Daniel Segura

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Several aspects of alginate and PHB synthesis in Azotobacter vinelandii at a molecular level have been elucidated in articles published during the last ten years. It is now clear that alginate and PHB synthesis are under a very complex genetic control. Genetic modification of A. vinelandii has produced a number of very interesting mutants which have(More)
Azotobacter vinelandii produces two polymers of industrial importance, i.e. alginate and poly-β-hydroxybutyrate (PHB). Alginate synthesis constitutes a waste of substrate when seeking to optimize PHB production and, conversely, synthesis of PHB is undesirable when optimizing alginate production. In this study we evaluated the effect of a mutation in algA,(More)
6 João C. Setubal, Patricia dos Santos, Barry S. Goldman, Helga Ertesvåg, 7 Guadelupe Espin, Luis M. Rubio, Svein Valla, Nalvo F. Almeida, Divya 8 Balasubramanian, Lindsey Cromes, Leonardo Curatti, Zijin Du, Eric Godsy, Brad 9 Goodner, Kaitlyn Hellner-Burris, José A. Hernandez, Katherine Houmiel, Juan 10 Imperial, Christina Kennedy, Timothy J. Larson, Phil(More)
Previous model-based analysis of the metabolic network of Geobacter sulfurreducens suggested the existence of several redundant pathways. Here, we identified eight sets of redundant pathways that included redundancy for the assimilation of acetate, and for the conversion of pyruvate into acetyl-CoA. These equivalent pathways and two other sub-optimal(More)
Alginate is an industrially relevant linear copolymer composed of β-1,4-linked D-mannuronic acid and its C-5 epimer L-guluronic acid. The rheological and gel-forming properties of alginates depend on the molecular weight and the relative content of the two monomers. Alginate produced by Azotobacter vinelandii was shown to be degraded towards the end of the(More)
Mutant AT268 of Azotobacter vinelandii — showing diminished production of poly-β-hydroxybutyrate (PHB) due to a mutation in phbR (the gene coding for the transcriptional activator of the phbBAC biosynthetic operon); mutant CNT26, containing a mutation (muc26) that increases the transcription of gene algD (encoding GDP mannose dehydrogenase, the key enzyme(More)
The Azotobacter vinelandii phbBAC genes encode the enzymes for poly-beta-hydroxybutyrate (PHB) synthesis. The phbR gene, which is located upstream of and in the opposite direction of phbBAC, encodes PhbR, a transcriptional activator which is a member of the AraC family of activators. Here we report that a mutation in phbR reduced PHB accumulation and(More)
The lipids poly-β-hydroxybutyrate (PHB) and alkylresorcinols are the major metabolic products of Azotobacter vinelandii cysts. Cysts are formed in less than 0.01% of late stationary phase cells grown on sucrose. Culturing vegetative cells in n-butanol or β-hydroxybutyrate induces encystment. After induction of encystment, PHB rapidly accumulates in large(More)
Strain AJ1678, an Azotobacter vinelandii mutant overproducing the storage polymer poly-β-hydroxybutyrate (PHB) in solid but not liquid complex medium with sucrose, was isolated after mini-Tn5 mutagenesis of strain UW136. Cloning and nucleotide sequencing of the affected locus led to identification of pycA, encoding a protein with high identity to the biotin(More)
Azotobacter vinelandii is proposed to contain a single beta-ketothiolase activity participating in the formation of acetoacetyl-CoA, a precursor for poly-beta-hydroxybutyrate (PHB) synthesis, and in beta-oxidation (Manchak, J., Page, W.J., 1994. Control of polyhydroxyalkanoate synthesis in Azotobacter vinelandii strain UWD. Microbiology 140, 953-963). We(More)