Production of the Cellulase Enzyme System by Locally Isolated Trichoderma and Aspergillus Species Cultivated on Banana Pseudostem during Solid-State Fermentation
Lesetja Moraba Legodi, Daniël C. la Grange, Elbert L. Jansen van Rensburg
Abstract
The production cost of cellulases is regarded as a limiting factor in the cellulosic ethanol production chain. Trichoderma and Aspergillus species were used to produce cellulases through solid-state fermentation (SSF) utilizing banana pseudostem (BPS) as a carbon source. The production of cellulases was investigated at various substrate moisture contents (65–80%), incubation temperatures (30–40 °C), substrate pre-treatment methods (3% w/v NaOH, 5% v/v H2SO4, and water), and with different co-culturing of microorganisms. Trichoderma longibrachiatum LMLSAUL 14-1 produced the maximum total cellulase (75 FPU/g d.s), endoglucanase (11.35 U/g d.s), and β-glucosidase (235.83 U/g d.s) activities at a 75% moisture content of the untreated BPS at 30 °C in static culture. Pre-treatment of BPS improved the production of specific enzymes. Aspergillus fumigatus LMLPS 13-4 produced more β-glucosidase (259.8 U/g d.s) when grown on acid-pre-treated BPS, whereas T. harzianum LMLBP07 13-5 produced the highest β-glucosidase activity (319.5 U/g d.s) on alkali-pre-treated BPS. Co-culturing of T. harzianum LMLBP07 13-5 and A. fumigatus LMLPS 13-4 improved the production of endoglucanase. These results suggest that banana pseudostem, a waste product of the banana industry, could be a potentially cheaper and abundant substrate for the production of the cellulase enzymes.