Gallotannin hydrolysis by immobilized fungal mycelia in a packed bed bioreactor

Abstract

Hydrolysis of gallotannin to gallic acid by immobilized mycelia of <i>Aspergillus niger </i>MTCC 282, <i>Aspergillus fischerii </i>MTCC 150, <i>Fusarium solani </i>MTCC 350 and <i>Trichoderma viride </i>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 <i>F. solani </i>and <i>T. viride </i>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 <i>p</i><span style="mso-bidi-font-style:italic">H<i> </i>5 for both the fungi. Immobilized mycelia of <i>A. niger </i>and <i>A. fischerii </i>revealed maximum operational stability. Loss of activity after eighth run was in the order of - <i>A. niger </i>(no loss), <i>A. fischerii </i>(7.5%), <i>F. solani (18%) </i>and <i>T viride </i>(18%). Stability in terms of retention of enzyme activity after 150 days of storage at 4°C was <i>A. niger </i>(58%), <i>A. fischerii </i>(26.8%), <i>F. solani </i>(83%) and <i>T viride </i>(85 .1 %).

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