Valorization of coffee silverskin lignocellulosic waste

Lignocellulosic waste represents the most abundant renewable raw material globally. The principles of a circular economy can be applied by optimizing the utilization of valuable properties from recycled materials. The objective of this study is to assess the potential of utilizing coffee silverskin, the sole by-product of coffee roasting, for submerged cultivation of xylotrophic basidiomycetes with subsequent enzyme production. The growth processes of Fomitopsis pinicola and Rhodofomes roseus became intensified along with the increased biosynthesis of enzymes in their mycelia in case of submerged cultivation on coffee silverskin, not during solid-phase cultivation. The Fomitopsis pinicola strain was observed to preferentially accumulate cellobiases (1800 units/g) and β-glucanases (1170 units/g), whereas the Rhodofomes roseus strain was found to accumulate xylanases (over 5000 units/g). Therefore, coffee silverskin can be recommended to be used as a promising substrate for the cultivation of xylotrophic basidiomycetes for the production of enzyme preparations.