Alginate biosynthesis in mucoid recombinants of Pseudomonas aeruginosa overproducing GDP-mannose dehydrogenase

摘要: Abstract The Pseudomonas aeruginosa algD gene, encoding GDP-mannose dehydrogenase (GMD) and cloned at Chakrabarty's Laboratory in the expression vector pMMB24 (plasmid pVD211), was mobilized into P.aeruginosa strains 8821 8821M. Strain 8821M a high-alginate-producing variant, spontaneously obtained from mucoid strain 8821, with derepressed levels of GMD, key enzyme regulation alginate biosynthesis, leading to irreversible oxidation GDP-mannuronic acid. A slight increase level both harboring plasmid pVD211 batchgrown 37° C without IPTG induction, led production rate final concentration produced by control cloning vector. However, viscosity aqueous solutions prepared (3 g l −1 ) lower than those controls (shear rates range 0.6–12 s ). specific activity GMD assayed crude extracts cells subjected induction (0.5 3 mM) presented highest values. either biosynthesis or recombinants grown were that possible overproduction. Therefore, stimulation pathway only manipulating step catalysed although within certain levels, expense exopolysaccharide quality.