Molecular weight and guluronic/mannuronic ratio of alginate produced by Azotobacter vinelandii at two bioreactor scales under diazotrophic conditions

ALVARO ENRIQUE DIAZ BARRERA, Francisco Sanchez-Rosales, Claudio Padilla-Córdova, Rodrigo Andler, Carlos Peña

Research output: Contribution to journalArticlepeer-review

Abstract

Alginates can be used to elaborate hydrogels, and their properties depend on the molecular weight (MW) and the guluronic (G) and mannuronic (M) composition. In this study, the MW and G/M ratio were evaluated in cultures of Azotobacter vinelandii to 3 and 30 L scales at different oxygen transfer rates (OTRs) under diazotrophic conditions. An increase in the maximum OTR (OTRmax) improved the alginate production, reaching 3.3 ± 0.2 g L−1. In the cultures conducted to an OTR of 10.4 mmol L−1 h−1 (500 rpm), the G/M increased during the cell growth phase and decreased during the stationary phase; whereas, in the cultures at 19.2 mmol L−1 h−1 was constant throughout the cultivation. A higher alginate MW (520 ± 43 kDa) and G/M ratio (0.86 ± 0.01) were obtained in the cultures conducted at 10.4 mmol L−1 h−1. The OTR as a criterion to scale up alginate production allowed to replicate the concentration and the alginate production rate; however, it was not possible reproduce the MW and G/M ratio. Under a similar specific oxygen uptake rate (qO2) (approximately 65 mmol g−1 h−1) the alginate MW was similar (approximately 365 kDa) in both scales. The evidences revealed that the qO2 can be a parameter adequate to produce alginate MW similar in two bioreactor scales. Overall, the results have shown that the alginate composition could be affected by cellular respiration, and from a technological perspective the evidences contribute to the design process based on oxygen consumption to produce alginates defined.

Original languageEnglish
JournalBioprocess and Biosystems Engineering
DOIs
StateAccepted/In press - 2021
Externally publishedYes

Keywords

  • Alginate
  • Azotobacter vinelandii
  • G/M ratio
  • Molecular weight
  • Oxygen transfer rate
  • Scale-up

Fingerprint

Dive into the research topics of 'Molecular weight and guluronic/mannuronic ratio of alginate produced by Azotobacter vinelandii at two bioreactor scales under diazotrophic conditions'. Together they form a unique fingerprint.

Cite this