A statistical approach for enhancing laccase yields from white rot fungi (WRF) using response surface methodology

Abstract

A high demand for fungal laccases on account of innumerable biotechnological applications necessitates enhanced production. Three novel isolates of white rot fungi (WRF) designated NI-07, NI-09 and NI-04 were subjected to submerged cultivation in liquid basal medium for laccase production. Of a total of 23 factors evaluated, 22 factors were selected for GLM using Proc GLM procedure of SAS (Version 9.3). The first optimization step identified the significant factors for laccase production and were used to construct RSM using PROC RSREG of SAS along with Lack Fit to maximize laccase enzyme activity. The statistical software, Design-Expert (version 9.0.1.0) was used to analyze the data and generate Response Surface Graphs (3D) for statistical optimal condition given by SAS (RSM) to build an optimized response using Response Surface Methodology (RSM). The initial laccase activity of 737U/mL increased to 7833U/mL in isolate NI-07, from 700 U/mL to7480 U/mL in NI-09 and from 1132 U/mL to 11141 U/mL in NI-04. When compared to the conventional method, a 10 fold increase in laccase activity could be obtained in the three isolates of WRF (10.62 for NI-07, 10.68 for NI-09 and9.84 for NI-04) after statistical optimization employing RSM. Validation experiments proved that experimentally determined production values were in close agreement with statistically predicted ones, confirming the reliability of the model. The results of this study serve as reference for optimization of medium composition for enhancing laccase production in WRF in submerged fermentation. Through statistical optimization maximum yields of laccase could be achieved at a minimum production cost.