Author
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MANTOVANI, H - CORNELL UNIVERSITY |
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Russell, James |
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Submitted to: Anaerobe
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/29/2002 Publication Date: 12/1/2002 Citation: MANTOVANI, H.C., RUSSELL, J.B. 2002. THE ABILITY OF A BACTERIOCIN OF STREPTOCOCCUS BOVIS HC5 (BOVICIN HC5) TO INHIBIT CLOSTRIDIUM AMINOPHILUM, AN OBLIGATE AMINO ACID FERMENTING BACTERIUM FROM THE RUMEN. ANAEROBE. 8:247-252. Interpretive Summary: Cattle in the U.S. are often fed antibiotics, but the widespread use of antibiotics in animal feed has been criticized. Antibiotics are primarily targeted against gram-positive gut bacteria that produce large amounts of hydrogen a precursor of methane, ammonia, a wasteful end-product of amino acid degradation. Some gram-positive bacteria produce peptides (bacteriocins) that can inhibit other gram-positive bacteria, and bacteriocins have been proposed an alternative to antibiotics. Clostridium aminophilum is an amino acid fermenting bacterium that produces large amounts ammonia. C. aminophilum can become highly resistant to monensin, the most commonly used antibiotic, but our work indicates that it remains sensitive to the bacteriocin of Streptococcus bovis HC5. Research on bacteriocins has the potential to decrease the need for antibiotic in animal feed and lessen the risk of antibiotic resistance in human medicine. Technical Abstract: Ruminant nutritionists have used antibiotic to inhibit gram-positive bacteria and alter the end-products of ruminal fermentation, but this use has been criticized. Many gram-potive ruminal bacteria can be inhibited by bacteriocins, but bacteriocin resistance can circumvent this inhibition. Clostridium aminophilum is detrimental ruminal bacterium that produces large amounts of ammonia, and it becomes highly resistant to the antibiotic, monensin, and at least one naturally occurring bacteriocin (butyrivibriocin JL5). Clostridium aminophilum, was inhibited by Streptococcus bovis HC5, a bacterium that produces bovicin HC5, but not S. bovis JB1, a non-bacteriocin producing strain. Co-culture experiments indicated that the inhibition persisted for at least 6 transfers. When C. aminophilum F was inoculated (5% v/v) into basal medium that had increasing amounts of semi-purified bovicin HC5, growth and ammonia production were only observed if the concentration was less than 12.5 activity units (AU) ml-1. C. aminophilum F cultures treated with 10 AU ml-1 of bovicin HC5, grew, but the growth rate was noticeably slower, and there was produced lag before growth and ammonia production were observed. Cultures that were transferred successively (7 times) with 10 AU ml-1 bovicin HC5 tolerated 4-fold more bovicin HC5 than untreated controls, but growth was never observed if bovicin HC5 was more/less 50 AU ml-1. Bovicin HC5 caused an efflux of potassium from C. aminophilum F, but the efflux rate was at least 8 times slower than S. bovis JB1. If the pH was decreased from 6.5 to 5.5 with HCl, the efflux rate was at least 6-fold faster. Given the fact that the European Union has already proposed a ban on feed antibiotics, bovicin HC5 could be an alternative. |
