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Study of Quorum Sensing in bacteria organized biofilm in light of the implementation of non toxic biocide

GOZOUA Emmanuel Axis 2

Beginning: December 2015



Supervisor: BLACHE Yves

Abstract

The marine environment is subject to a major handicap that answers the name of biofouling. Biofouling is a biological process that corresponds to the aggregation of microorganisms (bacteria, fungi, algae or protozoa) and macroorganisms (algae, sponges, balanes and invertebrates) on a natural or synthetic submerged surface. The formation of this type of structure on the hulls of ships generates significant damage both economic and ecological. Indeed, the formation of biofouling on the hulls of ships can lead to an increase in fuel consumption of about 40%, and to the relocation of non-native marine species to invasive species; Which could constitute an ecological disaster. Beyond these environmental considerations, biofilms represent an important public health issue because they are involved in medical infections and contamination in the agri-food industries. Several strategies to combat biofouling based on the use of chemical biocides have been developed until very recently, which unfortunately have proved toxic to marine organisms. This is the case of tributyltin (TBT), which was banned in the early 2000s by the International Maritime Organization (IMO).
The first step in the formation of biofouling, biofilm corresponds to the irreversible adhesion of bacteria and diatoms on an immersed surface. Biofilm-based bacteria possess the ability to resist antibacterial treatments and disinfectants by extracellular extracellular matrix (EPS), which they synthesize during their social life in biofilm. This is the case of several marine species of the genus Peudoalteromonas. Among these, we cite as examples P. tunicata, P. ruthenica, Peudoalteromonas sp and P. ulvae (TC14). These species have been described as being endowed in biofilm formation.
In this study, we will discuss the development of the QS inhibitory molecules of P. ulvea (TC14). This involves the inhibition of phenotypes controlled by the QS including the production of violacein, adhesion and biofilm formation. Thus, commercial molecules considered to have a broad spectrum of action on marine species were tested on TC14. These molecules consisting of boronic acids on the one hand and fatty acids on the other hand will then be combined with molecules synthesized in the MAPIEM laboratory, in order to optimize their effect on this species.



Laboratoire MAPIEM (EA 4323) - http://mapiem.univ-tln.fr/These.html - mapiem@univ-tln.fr