Screening and Identification of New Isolate: Thermostable Escherichia coli with Novel Thermoalkalotolerant Cellulases |
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Authors: | Xing-hua Li Roy Bhaskar Hua-jun Yang Dan Wang Yun-gen Miao |
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Affiliation: | (1) Key Laboratory of Animal Epidemic Etiology & Immunological Prevention of Ministry of Agriculture, College of Animal Sciences, Zhejiang University, 310029 Hangzhou, People’s Republic of China; |
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Abstract: | A cellulase-producing bacterium strain was isolated from soil that produced novel thermoalkalotolerant cellulases after growth on CMC-Na agar screening plate at 37°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 β-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°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°C and 10 min at 80°C, respectively, and retained approximately 50% of its maximal activity after incubating at 90°C for 10 min. The enzyme could be applied in bioconversion of lignocellulosic agricultural wastes. |
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