Bulletins of Natural and Applied Sciences
Vol. 4(1):1-10
Production of laccase by Pleurotus ostreatus through submerged fermentation and its decolourisation potential
Samuel Adedayo Fasiku1*, Muinat Titilope Abimbola1,2, Femi Johnson Afolabi1 1Department of Microbiology and Biotechnology, Ajayi Crowther University, Oyo-Town, Nigeria; 2Department of Microbiology, Micheal Adeni
ABSTRACT
Laccases are multicopper oxidase enzymes with significant industrial and environmental applications, including bioremediation and the degradation of textile dyes. This study investigated laccase production by Pleurotus ostreatus using submerged fermentation and assessed its decolourisation potential. Lignocellulosic wastes, including sugarcane bagasse, rice straw, maize cob, conifer litters, and maize straw, were evaluated as substrates for laccase production. Parameters such as carbon and nitrogen sources, pH, inoculum size, and incubation period were optimised. Enzyme activity was quantified using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as a substrate, characterised with respect to metal ions, pH, temperature, and time, and decolourisation ability was determined using various dyes. The highest laccase yield (435.04 µU/L) was recorded in a medium containing 1% of maize straw, supplemented with 1% glucose as the carbon source and 0.1% peptone as the nitrogen source, at an initial pH of 7.0, inoculated with four circular 7 mm Pleurotus ostreatus plugs, and incubated for 6 days. Metal ions affected laccase activity. Activity was stable across a wide pH range (3.6–9.5), with the highest activity recorded at pH 8.0. Laccase activity was also stable across temperatures (25–60℃) and time periods (10–60 minutes). Pleurotus ostreatus laccase decolourised malachite green and Leishman blue by 21.8% and 21.4%, respectively. Laccase production by Pleurotus ostreatus was optimised through submerged fermentation, promoting the utilisation of agro-wastes and offering a scalable method for industrial enzyme production. Dyes were decolourised by laccase, demonstrating the enzyme’s potential and its application in the textile industry.
