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Title: DIFFERENTIATION OF RUMINAL AND HUMAN STREPTOCOCCUS BOVIS STRAINS BY DNA HOMOLOGY AND 16S RRNA PROBES

Author
item NELMS LINDA F - CENTRAL MICH UNIV
item ODELSON DAVID A - CENTRAL MICH UNIV
item Whitehead, Terence
item Hespell, Robert

Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Streptococcus bovis is a bacterium commonly found in the rumen of cattle that aids the digestion of dietary grains. This bacterium thrives in the absence of oxygen, has simple nutritional requirements, grows very rapidly, and we have shown recently that it is able to take up foreign genes. This organism has commercial potential to produce degradable polymers and fuel alcohol from starch or to improve rumen feedstuff digestion. Bacterial strains characterized as S. bovis have been occasionally isolated from humans suffering from endocarditis or colon cancer. In this research a genetic probe was developed that reacted with ruminal S. bovis strains, but not those from humans. Our results indicate ruminal strains are genetically unrelated to human strains and are separate species. Other traits of ruminal S. bovis strains suggest them to be safe, non-pathogenic bacteria that could be used commercially.

Technical Abstract: Streptococcus bovis is commonly isolated from the rumen and often from animal feces and raw milk. Strains of S. bovis have occasionally been isolated from blood or fecal samples from humans. A DNA probe based on the V1 region of the 16sRNA of the ruminal S. bovis strain JB1 was found to hybridize to DNA's of other ruminal S. bovis strains (K27FF4, 21-09-6C, five new ruminal isolates), but not other major species of ruminal bacteria. Weak hybridization also was found with DNA's from S. bovis 33317 (type strain), S. bovis 26, S. equinus 9812, and five other new ruminal isolates. No hybridization occurred with strains representing different human biotypes/homology groups (43143, 43144, 27960, V1387). Ruminal and human strains also yielded different genomic DNA restriction endonuclease digest patterns when either the 16s rRNA gene amplified from S. bovis JB1 or a conserved universal 23s rRNA fragment were used as probes. All S. bovis strains had a guanosine plus cytosine DNA content of 37.4 to 38.8 mol%. Based on DNA-DNA genomic hybridizations, the ruminal strains could be separated into two homology groups, one of which included S. equinus 9812. Both ruminal groups had less than 38% DNA homology to the human strains, indicating these strains are separate species.