Evaluation of lactic acid production in different concentrations of sucrose and bioinformatic analysis of lactate dehydrogenase protein structure in probiotic bacteria

Abstract

Probiotics are useful bacteria that exert beneficial health effects on the host. These bacteria produce lactic acid as the main product of sugar fermentation via lactate dehydrogenase activity. Lactic acid is considered an important chemical compound which has significant applications in pharmaceutical and food industry. In the present study, lactic acid production and in silico properties of lactate dehydrogenase in three strains of probiotic bacteria were investigated. These three strains were Lactobacillus casei, Lactobacillus brevis and Lactobacillus plantarum. These strains were grown in the de Man, Rogose Sharpe (MRS) medium containing different concentrations of sucrose (20, 10, 5, 2.5, 0 g/l). These bacteria were incubated at 37°C for 72 hours. The bacterial growth and lactic acid production were estimated by colony-forming unit (CFU) and Gas Chromatography (GC) analyzes, respectively. In silico properties of lactate dehydrogenase, which is responsible for lactic acid production, was also evaluated. The result showed that 10 and 20% sucrose could greatly induce growth and production of lactic acid in these three strains. Among these three bacteria, L. plantarum and L. casei could produce more lactic acid. The in silico results of lactate dehydrogenase demonstrated that alpha-helix and beta-sheet percentage in L. plantarum and L. casei were significantly more than L. bervis. These results verified that lactate dehydrogenase of L. plantarum and L. casei is a good candidate for genetic engineering processes. © 2014, Iranian Neurogenetics Society. All rights reserved.