophs was found. Especially a large quantity of lysine was accumulated by homoserine-less mutant of glutamic acid producer, previously named Micrococcus glutamicus. All homoserine-less mutants tested including Bacillus subtilis and E. coli showed lysine accumulation. Considerable lysine accumulation occurred with mutants such as threonine-less, isoleucine-less, leucine-less and both isoleucine and leucine-less mutants. 2. Lysine accumulation by homoserine-less mutant of M. glutamicus was studied rather in detail. Lactic acid accumulated in place of lysine in excess of homoserine or threonine and biotin in media. In sufficient concentration of biotin and a proper amount of requiring amino acids, lysine accumulated. In low biotin concentration the tendency of glutamic acid accumulation was recognized. 3. Homoserine and threonine inhibited specifically the lysine accumulation from glucose and ammonia by washed cell suspension of homoserine-less mutant of M. glutamicus. The action of these amino acids was suggested to he inhibition of enzyme action rather than enzyme formation.
α, ε-Diaminopimelic acid (DAPA) and DAPA-decarboxylase were found in lysine requiring strains and a parent strain of Micrococcus glutamicus. With acetone dried cell, DAPA was decarboxylated quantitatively to lysine, while DAPA was not decarboxylated to lysine with intact cell. Lysine producing strain (M. 801) scarcely decomposed lysine. A biosynthetic pathway of lysine via DAPA was discussed.
α, ε-Diaminopimelic acid (DAPA) was accumulated by two lysine requiring strains of Micrococcus glutamicus in limited lysine concentration in media. These strains showed neither DAPA decarboxylase nor growth response to DAPA. A slow growth response to DAPA and DAPA decarboxylase was found in another lysine requiring strain. DAPA accumulation was not recognized by this strain, although trace amounts of DAPA were accumulated in some medium. Enzyme activity of lysine accumulating system in a lysine-producing strain was inhibited specifically by homoserine or threonine as shown in previous paper. Therefore, inhibition of DAPA accumulation or DAPA decarboxylation will be expected if lysine is synthesized via DAPA. But both homoserine and threonine showed no inhibitory effect either on DAPA synthesis or DAPA decarboxylation while lysine inhibited DAPA synthesis specifically. From these results, biosynthetic pathway of lysine via DAPA and different pathways of lysine and DAPA were discussed.
It has been recognized that the conversion from L-glutamic acid fermentation to succinic acid fermentation can be performed with Brevibacteriumflavum No. 1996. Succinic acid can be directly produced from glucose at a high yield of 28.3% for initial glucose in submerged culture (35.8% for consumed glucose). The optimal aeration rate and the optimal concentration of C.S.L. for the succinic acid production were 0.4 to 0.7×10-6 of Kd (g-mol/cc. min. atm.) and 1.0 to 2.0% of C.S.L., respectively. The activity of succinic decomposing enzyme in cell grown under the succinic acid producing condition was more feeble than that under the L-glutamic acid producing condition. Among the L-glutamic acid producing bacteria, genus Brevibacterium was able to perform this conversion of fermentations, while genus Bacillus was not.
The collection efficiencies of air sterilization filter were experimentally determined using a bacterial aerosol, the concentrations of which ranging from about 102 to 104 particles per cubic meter of air. The experimental results were compared with calculations. The correlations between the collection efficiencies and the design variables, thus obtained, will be of practical use in air sterilization by fibrous media.
The effects of incorporated P-32 upon the stability of genetic DNA was studied by using the transformation system of Bacillus subtilis. The DNA contained in average 0.28 P-32 atom in each molecule and lost its transforming activity more rapidly than the cold DNA which was stocked together with P-32. It seems that the genetic DNA becomes unstable when it incorporates P-32 and is stocked in alcohol.
A L-glutamic acid-producing bacterium, Brevibacterium divaricatum nov. sp. S-1627, accumulates a large amount of succinic acid in CSL-rich or insufficiently aerated culture. In order to obtain a good yield of succinic acid, it is desirable that CSL content is more than 1.5% in the culture medium and that aeration is insufficient so far as cells grow. Effect of CSL is proved due to biotin content in it. The optimal condition for the accumulation of succinic acid is also favorable to that of lactic acid and unfit for that of L-glutamic acid, and vice versa. When the organism is cultivated in CSL-deficient culture, the resting cells oxidize acetic and lactic acids and glucose very rapidly, but oxidize C4 dicarboxylic acids in the TCA cycle such as malic, fumaric, and succinic acids slowly, while the cells grown in CSL-rich culture have an increased activity of C4 dicarboxylic acid oxidation. α-Ketoglutaric acid is generally formed by the resting cells from various organic acids and glucose under fully aerated conditions, but under insufficient aeration succinic acid is formed. From fumaric and malic acids, succinic acid is formed both under fully and insufficiently aerated conditions. Tracer experiments using the resting or growing cells show that, though a little decreased values are observed under fully aerated conditions, approximately one mole of CO2 is incorporated into one mole of succinic acid. The formation of succinic acid by this organism is considered to be performed through the reduction of fumaric acid, quantitatively under insufficiently aerated conditions and mainly under fully aerated ones.
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