Quroum sensing disruption and the use of short-chain fatty acids and polyhydroxyalkanoates to control luminescent vibriosis

Luminescent vibrios are amongst the most important pathogens in aquaculture. As a result of the massive (mis)use of antibiotics in order to treat infections, these pathogens have acquired resistance to most of the antibiotics that are used. Consequently, antibiotics are not effective anymore to cure luminescent vibriosis disease and in addition, the transfer of resistance determinants constitutes a threat to public health. Therefore, alternative methods to control the disease are urgently needed. In the first part of this work, the disruption of quorum sensing, bacterial cell-to-cell communication, was studied as a possible new strategy to control luminescent vibriosis. First of all, it was shown that quorum sensing regulates the virulence of Vibrio harveyi towards gnotobiotic brine shrimp (Artemia franciscana) nauplii. Subsequently, halogenated furanones were shown to disrupt quorum sensing in these bacteria by decreasing the DNA-binding activity of the quorum sensing master regulator protein LuxR. Interestingly, the addition of 20 mg l-1 of the furanone to the culture water of gnotobiotic Artemia nauplii resulted in a significantly increased survival in challenge tests with different pathogenic luminescent vibrio isolates. Unfortunately, the furanone also appeared to be toxic to the brine shrimp, as high mortality was observed after the addition of 50 mg l-1 to the culture water. The second part of this work describes the application of short-chain fatty acids and polyhydroxyalkanoates. First, it was shown that formic, acetatic, propionic, butyric and valeric acid inhibit growth of luminescent vibrios in vitro in a pH-dependent way. Furthermore, the addition of 20 mM of the short-chain fatty acids to the culture water of gnotobiotic Artemia nauplii resulted in a significantly increased survival in challenge tests with a pathogenic luminescent Vibrio campbellii strain. Subsequently, the application of the homopolymer of the short-chain fatty acid β-hydroxybutyrate, the well-known bacterial storage compound poly-β-hydroxybutyrate, was shown to offer a more efficient protection. Finally, it was shown that poly-β-hydroxybutyrate containing bacteria can be used to protect brine shrimp from luminescent vibriosis. The addition of poly-β-hydroxybutyrate containing Brachymonas bacteria (yielding a poly-β-hydroxybutyrate concentration of 10 mg l-1) resulted in a complete protection from the pathogenic Vibrio campbellii strain.

Author dc:creator

• Defoirdt, Tom

Contributors dc:contributor

• Verstraete, W

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

und

Identifier

https://biblio.ugent.be/publication/469530
http://doi.org/1854/7229
https://biblio.ugent.be/publication/469530/file/1879671

OAI identifier oai:identifier

oai:archive.ugent.be:469530