1. More than ten strains of bacteria which are capable of producing large amounts of valine were selected under a screening program. The isolates from natural sources we classified as Paracolobacterum coliforme, P. intermedium, Escherichia coli, and Aerobacter aerogenes. 2. The production and accumulation of L-valine in P. coliforme and Brevibacterum ammoniagenes have been investigated rather in detail, showing the formation of up to 0.23 mole of valine from one mole of glucose. 3. The biosynthetic pathway of valine revealed in the valine-producing bacteria is similar to the known pathway of other microorganisms. It was made clear by experimental results that the enzymes responsible to the condensation of pyruvate in the valine-producing cells are active at pH 5.5 7.5 and different from the "orthodox" biosynthetic enzyme which is active at pH 8, as two enzymes are known in the reaction of acetolactate formation. 4. One of the mechanisms for the efficient production and accumulation of valine is ascribed to the action of an active acetolactate-forming enzyme which is present at least in the valine-producing cells and whose action is not suppressed by valine itself.
The decomposition of the nitrogen-fixing blue-green algae, Tolypothrixtenuis, Calothrix brevissima, Nostoc muscorum and Anabaenopsis circularis, brought about by the action of various soil bacteria was examined. A certain strain of Bacillus subtilis was found to give the most active production of ammonia; about 40 per cent of the algal nitrogen being converted to ammonia within 10 days of incubation. Practically no production of nitrogenous compounds other than ammonia was observed. On the basis of these results, the varying efficacy of blue-green algae as fertilizer in paddy fields was discussed.
The microscopic morphology of Streptomyces hygroscopicus and morphologically related strains are described. These strains have sinistrorse spirals in terminal filaments of side branches arisen from axial mycelia. Axial mycelia are fairly long but sometimes short, straight to flexous, and the branching system principally takes various monopodial forms in its early stage of growth, but often becomes to appear irregular after full growth has been attained. Side branches range from single to branched. Description of each strain employed is also given.
The whorl forming strains have long straight or long wavy axial aerial mycelia which branch repeatedly in monopodial alternate, opposite and verticillate forms, and occasionally diverge from a filament into two or three branches. The long axial aerial mycelium does not break into spores, but gives rise to short side branches which grow in verticils and form whorls. The typical whorl is "Biverticils", namely compound verticils consisting of primary and secondary elements. And there are sometimes atypical whorls in some unfavourable cultural condition or in some strains. Atypical whorls contain "Monoverticils" consisting of only primary verticils, mixed verticils of mono- and bi-verticils and sometimes various more compound polyverticils. The terminal hyphae of whorl are short straight or a little wavy in shape and break into spores. The whorl forming strains employed have no spirals. The description of each strain employed was also given.
The transfer of microbes from air bubbles into liquids was analysed using the bacterial cells of Serratia marcescens. Experimental data were compared with the calculations which were derived from several assumptions. The agreement between them was not satisfactory. The reasons of this disagreement remain to be investigated. The "bubble aeration" technique to supplement the air filter performances seems promising so far as the collection of microbes in the case of small bubbles and deep tanks are solely concerned.