3.3. Effect of substrate concentration
Suitable substrate level for xylanase production was also
checked by changing the amount of selected substrate (sugarcane
bagasse) in 500 ml Erlyenmer flask from 5 to 30 g. Of all
these tested concentrations of substrate 10 g in 500 ml flask
showed optimum enzyme production (64.2 1.24 U/g). As the
concentration of substrate was increased above this concentration,
decreased in enzyme production and protein secretion
were observed as shown in Fig. 3. Our findings were in
accordance with Haq, Javed, and Saleem (2006) who also reported
that 10% substrate level was best for CMCase production by using T. viride. Xia and Cen (1999) reported that
30% substrate was best for cellulase accumulation. Reis,
Costa, and Peralta (2003) obtained maximum xylanase activity
(130 16 IU/ml) with 5% sugarcane bagasse as a carbon
source in submerged fermentation using Aspergillus nidulans.
Substrate concentration of 14% w/v bagasse produced
maximum xylanase activity of 27.6 U/ml using strain of T.
harzianum Rifai (Rezende et al., 2002). High concentration of
carbon sources inhibits the enzyme synthesis (Naidu & Panda,
1998).