Bioconversion of industrial solid waste—Cassava bagasse for pullulan production in solid state fermentation

•Pullulan produced by bioconversion of an industrial waste, cassava bagasse.•Initial pH influence cell morphology and hence pullulan yield.•FTIR, 1H-NMR and 13C-NMR confirm product.•Addition of supplementary carbon source, mannose improved yield.•Average molecular weight of pullulan produced was 9.8×106g/mol. The purpose of the work was to produce commercially important pullulan using industrial solid waste namely cassava bagasse in solid state fermentation and minimize the solid waste disposal problem. First, influence of initial pH on cell morphology and pullulan yield was studied. Effect of various factors like fermentation time, moisture ratio, nitrogen sources and particle size on pullulan yield was investigated. Various supplementary carbon sources (3%, w/w) namely glucose, sucrose, fructose, maltose, mannose and xylose with cassava bagasse was also studied to improve the pullulan yield. After screening the suitable supplement, effect of supplement concentration on pullulan production was investigated. The pullulan from cassava bagasse was characterized by FTIR, 1H-NMR and 13C-NMR. Molecular weight of pullulan from cassava bagasse was determined by gel permeation chromatography. Thus, cassava bagasse emerged to be a cheap and novel substrate for pullulan production.