Isolation of AHL-degrading bacteria from micro-algal cultures and their impact on algal growth and on virulence of Vibrio campbellii to prawn larvae.
Inactivation of quorum sensing (QS) signal molecules, such as acylhomoserine lactones (AHLs) of pathogenic bacteria, has been proposed as a novel method to combat bacterial diseases in aquaculture. Despite the importance of micro-algae for aquaculture, AHL degradation by bacteria associated with micro-algal cultures has thus far not been investigated. In this study, we isolated Pseudomonas sp. NFMI-T and Bacillus sp. NFMI-C from open cultures of the micro-algae Tetraselmis suecica and Chaetoceros muelleri, respectively. An AHL degradation assay showed that either monocultures or co-cultures of the isolates were able to degrade the AHL N-hexanoyl-L-homoserine lactone. In contrast, only Bacillus sp. NFMI-C was able to inactivate N-hydroxybutanoyl-L-homoserine lactone, the AHL produced by Vibrio campbellii. The isolated bacteria were able to persist for up to 3 weeks in conventionalized micro-algal cultures, indicating that they were able to establish and maintain themselves within open algal cultures. Using gnotobiotic algal cultures, we found that the isolates did not affect growth of the micro-algae from which they were isolated, whereas a mixture of both isolates increased the growth of Tetraselmis and decreased the growth of Chaetoceros. Finally, addition of Bacillus sp. NFMI-C to the rearing water of giant river prawn (Macrobrachium rosenbergii) larvae significantly improved survival of the larvae when challenged with pathogenic V. campbellii, whereas it had no effect on larval growth.
Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Rozier 44, B-9000, Ghent, Belgium.|Department of Aquatic Resources Management, Faculty of Marine Science and Fisheries, Udayana University, Bali, Indonesia.
Gde Sasmita Julyantoro
GS
Pande
Department of Aquaculture, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Malaysia.|Laboratory of Marine Biotechnology, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
Fatin Mohd Ikhsan
FM
Natrah
Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Rozier 44, B-9000, Ghent, Belgium.
Ace Vincent Bravo
AV
Flandez
Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Rozier 44, B-9000, Ghent, Belgium.
Uday
U
Kumar
Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Rozier 44, B-9000, Ghent, Belgium.
Yufeng
Y
Niu
Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Rozier 44, B-9000, Ghent, Belgium.
Peter
P
Bossier
Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Rozier 44, B-9000, Ghent, Belgium. Tom.Defoirdt@UGent.be.
Tom
http://orcid.org/0000-0002-7446-2246
T
Defoirdt
D054742:Acyl-Butyrolactones / Q000378:metabolism*; D000818:Animals; D001407:Bacillus / Q000378:metabolism*; D001711:Biotransformation; D007814:Larva / Q000502:physiology; D058086:Microalgae / Q000254:growth & development*; D033541:Palaemonidae / Q000502:physiology*; D011549:Pseudomonas / Q000378:metabolism*; D016019:Survival Analysis; D014733:Vibrio / Q000254:growth & development / Q000502:physiology*; D014774:Virulence
D054742:Acyl-Butyrolactones
Acylase; Lactonase; Macrobrachium rosenbergii; Micro-algae; Quorum quenching; Vibriosis