Genome Analysis of Monochamus alternatus Gut BS16 and Characterization of Its Cellulase Activity

Bacillus cereus BS16 is a bacterium with cellulase activity screened from the intestinal tract of Monochamus alternatus. In order to understand the genomic characteristics of the BS16 strain and its cellulose degradation function, this study used scanning electron microscopy, genomics analysis, and DNS method to explore the morphological characteristics, cellulase enzymatic gene, and cellulase activity of BS16. The results showed that the cells of BS16 were capsules with a length of 3–4 µm and a diameter of 0.5–1.2 µm. The full length of B. cereus BS16 genome is 5 347 914 bp, containing 5 494 genes, including 5 338 protein-coding genes, 11 rRNA genes, 102 tRNA genes and 17 sRNA genes. Cellulase is mainly encoded by GH4, GH5, GH8 and GH13 families in BS16 genome. B. cereus BS16 has a complete cellulase system and the highest endoglucanase activity was 2.186 ± 0.081 U/mL. The optimal pH value and temperature of endoglucanase activity are 5.0 and 40 ℃ respectively.