Optimization of degradation of winery-derived biomass waste by Ascomycetes

BACKGROUNDRecently, winery wastes have been classified as pollutants by the European Union and post-product processing is required to lower their hazards. Individual fungal enzymes have limited capacity so mixed fungal degradation combined with pre-treatment can decrease biomass recalcitrance for more efficient breakdown, overcoming these limitations. RESULTSWinery biomass degradation by a mixture of Trichoderma harzianum, Aspergillus niger, Penicillium chrysogenum and P. citrinum in submerged fermentation and solid state fermentation (SSF) was evaluated. Higher cellulase and -glucosidase activities were observed in SSF and submerged fermentation, respectively. Statistical modelling predicted the fungal percentage ratio of 60:14:4:2 for A. niger: P. chrysogenum: T. harzianum: P citrinum with a substrate:medium ratio of 0.39:1. Under the optimized conditions, cellulase, xylanase and -glucosidase activities increased to 78.5, 3544.7 and 250.9 U mL(-1), respectively. Cellulases and xylanases activities increased more than two-fold. Lignin degradation increased from 8% in submerged fermentation (P. chrysogenum) to 17.9% under optimized conditions. Gas chromatography-mass spectrometry (GC-MS) analysis identified 78 significant metabolites, of which stigmasterol, glycerol, maleic acid, xylitol and citric acid were generated by fungal degradation. CONCLUSIONSEnhanced degradation of winery-derived biomass was achieved using mixed fungal cultures. GC-MS analysis indicated the production of commercially important metabolites during the process. (c) 2014 Society of Chemical Industry