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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Research » Publications at this Location » Publication #63099
Title: CATABOLITE REGULATION IN A DIAUXIC STRAIN AND A NON-DIAUXIC STRAIN OF STREPTOCOCCUS BOVIS

Author
item KEARNS, DANIEL - CORNELL UNIVERSITY
item Russell, James

Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Streptococcus bovis is an opportunistic bacterium that outgrows other ruminal and colonic bacteria when there is an abundance of carbohydrate. This overgrowth causes acute indigestion, ruminal acidosis, and even the death of cattle. In humans, S. bovis has been implicated in the etiology of colon cancer. We under took research to study the regulation of carbohydrate uptake by S. bovis. Strain JB1 and strain 581AXY2 had different patterns of glucose and lactose utilization. The JB1 used glucose preferentially to lactose, but 581AXY2 used both sugars simultaneously. Subsequent work indicated that the strains had different transport systems for glucose as well as fundamentally different mechanisms of regulating carbohydrate uptake. Information on the regulation of carbohydrate utilization may provide ways of inhibiting S. bovis, alleviating ruminal acidosis, improving the economics of animal production and decreasing colon cancer.

Technical Abstract: Streptocococcus bovis JB1 utilized glucose preferentially to lactose and grew diauxically, but S. bovis 581AXY2 grew non-diauxically and only used glucose preferentially when the glucose concentration was very high. JB1 and 581AXY2 had similar thresholds of glucose-dependent, inducer (thiomethylgalactoside) explusion, but glucose PTS of 581AXY2 had a lower affinity than JB1. Because 581AXY2 needed 15-fold more glucose to inhibit [14C] lactose uptake than JB1, 58AXY2 and JB1 had very different thresholds of glucose-dependent catabolite regulation. The Eadie-Hofstee plot of glucose phosphorylation by 581AXY2 was biphasic, but both JB1 and 581AXY2 had enzmye IIS that could phosphorylate glucose and mannose, but not a-mthylglucoside. The enzyme II glucose of 581AXY2 was competitively inhibited by 2-deoxyglucose, but it could not translocate or phosphorylate 2-deoxyglucose. Because 2-deoxyglucose was still able to exclude [14C] lactose from 581AXY2, it appeared that the binding of sugar to enzyme II was the most critical feature of glucose-mediated inducer exclusion.