Cellulolytic and ligninolytic potential of new strains of fungi for the conversion of fibrous substrates

Abstract

This research explored the lignocellulolytic potential of native strains (Hipoxylon sp, Curvularia kusanoi, Trichoderma sp and Aspergillus fumigatus) isolated from natural substrates. Their sequences were deposited in the GenBank, and it‘s lignocellulosic potentialities were determined quantitatively from kinetics of cellulase and ligninase production in wheat straw, and grass hay. All evaluated strains showed high cellulolytic potential and laccase activity where only found in the C. kusanoi L7 strain. The new strains where co-cultivated with a reference strains of Trichoderma viride to determinate the capacity of joint growth, to know if they can be used together for a better degradation of the cell wall. A three-phase purification system was used to isolate the C. kusanoi laccase where a preparation 10 times purer than the initial crude was obtained, with an enzymatic activity of 2800 U/L, a specific activity of 544.74 U/g and a yield higher than 100%, which showed a more stable behavior at alkaline pH than at acid pH. The purify enzymes showed an optimum range of activity between 30 and 40 °C, and a high thermal stability. It is concluded that the isolated strains have a high degradation capacity and the C. kusanoi L7 strain stands out as the one with the greatest potential when expressing in addition to the cellulolytic complex the enzymes involved in the degradation of lignin.