| Autor: |
Mayo, J. A., Zhu, H., Harty, D. W. S., Knox, K. W. |
| Předmět: |
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| Zdroj: |
Oral Microbiology & Immunology; Dec1995, Vol. 10 Issue 6, p342-348, 7p |
| Abstrakt: |
The effects of growth conditions on the properties of the endocarditis-producing oral bacterium Streptococcus sanguis FSS2 were studied. This strain produces a variety of proteases and glycosidases, including a thrombin-like activity that is a potential virulence factor for endocarditis. Cultures were grown with limiting glucose or galactose in chemostats over a range of dilution rates and pH levels, and the following activities were measured at pH 7.5: thrombin-like, Hageman factor-like, N-acetyl-β-D-galactosaminidase, β-D-glucosidase, and β-D-gaIactosidase. At growth pH 6.5, specific activities generally decreased as the dilution rate increased from 0.05 to 0.40 h-1. At a dilution rate of 0.1 h1-1, specific activities generally were highest at growth pH 6.5 and lower and approximately equal at growth pH 5.5 and 7.5. The major exception was the thrombin-like activity, for which the specific activity at growth pH 7.5 was approximately 5-fold higher than at growth pH 5.5. Hageman factor-like activity was apparently glucose catabolite repressible, as its activity was 3-fold higher in galactose cultures. The measured activities changed as functions of growth conditions and thus were modulated by environment. Environmental regulation of thrombin-like activity by pH is consistent with an activity that is less important on tooth surfaces than in tissues. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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