The effect of carbon source succession on laccase activity in the co-culture process of Ganoderma lucidum and a yeast

In the present paper, the mechanism of overproduction of laccase by microbe interaction was investigated in the co-culture process of Ganoderma lucidum and Candida sp. HSD07A. The results show that nitrogen source, sulfur source, hydrolytic enzymes and inducers do not have the significant influence on laccase activity, and glucose deprivation in the medium is also not the crucial reason why G. lucidum overproduces laccase although it can improve laccase activity at a certain extent. Furthermore, glucose deprivation is made by strain HSD07A, and NMR and GC data reveal that the yeast can convert glucose into glycerol and ethanol. G. lucidum cannot assimilate ethanol; however, glycerol is an efficient carbon source for G. lucidum. In the co-culture process, the appearance of the second carbon source, glycerol produced by the yeast, is the crucial reason why G. lucidum overproduces laccase because glycerol can make G. lucidum cells secrete more laccase by prolonging the secretion time under the condition of glucose deprivation. Thus, it is the carbon source succession in the co-culture process that leads to the overproduction of G. lucidum laccase.