Browsing by Author "Tom Defoirdt"

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    Significance of microalgal–bacterial interactions for aquaculture
    (Wiley Publishing Asia Pty Ltd, 2013-01) Fatin M. I. Natrah; Peter Bossier; Patrick Sorgeloos; Fatimah Md. Yusoff; Tom Defoirdt
    Knowledge on the importance of associations between bacteria and microalgae in aquatic ecosystems is rather limited at the moment, mostly due to a lack of studies at the molecular and biochemical level of microorganisms. This paper discusses the current knowledge on microalgae–bacteria interactions and their potential impacts on the productivity, efficiency and sustainability of aquaculture. Current findings suggest that the interactions are complex and specific. The release of stimulatory products by bacteria that enhance the growth of microalgae, and vice versa, indicates the existence of mutualistic relations. Other factors, such as signalling between bacteria and microalgae, may also play an important role. Although these interactions may be of significant importance, to date, only a few findings have been reported on the use of consortia consisting of microalgae and bacteria for practical purposes. Interestingly, these results pointed out that a combination of microalgae and bacteria is often better than using either of them alone. Further research is needed to obtain a thorough understanding of the mechanisms behind the interactions between these microorganisms, including the identification of active compounds. This knowledge will enable the selection of appropriate consortia for different applications in aquaculture, including disease control and high and sustainable production of feed.
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    Virulence mechanisms of bacterial aquaculture pathogens and antivirulence therapy for aquaculture
    (Wiley Publishing Asia Pty Ltd, 2013) Tom Defoirdt
    Although aquaculture continues to be the fastest-growing food-producing industry worldwide, the sector faces important challenges with respect to controlling infectious diseases. Indeed, the frequent use of antibiotics, which are traditionally the most important line of defence against bacterial disease, has raised problems related to the development and spread of resistance. As a result, we currently are in a race to develop novel therapeutics that should allow us to continue controlling bacterial disease in the future. In this respect, scientific progress of the past years has allowed us to start understanding the mechanisms by which bacterial pathogens are causing disease. This knowledge in its turn opens up novel possibilities to combat infections by interfering with these mechanisms, a strategy that has been termed antivirulence therapy. In this review, the current knowledge with respect to pathogenicity mechanisms of bacterial aquaculture pathogens is discussed, including adhesion mechanisms, production of extracellular polysaccharides and biofilm formation, production of lytic enzymes (e.g. haemolysins and proteases), mechanisms of iron acquisition, secretion systems and regulatory mechanisms such as quorum sensing and host–pathogen signalling with catecholamine stress hormones. Furthermore, an overview is given of the first steps towards antivirulence therapy for aquaculture, with a focus on quorum sensing disruption as a proof of concept.