Kenji Takumi

Nutrient Starvation Induces Cross Protection against Heat, Osmotic, or H2O2 Challenge in Vibrio parahaemolyticus

Glucose‐starved cells of Vibrio parahaemolyticus were compared with non‐starved counterparts with respects to heat, osmotic, and oxidative challenges. The starved cells demonstrated greater thermal and oxidative resistance than did the non‐starved cells. The starved cells also showed greater resistance against low osmotic challenge than did the non‐starved cells although both cells showed a comparable resistance against high osmotic challenge.

Antibacterial activity of Lactobacillus species against Vibrio species

Forty-one Lactobacillus strains were tested for antagonistic activity against nine strains of Vibrio. L. plantarum and L. casei were the most effective, and L. brevis was the least effective in inhibiting the growth of Vibrio species. L. gasseri and L. helveticus strains showed higher activity, while L. reuteri and L. fermentum showed lower inhibitory activity against Vibrio species. L. acidophilus strains exhibited various degrees of antagonistic activities against Vibrio species. However, none of the Lactobacillus species were able to inhibit the growth of Salmonella enteritidis, S. typhimurium, Escherichia coli, and Staphylococcus aureus. Inhibition of the Vibrio species was probably due to the production of organic acids by the Lactobacillus species.

Isolation and Characterization of Three Porin‐Like Proteins from Vibrio vulnificus: Effect of Different Growth Media on Their Production

The effect of the culture media on the composition of the outer membrane protein of Vibrio vulnificus strain 393 from human blood was examined. Only one major outer membrane protein, with an apparent molecular weight of 37,000 (37K protein) and 34,000 (34K protein), was formed in the cells grown in 3% NaCl‐BHI broth and chemically defined medium, respectively. The production of one major outer membrane protein was also observed in other isolates from humans and asari clam when they were grown in 3% NaCl‐BHI broth. On the other hand, three major outer membrane proteins, with apparent molecular weights of 48,000 (48K protein), 37,000 (37K protein), and 34,000 (34K protein), were produced in the cells grown in 3% NaCl‐nutrient broth. Three proteins, 48K, 37K, and 34K from strain 393, were purified and the amino acid compositions were determined. Although there was a little difference in the composition of amino acid among three proteins, the amino acid compositions of the three porin‐like proteins showed characteristic properties of the porins of Escherichia coli and Salmonella typhimurium. Immunoblot analysis of the outer membrane proteins from four vibrios, E. coli, and S. typhimurium using monospecific antisera against these three porin‐like proteins showed that only the antiserum against 37K protein cross‐reacted with the outer membrane proteins from all the strains tested.

Polypeptide compositions and antigenic homologies among prolamins from Italian, common and Japanese millet cultivars

Prolamins from Italian, common and Japanese millet cultivars were separately extracted with three kinds of alcohol (ethanol, propanol and isopropanol) and their component polypeptides and immunochemical relationships were examined by SDS-PAGE, two-dimensional electrophoresis and immunoblot analysis using the antiserum raised against Italian millet prolamin. Polypeptides of the individual millet prolamins appeared to be primarily composed of two major common subunit complexes with respective molecular masses ranging from about 19 to 23 kDa and from 13 to 14 kDa (groups A and B, respectively), although a few minor variations due to varietal differences were seen. Group A clearly contained one neutral subunit (21 kDa) and one basic one (22 kDa), while group B had one basic 14 kDa subunit. The Italian millet prolamin antiserum strongly bound with all three prolamin polypeptides but neither with the homologous non-prolamin fractions nor with the heterogeneous prolamins of the Triticeae (wheat, barley and rye). Amino acid compositions were found to be almost identical to one another.

Characterization of an amorphous and soluble hemagglutinin from Yersinia pseudotuberculosis

Yersinia pseudotuberculosis which were screened out depending on auto‐agglutination and Ca2+ dependency, were examined for their production of hemagglutinin (HA), and its purification and characterization were performed. The HA with a broad reactivity with various mammalian erythrocytes was recovered from the culture supernatant of these strains grown at 37 C but not 25 C. HAs from two strains, R148R and T1040, were purified by salt precipitation, gel filtration and anion‐exchange chromatography by HPLC. Both purified HAs were cysteine‐deficient acidic protein with an apparent molecular weight in the range of 15,000 to 16,000. N‐terminal amino acid sequences of the first 25 residues were found to share 12% identity with that of afimbrial adhesin from enterotoxigenic Escherichia coli 2230. Immunoelectron microscopy and immunodiffusion test with polyclonal antiserum raised against the purified R148RHA demonstrated that the HA was associated with the amorphous aggregates which were detached from bacteria. These results suggest that the HA of Y. pseudotuberculosis belongs to a third type of HA produced by the yersinial species.

Extracellular Localization of a Nonfimbrial Hemagglutinin of Yersinia pseudotuberculosis

A nonfimbrial hemagglutinin (HA) of Yersinia pseudotuberculosis was observed by immunoelectron microscopy using monospecific HA antiserum and protein A‐gold conjugate. The HA, an amorphous but morphologically identifiable entity, was located in a region distal to or detached from the outer edge of bacteria.