Journal of Industrial Microbiology and Biotechnology

, Volume 29, Issue 5, pp 209-213

First online:

Alginate production by Azotobacter vinelandii mutants altered in poly-β-hydroxybutyrate and alginate biosynthesis

  • C PeñaAffiliated withDepartment of Bioengineering, Institute of Biotechnology, Universidad Nacional Autónoma de México, Apdo. Post. 510-3, Cuernavaca 62250, Morelos, México
  • , L MirandaAffiliated withDepartment of Molecular Microbiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Apdo. Post. 510-3, Cuernavaca 62250, Morelos, México
  • , D SeguraAffiliated withDepartment of Molecular Microbiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Apdo. Post. 510-3, Cuernavaca 62250, Morelos, México
  • , C NúñezAffiliated withDepartment of Molecular Microbiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Apdo. Post. 510-3, Cuernavaca 62250, Morelos, México
  • , G EspínAffiliated withDepartment of Molecular Microbiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Apdo. Post. 510-3, Cuernavaca 62250, Morelos, México
  • , E GalindoAffiliated withDepartment of Bioengineering, Institute of Biotechnology, Universidad Nacional Autónoma de México, Apdo. Post. 510-3, Cuernavaca 62250, Morelos, México

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Mutant AT268 of Azotobacter vinelandii — showing diminished production of poly-β-hydroxybutyrate (PHB) due to a mutation in phbR (the gene coding for the transcriptional activator of the phbBAC biosynthetic operon); mutant CNT26, containing a mutation (muc26) that increases the transcription of gene algD (encoding GDP mannose dehydrogenase, the key enzyme in alginate biosynthesis); and mutant DM, carrying both phbR and muc26 mutations — were characterised in terms of alginate production, broth viscosity, and molecular weight of the alginate. All the mutants evaluated produced 25% less alginate with respect to that produced by the wild type. Unexpectedly and with no apparent relation to the phbR and muc26 mutations, mutant DM exhibited the highest molecular weight ever reported for a bacterial alginate (up to 4×106 Da), with a very low polydispersity index (1.3). Acetyl content in the alginate produced by this strain was low (1.4–2.6%). These characteristics make this mutant a very valuable source for producing alginates with improved properties.

Keywords: alginate; A. vinelandii; mutants; molecular weight