Valorization of Orange Peel Waste as a Potential Substrate for the Fermentative Production of Extracellular Laccase from Aspergillus Niger ISL-09 and Determination of its Kinetic Parameters

This research deals with the optimization of extracellular laccase production from Aspergillus niger ISL-09 using orange peel as a substrate. The high potential of laccase to oxidize phenolic compounds makes it attractive for various industrial sectors such as paper and pulp industry, textile applications, bioremediation, food processing, pharmaceutical and nanobiotechnological applications, bio-bleaching of synthetic dyes and biodegradation of xenobiotic compounds, hence, the enhanced production of laccase using lignocellulosic waste could prove extremely beneficial for both industrial as well as bioremediation perspectives.

The production of laccase was conducted via solid-state fermentation of Aspergillus niger ISL-09, using orange peels as substrate. Laccase production from A. niger ISL-09 was further optimized at different parameters i.e., substrate level, moisture content level, initial pH of productive liquid medium, time of incubation, size of inoculum, and kinetics of enzyme production were determined.

The highest laccase activity was observed as 39.16 IU by using 20 g of orange peels, moistened with 10 ml moisture (pH 6.0) after 72 h of incubation. The protein content at optimal conditions was observed as 134.15 mg ml^− 1. The maximum specific growth rate was observed at 0.0381 h^− 1 for 48 h incubation time. The highest Yield coefficient (Y_p/s) and volumetric rate constant (Q_p) remained at 11.82 IU g^− 1 for 72 h incubation and 2.84 IU g^− 1 h^− 1 for 48 h incubation respectively.

Significant production of extracellular laccase using orange peel confirms the application of lignocellulosic waste as an easily available and cost-effective solid substrate for fermentation. Therefore, our study not only highlights the production of industrially important enzyme laccase but also alleviates the pollution problem by re-utilizing agro-industrial waste.