Producing Aspergillus tubingensis CTM507 Glucose oxidase by Solid state fermentation versus submerged fermentation: process optimization and enzyme stability by an intermediary metabolite in relation with diauxic growth

BACKGROUND The variability of glucose oxidase (GOD) by Aspergillus tubingensis CTM507 in respect of titer under both submerged (SmF) and solid‐state fermentation (SSF) was assessed in relation to growth and substrate consumption. L27 Taguchi experimental design was applied to determine optimum culture conditions for GOD production in SSF. RESULTS Kinetic results showed that fungal growth is a diauxic process which used glucose and gluconic acid as substrates, respectively, and that SmF is suitable for fungi growth. However, SSF led to higher GOD activity (170.59 U mL−1 against 43.73 U mL−1 by SmF). Moreover, GOD stability and liberation were related to the presence and levels of glucose, gluconic acid and to a lesser degree, lactose and arabinose. Optimization of culture media of multi‐agro resources led to a final production yield of about 73103 U g−1 of substrates which corresponded to 10 and 84‐fold higher than the preliminary SFF and SmF results, respectively. These conditions were validated experimentally and revealed an enhanced GOD yield of 74%. CONCLUSION These findings help an understanding of the phenomena of supremacy of SSF vs SmF to produce functional biomolecules. They also define an SSF process for an important enzyme production at low cost with interesting properties for industrial application.