Frontiers in Microbiology (Oct 2018)

The Roles of Two Type VI Secretion Systems in Cronobacter sakazakii ATCC 12868

  • Min Wang,
  • Min Wang,
  • Min Wang,
  • Hengchun Cao,
  • Hengchun Cao,
  • Hengchun Cao,
  • Qian Wang,
  • Qian Wang,
  • Qian Wang,
  • Tingting Xu,
  • Tingting Xu,
  • Tingting Xu,
  • Xi Guo,
  • Xi Guo,
  • Xi Guo,
  • Bin Liu,
  • Bin Liu,
  • Bin Liu

DOI
https://doi.org/10.3389/fmicb.2018.02499
Journal volume & issue
Vol. 9

Abstract

Read online

The type VI secretion system (T6SS), which has been found in 25% of gram-negative bacteria, is a crucial virulence factor in several pathogens. Although T6SS gene loci have been discovered in Cronobacter species, one of the major opportunistic foodborne pathogens, its function has not been elucidated. In this study, the roles of two phylogenetically distinct T6SS gene clusters in Cronobacter sakazakii ATCC12868 were investigated. Analysis of 138 genome sequences of C. sakazakii strains, we found that one T6SS gene cluster (T6SS-1) was ubiquitous in all examined strains, whereas another (T6SS-2) was absent or degenerated in a large proportion of the strains (n = 97). In addition, we confirmed the T6SS-1 antibacterial function through an in-frame deletion in the vasK and hcp genes. Compared with the wild-type strain, the T6SS-2-deficient mutant presented a much stronger colonization of organs when infecting neonatal rats. Thus, we proposed that T6SS-2 plays a role in pathogenic processes. This is the first study to investigate the functions of T6SS in C. sakazakii, and the results will extend our understanding of the pathogenic and phylogenetic characteristics of C. sakazakii.

Keywords