초록
<P><B>Abstract</B></P> <P>A set of fifteen thermophilic fungi were isolated from various lignocellulosic and soil samples, among which <I>Thermomyces lanuginosus</I> VAPS24 showed highest xylanase activity. Xylanase production was optimized using various hybrid statistical tools and validated by batch fermentation using a 5 L bioreactor. Highest values of 130.98 U mL<SUP>−1</SUP> and 115.37 U mL<SUP>-1</SUP> xylanase production of was recorded in shake flask and fermenter, respectively. The xylanase from <I>T. lanuginosus</I> VAPS24 was purified by acetone precipitation followed by ultrafiltration, which resulted in five-fold (5.92) purification. Metal ions such as Hg<SUP>2+</SUP>, Fe<SUP>2+</SUP>, Cu<SUP>2+</SUP> and reagents such as PEG-2000 and EDTA were inhibitory, whereas Zn<SUP>2+</SUP>, Na<SUP>+</SUP>, K<SUP>+</SUP> and β-mercaptoethanol behaved as activators for xylanase activity. Thermostability of xylanase at 80 °C for 60 min, was enhanced by 1.52, 1.43 and 1.26 folds through the supplementation of polyols such as sorbitol, mannitol and glycerol, respectively. The agar-agar entrapment of xylanase increased its residual activity to 69.87%, as compared to 42.7% with free enzyme at 80 °C after 60 min. Our study provides a novel method of enhancing thermostability of xylanase from <I>Thermomyces lanuginosus</I> VAPS24, by addition of polyols or agar-agar entrapment, thereby facilitating various industrial applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Maximum xylanase production of 115.37 U mL<SUP>−1</SUP> was observed in fermenter level. </LI> <LI> The xylanase was purified up to 5.92 fold purification using ultrafiltration. </LI> <LI> Hg<SUP>2+</SUP>, Fe<SUP>2+</SUP>, Cu<SUP>2+</SUP>ions and PEG-2000, EDTA were found inhibitors of xylanase activity. </LI> <LI> Zn<SUP>2+</SUP>, Na<SUP>+</SUP>, K<SUP>+</SUP> ions and β-mercaptoethanol were found activators of xylanase activity. </LI> <LI> Polyols and agar-agar entrapment showed an increased thermostability of xylanase. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>