Isolation and characterisation of a new antagonistic Burkholderia strain from the rhizosphere of healthy tomato plants

A new Burkholderia strain (PVFi5A) which exhibits antagonism towards many b acterial 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 riboso mal 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 diffusib le pigments; it is avirulent to onion, able to grow at 41 degrees C and res istant to several antibiotic substances. Its fatty acid profile contains th e hydroxy acids 18:1 2OH, 14:0 3OH and 16:0 3OH, but not the hydroxy acids 16:0 2OH and 16:1 2OH. The antagonistic activity of strain PVFi5A is due to its production of various, as yet unidentified, antimicrobial compounds, o ne or more of which may differ from these reported previously for certain ' B. cepacia' strains. The ability of PVFi5A to suppress the growth of import ant bacterial and fungal phytopathogens makes this strain a potential bioco ntrol agent. (C) Elsevier, Paris.