Continuous cultures for alginate production by Azotobacter vinelandii growing at different oxygen uptake rates

Díaz‐Barrera, Alvaro; Aguirre, Alberto; Berríos, Julio; Acevedo, Fernando

doi:10.1016/j.procbio.2011.06.022

Cited by 26 publications

(44 citation statements)

References 31 publications

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“…A paramagnetic oxygen analyzer (Anarad Inc., USA) and infrared gas analyzer (LI-COR Biosciences, USA) were used for O 2 and CO 2 gas measurements, respectively. The OTR and the carbon dioxide transfer rate (CTR) were determined from gas analysis and calculated by carrying out gas balances [9]. Respiratory quotient (RQ) was determined using the OTR and CTR data (RQ = CTR/ OTR) .…”

Section: Respiratory Measurementsmentioning

confidence: 99%

“…Quantitative real-time PCR assay RNA extraction and cDNA synthesis were performed as previously described [9]. Cells were harvested by centrifugation at 6,8709g for 10 min at 4°C and stored at -80°C with RNAlater TM solution (RNA stabilization and protection solution).…”

Section: Respiratory Measurementsmentioning

confidence: 99%

“…Quantitative real-time PCR (qPCR) was performed using LightCycler Ò FastStart DNA Master SYBR Green I systems (Roche Applied Science). The sequences of the primers used for cDNA synthesis and for qPCR were designed using algorithm Primer 3 as previously indicated [9]. The level of gyrA mRNA was used as an internal control [17] to normalize the results obtained for the algL and alg8 mRNA.…”

Section: Respiratory Measurementsmentioning

confidence: 99%

“…The level of gyrA mRNA was used as an internal control [17] to normalize the results obtained for the algL and alg8 mRNA. The relative quantification of gene expression was performed as described previously [9] using the standard curve method with three measurements for each gene for each experimental condition evaluated. A maximum standard deviation (SD) of 10% was obtained.…”

Section: Respiratory Measurementsmentioning

confidence: 99%

“…Recently, Díaz-Barrera et al [9] indicated that alginate production, carbon distribution, and algL gene expression were affected by changes in the specific oxygen uptake rate as manipulated by the agitation rate in chemostat cultures of A. vinelandii growing diazotrophically (i.e., under nitrogen-fixing conditions). Nonetheless, a systematic study evaluating the effects of agitation rates and/or carbon source concentrations in the inlet medium (at a constant specific growth rate l) on alginate biosynthesis and genes expression in A. vinelandii cultures has not been performed.…”

Section: Introductionmentioning

confidence: 99%

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

Díaz‐Barrera

Soto

Altamirano

2012

Journal of Industrial Microbiology and Biotechnology

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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.

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Section: Respiratory Measurementsmentioning

confidence: 99%

Section: Respiratory Measurementsmentioning

confidence: 99%

Section: Respiratory Measurementsmentioning

confidence: 99%

Section: Respiratory Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Díaz‐Barrera

Soto

Altamirano

2012

Journal of Industrial Microbiology and Biotechnology

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Role of oxygen in the polymerization and de‐polymerization of alginate produced by Azotobacter vinelandii

Flores

Díaz‐Barrera

Martínez

et al. 2014

J of Chemical Tech & Biotech

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Microbial polymers have diverse chemical structures, which determine their functional properties. Many microbial sources produce either intracellular or extracellular biopolymers. For example, Azotobacter vinelandii is a non-pathogenic soil bacterium that produces alginate, an extracellular polysaccharide. Alginates are used mainly in the food and pharmaceutical industries as stabilizing, thickening, gel-or film-forming agents. Due to its characteristics of biocompatibility, biodegradability and non-antigenicity, new applications for alginate are being discovered, such as biomaterial in the biomedical field and tissue engineering.It is well established that alginate is first synthesized as a polymannuronate from its cytosolic precursor. However, the mechanisms involved in the polymerization, modification (acetylation, epimerization and depolymerization) and translocation of alginate have been poorly elucidated. Two of the most important parameters in alginate production by A. vinelandii are dissolved oxygen tension (DOT) and the oxygen supply conditions, as these impact both the polymer concentration and its composition, particularly its molecular weight (MW). Several studies have revealed that increased alginate molecular weight occurs in oxygen limited conditions, specifically at oxygen concentrations near zero. This article reviews recent studies examining the influence of oxygen, under limitation (microaerophilic) and non-limitation conditions (measured as DOT and oxygen transfer rate, OTR), on the polymerization and degradation of alginate produced by A. vinelandii. This review also provides evidence for understanding these processes at the cellular level and the effect of oxygen on alginate biosynthesis.

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Molecular weight and viscosifying power of alginates produced inAzotobacter vinelandiicultures in shake flasks under low power input

Gómez‐Pazarín

Flores

Castillo

et al. 2015

J. Chem. Technol. Biotechnol.

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Continuous cultures for alginate production by Azotobacter vinelandii growing at different oxygen uptake rates

Cited by 26 publications

References 31 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

Role of oxygen in the polymerization and de‐polymerization of alginate produced by Azotobacter vinelandii

Molecular weight and viscosifying power of alginates produced inAzotobacter vinelandiicultures in shake flasks under low power input

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