A novel agroresidue as a substrate for tannase and pyrogallol production by an A.niger isolate

An isolate of A.niger utilized pomegranate rind (PR) powder containing 17%(w/v) tannic acid most efficiently among various agroresidues tested for the production of tannase and gallic acid. The optimum conditions for maximum tannase production (30.30U/ml) were 37°C, 72 h, pH 5.0, 10% (v/v) inoculum and 4% (w/v)PR as substrate in submerged condition. The nature of the experimental data of optimization of tannase production on PR by the isolated strain, permitted excellent polynomial fit on the basis of which a master equation was derived for the estimation of enzyme activity for any set of values of incubation time, substrate concentration, temperature, pH and inoculum size within the indicated range. Tannase production was 25.4% higher on pure tannic acid (TA) compared to PR while biomass was 2.2 times more on the latter. The isolate also produced 235μg/ml, 85 μg/ml and 95 μg/ml of pyrogallol when grown on gallic acid (GA), PR and TA respectively. Gallic acid decarboxylase activities were 0.73U/ml and 0.75U/ml under static and aerobic conditions on GA indicating no inhibition of the enzyme in presence of oxygen as reported in bacterial species.