Quorum sensing negatively regulates chitinase in Vibrio harveyi
Article first published online: 1 JUL 2009
© 2009 Society for Applied Microbiology and Blackwell Publishing Ltd
Environmental Microbiology Reports
Special Issue: Vibrio Ecology. Editors: Carla Pruzzo, Balakrish Nair, Jim Oliver and Rita Colwell
Volume 2, Issue 1, pages 44–49, February 2010
How to Cite
Defoirdt, T., Darshanee Ruwandeepika, H.A., Karunasagar, I., Boon, N. and Bossier, P. (2010), Quorum sensing negatively regulates chitinase in Vibrio harveyi. Environmental Microbiology Reports, 2: 44–49. doi: 10.1111/j.1758-2229.2009.00043.x
- Issue published online: 8 FEB 2010
- Article first published online: 1 JUL 2009
- Received 30 April, 2009; accepted 8 June, 2009.
Quorum sensing, bacterial cell-to-cell communication, regulates the virulence of Vibrio harveyi towards different hosts. Chitinase can be considered as a virulence factor because it helps pathogenic bacteria to attach to the host and to penetrate its tissues (e.g. in case of shrimp). Here, we show that quorum sensing negatively regulates chitinase in V. harveyi. Chitinolytic activity towards natural chitin from crab shells, the synthetic chitin derivative chitin azure, and fluorogenic chitin oligomers was significantly higher in a mutant in which the quorum-sensing system is completely inactivated when compared with a mutant in which the system is maximally active. Furthermore, the addition of signal molecule containing cell-free culture fluids decreased chitinase activity in a Harveyi Autoinducer 1 and Autoinducer 2-deficient double mutant. Finally, chitinase A mRNA levels were fivefold lower in the mutant in which the quorum-sensing system is maximally active when compared with the mutant in which the system is completely inactivated. [Correction added on 25 September 2009, after first online publication: the preceding sentence was corrected from ‘Finally, chitinase A mRNA levels were fivefold lower in the mutant in which the quorum-sensing system is completely inactivated when compared with the mutant in which the system is maximally active.’] We argue that this regulation might help the vibrios to switch between host-associated and free-living life styles.