The Effect of Calcium and Magnesium on the Activity of Bovicin HC5 and Nisin
- 134 Downloads
Some Gram-positive bacteria produce small peptides (bacteriocins) that have antimicrobial activity, but many bacteria can become bacteriocin resistant. Bovicin HC5, a lantibiotic produced by Streptococcus bovis HC5, has the ability to inhibit nisin-resistant bacteria. Because nisin resistance has in many cases been correlated with an alteration of lipoteichoic acids or the polar head groups of membrane phospholipids, we decided to examine the effect of divalent cations on nisin and bovicin HC5 activity. Both bacteriocins catalyzed potassium efflux from S. bovis JB1, a non–bacteriocin-producing strain. The addition of large amounts (100 mM) of calcium or magnesium increased the ability of S. bovis JB1 to bind Congo red (an anionic dye) and counteracted bacteriocin-mediated potassium loss. Calcium was more effective than magnesium in decreasing nisin activity, but the reverse was observed with bovicin HC5. Nisin-resistant S. bovis JB1 cells bound three times as much Congo red as nisin-sensitive cells, and this result is consistent with the idea that changes in cell surface charge can be a mechanism of bacteriocin resistance. The nisin-resistant cells were less susceptible to bovicin HC5, but bovicin HC5 still caused a 50% depletion of intracellular potassium. These results indicate that nisin and bovicin HC5 react differently with the cell surfaces of Gram-positive bacteria.
KeywordsMonensin Polar Head Group Lipoteichoic Acid Bacteriocin Activity Intracellular Potassium
This research was supported by the United States Dairy Forage Research Center, Madison, WI.
- 1.Bassette R, Acosta JS (1999) Composition of milk products. In: Wong NP, Jenness R, Keeney M, Marth EH (eds) Fundamentals of dairy chemistry, 3rd ed. Gaithersburg, MD: Aspen, pp 58–70Google Scholar
- 14.Mackie RI, Therion JJ (1984) Influence of mineral interactions on growth efficiency of rumen bacteria. In: Gilchrist FMC, Mackie RI (eds) Herbivore nutrition. Craighall, South Africa: Science Press, pp 455–477Google Scholar
- 15.Mantovani HC, Kam DK, Ha JK, Russell JB (2001) The antibacterial activity and sensitivity of Streptococcus bovis strains isolated from the rumen of cattle. FEMS Microbial Ecol 37:223–229Google Scholar
- 20.National Dairy Council (1979) Newer knowledge of cheese and other cheese products, 3rd ed. Rosemont, IL: National Dairy CouncilGoogle Scholar
- 22.White JCD, Davies DT (1958) The relation between the chemical composition of milk and the stability of the caseinate complex. I. General introduction, description of samples, methods and chemical composition of samples. J Dairy Res 25:236–255Google Scholar