Influence of vitamins and osmolites on growth and bacteriocin production by Lactobacillus salivarius CRL 1328 in a chemically defined medium

The aim of this study was to analyze the influence of vitamins, glycerol, and salts on the growth and bacteriocin production by Lactobacillus salivarius CRL 1328, a human vagina isolate, by using a chemically defined medium to determine the optimal conditions for salivaricin production. The single omission of d-biotin, thiamine, p-aminobenzoic acid, folic acid, or cyanocobalamin did not affect the bacterial growth, whereas the removal of nicotinic acid, riboflavin, and pyridoxal produced a decrease of about 30% in the growth rate. Maximum salivaricin activity was observed after the addition of 5 or 10 g/L of NaCl. On the basis of the nutritional requirements and the levels of salivaricin production, a new optimized and simplified defined medium (SDM-NaCl) for L. salivarius CRL 1328 bacteriocin production was formulated. The kinetics of salivaricin production in SDM-NaCl and in the complex media LAPTg revealed that bacteriocin production was growth linked. A combination of tricine - sodium dodecyl sulfate polyacrylamide gel electrophoresis (Tricine-SDS-PAGE), Lumitein protein gel staining, and a bioassay for antibacterial activity indicated that the molecular mass of salivaricin CRL 1328 is about 4.5 kDa. The partially purified bacteriocin, obtained from SDM-NaCl after concentration, allowed for the design of a relatively simple method for the recovery of a biologically active protein.