Optimization of a Modified GS Medium for a Probiotic Strain (L. acidophilus ATCC4356)

Probiotics are defined as living microorganisms with beneficial effects on the host. Probiotics, according to the least negative effect on the body, are considered as a good alternative to chemical drugs. Lactobacillus acidophilus is used as a probiotic that is able to reduce cholesterol level in the blood. The effect of various concentrations of carbon, nitrogen and phosphorus for enhancing the biomass production of Lactobacillus acidophilus was examined. The response surface methodology based on Box–Wilson CCD was applied to explore the optimal medium composition. Glucose, yeast extract, K2HPO4 and K2HPO4 were selected as dependent variables. All experiments were run at 37°C for 31h under stationary conditions. By solving the regression equation and analyzing the response surface carton, optimal concentrations of the components were determined as glucose (5-8.75 g.l-1), yeast extract (36.75-39 g.l-1), K2HPO4 (0.1-0.2125 g.l-1) and K2HPO4 (0.3925-0.7075 g.l-1) (P<0.05). Validation experiment confirmed that the optimized medium was comparable to the MRS medium (the most common medium for Lactobacillus acidophilus strain) in biomass production, having the advantages of economy and practicality.