Submitted to: Federation of European Microbiological Societies Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2004
Publication Date: 3/1/2004
Citation: HOULIHAN, A.J., MANTOVANI, H.C., RUSSELL, J.B. THE EFFECT OF PH ON THE ACTIVITY OF BOVICIN HC5, A BACTERIOCIN FROM STREPTOCOCCUS BOVIS HC5. FEDERATION OF EUROPEAN MICROBIOLOGICAL SOCIETIES MICROBIOL LETTERS. 2004. V. 231. P. 27-32. 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. Gram-positive ruminal bacteria produce large amounts of hydrogen a precursor of methane, ammonia, a wasteful end-product of amino acid degradation, and lactic acid, an acid that causes ruminal acidosis, ruminal ulcers, founder and even death of the animal. Some bacteria produce peptides (bacteriocins) that can inhibit gram-positive bacteria, and bacteriocins have been proposed as an alternative to antibiotics. In this paper, we show that the activity of the bacteriocin, bovicin HC5 is greatly enhanced at acidic pH. Research on bacteriocins has the potential to decrease the need for antibiotic in animal feed.
Technical Abstract: The bacteriocin, bovicin HC5, catalyzed potassium efflux from Streptococcus bovis JB1, and this activity was highly pH-dependent. When the pH was near neutral, glucose energized cells counteracted bovicin HC5, but the steady state concentration of potassium decreased at acidic pH values. The idea that pH was affecting bovicin HC5 binding was supported by the observation that acidic pH also enhanced the efflux of potassium from non-energized cells that had been loaded with potassium. The relationship between bovicin HC5 concentration and potassium depletion was a saturation function, but cooperativity plots indicated that the binding of one bovicin molecule facilitated the binding of another.