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

Abstract

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 Trichoderma harzianum, Aspergillus tubingensis and Aspergillus tamarii 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 Aspergillus 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 T. harzianum, A. tubingensis and A. tamarii 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 T. harzianum and A. tubingensis 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.

Keywords:

• Fungi
• Trichoderma
• italique
• saccharification
• wheat bran
• cellulases
• hemicellulases

Disclosure statement

No potential conflict of interest was reported by the author(s).