Use of manure as a potential substrate for (hemi)cellulolytic enzymes production under solid-state fermentation

Animal manure is a major source of biomass that contains significant amounts of organic carbon and other nutrients. Production of (hemi)cellulolytic enzymes using inexpensive and readily-available substrates for solid-state fermentation (SSF) can contribute to the broader application of enzymes for the conversion of biomass into biofuels and chemicals. Within this context, the aim of the present work was to evaluate the feasibility of using manure as a substrate for the production of (hemi)cellulolytic enzymes by two different fungi (Aspergillus niger and Trichoderma reesei) cultivated under SSF. Supplementation of the substrate with different mineral salts was evaluated, as well as the use of a combination of manure and wheat bran. SSF cultivations using either manure or a mixture of manure and wheat bran, supplemented with ammonium sulfate medium, showed the best results for both fungi and the three enzymes quantified (endoglucanase, beta-glucosidase, and xylanase). Kinetic profiles revealed that the highest enzyme production occurred after 72 h of cultivation. For A. niger, the maximum activities achieved were 69.8 +/- 1.5 IU.g(-1) of dry solid substrate (endoglucanase), 70.6 +/- 4.6 IU.g(-1) (beta-glucosidase), and 92.4 +/- 9.8 IU.g(-1) (xylanase). For T. reesei, maximum activities were 78.4 +/- 9.8 IU.g(-1) (endoglucanase), 4.2 +/- 1.1 IU.g(-1) (beta-glucosidase), and 218.8 +/- 0.7 IU.g(-1) (xylanase). These results are very promising when compared with enzyme production under SSF using other substrates, and demonstrate the potential of manure for (hemi) cellulolytic enzyme production within the biorefinery concept.