Cyanobacterial biomass as N-supplement to agro-waste for hyper-production of laccase from Pleurotus ostreatus in solid state fermentation

The potential application of dry biomass of a cyanobacterium Anacystis nidulans as a supplement in SSF for the production of laccase from Pleurotus ostreatus was evaluated. Experiments were carried out in solid culture using groundnut shell as a basic substrate supplemented with four independent nitrogen sources (ammonium sulphate, urea, yeast extract and dry powder of cyanobacteria). All the four supplements enhanced the enzyme yield, and yeast extract showed precedence over inorganic nitrogenous sources. However, when dry biomass of A. nidulans was used as an additive to groundnut shell (agricultural residues), it supported maximum cell growth (56.83 ± 5.56 mg/g dry substrate) and laccase production (49.21 ± 4.89 U/g dry substrate). Addition of 1 mM copper salt in the medium containing groundnut shell supplemented with yeast extract gave laccase activity of 32.64 ± 3.4 U/g dry substrate. When dry powder of cyanobacterial biomass was used as N-supplement, laccase production enhanced to 65.42 ± 6.48 U/g dry substrate. In addition to the enhancement to enzyme production inhibitory effects of high concentrations of copper was also diminished in the medium having dry cyanobacterial biomass. This study, forms the first report on the potential application of cyanobacterial biomass as an additive for production of laccase by Pleurotus ostraetus MTCC 1804 in solid state fermentation and has relevance in scale-up production of this fungal enzyme of commercial significance.