Screening, Cloning and Characteristics of the Common Xylanase Gene in Anaerobic Fungi

The aim of this study was to screen, clone and characterize the xylanase genes and to determine the common xylanase gene in anaerobic fungi. For this purpose, genomic DNA of 45 anaerobic fungi were used to amplify xylanase genes using 9 different primer pairs. The PCR yield rates of the primers in fungal isolates ranged from 6.6% to 100%. The xynA gene encoding xylanase was amplified from all anaerobic fungal DNAs with OrpXA primers (100%). The xynA was cloned into E. coli and 17 recombinant E. coli strains were obtained. The nucleotide sequences of the cloned genes were determined and characterized. The molecular weight of open reading frames (ORF) regions of the cloned genes varied between 24.7-30.2 kDa and the catalytic domains are members of glycoside hydrolase family 11. The specific activity of xylanase enzymes varied between 4.99-37.6 U/mg. Xylanase enzymes showed remaining activities ranging between 71.52-100% after incubation at 50 ˚C for 1 hour. High correlation was found between specific activity and thermal stability. This study showed that the xynA gene is common in anaerobic fungi, but this finding needs to be validated with further studies including species from the genera not included in this study.