INTRASPECIFIC METABOLIC DIVERSITY AMONG STRAINS OF BURKHOLDERIA-CEPACIA ISOLATED FROM DECAYED ONIONS, SOILS, AND THE CLINICAL ENVIRONMENT

A collection of 218 strains of Burkholderia cepacia (including 18% str ain replicates) was assembled from organic soils, decayed onions, and clinical sources. Each strain was characterized for virulence to onion , catabolic ability using the Biolog GN microtiter plate, and several other behaviors. Overall test reproducibility was estimated at 98%. Th e results obtained using the Biolog GN system corresponded well to tho se obtained using standard methods. Three coefficients of resemblance (Gower similarity, pattern difference, and Jaccard similarity) were ca lculated and clustered by the group-average method. The sorted matrice s and phenograms, while giving evidence of an underlying phenetic stru cture to the B. cepacia nomenspecies, gave little evidence of sorting by broad source of isolation. Strains isolated from within fields or s amples were frequently found to be similar, however, strains isolated from fields with similar cropping histories were not. The Gower-transf ormed centroids of ordained clusters were projected in a principal coo rdinate system and estimates of disjunction were calculated. Strains o f B. cepacia were shown to be non-uniformly distributed in taxonomic s pace. Strains isolated by serial dilution on onion slices formed a tig ht phenetic cluster which includes the type strain of the nomenspecies and that of a synonymous group (Pseudomonas multivorans); the strains in this phenon were generally virulent to onion and were partially di fferentiated from others by pectolytic behavior and by the production of diffusible pigment on King's medium A. Further characterization sho uld better resolve the taxonomy of the nomenspecies.