Production of Ganoderma lucidum mycelium using cheese whey as an alternative substrate: response surface analysis and biokinetics

Abstract

A novel approach to utilize cheese whey, cultivating mycelium of an edible mushroom Ganoderma lucidum using cheese whey as a substrate, was introduced. Response surface analysis (RSA) with central composite in cube design was successfully applied to determine the optimal conditions where the maximum mycelial production occurred, which was at pH 4.2 and 28.3 degreesC. The high extract ratio as well as high content of polysaccharide, (i.e., 1.2 g/1) indicated that the whey could be an alternative substrate for the mycelial production. Soluble chemical oxygen demand (SCOD) removal ranged from 80.7 to 93.1% within the design boundary. Therefore, cultivation of G. lucidum mycelia using cheese whey can provide a unique solution to solve the dual problems of an alternative utilization of the whey and waste management. The substrate inhibition biokinetics at the optimal conditions were also evaluated using a method of fourth-order Runge-Kutta approximation. The nonlinear least-squares (NLLS) method with 95% confidence interval was used. The maximum microbial growth rate, mu(max), and half saturation coefficient, K,, for lactose and SCOD were determined to be 2.28+/-0.11 and 2.27+/-0.15 per day, and 95.5+/-9.1 and 128.0+/-12.1 g/1, respectively. The microbial yield coefficient, Y, and microbial decay rate coefficient, k(d), for lactose and SCOD were determined to be 0.49+/-0.03 and 0.39+/-0.03 g VSS/g of each substrate, and 0.05+/-0.01 and 0.05+/-0.01 per day, respectively. Inhibition coefficients were 37.6+/-2.9 and 49.3+/-3.3 g/1 for lactose and SCOD, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.