The role of quorum sensing and the effect of environmental conditions on biofilm formation by strains of Vibrio vulnificus

Abstract

It has been suggested that Vibrio vulnificus attaches to plankton and algae and is found in large numbers in the environment. Factors affecting attachment, biofilm formation and morphology of V. vulnificus have not been thoroughly investigated. This study evaluated the role of quorum sensing (QS) and environmental conditions on biofilm development of V. vulnificus. It was found that biofilm development by V. vulnificus was affected by nutrient and glucose concentration, but not by NaCl concentration or temperature under the conditions used here. Moreover, biofilm development of a QS mutant strain proceeded rapidly and sloughing occurred earlier than for the isogenic parent strain. There was a significant loss of viability for the QS mutant biofilm early in development. Hence, it is hypothesised that factors regulated by the QS system play a role in proper biofilm development and maintenance of V. vulnificus. Furthermore, it is shown that biofilm development varied among isolates.

Keywords:

• Biofilm
• quorum sensing
• Vibrio
• capsule
• AI-2
• opaque

Acknowledgements

We would like to kindly thank Professor Shin-Ichi Myoshi (Faculty of Pharmaceutical Sciences, Okayama University, Japan) for V. vulnificus strains I-21 and N-87. We would also like to thank the helpful comments of previous reviewers. This work was funded by National Health & Medical Research Council grant 222847.