The xylanase activities
obtained with different substrates increased with the increasing
hemicellulose content of the substrate. These xylanase activities
were accompanied by very low cellulase activities; wheat straw
(2.0 fpu/g) < wheat bran (1.9 fpu/g) < corn cob (1.4 fpu/
g) < sugarcane bagasse (1.3 fpu/g).Highest amount of cellulase
enzyme was produced when wheat straw (which had significantly
the highest amount of cellulose) was used as the substrate. Second
highest amount of cellulase was produced when wheat bran was
used as the substrate in spite of having low cellulose content as
compared to corn cob and sugar cane bagasse. This can be
attributed to the fact that wheat bran had significantly lower
amount of lignin as compared to corncob and sugarcane bagasse
which could have hindered the exposure of cellulose towards
degradation (Perez et al., 2002). The obtained values of cellulase
activities are very low in proportion to the xylanase activities and
thus xylanase produced on these substrates utilizing yeast extract
as the nitrogen medium could be utilized for the applications
where cellulase-free xylanase is required such as for bleaching of
the pulp in paper industries. Fig. 2b shows the total protein and
specific xylanase activity obtained with each of the substrate.
Highest specific xylanase activitywas obtained with corn cob as the
substrate (4.9 U/mg).