Development of a DNA probe for Streptococcus bovis by using a cloned amylase gene

Streptococcus bovis is a normal inhabitant of the rumen but has been implicated as a causative agent for ruminal lactic acidosis and related problems. While rarely isolated from humans, S. bovis has been identified as a causative agent for endocarditis, meningitis, and septicemia. Recent reports have also suggested a correlation between human colonic carcinoma and increased levels of S. bovis. Identification of S. bovis strains of human origin has been problematic because of variations in results of biochemical tests compared with results for ruminal strains. We have tested a cloned amylase gene from the ruminal strain S. bovis JB1 as a potential DNA probe for rapid and accurate identification of S. bovis strains from all sources. DNAs from strains identified as S. bovis, of both human and ruminal origin, were found to hybridize with the probe under stringent conditions. The probe also hybridized with variants of S. bovis that did not grow on starch. The probe did not hybridize with DNA isolated from other bacteria of human colonic and ruminal origin, including Bacteroides thetaiotaomicron, Bacteroides ruminicola, Butyrivibrio fibrisolvens, and Enterococcus faecalis but did demonstrate hybridization with Streptococcus salivarius.