Genetic boundaries delineate the potential human pathogen Salmonella bongori into discrete lineages: divergence and speciation

BMC Genomics

Randal N. Johnston¹  Yong-Guo Li²  Tie-Min Ding³  Shu-Lin Liu⁴  Hong-Xia Bao⁴  Le Tang⁴  Feng-Lin Cao⁴  Jian-Hua Zhao⁴  Xiaoyu Wang⁴  Songling Zhu⁴  Gui-Rong Liu⁴  Huidi Liu⁴ 

[1] Department of Biochemistry and Molecular Biology, University of Calgary;Department of Infectious Diseases, The First Affiliated Hospital, Harbin Medical University;Department of Medicine and Food Engineering, Harbin Labor Technician College;Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University;

关键词: Salmonella;    Bacterial pathogens;    Genomic divergence;    Genetic boundary;   

DOI  :  10.1186/s12864-019-6259-z

来源: DOAJ

【 摘 要 】

Abstract Background Salmonella bongori infect mainly cold-blooded hosts, but infections by S. bongori in warm-blooded hosts have been reported. We hypothesized that S. bongori might have diverged into distinct phylogenetic lineages, with some being able to infect warm-blooded hosts. Results To inspect the divergence status of S. bongori, we first completely sequenced the parakeet isolate RKS3044 and compared it with other sequenced S. bongori strains. We found that RKS3044 contained a novel T6SS encoded in a pathogenicity island-like structure, in addition to a T6SS encoded in SPI-22, which is common to all S. bongori strains so far reported. This novel T6SS resembled the SPI-19 T6SS of the warm-blooded host infecting Salmonella Subgroup I lineages. Genomic sequence comparisons revealed different genomic sequence amelioration events among the S. bongori strains, including a unique CTAG tetranucleotide degeneration pattern in RKS3044, suggesting non-overlapping gene pools between RKS3044 and other S. bongori lineages/strains leading to their independent accumulation of genomic variations. We further proved the existence of a clear-cut genetic boundary between RKS3044 and the other S. bongori lineages/strains analyzed in this study. Conclusions The warm-blooded host-infecting S. bongori strain RKS3044 has diverged with distinct genomic features from other S. bongori strains, including a novel T6SS encoded in a previously not reported pathogenicity island-like structure and a unique genomic sequence degeneration pattern. These findings alert cautions about the emergence of new pathogens originating from non-pathogenic ancestors by acquiring specific pathogenic traits.

【 授权许可】

Unknown