Sixty-one Burkholderia cepacia isolates from patients with cystic fibrosis (CF) and four plant isolates were screened for production of the siderophores salicylic acid (SA), pyochelin, cepabactin, and ornibactins and fingerprinted by a PCR-based randomly amplified polymorphic DNA (RAPD) method. Of the 24 RAPD types determined, 22 (92%) were associated with isolates that produced SA, 21 (87%) were associated with isolates that produced ornibactins, 15 (60%) were associated with isolates that produced pyochelin, and 3 (12%) were associated with isolates that produced cepabactin. Of the 24 RAPD types plus 2 phenotypic variants of types 1 and 9, 3 were associated with isolates that produced all four siderophores, 8 were associated with isolates that produced three siderophores, 12 were associated with isolates that produced two siderophores, and 3 were associated with isolates that produced only one siderophore. These results suggest that the numbers and types of siderophores produced by CF isolates of B. cepacia correlate with RAPD type and that SA and ornibactins are the most prevalent siderophores produced.

Ornibactins are linear hydroxamate siderophores produced by Burkholderia cepacia with peptide structures similar to that of pyoverdines produced by the fluorescent pseudomonads. The gene encoding the outer membrane receptor (orbA) was identified, sequenced, and demonstrated to have significant homology with hydroxamate receptors produced by other organisms. The orbA precursor was predicted to be a protein with a molecular mass of 81 kDa. An orbA mutant was constructed and demonstrated to be unable to take up 59 Fe-ornibactins or to grow in medium supplemented with ornibactins. Outer membrane protein profiles from the parent strain, K56-2, revealed an iron-regulated outer membrane protein of 78 kDa that was not detectable in the K56orbA::tp mutant. When this mutant harbored a plasmid containing the orbA gene, the 78-kDa protein was present in the outer membrane protein profiles and the mutant was able to utilize ornibactin to acquire iron. The orbA mutant was less virulent in a chronic respiratory infection model than the parent strain, indicating that ornibactin uptake and utilization are important in the pathogenesis of B. cepacia respiratory infections.

The secreted carbonic anhydrases, CA VI, are high molecular mass, oligomeric enzymes originally found in the sheep parotid gland and saliva. The enzymes have been purified from the saliva or parotid glands of several different species. All the CA VI enzymes studied have an apparent subunit Mr of about 45,000 as previously reported for the sheep enzyme. By Western analysis, CA VI from human, cow and dog cross-reacted with antibody raised against the purified sheep enzyme whereas that of the mouse did not. The N-terminal sequences of the sheep, human, cow and mouse enzymes are reported. The sheep, cow and human N-terminal sequences are similar to one another while the mouse sequence is substantially different. Nevertheless, the amino acids in the aromatic cluster I (Trp-5, Tyr-7, Trp-16 and Tyr/Phe-20) have all been conserved, as is the case with the cytoplasmic carbonic anhydrases. Eighteen tissues from the sheep have been examined for the presence of CA VI by Western analysis but it has been found only in the salivary glands. Northern analysis and hybridization histochemistry show that the mRNA for CA VI in sheep is expressed specifically in the acinar cells of the parotid and submandibular glands.