title: Rhodobacter sphaeroides adaptation to high concentrations of cobalt ions requires energetic metabolism changes.
abstract: Rhodobacter sphaeroides has for a long time been investigated for its adaptive capacities to different environmental and nutritional conditions, including presence of heavy metals, which make it a valuable model organism for understanding bacterial adaptation to metal stress conditions and future environmental applications, such as bioremediation of polluted sites. To further characterize the capability of R. sphaeroides to cope with high cobalt ion concentrations, we combined the selection of adaptive defective mutants, carried out by negative selection of transposon insertional libraries on 5 mM Co(2+) -enriched solid medium, with the analysis of growing capacities and transcriptome profiling of a selected mutant (R95). A comparative analysis of results from the mutant and wild-type strains clearly indicated that the adaptive ability of R. sphaeroides strongly relies on its ability to exploit any available energy-supplying metabolisms, being able to behave as photo- or chemotrophic microorganism. The selected R95 mutant, indeed, exhibits a severe down-expression of an ABC sugar transporter, which results nonpermissive for its growth in cobalt-enriched media under aerobic conditions. Interestingly, the defective expression of the transporter does not have dramatic effects on the growth ability of the mutant when cultivated under photosynthetic conditions.
authors.affiliation: Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.
authors.forename: Mariateresa
authors.initials: M
authors.lastname: Volpicella
authors.forename: Alessandra
authors.initials: A
authors.lastname: Costanza
authors.forename: Orazio
authors.initials: O
authors.lastname: Palumbo
authors.forename: Francesca
authors.initials: F
authors.lastname: Italiano
authors.forename: Leoni
authors.initials: L
authors.lastname: Claudia
authors.forename: Antonio
authors.initials: A
authors.lastname: Placido
authors.forename: Ernesto
authors.initials: E
authors.lastname: Picardi
authors.forename: Massimo
authors.initials: M
authors.lastname: Carella
authors.forename: Massimo
authors.initials: M
authors.lastname: Trotta
authors.forename: Luigi R
authors.initials: LR
authors.lastname: Ceci
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D002413:Cations, Divalent; D003035:Cobalt / Q000494:pharmacology*; D004734:Energy Metabolism / Q000235:genetics; D020869:Gene Expression Profiling; D009876:Operon; D010788:Photosynthesis; D012242:Rhodobacter sphaeroides / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D003035:Cobalt
keywords: Rhodobacter sphaeroides; bioremediation; heavy metal stress; negative selection; transcriptomics