High-level tannase production by Penicillium atramentosum KM using agro residues under submerged fermentation

A tannase-yielding fungal strain identified as Penicillium atramentosum KM was isolated from tannery effluent collected from a small-scale tannery. The fungal strain produced extracellular tannase under submerged fermentation (SmF) using amla (Phyllanthus emblica), ber (Zyzyphus mauritiana), jamoa (Eugenia cuspidate), jamun (Syzygium cumini) and keekar (Acacia nilotica) powdered leaves. Among the different substrates, amla and keekar leaves resulted in maximal extracellular production of tannase. Various process parameters were studied to optimize the extracellular yield of tannase under SmF. Maximum yield of tannase i.e., 32.8 and 34.7 U/ml was obtained with amla leaves (2% w/v) and keekar leaves (3% w/v), respectively, in selective mineral salt and production media, inoculated with 3 x 10(6) spores/ml cell suspension by incubating at 30 degrees C for 72 h. The production of enzyme was induced strongly by the presence of maltose (0.2% w/v) as carbon source. Crude enzyme was optimally active at pH 5.5 and pH 7.5 using amla and keekar leaves, respectively. The fungal strain produced yields of tannase about twice as high as the highest reported yield of tannase. Our findings suggest that agro residues in the form of amla and keekar leaves can be one of the best and most cost effective alternatives to the costly pure tannic acid for industrial production of microbial tannase. The novelty in the present investigation is that is that P. atramentosum KM is the first fungal isolate found to produce tannase at high pH (i.e. 7.5) using keekar leaves.