Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.

Alginates are polysaccharides used as food additives and encapsulation agents in biotechnology, and their functional properties depend on its molecular weight. In this study, different steady-states in continuous cultures of A. vinelandii were established to determine the effect of the dilution rate...

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Autores principales:	Alvaro Díaz-Barrera, Fabiola Martínez, Felipe Guevara Pezoa, Fernando Acevedo
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2014
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/103464f3dbe6478fb5c72b5c6f66e330
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spelling	oai:doaj.org-article:103464f3dbe6478fb5c72b5c6f66e3302021-11-25T06:02:55ZEvaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.1932-620310.1371/journal.pone.0105993https://doaj.org/article/103464f3dbe6478fb5c72b5c6f66e3302014-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/25162704/?tool=EBIhttps://doaj.org/toc/1932-6203Alginates are polysaccharides used as food additives and encapsulation agents in biotechnology, and their functional properties depend on its molecular weight. In this study, different steady-states in continuous cultures of A. vinelandii were established to determine the effect of the dilution rate (D) and the agitation rate on alginate production and expression of genes involved in alginate polymerization and depolymerization. Both, the agitation and dilution rates, determined the partitioning of the carbon utilization from sucrose into alginate and CO2 under oxygen-limiting conditions. A low D (0.07 h(-1)) and 500 rpm resulted in the highest carbon utilization into alginate (25%). Quantitative real-time polymerase chain reaction was used to determine the transcription level of six genes involved in alginate polymerization and depolymerization. In chemostat cultures at 0.07 h(-1), the gene expression was affected by changes in the agitation rate. By increasing the agitation rate from 400 to 600 rpm, the algE7 gene expression decreased tenfold, whereas alyA1, algL and alyA2 gene expression increased between 1.5 and 2.8 times under similar conditions evaluated. Chemostat at 0.07 h(-1) showed a highest alginate molecular weight (580 kDa) at 500 rpm whereas similar molecular weights (480 kDa) were obtained at 400 and 600 rpm. The highest molecular weight was not explained by changes in the expression of alg8 and alg44 (genes involved in alginate polymerization). Nonetheless, a different expression pattern observed for lyases could explain the highest alginate molecular weight obtained. Overall, the results suggest that the control of alginate molecular weight in A. vinelandii cells growing in continuous mode is determined by a balance between the gene expression of intracellular and extracellular lyases in response to oxygen availability. These findings better our understanding of the biosynthesis of bacterial alginate and help us progress toward obtain tailor-made alginates.Alvaro Díaz-BarreraFabiola MartínezFelipe Guevara PezoaFernando AcevedoPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 9, Iss 8, p e105993 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Alvaro Díaz-Barrera Fabiola Martínez Felipe Guevara Pezoa Fernando Acevedo Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.
description	Alginates are polysaccharides used as food additives and encapsulation agents in biotechnology, and their functional properties depend on its molecular weight. In this study, different steady-states in continuous cultures of A. vinelandii were established to determine the effect of the dilution rate (D) and the agitation rate on alginate production and expression of genes involved in alginate polymerization and depolymerization. Both, the agitation and dilution rates, determined the partitioning of the carbon utilization from sucrose into alginate and CO2 under oxygen-limiting conditions. A low D (0.07 h(-1)) and 500 rpm resulted in the highest carbon utilization into alginate (25%). Quantitative real-time polymerase chain reaction was used to determine the transcription level of six genes involved in alginate polymerization and depolymerization. In chemostat cultures at 0.07 h(-1), the gene expression was affected by changes in the agitation rate. By increasing the agitation rate from 400 to 600 rpm, the algE7 gene expression decreased tenfold, whereas alyA1, algL and alyA2 gene expression increased between 1.5 and 2.8 times under similar conditions evaluated. Chemostat at 0.07 h(-1) showed a highest alginate molecular weight (580 kDa) at 500 rpm whereas similar molecular weights (480 kDa) were obtained at 400 and 600 rpm. The highest molecular weight was not explained by changes in the expression of alg8 and alg44 (genes involved in alginate polymerization). Nonetheless, a different expression pattern observed for lyases could explain the highest alginate molecular weight obtained. Overall, the results suggest that the control of alginate molecular weight in A. vinelandii cells growing in continuous mode is determined by a balance between the gene expression of intracellular and extracellular lyases in response to oxygen availability. These findings better our understanding of the biosynthesis of bacterial alginate and help us progress toward obtain tailor-made alginates.
format	article
author	Alvaro Díaz-Barrera Fabiola Martínez Felipe Guevara Pezoa Fernando Acevedo
author_facet	Alvaro Díaz-Barrera Fabiola Martínez Felipe Guevara Pezoa Fernando Acevedo
author_sort	Alvaro Díaz-Barrera
title	Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.
title_short	Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.
title_full	Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.
title_fullStr	Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.
title_full_unstemmed	Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.
title_sort	evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of azotobacter vinelandii.
publisher	Public Library of Science (PLoS)
publishDate	2014
url	https://doaj.org/article/103464f3dbe6478fb5c72b5c6f66e330
work_keys_str_mv	AT alvarodiazbarrera evaluationofgeneexpressionandalginateproductioninresponsetooxygentransferincontinuouscultureofazotobactervinelandii AT fabiolamartinez evaluationofgeneexpressionandalginateproductioninresponsetooxygentransferincontinuouscultureofazotobactervinelandii AT felipeguevarapezoa evaluationofgeneexpressionandalginateproductioninresponsetooxygentransferincontinuouscultureofazotobactervinelandii AT fernandoacevedo evaluationofgeneexpressionandalginateproductioninresponsetooxygentransferincontinuouscultureofazotobactervinelandii
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Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.

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