Genetics of exopolysaccharide production by mucoid Pseudomonas aeruginosa

The secretion of the exopolysaccharide, alginate, is believed to contribute to the predilection for persistence of P. aeruginosa in respiratory tract infections of cystic fibrosis patients. To understand more about the pathway of alginate biosynthesis, we have cloned a gene, alg-50, which is involved in alginate biosynthesis. The alg-50 gene was physically mapped on a DNA fragment from P. aeruginosa by deletion analysis and transposition mutagenesis. The alginate trait is unstable, and another clone was found which may contain genes involved in this phenomenon. The two uronic acid components in alginate can vary, and a gene was cloned which increases the L-guluronate concentration of alginate produced by P. aeruginosa.