Pseudomonas rhizophila S211, a New Plant Growth-Promoting Rhizobacterium with Potential in Pesticide-Bioremediation

A number of Pseudomonas strains function as inoculants for biocontrol, biofertilization, and phytostimulation, avoiding the use of pesticides and chemical fertilizers. Here, we present a new metabolically versatile plant growth-promoting rhizobacterium, Pseudomonas rhizophila S211, isolated from a pesticide contaminated artichoke field that shows biofertilization, biocontrol and bioremediation potentialities. The S211 genome was sequenced, annotated and key genomic elements related to plant growth promotion and biosurfactant (BS) synthesis were elucidated. S211 genome comprises 5,948,515 bp with 60.4% G+C content, 5306 coding genes and 215 RNA genes. The genome sequence analysis confirmed the presence of genes involved in plant-growth promoting and remediation activities such as the synthesis of ACC deaminase, putative dioxygenases, auxin, pyroverdin, exopolysaccharide levan and rhamnolipid BS. BS production by P. rhizophila S211 grown on olive mill wastewater based media was effectively optimized using a central-composite experimental design and response surface methodology (RSM). The optimum conditions for maximum BS production yield (720.80 ± 55.90 mg/L) were: 0.5% (v/v) inoculum size, 15% (v/v) olive oil mill wastewater (OMWW) and 40◦C incubation temperature at pH 6.0 for 8 days incubation period. Biochemical and structural characterization of S211 BS by chromatography and spectroscopy studies suggested the glycolipid nature of the BS. P. rhizophila rhamnolipid was stable over a wide range of temperature (40–90◦C), pH (6–10), and salt concentration (up to 300mM NaCl). Due to its low-cost production, emulsification activities and high performance in solubilization enhancement of chemical pesticides, the indigenous BS-producing PGPR S211 could be used as a promising agent for environmental bioremediation of pesticide-contaminated agricultural soils

Etude des propriétés structurales et électroniques des composés métalliques à ligands polycycliques et hétéro-polycycliques

L'étude présentée dans cette thèse se situe dans le cadre des études théorique des complexes organométalliques de métaux de transitions des polyarènes, bi-métalliques et hétérobimétalliques synthétisées et hypothétiques, intéressant en particulier à la détermination de la structure électronique, du mode de coordination et de la liaison méta-métal des complexes bimétalliques et hétéro-bimétalliques de phénazine. Ce manuscrit est divisé en quatre chapitres, Le premier est une introduction à la théorie de la fonctionnelle de la densité (DFT), et aux règles empiriques de comptage électronique dans les complexes de métaux de transition.Nous avons focalisé l'attention au deuxième chapitre sur la communication électronique et la structure moléculaire des complexes [M(Phn)2] et [ML2(Phn)2] pour les métaux de transition Ti, Cr, Fe et Ni coordonnés au ligand phénazine. Les calculs indiquent que le ligand phénazine peut se lier à des métaux impliquant ses cycles C6 ou C4N2 par des modes de coordination η6ou η4 pour le complexe [M(Phn)2] non substitué. Les complexes substitués [TiL2(Phn)2], [CrL2(Phn)2] et [FeL2(Phn)2] avec CO ou PH3 ont favorisé la structure avec C1où le ligand auxiliaire le plus encombré situé à l'extérieur des deux phénazine donnant lieu respectivement des modes de coordination η6/4, η2/4. Le troisième chapitre rapporte une étude théorique de la structure électronique et moléculaire des complexes [(L3M)2](Phn) (phénazine) pour les métaux de transition de la première ligne (Sc-Ni) coordonnés au ligand phénazine dans leurs conformations syn et anti. Cette étude a montré que la structure la plus basse de l'énergie dépend de la nature du métal, de l'état de spin et de la symétrie moléculaire. La communication électronique entre les centres métalliques dépend de leur état d'oxydation et des ligands attachés. La liaison multiple métal-métal a été mise en évidence pour les complexes Sc, Ti et V afin de compenser la déficience électronique.Le dernier chapitre traite de la structure électronique des clusters bimétalliques de formules générales [M2Co(μ-PH2)(CO)4(PH3)2], [M2Mo(μ-PH2)Cp(CO)3(PH3)2] et [M2Cl(μ-PH2)(PH3)2] (M = Pd, Pt) , ces composés ont été optimisés avec différentes symétries, et montrent la présence de larges écarts énergétiques HOMO-LUMO. L’analyse des interactions confirme que Clet les metallo ligands Co(CO)4–et MoCp(CO)3 sont des analogues isolobau

Carbonylmetallates as versatile 2-, 4- or 6-Electron Donor Metalloligands in Transition-Metal Complexes and Clusters: A Global Approach

International audienceCarbonylmetallates [m]-, such as [MoCp(CO)3]-, [Mn(CO)5]-, [Co(CO)4]-, have long been successfully used in the preparation of hundreds of metal carbonyl complexes and clusters, in particular of the heterometallic type. We focus here on situations where [m]- can be viewed as a terminal, doubly- or even triply-bridging metalloligand, developing metal-metal interactions with one, two or three metal centres M, respectively. With metals M from the groups 10-12, is not straightforward or even impossible to rationalize the structure of the resulting clusters by applying the well-known Wade-Mingos rules. A very simple but global approach is presented to rationalize structures not obeying usual electron-counting rules by considering the anionic building blocks [m]- as metalloligands behaving formally as potential 2, 4 or 6 electron donors, similarly to what is typically encountered with e.g. halido ligands. Qualitative and theoretical arguments using DFT calculations highlight similarities between seemingly unrelated metal complexes and clusters and also entails a predicting power with high synthetic potential

Genome analysis provides insights into crude oil degradation and biosurfactant production by extremely halotolerant Halomonas desertis G11 isolated from Chott El-Djerid salt-lake in Tunisian desert

Here, we report the genomic features and the bioremediation potential of Halomonas desertis G11, a new halophilic species which uses crude oil as a carbon and energy source and displays intrinsic resistance to salt stress conditions (optimum growth at 10% NaCl). G11 genome (3.96 Mb) had a mean GC content of 57.82%, 3622 coding sequences, 480 subsystems and 64 RNA genes. Annotation predicted 38 genes involved in osmotic stress including the biosynthesis of osmoprotectants glycine-betaine, ectoine and osmoregulated periplasmic glucans. Genome analysis revealed also the versatility of the strain for emulsifying crude oil and metabolizing hydrocarbons. The ability of G11 to degrade crude oil components and to secrete a glycolipid biosurfactant with satisfying properties was experimentally confirmed and validated. Our results help to explain the exceptional capacity of G11 to survive at extreme desertic conditions, and highlight the metabolic features of this organism that has biotechnological and ecological potentialities

Table2.DOC

<p>A number of Pseudomonas strains function as inoculants for biocontrol, biofertilization, and phytostimulation, avoiding the use of pesticides and chemical fertilizers. Here, we present a new metabolically versatile plant growth-promoting rhizobacterium, Pseudomonas rhizophila S211, isolated from a pesticide contaminated artichoke field that shows biofertilization, biocontrol and bioremediation potentialities. The S211 genome was sequenced, annotated and key genomic elements related to plant growth promotion and biosurfactant (BS) synthesis were elucidated. S211 genome comprises 5,948,515 bp with 60.4% G+C content, 5306 coding genes and 215 RNA genes. The genome sequence analysis confirmed the presence of genes involved in plant-growth promoting and remediation activities such as the synthesis of ACC deaminase, putative dioxygenases, auxin, pyroverdin, exopolysaccharide levan and rhamnolipid BS. BS production by P. rhizophila S211 grown on olive mill wastewater based media was effectively optimized using a central-composite experimental design and response surface methodology (RSM). The optimum conditions for maximum BS production yield (720.80 ± 55.90 mg/L) were: 0.5% (v/v) inoculum size, 15% (v/v) olive oil mill wastewater (OMWW) and 40°C incubation temperature at pH 6.0 for 8 days incubation period. Biochemical and structural characterization of S211 BS by chromatography and spectroscopy studies suggested the glycolipid nature of the BS. P. rhizophila rhamnolipid was stable over a wide range of temperature (40–90°C), pH (6–10), and salt concentration (up to 300 mM NaCl). Due to its low-cost production, emulsification activities and high performance in solubilization enhancement of chemical pesticides, the indigenous BS-producing PGPR S211 could be used as a promising agent for environmental bioremediation of pesticide-contaminated agricultural soils.</p

Table1.DOC

<p>A number of Pseudomonas strains function as inoculants for biocontrol, biofertilization, and phytostimulation, avoiding the use of pesticides and chemical fertilizers. Here, we present a new metabolically versatile plant growth-promoting rhizobacterium, Pseudomonas rhizophila S211, isolated from a pesticide contaminated artichoke field that shows biofertilization, biocontrol and bioremediation potentialities. The S211 genome was sequenced, annotated and key genomic elements related to plant growth promotion and biosurfactant (BS) synthesis were elucidated. S211 genome comprises 5,948,515 bp with 60.4% G+C content, 5306 coding genes and 215 RNA genes. The genome sequence analysis confirmed the presence of genes involved in plant-growth promoting and remediation activities such as the synthesis of ACC deaminase, putative dioxygenases, auxin, pyroverdin, exopolysaccharide levan and rhamnolipid BS. BS production by P. rhizophila S211 grown on olive mill wastewater based media was effectively optimized using a central-composite experimental design and response surface methodology (RSM). The optimum conditions for maximum BS production yield (720.80 ± 55.90 mg/L) were: 0.5% (v/v) inoculum size, 15% (v/v) olive oil mill wastewater (OMWW) and 40°C incubation temperature at pH 6.0 for 8 days incubation period. Biochemical and structural characterization of S211 BS by chromatography and spectroscopy studies suggested the glycolipid nature of the BS. P. rhizophila rhamnolipid was stable over a wide range of temperature (40–90°C), pH (6–10), and salt concentration (up to 300 mM NaCl). Due to its low-cost production, emulsification activities and high performance in solubilization enhancement of chemical pesticides, the indigenous BS-producing PGPR S211 could be used as a promising agent for environmental bioremediation of pesticide-contaminated agricultural soils.</p

DataSheet1.DOC

<p>A number of Pseudomonas strains function as inoculants for biocontrol, biofertilization, and phytostimulation, avoiding the use of pesticides and chemical fertilizers. Here, we present a new metabolically versatile plant growth-promoting rhizobacterium, Pseudomonas rhizophila S211, isolated from a pesticide contaminated artichoke field that shows biofertilization, biocontrol and bioremediation potentialities. The S211 genome was sequenced, annotated and key genomic elements related to plant growth promotion and biosurfactant (BS) synthesis were elucidated. S211 genome comprises 5,948,515 bp with 60.4% G+C content, 5306 coding genes and 215 RNA genes. The genome sequence analysis confirmed the presence of genes involved in plant-growth promoting and remediation activities such as the synthesis of ACC deaminase, putative dioxygenases, auxin, pyroverdin, exopolysaccharide levan and rhamnolipid BS. BS production by P. rhizophila S211 grown on olive mill wastewater based media was effectively optimized using a central-composite experimental design and response surface methodology (RSM). The optimum conditions for maximum BS production yield (720.80 ± 55.90 mg/L) were: 0.5% (v/v) inoculum size, 15% (v/v) olive oil mill wastewater (OMWW) and 40°C incubation temperature at pH 6.0 for 8 days incubation period. Biochemical and structural characterization of S211 BS by chromatography and spectroscopy studies suggested the glycolipid nature of the BS. P. rhizophila rhamnolipid was stable over a wide range of temperature (40–90°C), pH (6–10), and salt concentration (up to 300 mM NaCl). Due to its low-cost production, emulsification activities and high performance in solubilization enhancement of chemical pesticides, the indigenous BS-producing PGPR S211 could be used as a promising agent for environmental bioremediation of pesticide-contaminated agricultural soils.</p