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A tannase yielding bacterial strain was isolated from soil sample collected from the area situated nearby small-scale tannery. It was identified as Pseudomonas aeruginosa IIIB 8914. The bacterial strain produced extracellular tannase under sub-merged fermentation (Smf) using amla (Phyllanthus emblica), keekar (Acacia nilotica), jamoa (Eugenia cuspidate) and jamun (Syzygium cumini) leaves. Among different substrates, amla and keekar leaves resulted in maximal extra-cellular production of tannase. Various process parameters were studied to optimize the extra-cellular yield of tannase under Smf. Maximum yield of tannase i.e., 13.65 and 12.90 U/ml was obtained when Smf was carried out using amla and keekar leaves (2% w/v) respectively in minimal media supplemented with MgSO 4 Á7H 2 O (amla)/HgCl 2 (keekar), NH 4 NO 3 and 0.2% Tween 80; inoculated with 2% cell suspension, and incubated at 37°C for 24 h. The bacterial strain produced about 2 times (13.65 U/ml) higher yield of tannase than the highest reported yield of tannase (6 U/ml). Our finding suggests that agro residues in the form of amla and keekar leaves can be one of the best and cost effective alternatives to the costly pure tannic acid for industrial production of microbial tannase.

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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°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.

To eliminate the elaborate processes employed in other non-biological-based protocols and low cost production of silver nanoparticles (AgNPs), this study reports biogenic synthesis of AgNPs using silver salt precursor with aqueous extract of Aspergillus fumigates MA. Influence of silver precursor concentrations, concentration ratio of fungal extract and silver nitrate, contact time, reaction temperature and pH are evaluated to find their effects on AgNPs synthesis. Ultraviolet-visible spectra gave surface plasmon resonance at 420 nm for AgNPs. Fourier transform infrared spectroscopy and X-ray diffraction techniques further confirmed the synthesis and crystalline nature of AgNPs, respectively. Transmission electron microscopy observed spherical shapes of synthesised AgNPs within the range of 3-20 nm. The AgNPs showed potent antimicrobial efficacy against various bacterial strains. Thus, the results of the current study indicate that optimisation process plays a pivotal role in the AgNPs synthesis and biogenic synthesised AgNPs might be used against bacterial pathogens; however, it necessitates clinical studies to find out their potential as antibacterial agents.