[MucA mutation and its alginate-production in clinically isolated Pseudomonas aeruginosa]

To determine the characterization of mucA gene mutation in clinically isolated Pseudomonas aeruginosa (P.aeruginosa), and the relation between mucA mutation and the mucoid phenotype.

A total of 58 strains of P. aeruginosa were collected. Of them, 8 were nonmucoid phenotype and 50 were mucoid phenotype. We detected mucA mutations with PCR-SSCP and sequencing analysis. Alginate was examined by colorimetry.

All strains had mucA mutations (100%), 16 of the 50 (32%) isolates contained mucA mutations that could alter the encoding sequence of amino acids, and the rate in nonmucoid isolates was 0. Fourteen mutation sites were found, 5 of which could alter the encoding sequence of amino acids, and the others were silent mutations. The alginate concentration of mucoid P.aeruginosa was higher than the nonmucoid P. aeruginos (P<0.01). The alginate concentration of the isolates which contained mucA mutations that could alter the encoding sequence of amino acid was higher than the strains only with silent mutations (P<0.01).

MucA mutation correlates with the alginate production and phenotype of bacterial colonies.