Complete genome sequence of novel isolate SYJ15 of Bacillus cereus group, a highly lethal pathogen isolated from Chinese soft shell turtle (Pelodiscus Sinensis).

Abstract

SYJ15 is a highly pathogenic Gram-positive Bacillus sp. with top bud spore newly isolated from dying soft shell turtle. 16SrDNA sequencing showed that it is highly homologous to B. cereus, B. thuringiensis and B. anthracis. Biochemical examinations showed that it belongs to B. cereus. To further study the new pathogen, we conducted whole-genome sequencing based on single-molecular sequencing technology from PacBio. Genome assembly analysis showed that the strain has a 5,296,886 bp chromosome, a 218,649 bp plasmid and a 5221 bp plasmid with GC content of 35.51%, 31.91% and 29.75%, respectively. The genome contains 5736 coding sequences and 6 CRISPR systems located in the chromosome as well as 11 genomic islands in the chromosome and the large plasmid. Genome function analyses were annotated by nr database, SwissProt, KEGG, COG, GO, PHI, VFDB, ARDB, Secretory_Protein and T3SS. In addition, 13 gene clusters of secondary metabolism were predicted by antiSMASH. Comparison of SYJ15 with B. subtilis, B. anthracis, B. cereus and B. thuringiensis identified 1031 core genes of the five strains and 816 genes specific to SYJ15. In addition, SYJ15 had the most common core genes with B. thuringiensis, and the least with B. subtilis. Phylogenetic analysis demonstrated that SYJ15 is between B. thuringiensis and B. cereus, suggesting that SYJ15 belongs to Bacillus cereus group. We designed a specific primer pair to distinguish SYJ15 from B. pumilus, B. licheniformis, B.subtilis, B. thuringiensis and B. cereus. In conclusion, information of SYJ15 genome will help to enhance our understanding of pathogenesis of SYJ15 and find effective treatment.