Biosynthesis of tannase from cashew testa using Aspergillus niger MTCC5889 by solid state fermentation

The use of better carbon sources and efficient production strains were deemed as promising strategies to economize tannase production. A novel agro-residue, cashew testa, was tested for the production of tannase under solid-state fermentation (SSF) using Aspergillus niger CEPC 11. CEPC 11 was identified by 18S rDNA typing as Aspergillus niger and deposited in International depositing Authority under MTCC number 5898 and NCBI accession number KM516789. The enzyme was purified 11 fold to obtain tannase with a specific activity of 10.22 U/mg and final yield of 48 %. SDS-PAGE analysis of purified enzyme gave a single band of 89.9KDa. The optimal temperature was found to be 40 °C, with an active range of 25–60 °C. The optimal pH was 5.5, and the enzyme was inactive at pH 8.0. The enzyme was identified through MALDI-TOF-MS tandem mass spectrometry as tannase. Km and Vmax were recorded at 0.1133 M (substrate concentration) and 44.79 μmol/min respectively. Heavy metals (Cadmium, Nickel, Lead, and Copper) in tannery effluent were analyzed before and after treatment with enzyme by AAS (Atomic Absorption spectroscopy). Gallic acid is also determined as an inter-mediatory by-product of this technology. Treatment with tannase enzyme improved the quality of fruit juices. This is the first report on production of tannase by Aspergillus niger under SSF with cashew industry by-product cashew testa as the substrate. The use of residues is an alternative to solve pollution problems that can be caused by an incorrect environmental disposal.