ISOLATION AND CHARACTERIZATION OF A BACTERIOCIN (BUTYRIVIBRIOCIN AR10) FROM THE RUMINAL ANAEROBE BUTYRIVIBRIO-FIBRISOLVENS AR10 - EVIDENCE IN SUPPORT OF THE WIDESPREAD OCCURRENCE OF BACTERIOCIN-LIKE ACTIVITY AMONG RUMINAL ISOLATES OF B-FIBRISOLVENS

Forty-nine isolates of Butyrivibrio fibrisolvens and a single isolate of Butyrivibrio crossotus were screened for the production of inhibito rs by a deferred plating procedure. Twenty-five isolates produced fact ors which, to various degrees, inhibited the growth of the other Butyr ivibrio isolates. None of the inhibitory activity was due to bacteriop hages. The inhibitory products from 18 of the producing strains were s ensitive to protease digestion. Differences in the ranges of activity among the Butyrivibrio isolates and protease sensitivity profiles sugg est that a number of different inhibitory compounds are produced. Thes e findings suggest that the production of bacteriocin-like inhibitors may be a widespread characteristic throughout the genus Butyrivibrio. The bacteriocin-like activity from one isolate, B. fibrisolvens AR10, was purified and confirmed to reside in a single peptide. Crude bacter iocin extracts were prepared by ammonium sulfate and methanol precipit ation of spent culture supernatants, followed by dialysis and high-spe ed centrifugation. The active component was isolated from the semicrud e extract by reverse-phase chromatography. Tricine-sodium dodecyl sulf ate polyacrylamide gel electrophoresis confirmed that the peptide was purified to homogeneity, having an estimated molecular mass of approxi mately 4,000 Da. The N terminus of the peptide was blocked. a cyanogen bromide cleavage fragment of the native peptide yielded a sequence of 20 amino acids [(M) GIQLAPAXYQDIVNXVA AG]. No homology with previousl y reported bacteriocins was found. Butyrivibriocin AR10 represents the first bacteriocin isolated from a ruminal anaerobe.