Influence of periplasmic oxidation of glucose on pyoverdine synthesis in Pseudomonas putida S11

Abstract

Fluorescent pseudomonads catabolize glucose simultaneously by two different pathways, namely, the oxidative pathway in periplasm and the phosphorylative pathway in cytoplasm. This study provides evidence for the role of glucose metabolism in the regulation of pyoverdine synthesis in Pseudomonas putida S11. We have characterized the influence of direct oxidation of glucose in periplasm on pyoverdine synthesis in P. putida S11. We identified a Tn5 transposon mutant of P. putida S11 showing increased pyoverdine production in minimal glucose medium (MGM). This mutant designated as IST1 had Tn5 insertion in glucose dehydrogenase (gcd) gene. To verify the role of periplasmic oxidation of glucose on pyoverdine synthesis, we constructed mutants S11 Gcd(-) and S11 PqqF(-) by antibiotic cassette mutagenesis. These mutants of P. putida S11 with loss of glucose dehydrogenase gene (gcd) or cofactor pyrroloquinoline quinone biosynthesis gene (pqqF) showed increased pyoverdine synthesis and impaired acid production in MGM. In minimal gluconate medium, the pyoverdine production of wild-type strain S11 and mutants S11 Gcd(-) and S11 PqqF(-) was higher than in MGM indicating that gluconate did not affect pyoverdine synthesis. In MGM containing PIPES-NaOH (pH 7.5) buffer which prevent pH changes due to gluconic acid production, strain S11 produced higher amount of pyoverdine similar to mutants S11 Gcd(-) and S11 PqqF(-). Therefore, it is proposed that periplasmic oxidation of glucose to gluconic acid decreases the pH of MGM and thereby influences pyoverdine synthesis of strain S11. The increased pyoverdine synthesis enhanced biotic and abiotic surface colonization of the strain S11.

Mineral Phosphate Solubilization: Concepts and Prospects in Sustainable Agriculture

“…Besides, the production of chelating substances H 2 S, CO 2 , mineral acids, siderophores, biologically active substances like indole acetic acid [119], gibberellins and cytokinins Penicillium bilaii Citric and oxalic acid [105] Penicillium regulosum Citric and gluconic acid [106] Pseudomonas aeruginosa Gluconic [97] Pseudomonas putida Gluconic acid [107] Pseudomonas sp. Citric, gluconic [108] Pseudomonas sp.…”

“…The characterization of different phosphate solubilizing bacteria has shown that direct oxidation pathway provides the biochemical basis for highly efficacious phosphate solubilization in Gram negative bacteria via diffusion of the strong organic acids like gluconic acid produced in the periplasm into the adjacent environment [59,[93][94][95]101,103,107]. Glucose is the precursor for synthesis of gluconic acid [122].…”

Gac‐mediated changes in pyrroloquinoline quinone biosynthesis enhance the antimicrobial activity of Pseudomonas fluorescens SBW25

“…The upregulation of the pqq and gcd genes in the gacS mutant was confirmed by qPCR (not shown). In Pseudomonas and other Gram‐negative bacteria, gluconic acid biosynthesis has been shown to be dependent on PQQ as an enzymatic cofactor of the membrane‐bound quinoprotein, glucose dehydrogenase (Gcd) (Goldstein, ; Kaur et al ., ; de Werra et al ., ; Kremmydas et al ., ; Ponraj et al ., ). Gcd acts as a glucose sensor and catalyses glucose into gluconic acid by periplasmic oxidation.…”

Plant growth promotion by Pseudomonas fluorescens : mechanisms, genes and regulation

“…Gcd acts as a glucose sensor and catalyses glucose into gluconic acid by periplasmic oxidation. A consecutive oxidation reaction converts gluconic acid to 2-keto gluconic acid (Schleissner et al, 1997;de Werra et al, 2009;Ponraj et al, 2013). This study showed, for the first time, that a mutation in the Gac-system of P. fluorescens SBW25 led to a significant transcriptional up-regulation of pqq biosynthesis genes and gcd gene.…”

“…The up-regulation of the pqq and gcd genes in the gacS mutant was confirmed by qPCR (not shown). In Pseudomonas and other Gram-negative bacteria, gluconic acid biosynthesis has been shown to be dependent on PQQ as an enzymatic cofactor of the membrane bound quinoprotein, glucose dehydrogenase (Gcd) Kaur et al, 2006;de Werra et al, 2009;Kremmydas et al, 2013;Ponraj et al, 2013). Gcd acts as a glucose sensor and catalyses glucose into gluconic acid by periplasmic oxidation.…”