title: Real-time PCR based analysis of metal resistance genes in metal resistant Pseudomonas aeruginosa strain J007.
abstract: A uranium (U)-resistant and -accumulating Pseudomonas aeruginosa strain was characterized to assess the response of toxic metals toward its growth and expression of metal resistance determinants. The bacterium showed MIC (minimum inhibitory concentration) values of 6, 3, and 2 mM for Zn, Cu, and Cd, respectively; with resistance phenotype conferred by periplasmic Cu sequestering copA and RND type heavy metal efflux czcA genes. Real-time PCR-based expression analysis revealed significant upregulation of both these genes upon exposure to low concentrations of metals for short duration, whereas the global stress response gene sodA encoding superoxide dismutase enzyme was upregulated only at higher metal concentrations or longer exposure time. It could also be inferred that copA and czcA are involved in providing resistance only at low metal concentrations, whereas involvement of "global stress response" phenomenon (expression of sodA) at higher metal concentration or increased exposure was evident. This study provides significant understanding of the adaptive response of bacteria surviving in metal and radionuclide contaminated environments along with the development of real-time PCR-based quantification method of using metal resistance genes as biomarker for monitoring relevant bacteria in such habitats.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology, Kharagpur, India.
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Choudhary
authors.affiliation: Department of Biotechnology, Indian Institute of Technology, Kharagpur, India.
authors.forename: Pinaki
authors.initials: P
authors.lastname: Sar
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002104:Cadmium / Q000633:toxicity; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000633:toxicity; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D000075322:Heavy Metal Poisoning; D008826:Microbial Sensitivity Tests; D011041:Poisoning; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D014501:Uranium / Q000633:toxicity; D015032:Zinc / Q000633:toxicity
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins; C071263:CopA protein, Bacteria; D002104:Cadmium; D014501:Uranium; D003300:Copper; C095500:SodA protein, Bacteria; D013482:Superoxide Dismutase; D015032:Zinc
keywords: Metal resistance; Pseudomonas aeruginosa; Real-time PCR; copA; czcA