Simultaneous improvement of yields of intracellular polysaccharide and extracellular polysaccharide in submerged cultivation from a strain of Lachnum sp

The correlations between the yield of intracellular polysaccharide (LIP), the yield of extracellular polysaccharide (LEP) and the biomass of a Lachnum YM281 in submerged fermentation were studied. Results showed that there was a significant linear relationship between the yield of LIP (Y) and the biomass (Z): Z=12.561Y-0.0148 (R=0.985). The yield of LIP (Y) and yield of LEP (X) were positively correlated, but the linear relationship was insignificant. Accordingly, in order to improve the two synchronously, the two response variables (X,Y) were integrated into a single response variable using the desirability functions and the fermentation conditions of LIP and LEP of Lachnum YM281 were optimized synchronously by uniform design to obtain the optimum condition: 46.6g/L glucose, 14.6g/L yeast extract, 6.50mg/L glycine, initial pH value =7.5, 12 days' fermentation at 25 , the other factors being the same as those of the basic fermentation condition. Under this condition, the yields of LIP and LEP increased by 2.35g/L and 6.28g/L, respectively, improving by 1.42 times and 1.23 times, respectively, compared to those before optimization.