Aspartase from Lactobacillus murinus CNRZ 313 (L-aspartate ammonia lyase, E.C. 126.96.36.199.), is one of the enzymes of aspartate metabolism in lactic acid bacteria. The growth of this microorganism in LAPTg medium is not altered by the addition of L-aspartate. Aspartase is a thermolabile enzyme. Its activity was not changed in one month at temperatures lower than 0°C, independently of the presence of 10% glycerol or 0.05M MgCl2. Maximum activity occurred at 32°C and pH 7.5 in 0.15M Tris-HCl pH 7.5. At pH values different from the optimum, positive cooperation between substrate molecules was observed. The Km values for L-aspartate at pH 7.5 and 7.0 were: 3.7×10-2M and 9.0×10-2M respectively. The pK values of pKa 6.75 and pKb 7.35 were calculated from Dixon plots. The ΔG of the reaction was calculated by Arrhenius plot. The values were 4, 807cal mol-1 below 25°C and 2, 665cal mol-1 above 25°C. Both 10-3M HgCl2 and NaCN had inhibitory effects.
Yeast strains were isolated from 265 samples of high-sugar foods and related materials, and 93 representative strains were identified. Fifty-four strains of ascosporogenous yeasts were identified as 12 species belonging to eight genera. Thirty-nine strains of asporogenous yeasts were identified as 26 species belonging to five genera. The major species identified wereZygosaccharomyces rouxii (23 strains), Hansenula anomala (eight strains), Debaryomyces hansenii (five strains), andSaccharomycescerevisiae (four strains). More than 60% of the isolates were sugar- tolerant yeasts, and all strains of Zygosaccharomyces rouxii were osmophilic. Approximately 80% of the isolates fermented glucose. It is suggested that these yeasts cause pouch swelling and produce alcohol in gas-exchange packaged foods or vacuum-packaged foods.
It has been shown that the restriction maps of Bacillus phages M2 and Nf are identical to each other except in the region 32 to 46% from the left ends of the genomes. Furthermore, in this region, genomes of the original stock of phage M2 were heterogeneous in length. We have found that M2 has the same origin as Nf and that the heterogeniety in the region is caused by deletions of various sizes. These results were obtained by electoron microscopic observations of heteroduplex molecules between the genomes of Nf and subclones of M2, and by fine physical mapping of the heterologous regions. Finally, it has been shown that these deletions affected phage morphology but not multiplication.
The generation of hydrogen peroxide by putrescine or cadaverine was studied using a cell-free extract of Micrococcus luteus from which catalase had been eliminated by immunoprecipitation. About 20 times more hydrogen peroxide was formed by putrescine than by cadaverine. Other substrates such as glucose, amino acids, xanthine and NAD(P)H did not produce hydrogen peroxide. Staining of gels by substrates after electrophoresis of the proteins suggested that putrescine oxidase in M. luteus also oxidizes cadaverine. A high level of putrescine oxidase was produced in cells from the late exponential growth phase. This enzyme level and the growth rate increased appreciably when the cells were grown with putrescine.
Nine strains of aerobic, gram positive, motile cocci in the genus Planococcus were studied taxonomically. They were divided into 2 groups according to their biochemical and chemotaxonomic characteristics. Four strains were those of Planococcus citreus Migula 1894. Five strains were regarded as belonging to a new species in the genus Planococcus, and Planococcus kocurii Hao and Komagata sp. nov. is proposed for these organisms. Strain HK 701 (=AJ 3345=CCM 1849=IAM 12847=JCM 2569=NCMB 629) is the type strain of this species.
Ninety-nine strains of ballistospore-forming yeasts were isolated from 43 samples of dead leaves and stems of the Japanese rice plant (Oryzasativa L.), and identified as belonging to the genera Bullera, Sporobolomyces, and Tilletiopsis. Thirty-one strains out of 55 of Bullera were assigned to B. alba (15 strains), B. crocea (13 strains), and B. piricola (3 strains). The remaining 24 strains of this genus were divided into 6 groups (species) which could not be assigned to any hitherto known species. Thirty-nine strains out of 41 of Sporobolomyces were assigned to S. roseus (35 strains) and S. shibatanus (4 strains). The remaining 2 strains of this genus were divided into 2 groups (species) which could not be assigned to any hitherto described species. Three strains of Tilletiopsis were assigned to T. lilacina. Of the 8 undescribed species, two were described respectively as the new species, B. oryzae and S. subbrunneus. Strains JCM 5281 and JCM 5278 respectively were designated as the types of the two species. Further study of the remaining 6 undescribed species is required before we determine their taxonomic position. The frequency of isolation of ballistospore- forming yeasts from Oryza sativa L. was 86%. Sporobolomyces roseus was found in the highest frequency, 72%, followed by Bullera sp. 1 (35%), B. crocea (30%), and B. alba (28%). The remaining species were found in relatively low frequencies below 9%.
Fourteen strains of acetic acid bacteria were isolated from fermented vinegar broth with high acidity. These isolates were useful for producing high-acidity vinegar and require acetic acid, ethanol and glucose for growth. The isolates differed from all the species of the genera Acetobacter and Gluconobacter so far validly published, with respect to their morphological, physiological, biochemical and chemotaxonomic characters' and their deoxyribonucleic acid homologies. The isolates are classified as a new species of the genus Acetobacter, and we propose Acetobacter polyoxogenes sp. nov. for them. The type strain of A. polyoxogenes is NBI 1060 (=JCM 3808).