Abstract:
This study focuses on the isolation and identification of xylanase
producing bacteria, and characterization of xylanase which is produced by
the selected isolate. Bacterial strains were isolated from corncob decaying
soil and the highest xylanase producing isolate (CS1) was selected. Strain
CS1 produced highest xylanase activity [328.0(±0.7)UmL-1] in 32 h while
growth showed lag phase up to 8 h and log phase up to 16h at pH 8.5 and
45oC. The isolate was identified as Bacillus pumilus based on biochemical
characterization and 16S rDNA amplification. Crude xylanase showed zero
order kinetics for 4min and gave highest activity [301.5(±0.26)UmL-1] at
55oC and pH 8.4. Michaelis constant of the crude enzyme to soluble
Birchwood xylan was 7.1gL-1 and Vmax value was 1666 μmolmL-1 at 55oC and
pH 8.4. In the absence of additives, at 30min the xylanase retained 5
(±0.92)% of its initial activity at 60oC and pH 8.4 while at 55oC and pH 8.4,
it retained 38 (±1.0)% of its initial activity. B. pumilus xylanase produced
xylotriose as the final hydrolysed product of Birchwood xylan. Based on the
results, the isolate selected and identified as B. pumilus, produced xylanase
which may be useful in industrial applications to remove hemicelluloses.
