سحر زنگنه

Production of Biopolymers by different microorganisms for industrial applications has been considered in recent years. Lactobacillus kefiranofaciens bacterium produces exopolysaccharid exists in kefir grains called kefiran. The objective of this study was optimization of environmental conditions to produce kefiran polysaccharide in a synthetic media based on whey substrate by using response surface methodology (RSM). Therefore, different combinations of factors including pH (4.7-6.3), temperature (23-37º C) and agitation rate (70-170 rpm) on production of kefiran (g/L) were studied. According to the results, the optimum condition for production of kefiran included pH equal to 5.7, 31º C and agitation rate of 127 rpm which led to producing 1.14 g/L kefiran after five days incubation period. Furthermore, the molecular weight of produced kefiran in pure culture of L.kefiranofaciens measured by gel filtration chromatography was 1.1× 106 Da.