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Role of bacterial quorum sensing and micro-algae in fish and crustacean larviculture

Natrah Fatin Mohd Ikhsan (2011)
abstract
Bacterial disease is one of the major problems in aquaculture. Pathogenic bacteria such as V. harveyi and Aeromonas spp. infect various host species. Antibiotics remain by far the easiest and fastest solution to cure bacterial disease. However, the overuse of antibiotics has lead to resistant bacteria, causing the problem to become even more severe. As a result, antibiotics are not able anymore to cure infections in many cases. In this work, disruption of bacterial communication or quorum sensing (QS) is investigated as a novel approach to control bacterial infections in aquaculture. The first part of the research studied the effects of V. harveyi quorum sensing on virulence factor regulation and the impact of quorum sensing disruption on the virulence of V. harveyi and Aeromonas spp. towards giant river prawn (M. rosenbergii) and burbot (Lota lota) larvae, respectively. It was shown that QS negatively regulates the production of phospholipase, while caseinase and gelatinase are positively regulated. Meanwhile, hemolysin and lipase were found to be independent of QS. Furthermore, HAI-1 and AI-2 quorum sensing were found to be important for the virulence of V. harveyi towards prawn larvae. The CAI-1 system, on the other hand, had no effect on virulence of the bacterium in this host system. Similarly, AHL quorum sensing regulates the virulence of A. hydrophila towards burbot larvae. Meanwhile, QS antagonists (Ntetradecanoyl-L-homoserine lactone and cinnamaldehyde) protected burbot from A. salmonicida. In the second part of the research, the ability of micro-algae to interfere with QS was investigated through screening the effect of algal extracts on different bacterial QS reporter strains, including V. harveyi. The screening results showed that extracts from different micro-algal strains were able to interfere with QS regulated gene expression in the reporter strains. The interference activities were dependent on the QS signal type (unsubstituted, oxo-substituted and hydroxyl-substituted). The most interesting micro-algal strain was found to be C. saccharophila CCAP211/48 as it was able to inhibit QS-regulated gene expression in all three reporters used in this study. In another study, freshwater micro-algae (C. saccharophila CCAP211/48 and C. reinhardtii CCAP11/45) were also able to protect burbot larvae from Aeromonas disease. In conclusion, the results presented in this study showed that there is a link between QS and the production of virulence factors and pathogenicity towards aquatic animal larvae. Quorum sensing disruption through QS antagonists and micro-algae are promising as novel methods to
Please use this url to cite or link to this publication:
author
promoter
UGent, UGent and UGent
organization
alternative title
De rol van bacteriële quorum sensing en micro-algen in de larvicultuur van vissen en garnaalachtigen
year
type
dissertation
publication status
published
subject
keyword
Quorum Sensing, Larviculture, Micro-algae
pages
153 pages
publisher
Ghent University. Faculty of Bioscience Engineering
place of publication
Ghent, Belgium
defense location
Gent : Faculteit Bio-ingenieurswetenschappen (A0.030)
defense date
2011-11-18 10:00
ISBN
9789059894822
language
English
UGent publication?
yes
classification
D1
additional info
dissertation consists of copyrighted material
copyright statement
I have transferred the copyright for this publication to the publisher
id
2057516
handle
http://hdl.handle.net/1854/LU-2057516
date created
2012-03-02 15:07:32
date last changed
2017-01-16 10:38:49
@phdthesis{2057516,
  abstract     = {Bacterial disease is one of the major problems in aquaculture. Pathogenic bacteria such as V. harveyi and Aeromonas spp. infect various host species. Antibiotics remain by far the easiest and fastest solution to cure bacterial disease. However, the overuse of antibiotics has lead to resistant bacteria, causing the problem to become even more severe. As a result, antibiotics are not able anymore to cure infections in many cases. In this work, disruption of bacterial communication or quorum sensing (QS) is investigated as a novel approach to control bacterial infections in aquaculture. The first part of the research studied the effects of V. harveyi quorum sensing on virulence factor regulation and the impact of quorum sensing disruption on the virulence of V. harveyi and Aeromonas spp. towards giant river prawn (M. rosenbergii) and burbot (Lota lota) larvae, respectively. It was shown that QS negatively regulates the production of phospholipase, while caseinase and gelatinase are positively regulated. Meanwhile, hemolysin and lipase were found to be independent of QS. Furthermore, HAI-1 and AI-2 quorum sensing were found to be important for the virulence of V. harveyi towards prawn larvae. The CAI-1 system, on the other hand, had no effect on virulence of the bacterium in this host system. Similarly, AHL quorum sensing regulates the virulence of A. hydrophila towards burbot larvae. Meanwhile, QS antagonists (Ntetradecanoyl-L-homoserine lactone and cinnamaldehyde) protected burbot from A. salmonicida. In the second part of the research, the ability of micro-algae to interfere with QS was investigated through screening the effect of algal extracts on different bacterial QS reporter strains, including V. harveyi. The screening results showed that extracts from different micro-algal strains were able to interfere with QS regulated gene expression in the reporter strains. The interference activities were dependent on the QS signal type (unsubstituted, oxo-substituted and hydroxyl-substituted). The most interesting micro-algal strain was found to be C. saccharophila CCAP211/48 as it was able to inhibit QS-regulated gene expression in all three reporters used in this study. In another study, freshwater micro-algae (C. saccharophila CCAP211/48 and C. reinhardtii CCAP11/45) were also able to protect burbot larvae from Aeromonas disease. In conclusion, the results presented in this study showed that there is a link between QS and the production of virulence factors and pathogenicity towards aquatic animal larvae. Quorum sensing disruption through QS antagonists and micro-algae are promising as novel methods to},
  author       = {Mohd Ikhsan, Natrah Fatin},
  isbn         = {9789059894822},
  keyword      = {Quorum Sensing,Larviculture,Micro-algae},
  language     = {eng},
  pages        = {153},
  publisher    = {Ghent University. Faculty of Bioscience Engineering},
  school       = {Ghent University},
  title        = {Role of bacterial quorum sensing and micro-algae in fish and crustacean larviculture},
  year         = {2011},
}

Chicago
Mohd Ikhsan, Natrah Fatin. 2011. “Role of Bacterial Quorum Sensing and Micro-algae in Fish and Crustacean Larviculture”. Ghent, Belgium: Ghent University. Faculty of Bioscience Engineering.
APA
Mohd Ikhsan, N. F. (2011). Role of bacterial quorum sensing and micro-algae in fish and crustacean larviculture. Ghent University. Faculty of Bioscience Engineering, Ghent, Belgium.
Vancouver
1.
Mohd Ikhsan NF. Role of bacterial quorum sensing and micro-algae in fish and crustacean larviculture. [Ghent, Belgium]: Ghent University. Faculty of Bioscience Engineering; 2011.
MLA
Mohd Ikhsan, Natrah Fatin. “Role of Bacterial Quorum Sensing and Micro-algae in Fish and Crustacean Larviculture.” 2011 : n. pag. Print.