Moringa straw as cellulase production inducer and cellulolytic fungi source

摘要

Currently, the valorization of agroindustrial waste is of great interest.Moringa oleiferais a multipurpose tree whose softwood residues could be used as raw material for low-cost cellulase production. The aim of this study was to isolate, identify, and characterize microorganisms with cellulolytic activity in different carbon sources. We isolated and purified 42 microorganisms fromM. oleiferabiomass. Fungi presenting the largest hydrolytic halos in carboxymethylcellulose as a substrate were molecularly identified asPenicillium funiculosum(FG1),Fusarium verticillioides(FG3) andCladosporium cladosporioides(FC2). The ability of these fungal strains to break down cellulose was assessed in a submerged fermentation using either amorphous CMC or crystalline form (Avicel).P.funiculosumandC.cladosporioidesdisplayed similar endoglucanase (606U/l) and exoglucanase (205U/l) activities in the Avicel-containing medium, whereasF.verticillioidesshowed the highest level of β-glucosidase activity (664U/l) in the carboxymethylcellulose medium. In addition, the effect of three culture media (A, B, and C) on cellulase production was evaluated inP.funiculosumusing moringa straw as a carbon source. The results showed a volumetric productivity improvement of cellulases that was 2.77-, 8.26-, and 2.30-fold higher for endoglucanase, exoglucanase and β-glucosidase, respectively when medium C containing moringa straw was used as a carbon source. The enzymatic extracts produced by these fungi have biotechnological potential especially for second-generation bioethanol production (2G) from moringa straw. This is the first report on the use ofM. oleiferabiomass to induce the production of various cellulases inP.funiculosum.