High potential low-cost crude enzymes from Algerian fungal strains for plant polysaccharides hydrolysis

Fungi secrete large enzyme sets, such as glycosyl hydrolases (GH) capable of targeting plant polymers, making them a valuable enzymes source. In this study, three fungal strains were isolated from the rhizosphere area and identified as <i>Trichoderma harzianum</i>, <i>Aspergillus tubingensis</i> and <i>Aspergillus tamarii</i> by molecular analysis. The strains were able to grow on mono-, di- and polysaccharides as sole carbon sources, and even on D-galactose and cellulose which is rare for <i>Aspergillus</i> species. Besides, GH activities such as cellobiohydrolase, β-1,4-D-galactosidase, β-mannosidase glucoamylase and β-1,4-D-galactosidase were revealed in secretome of the strains cultivated on wheat bran with optimum obtained between 4th and 7th day. Furthermore, hydrolysis of wheat bran with <i>T. harzianum</i>, <i>A. tubingensis</i> and <i>A. tamarii</i> culture supernatant resulted in the release of 4.6, 5.5 and6.8 g/L of glucose, respectively. The yield increased two-fold by applying a mix of <i>T. harzianum</i> and <i>A. tubingensis</i> enzymes extracts at a ratio 1:1. In addition, the combination of the crude enzymes with commercial cellulase enhanced 3 times the glucose content. The results present enzyme extracts with high yield in saccharification of complex substrates with a potential application in bioethanol production.