One flask was removed after every 24 h for six
days and 100 mL of 0.05 M citrate buffer (pH 5.3) and Tween 80
(0.1%) were added to it and it was agitated at 180 rpm for 1 h in an
orbital shaker. The contents of the flasks were filtered through
Whatman No. 1 filter paper and the filtrate was centrifuged at
10,000 rpm and 4 C for 10 min and supernatant was collected and
tested for crude endo-b-1,4-xylanase activity. Crude endo-b-1,4-
xylanase enzyme activities were determined spectrophotometrically
at 540 nm using di-nitrosalicylic (DNS) acid method based on
the release of reducing sugars from oat spelt xylan (Bailey et al.,
1992) at pH 5.3 and temperature 50 C utilizing 1% xylan as the
substrate. For the sake of convenience and as per the literature, this
activity has been termed as xylanase activity throughout the text.
One unit of xylanase activity is defined as the amount of enzyme
required to produce 1 mmol of xylose per minute under standard
assay conditions. Crude cellulase activity was determined through
filter paper unit assay (Ghosh, 1987).