Plasmid-determined inducible efflux is responsible for resistance to cadmium, zinc, and cobalt in Alcaligenes eutrophus

Nies, Dietrich H.; Silver, Simón

doi:10.1128/jb.171.2.896-900.1989

Cited by 182 publications

(118 citation statements)

References 17 publications

(7 reference statements)

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“…A similar resistance to several metals, including Cd, was observed in Alcaligenes eutrophus by Nies and Silver (1988). There are numerous additional examples such as the ability to withstand high arsenic concentrations described for several aquatic bacterial strains by Takeuchi et al (2007).…”

Section: Discussionmentioning

confidence: 70%

REMOVAL OF CADMIUM AND LEAD BY ADAPTED STRAINS OF Pseudomonas aeruginosa AND Enterobacter cloacae

Bojórquez

Frías-Espericueta

Voltolina

2016

Rev. Int. Contam. Ambie.

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This study determined the cadmium and lead (Cd and Pb) biosorption of two bacterial strains identified with molecular techniques as Pseudomonas aeruginosa and Enterobacter cloacae. These species were isolated from domestic wastewater and adapted to a maximum of 2.83 and 17.4 mg/L of Cd and Pb, respectively. Cd sorption by both strains, determined by atomic absorption spectrophotometry, ranged from 14.4 to 16.5 %. However, the difference between strains was not significant. P. aeruginosa and E. cloacae were comparatively more efficient in the sorption of Pb (82.47and 72.16 % respectively) than for Cd. The amount of Pb absorbed by the bacterial biomass was significantly higher in P. aeruginosa than in E. cloacae cultures.Palabras clave: metales pesados, cepas bacterianas, adaptación, remoción de metales RESUMEN El presente estudio evaluó la capacidad de absorción y adsorción de cadmio y plomo (Cd y Pb) de Psudomonas aeruginosa y Enterobacter cloacae, identificadas mediante técnicas moleculares. Estas dos cepas fueron aisladas de efluentes residuales domésticos y adaptadas hasta concentraciones de 2.83 mg/L de cadmio y 17.4 mg/L de plomo. Para determinar la capacidad de remoción de Cd y Pb en estas especies, se realizaron cultivos de 24 h y se cuantificó la cantidad de metal adsorbido y absorbido en la biomasa celular mediante espectrofotometría de absorción atómica. Los resultados muestran que en ambas cepas el porcentaje de adsorción y absorción de Cd se encontró entre el 14.4 y 16.5 % de la concentración inicial, sin diferencias entre cepas. En el caso del Pb ambas cepas son eficientes, ya que los porcentajes retenidos por los dos procesos tanto en P. aeruginosa como en E. cloacae suman el 82.47 y 72.16 % de la concentración inicial, respectivamente. La absorción en la biomasa bacteriana resultó significativamente mayor en los cultivos de P. aeruginosa.

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Section: Discussionmentioning

confidence: 70%

REMOVAL OF CADMIUM AND LEAD BY ADAPTED STRAINS OF Pseudomonas aeruginosa AND Enterobacter cloacae

Bojórquez

Frías-Espericueta

Voltolina

2016

Rev. Int. Contam. Ambie.

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“…It cannot be excluded that other transporters present in PT5 may contribute to the intrinsic resistance of this organism to heavy metals. Overexpression of the heavy metal pumps could be obtained upon exposure to zinc and cadmium (36) or by constitutive expression resulting, as we show here, from mutations in the two-component sensor CzcS. Zinc in the growth medium not only induced the czcCBA efflux pump operon but at the same time transcription of the two-component regulator genes czcR and czcS.…”

Section: Discussionmentioning

confidence: 71%

CzcR-CzcS, a Two-component System Involved in Heavy Metal and Carbapenem Resistance in Pseudomonas aeruginosa

Perron

Caille

Rossier

et al. 2004

Journal of Biological Chemistry

291

272

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Pseudomonas aeruginosa is an environmental bacterium involved in mineralization of organic matter. It is also an opportunistic pathogen able to cause serious infections in immunocompromised hosts. As such, it is exposed to xenobiotics including solvents, heavy metals, and antimicrobials. We studied the response of P. aeruginosa upon exposure to heavy metals or antibiotics to investigate whether common regulatory mechanisms govern resistance to both types of compounds. We showed that sublethal zinc concentrations induced resistance to zinc, cadmium, and cobalt, while lethal zinc concentrations selected mutants constitutively resistant to these heavy metals. Both zinc-induced and stable zinc-resistant strains were also resistant to the carbapenem antibiotic imipenem. On the other hand, only 20% of clones selected on imipenem were also resistant to zinc. Heavy metal resistance in the mutants could be correlated by quantitative real time PCR with increased expression of the heavy metal efflux pump CzcCBA and its cognate two-component regulator genes czcR-czcS. Western blot analysis revealed reduced expression of the basic amino acid and carbapenem-specific OprD porin in all imipenem-resistant mutants. Sequencing of the czcR-czcS DNA region in eight independent zincand imipenem-resistant mutants revealed the presence of the same V194L mutation in the CzcS sensor protein. Overexpression in a susceptible wild type strain of the mutated CzsS protein, but not of the wild type form, resulted in decreased oprD and increased czcC expression. We further show that zinc is released from latex urinary catheters into urine in amounts sufficient to induce carbapenem resistance in P. aeruginosa, possibly compromising treatment of urinary tract infections by this class of antibiotics.Pseudomonas aeruginosa is a Gram-negative bacterium thriving in environments polluted with organic matter. It is also an opportunistic pathogen frequently encountered in the hospital, causing morbidity and mortality in immunocompromised and cystic fibrosis patients (1). P. aeruginosa is characterized by an intrinsically high level of resistance to xenobiotics including antimicrobial agents, solvents, and heavy metals (2), which can be accounted for by a combination of its low outer membrane permeability and the presence of multiple efflux pumps (3). These pumps belong to the resistance, nodulation, cell division (RND) 1 transporter family, present in many Gramnegative bacteria (4). To extrude substrates from the cytoplasm across the two membranes, these systems are composed of a proton antiporter located in the cytoplasmic membrane, a membrane fusion protein spanning the periplasmic space, and an outer membrane protein (5). Members of the RND family, namely the Mex pumps, have recently gained increasing interest. In particular, the constitutively expressed MexAB-OprM (6, 7) and the inducible MexXY (8) efflux pumps endow the PAO1 reference strain and other clinical isolates (9) with a natural resistance to a wide range of antimicrobial agents. Proton-dr...

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“…In fact, evidence has been provided for the ability of cadmium to enter in bacterial cells through metal importers involved in the uptake of magnesium, manganese and zinc (Nies and Silver 1989;Grass et al 2002). Interestingly, similar mechanisms are known to facilitate cadmium entry also in mammalian cells (Okubo et al 2003;Fujishiro et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Deregulation of transition metals homeostasis is a key feature of cadmium toxicity in Salmonella

2014

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Cadmium is a highly toxic metal whose presence in the environment represents a challenge for all forms of life. To improve our knowledge on cadmium toxicity, we have explored Salmonella Typhimurium responses to this metal. We have found that cadmium induces the concomitant expression of the cation efflux pump ZntA and of the high affinity zinc import system ZnuABC. This observation suggests that cadmium accumulation within the cell induces a condition of apparent zinc starvation, possibly due to the ability of this metal to compete with zinc for the metal binding site of proteins. This hypothesis is supported by the finding that strains lacking ZntA or ZnuABC are hyper-susceptible to cadmium and that the cadmium-induced growth defect of a znuABC mutant strain is largely relieved by zinc supplementation. A similar growth defect was observed for a mutant with impaired ability to acquire iron, whereas cadmium does not affect growth of a strain defective in manganese import. Cadmium also influences the expression and activity of the two cytoplasmic superoxide dismutases FeSOD and MnSOD, which are required to control cadmiummediate oxidative stress. Exposure to cadmium causes a reduction of FeSOD activity in Salmonella wild type and the complete abrogation of its expression in the strain defective in iron import. In contrast, although MnSOD intracellular levels increase in response to cadmium, we observed discrepancies between protein levels and enzymatic activity which are suggestive of incorporation of non-catalytic metals in the active site or to cadmium-mediated inhibition of manganese import. Our results indicate that cadmium interferes with the ability of cells to manage transition metals and highlight the close interconnections between the homeostatic mechanisms regulating the intracellular levels of different metals.

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Plasmid-determined inducible efflux is responsible for resistance to cadmium, zinc, and cobalt in Alcaligenes eutrophus

Cited by 182 publications

References 17 publications

REMOVAL OF CADMIUM AND LEAD BY ADAPTED STRAINS OF Pseudomonas aeruginosa AND Enterobacter cloacae

REMOVAL OF CADMIUM AND LEAD BY ADAPTED STRAINS OF Pseudomonas aeruginosa AND Enterobacter cloacae

CzcR-CzcS, a Two-component System Involved in Heavy Metal and Carbapenem Resistance in Pseudomonas aeruginosa

Deregulation of transition metals homeostasis is a key feature of cadmium toxicity in Salmonella

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