A low-cost Lactobacillus salivarius L29 growth medium containing molasses and corn steep liquor allows the attainment of high levels of cell mass and lactic acid production

Abstract

The aim of the present work was to formulate a Lactobacillus salivarius L29 industrial fermentation \rmedium. High cell numbers and good levels of lactic acid by a L. salivarius L29 were obtained after \rshake flask fermentation using molasses as the sole carbon source and corn steep liquor (CSL \r(industrial grade); an organic source of N) as the principal nitrogen source. The optimum \rconcentrations of molasses and CSL facilitating good cell growth and high-level lactic acid production \rwere found to be 6 and 6% (both v/v), respectively. The maximum cell yield was 2.02 × 10\r9 \rCFU/mL, thus \rabout 15% lower than that obtained when MRS broth was employed for 5-L fermenters culture. Lactic \racid production upon growth in industrial broth was 105 g/L; the total sugar content of the medium was \r118 g/L (sucrose: glucose: fructose 68:14:18; w/w/w). Upon growth in De Man, Rogosa and Sharpe \r(MRS) broth (the total sugar content of which was 127 g/L, all of which was glucose), the lactic acid \ryield was 120 g/L. The optimized industrial growth medium was significantly more economical than \rwere conventional broths.