The acetylation degree of alginates in Azotobacter vinelandii ATCC9046 is determined by dissolved oxygen and specific growth rate: studies in glucose-limited chemostat cultivations
- 392 Downloads
Alginates are polysaccharides that may be used as viscosifiers and gel or film-forming agents with a great diversity of applications. The alginates produced by bacteria such as Azotobacter vinelandii are acetylated. The presence of acetyl groups in this type of alginate increases its solubility, viscosity, and swelling capability. The aim of this study was to evaluate, in glucose-limited chemostat cultivations of A. vinelandii ATCC9046, the influence of dissolved oxygen tension (DO) and specific growth rate (μ) on the degree of acetylation of alginates produced by this bacterium. In glucose-limited chemostat cultivations, the degree of alginate acetylation was evaluated under two conditions of DO (1 and 9 %) and for a range of specific growth rates (0.02–0.15 h−1). In addition, the alginate yields and PHB production were evaluated. High DO in the culture resulted in a high degree of alginate acetylation, reaching a maximum acetylation degree of 6.88 % at 9 % DO. In contrast, the increment of μ had a negative effect on the production and acetylation of the polymer. It was found that at high DO (9 %) and low μ, there was a reduction of the respiration rate, and the PHB accumulation was negligible, suggesting that the flux of acetyl-CoA (the acetyl donor) was diverted to alginate acetylation.
KeywordsAzotobacter vinelandii Alginate acetylation Specific growth rate Dissolved oxygen tension Poly(3-hydroxybutyrate)
Financial support of DGAPA-UNAM (grant IN110310-3). PhD grant of Tania Castillo from CONACYT. The authors acknowledge the helpful discussions with Dr. Cinthia Núñez and Dr. Álvaro Lara.
Conflict of interest
The authors declare that they have no competing interests.
- 3.Chang W-S, Van de Mortel M, Nielsen L, Nino de Guzmán G, Li X, Xalverson LJ (2007) Alginate production by Pseudomonas putida creates a hydrated microenvironment and contributes to biofilm architecture and stress tolerance under water-limiting conditions. J Bacteriol 189(22):8290–8299Google Scholar
- 4.Cheetham NWH, Punruckvong A (1985) An HPLC method for the determination of acetyl and pyruvyl groups in polysaccharides. Carbohy Polym 5:399–406Google Scholar
- 5.Clarke AJ, Strating H, Blackburne NT (2000) Pathways for the O-acetylation of bacterial cell wall polysaccharides. In: Ron J (ed) Glycobiology published on line. Doyle. doi: 10.1007/b113570
- 10.Galindo E, Peña C, Núñez C, Segura D, Espín G (2007) Molecular and bioengineering strategies to improve alginate and polyhydroxyalkanoate production by Azotobacter vinelandii. Microb Cell Fact 6:7Google Scholar
- 12.Horan NJ, Jarman TR (1983) Studies on some enzymes of alginic acid biosynthesis in Azotobacter vinelandii grown in continuous culture. J Gen Microbiol 129:2985–2990Google Scholar
- 16.Lozano E, Galindo E, Peña C (2011) Oxygen transfer rate during the production of alginate by Azotobacter vinelandii under oxygen-limited and non oxygen-limited conditions. Microb Cell Fact 10:13Google Scholar
- 23.Peña C, Castillo T, Núñez C, Segura D (2011) Bioprocess design: fermentation strategies for improving the production of alginate and poly β hydroxyalkanoates (PHAs) by Azotobacter vinelandii. INTECH- Open Access Publisher, London, pp 217–242Google Scholar
- 26.Sabra W, Zeng A-P, Lunsdorf H, Deckwer W-D (2000) Effect of oxygen on formation and structure of A. vinelandii alginate and its role in protecting nitrogenase. Appl Environ Microbiol 66(9):4037–4044Google Scholar
- 27.Sengha S, Anderson AJ, Hacking AJ, Dawes EA (1989) The production of alginate by Pseudomonas mendocina in batch and continuous culture. J Gen Microbiol 135:795–804Google Scholar
- 32.Straathman A, Windhues T, Borchard W (2004) Effects of acetylation on thermodynamic properties of seaweed alginate in sodium chloride solutions. Prog Colloid Poly Sci 127:26–30Google Scholar
- 36.Worlitzch D, Tarran R, Urlich M, Schwab U, Cekici A, Meyer K, Birrer P, Bellon G, Berger J, Weiss T, Botzenhart K, Jankaskas JR, Randell S, Boucher RC, Döring G (2002) Effects of mucus oxygen concentration in airway Pseudomonas infections of cystic fibrosis patients. J Clin Invest 109(3):317–325Google Scholar