Cellulase and xylanase production at pilot scale by solid-state fermentation from coffee husk using specialized consortia : the consistency of the process and the microbial communities involved

Abstract

Solid state fermentation is a promising technology however rising concerns related to scale up and reproducibility in a productive process. Coffee husk and a specialized inoculum were used in a 4.5L and then in 50L reactors to assess the reproducibility of a cellulase and hemicellulase production system. Fermentations were consistent in terms of cellulase production and microbial communities. The higher temperatures achieved when operating at 50L generated a shift on the microbial communities and a reduction of nearly 50% on cellulase production at pilot scale. In spite, an overall enzymatic production of 3.1±0.5FPUg⁻¹DM and 48±4Ug⁻¹DM for FPase and Xyl activities was obtained, respectively, with low deviation coefficients of 16 and 19% for FPase and Xyl production. Gaseous emissions assessment revealed an emission factor of 2.6·10⁻³kg volatile organic compounds per Mg of coffee husk and negligible NH₃, CH₄ and N₂O emissions.