The copper resistance of a strain of Escherichia coli isolated from the effluent of a piggery where pigs were fed a diet supplemented with copper sulfate was controlled by a conjugative 78-megadalton plasmid designated pRJ1004. Plasmid pRJ1004 exhibited surface exclusion and incompatibility with standard plasmids belonging to incompatibility groups I1 and K. Sensitive strains of E. coli K-12 were unable to form colonies on nutrient agar containing more than 4 mM copper, whereas transconjugants which harbored pRJ1004 were able to form colonies on medium containing up to 20 mM copper.

Plasmid-controlled resistance to copper in Escherichia coli.

Sewage effluent and outfall confluence samples were collected at the Barceloneta Regional Treatment Plant in Barceloneta, Puerto Rico; outfall confluence samples at Ocean City, Md., were also collected. Samples from uncontaminated open ocean areas served as clean-water controls. Bacteria were enriched in marine broth 2216 amended with 1 microgram of one of a set of chemicals selected for study per ml: nitrobenzene, dibutyl phthalate, m-cresol, o-cresol, 4-nitroaniline, bis(tributyltin) oxide, and quinone. MICs of the chemicals were determined individually for all isolates. Bacterial isolates were evaluated for resistance to nine different antibiotics and for the presence of plasmid DNA. Treated sewage was found to contain large numbers of bacteria simultaneously possessing antibiotic resistance, chemical resistance, and multiple bands of plasmid DNA. Bacteria resistant to penicillin, erythromycin, nalidixic acid, ampicillin, m-cresol, quinone, and bis(tributyltin) oxide were detected in nearly all samples, but only sewage outfall confluence samples yielded bacterial isolates that were resistant to streptomycin. Bacteria resistant to a combination of antibiotics, including kanamycin, chloramphenicol, gentamicin, and tetracycline, were isolated only from sewage effluent samples. It is concluded that bacterial isolates derived from toxic chemical wastes more frequently contain plasmid DNA and demonstrate antimicrobial resistance than do bacterial isolates from domestic sewage-impacted waters or from uncontaminated open ocean sites.

https://aem.asm.org/content/aem/51/6/1285.full.pdf

Coincident plasmids and antimicrobial resistance in marine bacteria isolated from polluted and unpolluted Atlantic Ocean samples.

SUMMARY: The copper resistance in Escherichia coli determined by plasmid pRJ 1004 is inducible. The level of resistance is proportional to the inducing dose of copper. The level of copper resistance in induced and uninduced cells changes with the growth phase of the culture. Induced resistant cells accumulate less copper than uninduced cells, so that reduced accumulation may be the mechanism of resistance. We propose that the inducible plasmid-coded copper resistance interacts with the normal metabolism of the cell to protect against toxic levels of copper while allowing continued operation of copper-dependent functions.

Inducible plasmid-mediated copper resistance in Escherichia coli.

Estuarine bacteria isolated on metal-containing media were also found to be antibiotic resistant; ampicillin and chloramphenicol were the antibiotics to which resistance was most common. Patterns of antibiotic resistance were found associated with a variety of taxa.

Antibiotic Resistance Patterns of Metal-Tolerant Bacteria Isolated from an Estuary

Chelating agents produced by microorganisms enhance the dissolution of iron and increase its mobility and bioavailability. Since there are some similarities in the biological behavior of ferric, thorium and uranuyl ions, microorganisms resistant to thorium and uranium and capable of growing in their presence may produce sequestering agents for these metals in a manner similar to those produced for iron. Such complexation would increase the mobility and bioavailability of thorium and uranium in the environment.Pseudomonas aeruginosa species are resistant to certain heavy metals and have also been found in thorium, uranium and plutonium contaminated areas. In the present work, the ability ofP. aeruginosa to elaborate sequestering agents in medium containing thorium or uranium salts was tested. Addition of 10, 100, and 1,000 ppm of uranium or thorium to culture medium increased the lag period of the organism as the concentration of the metal increased. At concentrations of 1,000 ppm and higher, there was an extended lag period followed by reduction in growth. Uranium has a stronger inhibitory effect on growth of the organism than thorium at similar concentrations. Analyses of the culture media have shown, that relative to the control and under the experimental conditions used, the microorganisms have produced several new chelating agents for thorium and uranium. Some of the bacterially produced compounds resemble, but are not identical to the known iron chelating siderophores isolated from microorganisms, and some of their chemical properties are discussed in this report.

Induced Formation of Chelating Agents by Pseudomonas aeruginosa Grown in Presence of Thorium and Uranium

1Lead-resistant bacteria isolated from domestic sewage showed simultaneous resistance to other inorganic metals and also antibiotics.

Resistance to inorganic salts and antibiotics among sewage-borne Enterobacteriaceae and Achromobacteriaceae.

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Resistance to inorganic salts and antibiotics among sewage-borne Enterobacteriaceae and Achromobacteriaceae.