Development of cultivation medium for high yield kefiran production by Lactobacillus Kefiranofaciens

Abstract

Objective: Kefiran is one of the important microbial polysaccharides of many pharmaceutical and nutraceutical applications. It shows many potential medical applications as antimicrobial and immunomodulatory compound. The present work focuses on medium optimization for kefiran production using the standard strain Lactobacillus kefiranofaciens in submerged cultivation system. Methods: Different types and concentrations of key nutrients such as carbon sources (glucose, mannitol, sucrose, lactose), nitrogen sources (yeast extract, peptone, meat extract, casein hydrolysate) and inorganic phosphate were evaluated to select the most appropriate nutrients and concentrations for kefiran production. Growth curve kinetics were also carried out to compare between the kinetics of cell growth and kefiran production in medium before and after optimization. Results: It was clearly observed that type and concentration of carbon and nitrogen sources showed the significant effect on kefiran production. On the other hand, phosphate showed less effect on this process. The maximal kefiran production of about 1.25 g/l was obtained in medium composed of (g/l): lactose, 50.0; yeast extract, 12.0; KH2PO4, 0.25; sodium acetate, 5.0; Triammonium citrate, 2.0; MgSO4.7H2O, 0.2; MnSO4.5H2O, 0.05. Conclusion: The new medium formulation increased the kefiran production from 0.23 g/l upto 1.29 g/l concomitant with the reduction of production time from 72 to 60 h.