Due to its pathogenic traits and agricultural benefits, there is some chall
enge in detecting Burkholderia in the soil environment. In this perspective
, an existing semi-selective medium, (PCAT), was combined with a Burkholder
ia specific molecular probe. Using the complete 16S rRNA sequences of all a
vailable Burkholderia series type strains, we selected the p following sequ
ence: 5 ' -ACCCTCTGTTCCGACCATTGTATGA-3 '. The probe was validated against G
enBank sequences, with dot blots and colony hybridization tests. A diversit
y study of all strains growing on a PCAT plate after plating a soil dilutio
n (75 strains) was carried out with ARDRA analysis and colony hybridization
tests. All the hybridizing strains belonged to genus Burkholderia. The maj
or type of non-hybridizing isolates belonged to Pseudomonas (16S rRNA seque
ncing). Both tools were combined to compare the Burkholderia populations in
a rhizosphere (maize) and a non-rhizosphere soil, Based on hybridizing PCA
T isolates, we were able to show an increase in Burkholderia populations in
the maize rhizosphere. This genus represented 2% and 16% of the total cult
ivable microflora in the non-rhizosphere and rhizosphere soils, respectivel
y. Although PCAT was shown not to be appropriate to routinely enumerate Bur
kholderia populations in soil, it allowed environmental investigations at t
he genus level, when combined with a molecular specific probe. (C) 2001 Els
evier Science B.V. All rights reserved.