The effect of starch on biosurfactant production in Lactobacillus casei

BACKGROUND AND OBJECTIVESBiosurfactants are amphiphilic compounds with many applications as detergents, emulsifiers, and foaming agents. In recent years, microbial biosurfactants have received a lot of attention compared to chemical surfactants due to their diversity and unique characteristics, including biodegradability, and low toxicity, and have replaced chemical surfactants such as sodium lauryl sulfate in detergents. Lactobacillus species are capable of producing biosurfactants, which have great potential for use in various industries, or as food ingredients. Low production efficiency is one of the problems to run large scale fermentations .MATERIALS AND METHODSIn this study, the effect of starch to increase biosurfactant production in Lactobacillus casei was investigated. Biosurfactant production by Lactobacillus casei in ۲۰۰ cc of MRS broth and۱% starch was investigated after ۴۸, ۷۲ and ۹۶ hours at ۳۷ ° C and compared with the starch-free medium. In order to extract the biosurfactant from cell-fre extract, bacterial cells were first removed from the broth by centrifugation at ۳۸۰۰ rpm for ۲۵ min. Then the pH of the cell-free broth was set at ۲.۰ with concentrated HCl and were saved at ۴◦C for ۳۰ min. The samples were centrifuged for ۲۵ min at ۳۸۰۰ rpm and the broth was discarded. The pellets were washed and centrifuged with PSB. After that, the pellets were resuspended with ۲.۰ mL of distilled water. The dry weight of sediment was obtained and compared in both mediums.RESULTS AND DISCUSSIONThe results showed that ۱% starch could increase the amount of biosurfactant produced by Lactobacillus casei. According to the results, ۰.۱۴, ۰.۳۰, and۰.۳۸mgr biosurfactants were obtained from MRS medium after ۴۸, ۷۲ and ۹۶ hours of incubation. The highest amount of biosurfactant production in this bacterium was obtained in starch containing MRS medium after ۹۶ hours (۰.۳۸ mgr), which showed a ۱۰% -fold increase.CONCLUSIONUsage of starchy substances as cheap renewable additives in the fermentation medium of Lactobacillus casei can increase the biosurfactant production and reduce costs on an industrial scale.

کلیدواژه ها:

Biosurfactant ، starch ، Probiotics ، Lactobacillus casei