Production of Trichoderma Reesei RUT C-30 Lignocellulolytic Enzymes Using Paper Sludge as Fermentation Substrate: An Approach for On-Site Manufacturing of Enzymes for Biorefineries

Abstract

Different types of pulp and paper sludge were used as raw materials for the production of a cocktail of lignocellulolytic enzymes of Trichoderma reesei RUT C-30 (T. reesei RUT C-30). The fungus were grown in pellets to produce cellulases (carbomethylcellulase, β-glucosidase) and hemicellulases (xylanase, β-xylosidase) in three types of sludge: primary (PS), secondary (SS) and mixed sludge (MS). The highest carbomethylcellulase activities obtained after 7 days of fermentation were 7.3, 4.8, and 1.5 IU/ml in MS, SS, and PS, respectively. Sludge modification such as the mixing SS and PS at 1:1 (v/v) ratio, the addition of ammonium sulfate as an inorganic nitrogen source, and the increase of the solids content were shown to improve enzyme production. The crude enzyme mixture obtained from the sludge samples showed a synergistic effect to hydrolyze various biomasses into monosugars. The tested biomasses included highly purified CMC, xylan from birch wood and lignocellulosic materials (corn stover and primary pulp and paper sludge). The addition of a surfactant (polysorbate 20) to the enzyme cocktail enhanced the saccharification efficiency of the sludge, in particular the hydrolysis of the corn stover which contains lignin. The obtained results contribute to the assessment of the feasibility of on-site low cost enzyme production at paper mills generating the sludge, or for neighboring or local biorefineries.