title: Alginate production by an Azotobacter vinelandii mutant unable to produce alginate lyase.
abstract: Alginate is an industrially relevant linear copolymer composed of beta-1,4-linked D-mannuronic acid and its C-5 epimer L-guluronic acid. The rheological and gel-forming properties of alginates depend on the molecular weight and the relative content of the two monomers. Alginate produced by Azotobacter vinelandii was shown to be degraded towards the end of the culture, an undesirable situation in terms of potential alginate applications. A gene ( algL) encoding the alginate lyase activity AlgL is present within the alginate biosynthetic gene cluster of A. vinelandii. We constructed strain SML2, an A. vinelandii strain carrying a non-polar mutation within algL. No alginate lyase activity was detected in SML2. Under 3% dissolved oxygen tension, higher values of maximum mean molecular weight alginate were obtained (1240 kDa) with strain SML2, compared to those from the parental strain ATCC 9046 (680 kDa). These data indicate that AlgL activity causes the drop in the molecular weight of alginate produced by A. vinelandii.
authors.affiliation: Department of Bioengineering, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apartado Postal 510-3, Cuernavaca 62250 Morelos, Mexico.
authors.forename: M A
authors.initials: MA
authors.lastname: Trujillo-Roldán
authors.forename: S
authors.initials: S
authors.lastname: Moreno
authors.forename: D
authors.initials: D
authors.lastname: Segura
authors.forename: E
authors.initials: E
authors.lastname: Galindo
authors.forename: G
authors.initials: G
authors.lastname: Espín
mesh_terms: D000464:Alginates / Q000737:chemistry / Q000378:metabolism*; D016948:Azotobacter vinelandii / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D007218:Industrial Microbiology; D008970:Molecular Weight; D016296:Mutagenesis; D011133:Polysaccharide-Lyases / Q000172:deficiency* / Q000235:genetics; D013171:Spores, Bacterial; D014158:Transcription, Genetic; D014783:Viscosity
chemical_list: D000464:Alginates; D001426:Bacterial Proteins; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D011133:Polysaccharide-Lyases; C016158:poly(beta-D-mannuronate) lyase