Isolation and characterization of a Bacillus cereus strain with cellulose-degradation activity from a termite-inhabiting soil

Abstract:

[Objective] The study aims to determine whether the termite-inhabiting soil harbors cellulose-degradation bacteria. [Methods] Using a selective medium supplemented with sodium carboxymethyl cellulose (CMC-Na) as the sole carbon source and the Congo red activity staining method, we have isolated a cellulose-degradation strain. Microscope morphology, Gram-staining, and 16S rRNA gene sequencing analyses were utilized to characterize the isolated strain. Enzyme activity and properties were assayed by the DNS method. [Results] A Gram-positive strain (named as TT15) with high cellulase activity was obtained from a Coptotermes formosanus-inhabiting soil. Based on the 16S rDNA analysis, TT15 was identified to be a strain of Bacillus cereus Gd2T. The cellulase activity was not detected in the first 12 h of continuous culture, but afterwards, the enzyme activity was detected and increased with culture time. The activity reached the maximum level at the early stationary phase of growth (48 h) and remained stable later on. The optimum pH and temperature were 5.0 and 50 °C, respectively. [Conclusion] We have isolated a B. cereus Gd2T strain TT15 with high cellulase activity from a C. formosanus-inhabiting soil. The strain might be used for biomass conversion biotechnology.