The physiological and genetic diversity of bovine Streptococcus bovis strains

Laboratory Streprococcus bovis strains and isolates obtained from a steer f ed 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 differences 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 d iet (P < 0.001). All S. bovis laboratory strains and isolates had an identi cal restriction fragment length polymorphism pattern, when their 16S rDNA w as digested with HaeIII and HnaI, However, when genomic BOX elements were a mplified, 5-12 bands were observed, and the S. bovis isolates and laborator y strains could be grouped into 13 different BOX types. Strains 26 and 581A XY2 had the same BOX type, but the remaining laboratory strains did not for m closely related clusters. Strains JB1 and K27FF4 were most closely relate d 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 isol ates from all three diets, but it did not have any of the laboratory strain s. The majority (90%) of the isolates obtained from the hay-fed steer exhib ited the same BOX type, Because more BOX types were observed if grain was a dded to the diet, it appears that ruminal S. bovis diversity may be a diet- dependent phenomenon. (C) 2001 Federation of European Microbiological Socie ties, Published by Elsevier Science B.V. All rights reserved.