Production and Characterization of Cellulase Enzyme Produced by Bacillus Isolates from Different Sources

Abstract

This study was conducted to produce and characterize cellulase
enzymes from Bacillus isolates and to determine the optimum conditions
for cellulase activity. Four Bacillus isolates were used: iso 9+ from
compost and iso13, iso23 and iso20 from soil. The four isolates (9+, 23,
13 and 20) gave average cellulase activities of 2.89, 3.12, 3.48 and 3.53
Unit/ml, respectively. The pH optimum for cellulases from the four
isolates was 6, and the temperature optima were 45, 60, 60 and 80°C,
respectively. Cellulases from isolates 13 and 23 were more thermostable
and retained 40.2% and 21.9% of their initial activities after incubation
for 110 min at 90°C. Cellulase was produced under solid state
fermentation conditions in maize cobs, sorghum stover or bagasse
pretreated with 2% hydrochloric acid from the above four isolates as well
as from two more isolates (iso4- and iso2-) which were isolated from cow
dung. Maximum cellulase activity was 3.78 Unit/ml from isolate 4- using
bagasse and maize cobs as substrate. These results demonstrated that
Bacillus isolates 13, 23, 20 and 9+ produced active thermostable
extracellular cellulase. Bagasse and maize cobs are suitable as substraes
for production of the enzyme cellulase under solid state fermentation.