title: Multidrug resistance operonemrABcontributes for chromate and ampicillin co-resistance in aStaphylococcusstrain isolated from refinery polluted river bank.
abstract: EmrABoperon is known for multidrug resistance in bacteria and yet has not been reported related to heavy metal resistance or antibiotics/heavy metal co-resistance. StrainStaphylococcus aureusLZ-01 which was isolated from industrial wastewater discharging site can co-resist to 6 mM Cr(VI) and 0.75 mg/ml ampicillin. Transcriptome data showed that anemrABoperon was upregulated (1.29-folds foremrA,2.14-folds foremrB) under 0.4 mM Cr(VI) treatment. Quantitative PCR results revealed that this operon was upregulated (1.60-folds foremrA,2.34-folds foremrB) after 0.20 mg/ml ampicillin treatment. Mutant strain withemrAgene knockout resulted in a 0.83-folds decrease in chromate resistance, and a 0.80-folds decrease in ampicillin resistance; whileemrBknockout strain resulted in a 0.33-folds decrease in chromate resistance, and a 0.60-folds decrease in ampicillin resistance. The complemented strains of both deletion mutants basically restored their resistant performance. The presence of 0.50 mM Cr(VI) induced an elevation in ampicillin resistance from 0.50 to 2.50 mg/ml in the strain LZ-01, similarly, its Cr(VI) resistance was also found to be elevated from 6 to 10 mM by 0.15 mg/ml ampicillin induction. The induction effect could be eliminated by deletion ofemrAoremrB. Our results demonstrated that the chromosomalemrABoperon inStaphylococcus aureusLZ-01 was a new type of multidrug resistance system, which conferred both ampicillin and chromate resistance to host cells inhabiting polluted environments.
authors.affiliation: MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000 Gansu People's Republic of China.
authors.forename: He
authors.initials: H
authors.lastname: Zhang
authors.affiliation: MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000 Gansu People's Republic of China ; School of Life Sciences, Nanchang University, Nanchang, 300031 Jiangxi People's Republic of China.
authors.forename: Yantian
authors.initials: Y
authors.lastname: Ma
authors.affiliation: MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000 Gansu People's Republic of China.
authors.forename: Pu
authors.initials: P
authors.lastname: Liu
authors.affiliation: MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000 Gansu People's Republic of China.
authors.forename: Xiangkai
authors.initials: X
authors.lastname: Li
keywords: Ampicillin; Chromate; Co-resistance; Staphylococcus aureus LZ-01; emrAB operon