Secondary Screening of Various Cheaper Nutrients for Dextran Production by Weissella Confusa Using Plackett-burman Design

Dextran a bacterial exopolysaccharide and a polymer of glucose is produced by different microorganisms like Leuconostoc mesenteroides, Lactobacillus spp, Streptococcus mutans, Weissella confusa etc. It has a wide range of applications in the food, pharmaceutical and other industries. Dextran and its derivatives like iron dextran, clinical dextran, food grade dextran are rapidly emerging as new and industrially significant products. Selection of the best nutrients is one of the most critical stage in media optimization for dextran production. Plackett-Burman designs of 12 and 8 faciors were used to screen various cheaper carbon sources, nitrogen sources, micronutrients and macronutrients respectively for dextran production by Weissella confusa. The most influential or significant nutrients short listed by the first step screening based on regression coefficients and t-values obtained after subjecting the experimental data to statistical analysis using Indostat software were selected for second level screening. In the present study eleven significant nutrients like four cheaper carbon sources namely molasses, sugarcane juice, banana pulp and sapota, two nitrogen sources namely black gram and soyabeans, four micronutrients like MgCl2, MnCl2, MgSO4 and MnSO4 and one macronutrient like K2HPO4 were selected for second level screening using 12 experimental design of Plackett-Burman. Sugarcane juice as cheaper carbon (sucrose) source, black gram as nitrogen source, MgCl2 and MgSO4 as micronutrients and K2HPO4 as macronutrient showed maximum dextran production and this data was analysed by Indostat software and so were selected for further quantitative optimization.