Xylan-decomposing fungi and xylanolytic activity in agricultural and industrial wastes

Screening of xylan-decomposing filamentous fungi were carried out in two agricultural and one industrial wastes (30 samples each) collected from Qena Governorate (South Valley) using xylan agar medium. Twenty-six species representing 13 genera were identified from rice straw, wheat straw and sugarcane bagasse on the medium used. Aspergillus flavus, A. niger, Penicillium chrysogenum, P. corylophilum, P. funiculosum, P. oxalicum and Trichoderma harzianum were the most prevalent species on the three substrates. Extracellular xylanase production by selected isolates of the current study was characterized during their growth on xylan as a sole carbon source on solid medium. The results revealed that 93.3% of the isolates tested could degrade xylan and the highest activity against xylan was showed by members of Aspergillus, Fusarium, Penicillium and Trichoderma. The optimum conditions for maximum production of xylanase by Trichoderma harzianum were 8 days after incubation at 35°C and maltose and starch were used as carbon sources, NaNO3 and peptone as nitrogen sources and the culture was initially adjusted to pH 6.