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 188.8.131.52) 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.
Adeoyo Olusegun Richard, Pletschke Brett Ivan and Dames Joanna Felicity