THE PHYSIOLOGICAL AND GENETIC DIVERSITY OF BOVINE STREPTOCOCCUS BOVIS STRAINS

Authors: JARVIS, GRAEME - CORNELL UNIVERSITY; KUTOVIC, AMINA - CORNELL UNIVERSITY; HAY, ANTHONY - CORNELL UNIVERSITY; Russell, James

Submitted to: Federation of European Microbiological Societies Microbiology Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Streptococcus bovis is a opportunistic bacterium that causes acute indigestion and the death of cattle that are fed an abundance of grain. Previous work indicated that the non-metabolizable sugar, 2-deoxyglucose (2DG), promoted the lysis and death of a laboratory strain of S. bovis, but the effect of 2DG on freshly isolated bacteria had not been determined. We eisolated S. bovis strains from a steer that was fed increasing amounts of grain and determined the effect on 2-deoxyglucose (2DG). Results indicated that S. bovis strains from cattle fed grains were more prone to lysis than those from cattle fed hay. Molecular techniques (16S rDNA RFLP and BOX PCR) indicated that S. bovis strains were genetically diverse, but this diversity could not be directly correlated with 2DG sensitivity. Knowledge of S. bovis may help nutritionists design rations that are safer for cattle.

Technical Abstract: Laboratory Streptococcus bovis strains and isolates obtained from a steer fed increasing amounts of grain had similar growth characteristics, but they differed in their sensitivity to 2-deoxyglucose (2DG), a non-metabolizable glucose analog. The addition of 2DG decreased both growth rate (0.92 + 0.34 h-1) and growth yield (ranging from 25 to 63%), but these edifferences could not be correlated with diet. However, isolates from a steer fed a 90% grain diet were more prone to 2DG-dependent lysis than those from a hay diet (P < 0.001). All S. bovis laboratory strains and isolates had an identical restriction fragment length polymorphism (RFLP) pattern, when their 16S rDNA was digested with Hae III and Hha I. However, when genomic BOX elements were amplified, 4 to 11 bands were observed, and the S. bovis isolates and laboratory strains could be grouped into 12 different BOX types. Strains 26 and 581AXY2 had the same BOX type, but the remaining laboratory strains did not form closely related clusters. Strain JB1 and K27FF4 were most closely related to each other. Most of the fresh isolates (24 out of 30) could be grouped into a single cluster (>90% Dice similarity). This cluster contained isolates from all 3 diets, but it did not have any of the laboratory strains. The majority (90%) of the isolates obtained from the hay-fed steer exhibited the same BOX type. Because more BOX types were observed if grain was added to the diet, it appears that ruminal S. bovis diversity may be a diet-dependent phenomenon.