Growth and invertase production by Neurospora crassa in submerged and solid-state cultures

Filamentous fungi are widely used in industry to produce enzymes, organic acids, and secondary metabolites. Neurospora crassa has gained attention due to its flexibility for easy genetic manipulation, fast growth, and non-pathogenic characteristics. This study evaluated the growth of N. crassa and invertase production in submerged culture (SC) and solid-state culture (SSC) using pine sawdust (SSC-PS) and polyurethane foam (SSC-PUF) as supports. Modified Vogel's medium with initial sucrose concentrations of 1.5%, 3%, and 5% was used. The specific and maximum CO2 production rates were higher in SSC than SC, particularly with SSC-PS. Protein and invertase production were higher in SSC, with SSC-PS demonstrating the highest sucrose concentration as the inducer and carbon source. The water-holding capacity (WHC) of SSC-PUF was approximately 25 times higher than that of SSC-PS, facilitating a more productive process. SSC-PUF enables higher biomass growth, protein, and invertase production than SC. Moreover, using inert supports, such as PUF, allows the correct substrates and product assessment without interferences due to the chemical composition and heterogeneity of conventional agro-industrial by-products, such as PS.