The binding and degradation of nisin by mixed ruminal bacteria

Abstract

We found that nisin catalyzed potassium efflux from glycolyzing Streptococcus bovis JB1 cell suspensions and that the steady state concentration of residual potassium was dependent upon the amount of nisin added. The relationship between nisin concentration and potassium depletion was a saturation function that had considerable cooperativity. By pre-incubating mixed ruminal bacteria with nisin and removing them prior to S. bovis JB1 addition, it was possible to estimate the ability of mixed ruminal bacteria to bind or degrade nisin. Low concentrations of mixed ruminal bacteria did not bind or degrade all of the nisin in 6 h, but little nisin remained if the mixed ruminal bacteria were present at more than 50 microg protein ml(-1). Because cell-free ruminal fluid (10% v/v) inactivated the nisin in less than 2 h, and this inactivation could be counteracted by autoclaving, ultra-filtration or proteinase inhibitor, 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.

Effect of pH on the activity of bovicin HC5, a bacteriocin fromStreptococcus bovisHC5

“…A cooperativity plot indicated positive cooperativity, and the binding of one nisin molecule to the cell membrane facilitated the binding of another, particularly if the nisin concentration was low. Our results indicated a similar effect with bovicin HC5, but the slopes of the cooperativity plots were only half as large as the one reported by Lee et al [29].…”

“…Previous work with S. bovis indicated that nisin also caused a decrease in intracellular potassium, but the relationship between nisin concentration and potassium depletion was not a simple saturation function [29]. A cooperativity plot indicated positive cooperativity, and the binding of one nisin molecule to the cell membrane facilitated the binding of another, particularly if the nisin concentration was low.…”

The use of direct-fed microbials for mitigation of ruminant methane emissions: a review

“…In vitro experiments have shown that nisin suppresses methanogenesis as much as 20% without negative impact on VFA production (Callaway et al, 1997;Sar et al, 2005a). However, nisin is susceptible to rumen proteases (Lee et al, 2002a) limiting its utilisation in vivo. The spent media of L. plantarum decreased methanogenesis by 18% in vitro (Nollet et al, 1998) while compounds produced by another L. plantarum strain decreased methanogenesis by 90% (Asa et al, 2010).…”

Use of Bacteriocinogenic Cultures without Inhibiting Cheese Associated Nonstarter Lactic Acid Bacteria; A Trial with Lactobacillus plantarum

“…Nisin activity fluctuated during incubation, possibly because it was degraded and produced again later. The possibility of enzymatic degradation of nisin by bacterial proteases was demonstrated in a study with ruminal mixed cultures [25]. The evidences of its new formation during incubation indicated that using a producing culture instead of preparations of the bacteriocin can ensure the maintenance of the antimicrobial effect of the bacteriocin for longer time in a fermented food system.…”