Purification and characterization of α-amylase from <i>Ganoderma tsuage</i> growing in waste bread medium

Abstract

The objective of this study was to purify and characterize the α-amylase for industrial perspective. The production of α-amylase through solid-state fermentation by Ganoderma tsuage was investigated by using waste bread as substrates. Production parameters were optimized as 2 mL of inoculum size, moisture 50%, additional carbon source (glucose) and nitrogen source (ammonium nitrate) 10:1, 1 mM/mL MgSO₄, 0.75 mM/mL CaCl₂ and 0.50 mM/mL KH₂PO₄. The purification value of α-amylase was observed as 1.2 fold with specific activity of 112 U/mg having a yield of 22%. Specific activity of α-amylase increased up to the level of 143 U/mg and had 1.5-fold purification factor having a yield of 6% after Sephadex gel filtration. Optimum value of α-amylase was obtained at 35°C and at pH 6 for the time duration of 72 h. The K_m and V_max values for α-amylase were 1.3 mg and 39 mg/min, respectively. Calcium chloride (CaCl₂) was found to increase the activity of α-amylase while all other compounds seemed to have inhibitory action against α-amylase. Silver nitrate (AgNO₃) was the strongest inhibitor and therefore would not be advised for use in future research against α-amylase production.

Keywords: α-Amylase, purification, characterization, waste bread, Ganoderma tsuage