PROCEDURE FOR QUANTIFIABLE ASSESSMENT OF NUTRITIONAL PARAMETERS INFLUENCING NISIN PRODUCTION BY LACTOCOCCUS-LACTIS SUBSP LACTIS

A modified rapid plate assay procedure was developed, that allowed qua ntifiable measurement of nisin production by Lactococcus lactis growin g directly on agar media. Using this direct plate assay, several nutri tional parameters were assessed for their influence on nisin productio n (as distinct from their influence on growth) by L. lactis subsp. lac tis ATCC 11454 growing on standard M17 based media over 3 and 6 h incu bation periods. Glucose was found to be the optimal carbon source test ed, with glycerol having the greatest suppressive effect. The addition of salts suppressed nisin production on a per cell basis, except MnC1 (2). This direct plate method proved to be a good pilot assay for rapi dly and quantifiably investigating the initial effects of different pa rameters on nisin production by L. lactis, prior to conducting more in tensive broth batch culture assays. The data obtained in this study in dicate that certain nutritional parameters can impose a repressive eff ect on nisin production. Elucidation of how these parameters control t he amount of nisin produced will provide further insight into the regu lation of nisin biosynthesis in L. lactis. (C) 1998 Elsevier Science B .V. All rights reserved.