Partial Purification and Characterization of Endoxylanase from a fungus, Leohumicola incrustata

Xylanases are glycoside hydrolases (GH) that degrade β-1,4-xylan, a linear polysaccharide found as hemicellulose in cell wall of plants. Endoxylanase (Endo-1,4-β-xylanase, EC 3.2.1.8) randomly catalyses xylan to produce varying short xylooligosaccharides (XOS). This study aimed to determine the characteristics of a partially purified endoxylanase from Leohumicola incrustata. Enzyme production was carried out using beechwood (BW) xylan, after which the cell-free crude filtrate was concentrated using the ammonium sulphate precipitation method. The hydrolysed products were analysed by thin-layer chromatography (TLC) and zymography. The result showed that the enzyme produced varying smaller-sized linear xylooligosaccharides with Rf values corresponding to those of xylobiose, xylotriose, xylotetraose, xylopentaose, xylohexaose and other higher oligomers. The endoxylanase had a molecular mass of 72 kDa. The enzyme is stable in the presence of K+, Na+, Ca2+, Fe2+, Mg2+, Zn2+, Co2+, pH of 5.0 and temperature of 37oC. However, the activity gradually decreased after 60 min at 50oC and retained over 69% activity after 120 min, while at 60 and 70oC, the enzyme activity sharply decreased (pre-incubation periods). Endoxylanase from L. incrustata is comparable to those of other microorganisms and should be considered an attractive candidate for future industrial applications.