NUTRITIONAL FACTORS AFFECTING NISIN PRODUCTION BY LACTOCOCCUS-LACTIS SUBSP LACTIS NIZO-22186 IN A SYNTHETIC MEDIUM

A minimal synthetic medium (SM8) for nisin-producing Lactococcus lactis subsp. lactis strains has been designed; it consists of eight growth-stimulating amino acids (glutamic acid, methionine, valine, leucine, threonine, arginine, isoleucine and histidine), five vitamins (biotin, calcium pantothenate, nicotinic acid, pyridoxine and riboflavin) anti the mineral salts dihydrogen phosphate, disodium hydrogen phosphate, sodium chloride, magnesium sulphate and trisodium citrate. Nisin biosynthesis is strongly dependent on the presence of a sulphur source, either an inorganic salt (magnesium sulphate or sodium thiosulphate) or the amino acids methionine, cysteine or cystathionine. The amino acids serine, threonine and cysteine highly stimulate nisin production without affecting the final cell yield, indicating their precursor role during nisin biosynthesis.