HETEROLOGOUS EXPRESSION OF AN ALGINATE LYASE GENE IN MUCOID AND NONMUCOID STRAINS OF PSEUDOMONAS-AERUGINOSA

A 1.95 kb DNA fragment containing the aly gene from Klebsiella pneumoniae, which encodes an alginate lyase, has been ligated into the broad-host-range vector pLAFR3. Transfer of the resultant recombinant plasmid, pALY8, into mucoid and non-mucoid strains of Pseudomonas aeruginosa resulted in expression of the alginate lyase. The heterologously expressed alginate lyase, which had the same isoelectric point and substrate specificity as the native enzyme, altered the morphology of mucoid strains. Analysis of the extracellular material from mucoid strains revealed that lyase expression reduced the M(r) and overall yield of alginate produced. The mature form of the recombinant enzyme was the same as that produced extracellularly by Klebsiella pneumoniae; however, most of the alginate lyase was retained intracellularly by P. aeruginosa.