AUXOTROPHY OF BURKHOLDERIA (PSEUDOMONAS) CEPACIA FROM CYSTIC-FIBROSISPATIENTS

The nutritional status of 89 isolates of Burkholderia cepacia from 81 cystic fibrosis (CF) patients was evaluated. Forty of the isolates, fr om 38 patients, were not able to grow in a minimal medium containing g lucose and mineral salts only and were thus auxotrophs. In contrast, a ll of 29 isolates from non-CF (clinical and environmental) sources wer e prototrophic. Addition of a pool of amino acids to the minimal mediu m was sufficient to promote growth of ah tested CF auxotrophic isolate s. Indeed, phenylalanine, tyrosine, cysteine, methionine, and histidin e alone or in combination were required for growth by the majority of the nutritionally deficient B. cepacia isolates. Furthermore, extracts of sputum from CF patients, when added to minimal medium, promoted gr owth of 29 auxotrophic B. cepacia isolates regardless of their amino a cid requirements. Finally, auxotrophic and prototrophic isolates from the same patient exhibited a conserved genotype, as determined by macr orestriction analysis of chromosomal DNA These results suggest that th e auxotrophic mutants are selected from the prototrophic population an d maintained by the nutritionally rich environment of the CF airways.