Production optimization and characterization of mannooligosaccharide generating β-mannanase from Aspergillus oryzae

A multi-tolerant β-mannanase (ManAo) was produced by Aspergillus oryzae on copra meal, a low-cost agro waste. Under statistically optimized conditions, 4.3-fold increase in β-mannanase production (434 U/gds) was obtained. Purified ManAo had MW ∼34 kDa and specific activity of 335.85 U/mg with optimum activity at 60 °C and at pH 5.0. Activity of ManAo was enhanced by most metal ions and modulators while maximum enhancement was noticed with Ag+ and Triton X-100. Km and Vmax were 2.7 mg/mL and 1388.8 µmol/min/mg for locust bean gum while the enzyme showed lower affinity towards konjac gum (8.8 mg/mL, 555.5 µmol/min/mg). Evaluation of various thermodynamic parameters indicated high-efficiency of the ManAo with activation energy 12.42 KJ/mol and 23.31 KJ/mol towards LBG and konjac gum, respectively. End product analysis of β-mannanase action by fluorescence assisted carbohydrate electrophoresis (FACE) revealed the generation of sugars from DP 1-4 with some higher DP MOS from different mannans.