Optimization of polysaccharide productio by Lactobacillus kefiranofaciens using response surface methdology

Abstract

Kefiran is an exopolysaccharides produced by Lactobacillus kefiranofaciens which was isolated from kefir grains. Kefiran has wide applications mainly in food and pharmaceutical industries. Growth and kefiran production of L. kefiranofaciens can be significantly enhanced by using mixed culture technique. Saccharomyces cerevisiae in this study was used to enhance the kefiran production by reducing lactic acid accumulation in the cultivation medium. The statistical analysis was used for optimization study by using response surface methodology based on Box-Behnken design. The interaction was studied between three different levels of variables that were lactose, yeast extract and phosphate. A second order polynomial model was used to correlate the factors. The model was found to be significant. The optimum concentration of lactose, yeast extract and phosphate obtained using statistical media optimization is 59.09 g L-1, 8.69 g L-1and 0.5 g L-1 respectively. Kefiran production in optimized medium was 0.97 g L-1 which gave an increase in kefiran production up to 42.65 % compared to the un-optimized medium which was only 0.68 g L-1 of kefiran.