A β-mannanase from Fusarium oxysporum SS-25 via solid state fermentation on brewer spent grain: Medium optimization by statistical tools, kinetic characterization and its applications

This study concerned with the optimization of fermentation parameters for the hyper production of mannanase from Fusarium oxysporum SS-25 employing two step statistical strategy and kinetic characterization of crude enzyme preparation. The Plackett-Burman design was first used to screen out the important factors in the culture medium which were found to be: 20% (w/w) wheat bran, 2% (w/w) each of potato peels, soybean meal, malt extract, 1% tryptone, 0.14% NH4SO4, 0.2% KH2PO4, 0.0002% ZnSO4, 0.0005% FeSO4, 0.01% MnSO4, 0.012% SDS, 0.03% NH4Cl, 0.1% NaNO3 in brewer’s spent grain based medium with 50% moisture content, inoculated with 2.8×107 spores and incubated at 30oC for 6 days. Out of twenty seven factors, four variables including soybean meal, FeSO4, MnSO4 and NaNO3 were selected to study the interactive effects and optimum level of these variables in central composite design of response surface methodology. The final mannanase yield was 193 IU/g which was active at broader temperature and pH range and could result in 26.6% reduction in kappa number with 4.93% higher tear index and 1% increase in brightness when used to treat the wheat straw based kraft pulp. The hydrolytic potential of enzyme was demonstrated on both locust bean gum and guar gum.