Optimizing bioconversion of deproteinated cheese whey to mycelia of Ganoderma lucidum

Abstract

A novel approach to utilize deproteinated cheese whey by cultivating mycelia of the edible mushroom Ganoderma lucidum is described. A central composite in cube design for the experiments was used to develop empirical models providing a quantitative interpretation of the relationships between the two variables studied, which were pH and temperature. The designed intervals were 3.3<pH<4.7, 23 °C<temperature<37 °C, respectively. Response surface methodology was successfully applied to determine the optimum condition where the maximum mycelial production occurred, which was pH 4.2 at 28.3 °C. The soluble chemical oxygen demand (SCOD) removal ranged from 80.7 to 93.1% within the design boundary, where the condition for maximum SCOD removal was pH 4.6 and 27.1 °C soluble chemical oxygen demand (COD). The condition for a maximum mycelial yield, 0.35 mg mycelial weight per mg SCOD removed, was calculated as pH 4.2, and 28.5 °C soluble COD; which was almost the same as optimum condition for mycelial production. The high extract ratio of 10.7% (i.e. 1820 mg extract/17 057 mg mycelium) as well as high content of polysaccharide (i.e. 1.12 g/l) indicated that the deproteinated whey could be an alternative substrate for mycelial production. Therefore, cultivation of G. lucidum mycelia can offer a potential cost-effective solution for an alternative utilization of the deproteinated cheese whey.