Gallotannin hydrolysis by immobilized fungal mycelia in a packed bed bioreactor

94-97Hydrolysis of gallotannin to gallic acid by immobilized mycelia of Aspergillus niger MTCC 282, Aspergillus fischerii MTCC 150, Fusarium solani MTCC 350 and Trichoderma viride MTCC 167 in a packed bed bioreactor was studied. Fungal mycelia pre induced with 5 g L-1 gallotannin were immobilized in calcium alginate gel (1.5%) and the resultant beads were packed in a column to a bed volume of 175 mm3. Gallotannin dissolved in distilled water was passed through the column and the eluate was recycled after adjusting pH to 6 with ammonium hydroxide (10%). Maximwn hydrolysis of gallotannin was recorded by immobilized mycelia of F. solani and T. viride at 35° and 45°C after 175 and 60 min of residency period respectively. Optimum substrate concentration required for maximum hydrolysis was 10g L-1 at pH 5 for both the fungi. Immobilized mycelia of A. niger and A. fischerii revealed maximum operational stability. Loss of activity after eighth run was in the order of - A. niger (no loss), A. fischerii (7.5%), F. solani (18%) and T viride (18%). Stability in terms of retention of enzyme activity after 150 days of storage at 4°C was A. niger (58%), A. fischerii (26.8%), F. solani (83%) and T viride (85 .1 %). </span

Production and Characterization of α-Amylase from an Extremely Halophilic Archaeon, Haloferax sp. HA10

Haloarchaea are found at very high concentrations in salt-conditioned environments, hence produce enzymes which are able to catalyze reactions under harsh conditions, typical of many industrial processes. In the present study, culture conditions for extracellular amylase production from Haloarchaea isolated from a solar saltern were optimized and the purified enzyme was characterized. Haloferax sp. HA10 showed maximum amylase production at 3 M NaCl, 37 °C, pH=7 and 1 % starch content. Purified α-amylase was a calcium-dependent enzyme with an estimated molecular mass of about 66 kDa and many industrially useful properties. It was found to be stable in a broad range of pH (from 5 to 9) and NaCl concentrations (from 0.5 to 3.0 M), retaining 48 % activity even at 4 M. The optimal temperature for Haloferax sp. HA10 amylase activity was 55 °C (99 % activity), and 57 % activity was retained at 80 °C, which dropped to 44 % with the increase of temperature to 90 or 100 °C. It was able to sustain various surfactants and detergents. To the best of our knowledge the detergent-stable α-amylases from halophilic archaeon have not been reported yet