An L-lactate producing strain whose optimal temperature for growth and L-lactate production was 37°C, previously labeled as Streptococcus species IO-1, was characterized biochemically and genetically and identified as a variant strain of Lactococcus lactis. This strain tolerated 6.5% NaCl and grew on bile esculin agar. Thus the strain resembled enterococci biochemically. However, there was no Lancefield's group D antigen in the strain, but group N antigen was present. Quantitative DNA-DNA hybridization experiments showed that the strain did not resemble enterococci and should be assigned to the genus Lactococcus. Strain IO-1 was identified as a strain of Lactococcus lactic because the homology values between it and the type strain of the L. lactis, NCFB 604T were in a range of 62-77%. The growth of L. lactis is usually suppressed and very slow at 42°C but strain IO-1 grew confluently and very quickly at that temperature. It was also different from the type strain of L. lactis in that it produced antibiotics, which were not nisin but were similar to nisin to which other lactococci and some species of genus Bacillus and Clostridium were sensitive. This strain has been deposited in the Japan Collection of Microorganisms as L. lactis IO-1 JCM 7638.
A mechanism that represses the growth of facultative alkalophilic Bacillus sp. ASSC-2 at neutral pH has been examined. When the pH of K+-limited culture medium was shifted from 9 to 7, acidification of the intracellular pH (pHin) occurred causing cessation of growth and a decrease in cell viability. When the pHin was lowered below 7 by treatment with nigericin, the viability decreased with decreasing pHin. Apparently the impairment of the pHin regulation at neutral pH caused the striking loss of viability. Compared with neutrophilic Bacillus subtilis, strain B. ASSC-2 involved low K+-transport activity: the K+ transporter allows more H+ to be extruded from the cells by the respiratory pump and alkalizes the pHin. Further, the Na+/H+ antiporter, which acidified the pHin in the external alkaline pH range was active even at neutral pH. These results indicate that inability of the growth at pH 7 in K+-limited medium may be due to a decrease in the activity in the K+-transport system, causing excessive acidification of the pHin under the active Na+/H+ antiport system.
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was purified to electrophoretic homogeneity from the halophilic archaebacterium Haloarcula (Halobacterium) vallismortis. The purification was achieved by (NH4)2SO4-mediated chromatography on Sepharose 4B and DEAE- cellulose, and hydrophobic and hydroxylapatite chromatography. In contrast to nonhalophilic archaebacteria, only a single NAD+-specific GAPDH was found in the halobacterium. However, it shares the property of insensitivity to the antibiotic pentalenolactone with the enzymes from other archaebacterial sources. Like all other GAPDHs the enzyme from H. vallismortis is a homomeric tetramer with catalytic properties comparable to the NAD+-specific enzymes characterized so far. The molecular mass of the subunit, deduced under denaturing conditions in the presence of a cationic detergent, was 40±2kDa. The halobacterial GAPDH is a halophilic enzyme requiring high concentrations of salt for activation and tability and is an acidic protein. Immunological tests between the halobacterial enzyme and its counterparts from eubacterial, mammalian and nonhalophilic archaebacterial sources were negative.
A new species of ballistospore-forming yeast, Bullera miyagiana Nakase, Itoh, Takematsu et Bandoni is described. This yeast was isolated from Abies firma collected at Sendai, a northeast region in Japan. It is characterized by Q-10 as the major ubiquinone, xylose in the cells and high G+C content in DNA, 61.4mol% (calculated from Tm) or 58.9mol% (analyzed by high performance liquid chromatography). These characteristics resemble those of Bullera oryzae, but there is a clear difference between B. miyagiana and B. oryzae in the electrophoretic patterns of enzymes. Practically, B. miyagiana is differentiated from B. oryzae by its assimilation of nitrate, ethanol and ribitol, and its lack of assimilation of ethylamine or L-lysine.
We studied different factors which affect sulfite oxidation in Thiobacillusthiooxidans S3 cells during storage. The cells continued the oxidation for 27 days when they were preserved at 4°C in a 0.1M citrate buffer (pH 6.0), or for 22 days when 20% glycerol was added to the same buffer and storage was at -20°C. When the cells were stored at 4°C, they kept full activity even after 45 days. If the cells were immobilized before they were stored at 4°C in the buffer, they kept their full activity for 90 days. The cells treated by lyophilization or drying at room temperature lost about 90% of the original activity. T. thiooxidans S3 cells were more stable than T. novellus cells under the same storage conditions.