Enhancement of laccase production by optimizing the cultural conditions for pleurotus sajor-caju in solid-state fermentation

Abstract

Nowadays, a lot of interest has been given to the development of cost-effective and efficient enzyme production technologies. Laccase enzymes are widely used in biotechnological, environmental and industrial sectors. Due to the cost-effectiveness of the solid-state fermentation (SSF) process, it is widely used to produce a broad range of biological products. In this study, optimization of moisture content, temperature, pH, and inoculum size were studied to enhance laccase production ability of Pleurotus sajor-caju in SSF by using One Factor At Time (OFAT) and Response Surface Methodology (RSM). OFAT was used as a baseline study for deducing the experimental design of RSM. The highest production of laccase enzyme (1450 U/g) by Pleurotus sajor-caju on wheat straw was observed at 26°C, 6.0 pH, 72.5 % moisture content, 7.5% inoculum size, 1% fructose and 0.5 % peptone. Unlike the conventional inoculum preparation method, here the inoculum was generated by the spawning method for SSF. The molecular weight of partially purified laccase from Pleurotus sajor-caju was estimated to be around 62 K Da using SDS PAGE. The activity staining of laccase was observed as a zymogram on Native PAGE using ABTS as a substrate. Lignin degradation of wheat straw and its structural disruption due to laccase was observed by Scanning Electron Microscopy (SEM).