Production, medium optimization, and structural characterization of an extracellular polysaccharide produced by Rhodotorula minuta ATCC 10658

Abstract

Several strains of microorganism are capable of converting carbohydrates into extracellular polysaccharide. The preset research is a first effort made to optimize extracellular polysaccharide (CRMEP) by Rhodotorula minuta ATCC 10658 using one factor at time and response surface methods. One factor at time was applied in the initial screening of substrates prior to optimization study. Of all the substrates examined, starch as carbon source and defatted soy bean powder as protein source were discovered to be best for CRMEP production. Response surface analysis revealed that 15 g/L starch and 30g/L defatted soy bean powder were the optimal chemical conditions. The model predicted 13.22 g/L for CRMEP, which went along with the experimentally observed result. Purification of CRMEP by anion-exchange column of DEAE-cellulose yielded RMEP. Structural investigation indicated that the main chain of RMEP was composed of (1 → 3) and (1 → 4)-linked mannopyranosyl residues, with branches attached to O-6 of some (1 → 3)-linked mannopyranosyl residues. The branches were composed of Glcp-(1 → residues.