- Why are V. cholerae bacteria that grow on chitin-containing shells more toxic to predators?
- How do these bacteria work together to initiate an ‘anti predator’ response?
- Could the anti-parasitics excreted by V. cholerae bacteria to protect themselves have commercial value?
- How do Pseudomonas aeruginosa biofilms disperse when starved?
Predators of marine bacteria include animal-like (heterotrophic) protists called protozoa that eat bacteria as their food. Most of these protists are single celled – for example, amoeba and ciliates. In the ocean, bacteria that live and grow in communities anchored to a surface – known as biofilms - are less likely to be preyed upon than those that are free-swimming. These surfaces include the chitin-containing shells of tiny crustaceans called copepods that grow to about 2mm in length.
The bacterial pathogen Vibrio cholerae, which causes cholera* is well-adapted to the ocean environment and has several protective behaviors that help to stave off predation. For example, it becomes more toxic to predators when it is growing on a chitinous substrate as opposed to an abiotic surface. In addition to biofilm formation, these bacteria employ a cell-cell communication system based on a phenomenon of quorum sensing (QS) that allows a bacterium to determine whether there is the required aggregate numbers for a coordinated ‘anti predator’ response. This may involve the release of anti-protozoal compounds or the acquisition of genes to aid survival – a process called horizontal gene transfer.
V. cholerae is an excellent model for behavioural investigations due to its fast growth rate and complex community interactions. We are interested in bacterial communication systems as well as chemical communication between bacteria and higher organisms, such as protists, that lead to adaption and persistance. Our translational work centres on the anti-parasitic potential of the anti-protozoal compounds excreted by bacteria. Our research also encompasses the molecular control of stress response mechanisms in Pseudomonas sp.
*Cholera is characterised by severe diarrhea, vomiting, dehydration and sometimes death. It is usually spread and contracted through drinking contaminated water with most reported cases occurring in developing countries.
Research focus: Bacterial communication, adaption to stress including predation, and virulence
Tags: Biofilms, Cell-to-cell communication, Cholera, Marine bacteria, Pathogen evolution, Pseudomonas, Quorum sensing, Vibrio
Phone: +61 2 9514 4869