Screening and identification of new isolate: thermostable Escherichia coli with novel thermoalkalotolerant cellulases.

A cellulase-producing bacterium strain was isolated from soil that produced novel thermoalkalotolerant cellulases after growth on CMC-Na agar screening plate at 37 degrees C. It was identified as Escherichia coli using the method of 16S rRNA and intergenic spacer gene analysis combined with morphological, physiological, and biochemical tests. Three major components of the cellulases [carboxymethyl cellulase (CMCase), filter paper cellulase, and beta-glucosidase] were produced with maximal activities (0.23, 0.08, and 0.15 U/ml) and maximum specific activities 4.13, 0.56, and 0.50 U/mg protein after 72, 96, and 120 h growth, respectively. Maximum CMCase activity was measured at 50 degrees C and pH 6.0, respectively, and it also retained more than 60% of its maximal activity for at least 20 min at 50-70 degrees C and 10 min at 80 degrees C, respectively, and retained approximately 50% of its maximal activity after incubating at 90 degrees C for 10 min. The enzyme could be applied in bioconversion of lignocellulosic agricultural wastes.