THE BINDING AND DEGRADATION OF NISIN BY MIXED RUMINAL BACTERIA

Authors: LEE, S - CORNELL UNIVERSITY; MANTOVANI, H - CORNELL UNIVERSITY; Russell, James

Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/20/2002
Publication Date: 7/20/2002
Citation: LEE, S.S., MANTOVANI, H.C., RUSSELL, J.B. 2002. THE BINDING AND DEGRADATION OF NISIN BY MIXED RUMINAL BACTERIA [abstact]. AMERICAN DAIRY SCIENCE ASSOCIATION ABSTRACTS. 85(1):398.

Interpretive Summary:

Technical Abstract: Monensin and the bacteriocin, nisin, have similar effects on ruminal fermentation, and bacteriocins have been suggested as another means of altering ruminal fermentation. Potassium depletion can be used as an index of sensitivity because monensin & nisin both catalyze potassium efflux from sensitive bacteria. Nisin catalyzed potassium efflux from glycolyzing S. bovis cell suspensions, & the steady state concentration of residual potassium was dependent on the amount of nisin added. The relationship between nisin concentration & potassium depletion was a saturation function that had considerable cooperativity. By pre-incubating mixed ruminal bacteria with nisin & removing them prior to S. bovis JB1 addition, it was possible to estimate the ability of mixed ruminal bacteria to degrade or bind nisin. Low concentrations of mixed ruminal bacteria did not degrade or bind all of the nisin in 6 h but little nisin remained if the mixed ruminal lbacteria were present at more than 50 ug protein per ml. Because cell-free ruminal fluid (10% v/v) inactivated the nisin in < 2 h, & this inactivation could be counteracted by autoclaving, ultra-filtration & proteinase inhibitors it appeared that there was an enzymatic degradation of nisin. Mixed ruminal bacteria degraded nisin rapidly, but this degradation did not prevent potassium depletion from mixed ruminal bacteria. These latter results indicated that nisin binding was faster than nisin degradation. The idea that nisin binding could protect nisin from degradation was supported by the observation that intact nisin could be extracted from mixed ruminal bacteria. These observations support the hypothesis that bacteriocins can be used to modify ruminal fermentation, but further work will be needed to see if these peptides can be produced economically.