Valorization of Corn-Cob by Fungal Isolates for Production of Xylanase in Submerged and Solid State Fermentation Media and Potential Biotechnological Applications

Abstract

The increasing awareness of importance of xylanases in various industrial processes has led to intensive research in effective production of xylanases. In this study, eight fungal strains were screened for the production of xylanases in submerged (SmF) and solid state fermentations (SSF) in corncob-based media. Positive results of reddish orange halo-zones of hydrolysis were obtained for qualitative screening. In SmF, xylanase activity from Aspergillus fumigatus SD5A yielded highest activity (50.55 U/ml) in 168 h, while Aspergillus flavus SD4A, A. fumigatus L1, Fusarium solani SD3C, Aspergillus niger L3, Trichoderma longibrachiatum L2, Botryodiplodia sp. L5 and A. flavus L4, showed xylanase activities ranging from 10.38 to 44.81 U/ml. In SSF, xylanase activities ranged from 12.30 to 48.63 U/g in 120 h, with the highest activity obtained from A. fumigatus L1. Optimum temperatures for xylanases obtained in SmF ranged from 55 to 70 °C, while that of SSF ranged from 50 to 70 °C. Also, the optimum pH for xylanases obtained in both SmF and SSF ranged from 5.0 to 7.0. All the fungi did not produce aflatoxin on neutral red desiccated coconut agar. The fungal xylanases improved dough rising of bread and clarification of orange juice by 1.87–2.2-folds and 58.12–74.22% respectively. The results reported here showed that the range of characteristics exhibited by the xylanases could make them widely applicable in various industries, and also an important way for the valorization of agricultural waste.