1887

Microbiology Society logo - Volume 127, Issue 1, 1981

Volume 127, Issue 1

Volume 127, Issue 1, 1981

  • Physiology And Growth

      • Regulation of Extracellular Alkaline Protease Activity by Histidine in a Collagenolytic Strain

        https://doi.org/10.1099/00221287-127-1-193

        synthesized an inducible extracellular collagenase in a peptone medium during the stationary growth phase. These cultures also possessed extracellular alkaline serine protease activity. The alkaline protease activity did not require a specific inducer and it was produced in tryptone or minimal media. The collagenase was not produced in either the tryptone or minimal media. The alkaline protease activity was sensitive to catabolite repression by a number of carbon sources, including glucose, and by amino acids and ammonium ions. Cyclic AMP, dibutyryl cyclic AMP and cyclic GMP did not relieve catabolite repression. Histidine and urocanic acid stimulated the production of alkaline protease activity in tryptone and minimal media. Other compounds associated with the histidine utilization () pathway did not increase alkaline protease activity. Histidine reversed the repression of alkaline protease activity by glucose or (NH)SO in minimal medium. Histidine and the compounds associated with the pathway inhibited collagenase production.

    • Metabolism of the Polysaccharides of Human Dental Plaque: Release of Dextranase in Batch Cultures of

      https://doi.org/10.1099/00221287-127-1-201

      Dextranase activity was determined in cell extracts and cell-free filtrates of strains which had been grown in batch culture. Exo-dextranase activity was located chiefly in cell extracts, whereas endodextranase was mainly extracellular. Release of endo-dextranase began early in the exponential phase of growth, and ended when the concentration of residual sugar was low. Thus, dextranase expression was associated with rapidly growing cells, and the yield of dextranase was increased several fold when the initial concentration of -glucose in the medium was changed from 0·5% to 2%. The endo-dextranase was not stable at pH 5, and control of the pH of the culture was essential to preserve active dextranase during overnight growth. Strain Ingbritt (serotype ) and serotype strains were the best dextranase producers; other strains (serotypes and ) displayed much lower activity. The ability to produce endo-dextranase, and to synthesize a-D-glucans with a high proportion of (1→3)-linked sequences, appeared to be related properties. The possibility is discussed that the release of two enzymes, namely endo-dextranase and the -glucosyltransferase (GTF-I) that synthesizes (1→3)-α--glucan, are factors that contribute to the cariogenicity of serotype .

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  • Taxonomy

      • Characterization of and by the Electrophoretic Patterns of their Esterases

        https://doi.org/10.1099/00221287-127-1-161

        Esterases of 15 strains of 14 strains of and 13 strains of were resolved by horizontal electrophoresis in polyacrylamide-agarose gel. Esterase bands were defined by their range of activity towards several synthetic substrates and their sensitivity or resistance to di-isopropyl fluorophosphate. strains showed three to five major esterase bands and three minor bands. strains showed three or four major bands and one minor band. strains showed three to five major bands and one minor band. The comparative distribution of bands revealed that these three newly described species could be distinguished by the electrophoretic patterns of their esterases. Congruence was found between biotypes 1 and 2 of and These species-specific patterns were different from those of and previously characterized.

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