title: Modulation of glycosidase and protease activities by chemostat growth conditions in an endocarditis strain of Streptococcus sanguis.
abstract: 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-beta-D-galactosaminidase, beta-D-glucosidase, and beta-D-galactosidase. 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 h(-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.
authors.affiliation: Institute of Dental Research, Surry Hills, New South Wales, Australia.
authors.forename: J A
authors.initials: JA
authors.lastname: Mayo
authors.forename: H
authors.initials: H
authors.lastname: Zhu
authors.forename: D W
authors.initials: DW
authors.lastname: Harty
authors.forename: K W
authors.initials: KW
authors.lastname: Knox
mesh_terms: D000222:Adaptation, Physiological; D000704:Analysis of Variance; D002455:Cell Division; D003470:Culture Media / Q000737:chemistry; D004697:Endocarditis, Bacterial / Q000382:microbiology; D010450:Endopeptidases / Q000378:metabolism*; D005174:Factor XII / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018709:Statistics, Nonparametric; D013298:Streptococcus sanguis / Q000254:growth & development / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism
chemical_list: D003470:Culture Media; D005174:Factor XII; D006026:Glycoside Hydrolases; D010450:Endopeptidases; D013917:Thrombin; D005947:Glucose; D005690:Galactose