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Fermentable sugars are important intermediate products in the conversion of lignocellulosic biomass to biofuels and other value-added bio-products. The main bottlenecks limiting the production of fermentable sugars from lignocellulosic biomass are the high cost and the low saccharification efficiency of degradation enzymes. Herein, we report the secretome of Trichoderma harzianum EM0925 under induction of lignocellulose. Numerously and quantitatively balanced cellulases and hemicellulases, especially high levels of glycosidases, could be secreted by T. harzianum EM0925. Compared with the commercial enzyme preparations, the T. harzianum EM0925 enzyme cocktail presented significantly higher lignocellulolytic enzyme activities and hydrolysis efficiency against lignocellulosic biomass. Moreover, 100% yields of glucose and xylose were obtained simultaneously from ultrafine grinding and alkali pretreated corn stover. These findings demonstrate a natural cellulases and hemicellulases mixture for complete conversion of biomass polysaccharide, suggesting T. harzianum EM0925 enzymes have great potential for industrial applications.

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h i g h l i g h t sStrain A21 was isolated from special eco-environment in Tibet, China. First report on expression of P. polymyxa glucanase in industrial strain. Enhanced antifungal activity is due to synergy of three factors. a b s t r a c tStreptomyces lydicus strain A01, which can produce natamycin and chitinase, has a significant inhibition effect on gray mold disease caused by Botrytis cinerea. However, it has no detectable glucanase activity. Strain A21 isolated from the snow covered high altitude area in Tibet, China, also has a high antagonistic activity against B. cinerea. It displayed an obvious halo on lichen polysaccharides plates by congo red staining, indicating a strong glucanase activity. A21 was identified as Paenibacillus polymyxa using 16S rDNA gene analysis and biochemical and physiological analysis. To obtain the synergistic antifungal effects of natamycin, chitinase, and glucanases on B. cinerea, this study transformed the b-1,3-1,4-glucanase gene from P. polymyxa A21 to S. lydicus A01. The engineered S. lydicus AG01 showed substantially high glucanase activity, and had similar natamycin production and chitinase activity as the wild-type strain A01. Compared to the wild-type strain A01, the antifungal effects of S. lydicus AG01 on B. cinerea, including inhibition of spore germination and mycelial growth, were highly improved. The improved biocontrol effect of S. lydicus AG01 is likely attributed to the heterologous expression of glucanase from P. polymyxa, which acted synergistically with natamycin and chitinase to increase the antifungal activity of the strain.

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