RESUMO
Lung infections due to Burkholderia cepacia and Pseudomonas aeruginosa in patients with cystic fibrosis (CF) are common, are associated with respiratory morbidity and are a cause of mortality. Respiratory mucin in CF patients is highly sulphated, which increases its resistance to bacterial degradation. Desulphation increases the susceptibility of mucin to degradation by bacterial glycosidases and proteinases, and subsequent deglycosylation may facilitate bacterial colonisation by increasing available substrates and binding sites. This study determined whether clinical and environmental strains of B. cepacia and P. aeruginosa had the ability to desulphate mucin. Mucin-sulphatase activity was tested by incubating bacterial cell suspensions with 35S-sulphated mucins purified from LS174T and HT29-MTX human colon carcinoma cell lines. These mucins were also used to test for differences in substrate specificities. Mucin-sulphatase activity was detected in all nine B. cepacia strains and in four of six P. aeruginosa strains. There was strain variability in the level of mucin-sulphatase activity. Aryl-sulphatase activities of Pseudomonas isolates (determined with methylumbelliferyl sulphate) were c. 20-fold higher than those of B. cepacia strains, and were independent of mucin-sulphatase activity. This is the first report to demonstrate desulphation of mucin by B. cepacia and P. aeruginosa. It is concluded that B. cepacia and P. aeruginosa produce one or more cell-bound glycosulphatase(s), in addition to aryl-sulphatase activity. Mucin-sulphatase activity of B. cepacia and P. aeruginosa may contribute to their association with airway infections in patients with cystic fibrosis.
