Insight into the resilience and susceptibility of marine bacteria to T6SS attack by Vibrio cholerae and Vibrio coralliilyticus

PLoS One. 2020 Jan 28;15(1):e0227864. doi: 10.1371/journal.pone.0227864. eCollection 2020.


The type VI secretion system (T6SS) is a nanomachine capable of killing adjacent microbial cells in a contact-dependent manner. Due to limited studies, relatively little is known about the range of marine bacteria that are susceptible to T6SS attack. Here, 15 diverse marine bacterial isolates from the phyla Bacteroidetes and Ɣ-Proteobacteria were challenged against the marine bacterium and human pathogen, Vibrio cholerae, which has a well described T6SS. V. cholerae killed several of the tested Ɣ-Proteobacteria, including members of the orders Vibrionales, Alteromonadales, Oceanospirillales, and Pseudomonadales. In contrast, V. cholerae co-existed with multiple Bacteroidetes and Ɣ-Proteobacteria isolates, but was killed by Vibrio coralliilyticus. Follow-up experiments revealed that five V. coralliilyticus strains, including known coral and shellfish pathogens survived the T6SS challenge and killed V. cholerae. By using predicted protein comparisons and mutagenesis, we conclude that V. coralliilyticus protected itself in the challenge by using its own T6SS to kill V. cholerae. This study provides valuable insight into the resilience and susceptibility of marine bacteria to the V. cholerae T6SS, and provides the first evidence for a functional T6SS in V. coralliilyticus, both of which have implications for human and ocean health.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anthozoa / microbiology
  • Antibodies, Bacterial / genetics
  • Bacterial Proteins / genetics
  • Bacteroidetes / genetics
  • Gene Expression Regulation, Bacterial / genetics
  • Proteobacteria / genetics
  • Shellfish / microbiology
  • Type VI Secretion Systems / genetics*
  • Vibrio / genetics*
  • Vibrio cholerae / genetics
  • Vibrio cholerae / pathogenicity*


  • Antibodies, Bacterial
  • Bacterial Proteins
  • Type VI Secretion Systems

Supplementary concepts

  • Vibrio coralliilyticus

Grant support

This work was supported by the Gordon & Betty Moore Foundation Grant #4827 to (F.A.). B.U. and C.H. were supported by internal funds from the Carlson College of Veterinary Medicine to C.H. There was no additional external funding received for this study.