Assessing the impact of corn steep liquor as an inducer on enhancing laccase production and laccase gene (Lac1) transcription in Pleurotus pulmonarius during solid-state fermentation

Abstract

Laccases are crucial for agro-waste delignification in sustainable practices. Considering the necessity for cost-effective laccase pretreatments in industrial applications, numerous efforts have been directed towards identifying potential enzyme inducers for increasing laccase production. This study explored corn steep liquor as a cost-effective laccase inducer in Pleurotus pulmonarius solid substrate fermentation of tender coconut fiber. Utilizing tender coconut fiber for laccase production offers dual benefits of fiber valorisation and enzyme synthesis sustainably. We investigated the impact of corn steep liquor on transcription of Lac1 gene in P. pulmonarius and on extracellular laccase activity. Adding 2 % CSL notably boosted laccase production (314.62 + 5.93 IU/mL) and increased Lac1 transcript levels by 5.6-fold compared to non-induced cultures. SEM analysis revealed improved delignification as a result of increased laccase production. Our findings suggest that corn steep liquor serves as an inducer for regulating laccase gene expression in P. pulmonarius, leading to increased extracellular laccase production.