Manipulating the molecular weight of alginate produced by Azotobacter vinelandii in continuous cultures

Díaz‐Barrera, Alvaro; Silva, Paulina; Berríos, Julio; Acevedo, Fernando

doi:10.1016/j.biortech.2010.07.038

Cited by 24 publications

(20 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Before use, the strain was isolated on agar plates containing the same medium. In preliminary experiments using sucrose and ammonium (i.e., non-nitrogen-fixation conditions), chemostat cultures showed higher alginate production compared with the results of studies by Díaz-Barrera et al [8] in which A. vinelandii was grown under nitrogen fixation conditions.…”

Section: Bacterial Strain and Culture Mediummentioning

confidence: 44%

“…During steady state conditions, the level of DOT was nearly zero in all cases, suggesting that the cultures were oxygen-limited. Similar observations have been described previously for continuous cultures of A. vinelandii [8,9]. It is known that adequate oxygen transfer to bioreactors can be evaluated by considering the characteristic time for oxygen uptake (C Ã L =O 2 uptake rate) and the mixing time (t m ) [14].…”

Section: Resultsmentioning

confidence: 72%

“…Recently, Lozano et al [15] showed that the molecular weight of alginate produced under non-oxygen-limited conditions increased by decreasing the OTR of batch cultures of A. vinelandii. On the other hand, Díaz-Barrera et al [8] reported that alginate molecular weight can be influenced by the dilution rate and the carbon source concentration in the inlet medium in chemostat cultures of A. vinelandii growing under nitrogen fixation conditions. The changes were attributed to variations in the specific sucrose uptake rate.…”

Section: Introductionmentioning

confidence: 97%

See 2 more Smart Citations

Alginate production and alg8 gene expression by Azotobacter vinelandii in continuous cultures

Díaz‐Barrera

Soto

Altamirano

2012

Journal of Industrial Microbiology and Biotechnology

Self Cite

View full text Add to dashboard Cite

Alginates are polysaccharides that are used as thickening agents, stabilizers, and emulsifiers in various industries. These biopolymers are produced by fermentation with a limited understanding of the processes occurring at the cellular level. The objective of this study was to evaluate the effects of agitation rate and inlet sucrose concentrations (ISC) on alginate production and the expression of the genes encoding for alginate-lyases (algL) and the catalytic subunit of the alginate polymerase complex (alg8) in chemostat cultures of Azotobacter vinelandii ATCC 9046. Increased alginate production (2.4 g l⁻¹) and a higher specific alginate production rate (0.1 g g⁻¹ h⁻¹) were obtained at an ISC of 15 g l⁻¹. Carbon recovery of about 100% was obtained at an ISC of 10 g l⁻¹, whereas it was close to 50% at higher ISCs, suggesting that cells growing at lower sucrose feed rates utilize the carbon source more efficiently. In each of the steady states evaluated, an increase in algL gene expression was not related to a decrease in alginate molecular weight, whereas an increase in the molecular weight of alginate was linked to higher alg8 gene expression, demonstrating a relationship between the alg8 gene and alginate polymerization in A. vinelandii for the first time. The results obtained provide a possible explanation for changes observed in the molecular weight of alginate synthesized and this knowledge can be used to build a recombinant strain able to overexpress alg8 in order to produce alginates with higher molecular weights.

show abstract

Section: Bacterial Strain and Culture Mediummentioning

confidence: 44%

Section: Resultsmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Alginate production and alg8 gene expression by Azotobacter vinelandii in continuous cultures

Díaz‐Barrera

Soto

Altamirano

2012

Journal of Industrial Microbiology and Biotechnology

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is known that if M-blocks formed by consecutive mannuronic acid residues are dominant, soft and more flexible gels are formed; whereas if stretches of consecutive guluronic acid residues (G-blocks) are dominant, strong gels that are mostly resembled by an "egg-box structure" are formed (Grant et al 1973). Production of alginate from Azotobacter vinelandii has been widely studied by using shake flasks and fermenters (Clementi et al 1999;Diaz-Barrera et al 2010;Mejia et al 2010;Peña et al 1997;Savalgi and Savalgi 1992), and by differing the growth conditions, it is possible to reproducibly produce alginates with different content of G-blocks (Moral and Sanin 2012;Sabra et al 2000;Sabra et al 1999). A. vinelandii encode seven different secreted mannuronan C-5-epimerases (AlgE1-7) which introduce G residues in the polymer, and these may be used to increase the amount of G and G-blocks in vitro (Ertesvåg 2009).…”

Section: Introductionmentioning

confidence: 99%

Guluronic acid content as a factor affecting turbidity removal potential of alginate

Moral

Ertesvåg

Sanin

2016

Environ Sci Pollut Res

View full text Add to dashboard Cite

Alginates are natural polymers composed of mannuronic and guluronic acid residues.They are currently extracted from brown algae, however, alginate can also be synthesized by some species of Azotobacter and Pseudomonas. Alginates with different proportion of mannuronic and guluronic acids are known to have different characteristics and form gels at different extents in the presence of calcium ions. The aim of this work was to investigate the usefulness of alginate as a non-toxic coagulant used in purification of drinking water. This study utilized alginates from Azotobacter vinelandii having different guluronic acid levels. These were obtained partly by changing the cultivation parameters, partly by epimerizing a purified alginate sample in vitro using the A. vinelandii mannuronan-C-5-epimerase AlgE1. The different alginates were then used for coagulation together with calcium. The results showed that turbidity removal capability was dependent on the content of guluronic acid residues. For the best performing samples the turbidity decreased from 10 NTU to 1 NTU by the use of only 2 mg/L of alginate and 1.5 mM of calcium chloride.

show abstract

“…Under these conditions, the relative respiration rate (RRR) of A. vinelandii diminished drastically; this parameter has been defined as the current respiration rate divided by the maximum respiration rate (Charoenrat et al, 2005). (Díaz-Barrera et al, 2007;Díaz-Barrera et al, 2009) . Díaz-Barrera et al (2007) found that the MMW of the alginate increased as OTRmax decreased in cultures performed without pH and oxygen control, cond itions used in this work.…”

Section: Vol Um Etri C Oxygen Tr An Sfer Co Effi Ci Ent (Kla) and O Xmentioning

confidence: 99%

ALGINATE PRODUCTION BY Azotobacter vinelandii AS A VIRTUAL SENSOR TO ESTIMATE EFFECTIVE SHEAR RATE ON STIRRED TANK FERMENTERS

Barrales-Cureño¹,

Reyes²,

Peña³

et al. 2017

Egypt. J. Exp. Biol. (Bot.)

View full text Add to dashboard Cite

Manipulating the molecular weight of alginate produced by Azotobacter vinelandii in continuous cultures

Cited by 24 publications

References 19 publications

Alginate production and alg8 gene expression by Azotobacter vinelandii in continuous cultures

Alginate production and alg8 gene expression by Azotobacter vinelandii in continuous cultures

Guluronic acid content as a factor affecting turbidity removal potential of alginate

ALGINATE PRODUCTION BY Azotobacter vinelandii AS A VIRTUAL SENSOR TO ESTIMATE EFFECTIVE SHEAR RATE ON STIRRED TANK FERMENTERS

Contact Info

Product

Resources

About