affecting the interplay between microbiological organisms and their hosts,
the latter phase of
tested the responses of larvae to benign microorganisms, to assess whether they could counter biological
threats.
Traditionally there has been more focus on malign than on benign microbe-fish interactions, despite the fact that being healthy should be the normal situation. Trials were also conducted to ascertain the benevolent effects of microbes, as an agent to combat
invasive
pathogens. “Using
molecular
tools, we’ve generated some quite unexpected results,”
says project
coordinator Professor Peter Bossier of Ghent University. ”We can now revisit much of our prior work on larvae. Formerly, growth
only rates the and
enzyme activity of larvae were quantified, but now we can also examine how the development of experimental
situation are linked to well
the fish and the to
expression of genes, including specific responses
defined microbial
communities. We’ve obtained far more information about the varied mechanisms which govern healthy development of larvae than we had previously, although much remains to be learned about the molecular basis of
host-microbe
interactions in the larval phase.” To enhance the microbial quality of the
aquatic environment and to suppress the proliferation of
damaging microbes
within it, the group suggests a two- pronged intervention. The first of these is related to improved health by steering microbiota in the water. By channeling water through biofilters, microbes are forced to compete for nutrients, resulting in exclusion of opportunistic bacteria and creating a more stable and diverse microbial environment. The group found that such a microbial community results in more viable larvae, and in experiments with Atlantic cod larvae, managing bacterial communities in this way resulted in a 60% higher survival rate compared to a conventional setup. The system limits the availability of nutrients within larval tanks and stabilises the
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the project
amount of waste organic matter available to the microbial biomass in the tank, thus restricting microbial growth minimising
oscillations in
AT A GLANCE and microbial
biomass and activity. “We’ve consequently developed the possibility of steering, or controlling microbial community composition and activity in a way which enhances appetite, growth and survival of larvae,” says
“We’ve consequently developed the
possibility of steering, or controlling
microbial community composition and activity in a way which enhance
appetite, growth and survival of larva”
“Formerly, thinking
is
the general was
microbiological quality
critical
water to
larvae only for the first few days, and, thereafter, it’s primarily the microbiota of their diet which affects them. Our findings indicate that
this is incorrect.
Moreover, recirculating aquaculture
systems
seem to function as a microbial management technology - an aspect that
has been almost
completely overlooked.” Finally it appears that is not only possible
to steer microbial community composition but also their activity. Depending on the microbe-host
interaction under study, it
has been established that the outcome of these interactions might be determined by secreted quorum-sensing molecules. Such types of molecules contribute to the production of
molecules can be of Project Information
Project Title: PROMICROBE: Microbes as positive actors for more sustainable aquaculture
Vadstein. that
Project Objective: This project suggests bringing together various European research groups that have contributed to some important methodological breakthroughs that can be used in the study of host/microbe interactions and can help to disentangle the complex interplay between the different components of the aquaculture ecosystem
Project Duration and Timing: 5 years, Feb 2009 to April 2013
Project Funding: EU FP7
Project Partners: 1 Coordinator Ghent University (Ugent) Belgium
2 Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER) France
3 Wageningen University (WU) The Netherlands
4 Norwegian University for Science and Technology (NTNU)Norway
5 SINTEF Materials and Chemistry (SINTEF- MC) Norway
6 SINTEF Fisheries and Aquaculture (SINTEF- FA) Norway
7 Flanders Institute for Biotechnology (VIB) Belgium
MAIN CONTACT virulence factors.
Interference with the production of these quorum-sensing
beneficial to the host. Quorum quenching, as the technique is called, can be realised through
the addition molecules (contrary to antibiotics,
antagonistic these
compounds inhibit certain microbial activity rather
Future full-scale than trying to eliminate
them) or through the addition of microorganisms able to degrade quorum- sensing molecules.
experiments are needed to establish whether this
can become a reliable
microbial management technique. “Relationships between the larvae and should be mutualistic and
microbiota
symbiotic,” summarises Vadstein. “There is
no uniform solution, or magic
ingredient you can simply add to the water which improves larval survivability. Nonetheless, we have begun to explore and control a complex of underlying mechanism at work here.”
65
Contact: Tel: 32 9 264 37 59 Email:
Peter.bossier@
ugent.be Web:
www.promicrobe.ugent.be/
Peter Bossier Peter Bossier has been a researcher for 30 years in the domains of microbial ecology, molecular genetics (of stress response) and fish quality. At the moment, his focus is on host microbial interactions in larviculture. His research output stands at 167 A1 papers.
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