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ANR funded project

Emergence (Emergence) 2012
Projet Bt-Surf

Characterization and production of biosurfactants from Bacillus thuringiensis

Surfactants are amphiphilic compounds which reduce the surface tension of water. They are used, among other applications, as detergents, emulsifyers, anti-foaming, and dispersing agents. Most of the surfactants currently used are chemically synthesized. However, interest in biosurfactants of microbial origin has significantly increased during the last decade. Biosurfactants are highly diverse and readily biodegradable. Moreover, the reduction of production costs through fermentation processes and the diversity of their potential applications make these molecules highly attractive in socio-economic terms. Among the microorganims which produce biosurfactants, the Bacillus species are the most known.
A new area of research is now emerging which focuses on the search for new biosurfactant molecules, especially lipopeptides, which can be used as phytosanitary products or adjuvants to improve both the ecological fitness and the efficacy of existing biopesticides. Among the set of known lipopeptides, kurstakins produced by Bacillus thuringiensis (Bt) is quite interesting because this is one of the sole cationic lipopeptide family. Bt is the most successful biopesticide used worldwide in agriculture, forest management, and mosquito control. This bacterium, which is recognized as a safe (GRAS) microorganism for environment, animals and humans, is easy to cultivate in large amounts with a low production cost and is fully accepted in organic farming. The capacity of the bacteria to multiply and sporulate in the insect cadaver increases the horizontal transmission of Bt on the leaf surface and might be a key factor for bacterial spreading and, in fine, for the success of the biopesticide treatment. We have recently shown that lipopeptides named kurstakins are essential to the saprophytic properties of Bt, permitting the bacteria to survive and to sporulate in the cadaver of an infected host (an insect larva). Moreover, the results show that these lipopeptides are essential for swarming and biofilm formation, two surface-associated traits requiring biosurfactants. These results indicate that kurstakins might be interesting enhancers of colonisation and persistence of Bacillus strains in the rhizosphere or the phyllosphere. However the main technological barriers for the production and extraction at industrial scale of these compounds are the low level of expression of kurstakin genes and and the resulting low production of the lipopeptide.
Our project aims at characterizing and overproducing, on a large scale, a Bt lipopeptide, and at confirming its interest to improve the efficacy of the biopesticide formulations. It is divided into four tasks handled by three teams with complementary competences. The selection of a kurstakin variant, with the most efficient biosurfactant activity and the lowest ecotoxicity, will be performed in task 1. A second task aims to construct a non-sporulating and overproducing strain. This construction will be based on various data including very recent results concerning the regulation of kurstakin expression in Bt obtained by Team 1. A task will focus on the properties and the use of kurstakins as an adjuvant for the formulation of biopesticides. Finally, an important task of this project will be the determination of an appropriate bioprocess for industrial production and purification of kurstakin based on an integrated bioprocess for biosurfactant production recently patented by Team 2. An additional task concerning the commercial development of this technology will be achieved by the INRA-Transfert team.

Partners

INRA-Transfert Département valorisation

ProBioGem Polytech-Lille - Procédés Biologiques et Génie enzymatique et microbien

INRA UMR 1319 - Micalis - GME

INRA UMR 1319 - Micalis - RG2B

ANR grant: 273 148 euros
Beginning and duration: mars 2013 - 24 mois

 

ANR Programme: Emergence (Emergence) 2012

Project ID: ANR-12-EMMA-0005

Project coordinator:
Monsieur Didier Lereclus (UMR 1319 - Micalis - GME)
didier.lereclus@nulljouy.inra.fr

 

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The project coordinator is the author of this abstract and is therefore responsible for the content of the summary. The ANR disclaims all responsibility in connection with its content.