The activity and stability of cell associated activity of bovicin HC5, a bacteriocin from Streptococcus bovis HC5

Authors: XAVIER, B - CORNELL UNIVERSITY; HOULIHAN, A - CORNELL UNIVERSITY; Russell, James

Submitted to: Federation of European Microbiological Societies Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2008
Publication Date: 5/23/2008
Citation: Xavier, B.M., Houlihan, A.J., Russell, J.B. 2008. The activity and stability of cell associated activity of bovicin HC5, a bacteriocin from Streptococcus bovis HC5. Federation of European Microbiological Societies. 283:162-166.

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 bacteriocin, bovicin HC5, forms pores in the cells membrane of target bacteria, can be released from the cells or remain cell associated. The cell associated form is just as active as the cell-free form but is much less susceptible to degradation by peptidases that are common in the rumen. Research on bacteriocins has the potential to decrease the need for antibiotic in animal feed.

Technical Abstract: Streptococcus bovis HC5 cultures released a broad spectrum lantibiotic, bovicin HC5, into the cell-fee culture supernatant after they reached stationary phase, but most of the antibacterial activity remained cell-associated. Cell-associated bovicin HC5 was more resistant to degradation by Pronase E than the cell-free activity. Acidic NaCl (pH 2.0, 100 mM) did not release all of the cell-associated activity, and cells that were sequentially treated with acidic NaCl and Pronase E still had antibacterial activity. Cell-associated activity retained after acidic NaCl treatment was still able to catalyze potassium efflux from S. bovis JB1, a sensitive strain. These results indicate that cell associated bovicin HC5 is more active and stable than cell-free bovicin HC5.