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% NH₄SO_4, 0.2% KH₂PO₄, 0.0002% ZnSO₄, 0.0005% FeSO_4, 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 30^oC 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.