A<space>new Burkholderia strain (PVFi5A) which exhibits antagonism towards many bacterial and fungal plant pathogens has been partially characterised. This strain was isolated from the rhizosphere of tomato plants and was referred to the Burkholderia cepacia complex on the basis of cultural, morphological and biochemical characteristics, including determination of the 16S ribosomal DNA sequence and fatty acid profile. Strain PVFi5A is a Gram-negative, aerobic bacterium, oxidase- and catalase-positive, motile with a polar tuft of flagella, able to grow on a variety of media without producing diffusible pigments; it is avirulent to onion, able to grow at 41<space> o C and resistant to several antibiotic substances. Its fatty acid profile contains the hydroxy acids 18:1<space>2OH, 14:0<space>3OH and 16:0<space>3OH, but not the hydroxy acids 16:0<space>2OH and 16:1<space>2OH. The antagonistic activity of strain PVFi5A is due to its production of various, as yet unidentified, antimicrobial compounds, one or more of which may differ from those reported previously for certain 'B. cepacia' strains. The ability of PVFi5A to suppress the growth of important bacterial and fungal phytopathogens makes this strain a potential biocontrol agent.
Isolement, de la rhizosphere de plants de tomate sains, et caracterisation d'une nouvelle souche de Burkholderia antagoniste. Nous avons partiellement caracterise une nouvelle souche de Burkholderia (PVFi5A) qui se montre antagoniste pour de nombreux agents bacteriens et fongiques pathogenes. Cette souche a ete isolee de la rhizosphere de plants de tomate, et a ete apparentee au complexe Burkholderia cepacia sur la base des caracteristiques de sa culture, de sa morphologie et de sa biochimie, y compris sur la base de la determination de la sequence de l'ADNr 16S et du profil des acides gras. La souche PVFi5A est une bacterie aerobie gram-negative, oxidase- et catalase-positive, mobile grace a une touffe de flagelles polaires, capable de croitre sur divers milieux sans produire de pigments diffusibles; elle est non virulente pour l'oignon, capable de croitre a 41<space> o C et resistante a plusieurs substances antibiotiques. Son profil en acides gras comprend les hydroxy-acides 18:1<space>2OH, 14:0<space>3OH et 16:0<space>3OH mais non les acides 16:0<space>2OH et 16:1<space>2OH. L'activite antagoniste de cette souche est due a divers composes antimicrobiens non encore identifies, un ou plusieurs d'entre eux pouvant differer de ceux deja connus chez certaines souches de 'B. cepacia'. La capacite de la souche PVFi5A d'empecher la croissance d'importants agents phytopathogenes, bacteriens ou fongiques, fait de cette souche un agent potentiel pour la lutte biologique.