Isolation, Screening and Optimization of Xylanase Producing Fungi from Rhizosphere Soil of Cassava Tuber

Abstract

Microbial xylanases have attracted a great deal of attention, due to their biotechnological potential in various industrial processes. In this study, the isolation, screening and optimization of xlanase-producing fungi from rhizosphere soil of cassava tuber under submerged fermentation were carried out. Altogether, eight fungal strains were isolated from the rhizosphere soil of cassava. All the fungal isolates were screened positive for xylanase activity on mineral salt medium supplemented with araboxylan as sole carbon source. The process parameters were optimized using one factor at a time technique. The identities of the isolates authenticated as Debaryomyces nepalensis and Penicillium polonicum by molecular techniques were regarded as good xylanase producers and they were selected for optimization studies. In order to maximize enzyme synthesis from fungi, the effect of nutritional and environmental conditions on xylanase production was investigated. The optimal incubation periods for maximal xylanase production by Penicillium polonicum and Debaryomyces nepalensis were 120 and 144 hours respectively while the optimal pH and temperature for xylanase production were 5.0 and 50oC respectively by Penicillium polonicum and Debaryomyces nepalensis. The best carbon sources for xylanase production from both fungi were found to be xylan. As a result of this, both fungal species have significant potential as sources of xylanases for industrial and biotechnological applications.