Effect of initial pH and culture time on production of polysaccharide by submerged fermentation of Russula sp.
The effects of initial pH and culture time on Russula sp. growth and polysaccharide production in submerged cultivation were investigated. The optimal initial pH and culture time for cell growth and accumulation of EPS, IPS was identified. These results indicate that culture time conditions affect cell growth and product biosynthesis. Biomass, EPS,IPS,TPS, final pH and yield of polysaccharides in cultures of Russula sp. were greatly affected by culture time, and EPS, TPS, residual sugar and Final pH were affected by culture pH. The biomass, EPS,IPS and TPS reached its peak of(21.83±0.42)g/L, (1.351±0.117)g/L, (79.87±6.25)mg/g and (2.539±0.187)g/L at culture time 180h,180h,120h and 140h, respectively. The maximal biomass of(19.34±0.12)g/L, EPS of(1.390±0.048)g/L, IPS of(81.98±5.06)mg/g and TPS of(2.943±0.073)g/L reached at initial pH5.8, 4.8, 5.8, 5.8, respectively. From the above results, it is concluded that the optimal initial pH and culture time was around pH 6 and 140h, respectively. The pattern of polysaccharide product is the type of growth associated. The work is useful for further optimization of this Russula sp. submerged fermentation process for highly efficient production of the valuable bioactive metabolites.