Synergistic production of highly active enzymatic cocktails from lignocellulosic palm wastes by sequential solid state-submerged fermentation and co-cultivation of different filamentous fungi

Abstract

Lignocellulolytic enzymes were produced from industrial crop wastes, palm empty fruit bunches (EFB), through various fermentation modes and co-cultivation of different filamentous fungi. Among the fermentation modes and fungi tested, Aspergillus tubingensis TSIP9 produced enzymatic cocktails with the highest cellulase (89.6 ± 5.7 U/g-EFB) and xylanase (196.8 ± 3.6 U/g-EFB) activities through sequential solid-state and submerged fermentation (SoSF-SmF), while Trichoderma reesei QM 9414 showed the highest β-glucosidase (47.9 ± 0.9 U/g-EFB) activity through SmF. Interestingly, their co-cultivation in sequential SoSF-SmF significantly improved overall enzyme production possibly due to synergism of the enzymes produced by both strains and combined advantages of SoSF and SmF. After optimization and scale-up in bioreactor with helical impeller, the cellulase, xylanase and β-glucosidase activities were enhanced up to 374.8 ± 4.23 U/g-EFB (4.2 folds), 623.7 ± 4.59 U/g-EFB (3.2 folds) and 161.87 ± 1.74 U/g-EFB (3.4 folds), respectively. These enzymes are highly active and stable at pH 5–6 and temperature of 50–60 °C. These strategies could be viable options for effective and low-cost production of lignocellulolytic enzymes and further application in bioproduction and biorefinery.