Influence of vitamins and osmolites on growth and bacteriocin production byLactobacillus salivariusCRL 1328 in a chemically defined medium

Abstract

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.