shows the
thermo-stability profile of crude xylanase from A. lentulus. For
thermo-stability studies, the diluted crude enzyme was incubated at respective temperatures (50e80 C) for different time intervals
and their activity was checked. Results show that the enzyme was
most stable at 50 C retaining 85.4% activity even after 60 min of
incubation. The enzyme had good stability at higher temperatures
for initial 0.5 h (more than 85% activity retained at 60 and 70 C).
However, beyond 0.5 h, activity declined sharply at 70 C (70.1%
activity after 0.75 h min and 49.2% activity after 1 h). The decline
was steeper when enzyme was incubated at 80 C, retaining only
35.2% activity after 1 h of incubation. At the end of 3 h, 15.4% and
4.8% enzyme activity was observed at 70 and 80 C, respectively.
The thermostability profile of endoxylanases could be further
improved using recombinant technology. Fedrova et al. (2012) reported
the optimum activity of mutant endoxylanase at pH 6.0 and
temperature 70 C with half inactivation period of 7h at 60 C when
the gene encoding endo-1,4 b-xylanase, gene xylE, from Penicillium
canescens was expressed under the control of strong promoter, bga
S (gene encoding b-galactosidase).