Adaptation of metal and antibiotic resistant traits in novel β-ProteobacteriumAchromobacter xylosoxidansBHW-15

Abstract

Chromosomal co-existence of metal and antibiotic resistance genes in bacteria offers a new perspective to the bacterial resistance proliferation in contaminated environment. In this study, an arsenotrophic bacteriumAchromobacter xylosoxidansBHW-15, isolated from Arsenic (As) contaminated tubewell water in the Bogra district of Bangladesh, was analyzed using high throughput Ion Torrent Personal Genome Machine (PGM) complete genome sequencing scheme to reveal its adaptive potentiality. The assembled draft genome ofA. xylosoxidansBHW-15 was 6.3 Mbp containing 5,782 functional genes, 1,845 pseudo genes, and three incomplete phage signature regions. Comparative genome study suggested the bacterium to be a novel strain ofA. xylosoxidansshowing significant dissimilarity with other relevant strains in metal resistance gene islands. A total of 35 metal resistance genes along with arsenite-oxidizingaioSXBA, arsenate reducingarsRCDAB, and mercury resistancemerRTPADEoperonic gene cluster and 20 broad range antibiotic resistance genes including β-lactams, aminoglycosides, and multiple multidrug resistance (MDR) efflux gene complex with a tripartite system OM-IM-MFP were found co-existed within the genome. Genomic synteny analysis with reported arsenotrophic bacteria revealed the characteristic genetic organization ofarsandmeroperonic genes, rarely described in β-Proteobacteria. A transposonTn21and mobile element protein genes were also detected to the end ofmer(mercury) operonic genes, possibly a carrier for the gene transposition. In vitro antibiotic susceptibility assay showed a broad range of resistance against antibiotics belonging to β-lactams, aminoglycosides, cephalosporins (1st, 2nd, and 3rd generations), monobactams and even macrolides, some of the resistome determinants were predicted during in silico analysis. KEGG functional orthology analysis revealed the potential of the bacterium to utilize multiple carbon sources including one carbon pool by folate, innate defense mechanism against multiple stress conditions, motility, a proper developed cell signaling and processing unit and secondary metabolism-combination of all exhibiting a robust feature of the cell in multiple stressed conditions. The complete genome of the strain BHW-15 stands as a genetic basis for the evolutionary adaptation of metal and the antibiotic coexistence phenomenon in an aquatic environment.

Bioaccumulation and detoxification of trivalent arsenic by Achromobacter xylosoxidans BHW-15 and electrochemical detection of its transformation efficiency

“…The electrochemical detection process of As (III) transformation is shown in Fig. 7 a and a model representing the molecular interaction of A. xylosoxidans BHW-15 with the arsenic species is proposed based on both the experimental findings of this study and the genome sequence of A. xylosoxidans BHW-15 26 (Fig. 7 b).…”

“…The genome of BHW-15 carried two operons—aioSXBA (oxidation) and arsRCAD (reduction). Cytoplasmic reduction of As (V) to As (III) is occurred by the ArsC protein leading to subsequent extrusion via ArsB or ArsAB pump is pumped out from the cell by efflux pump specific ArsB transporter while, aio operon regulates the oxidation of the arsenite to arsenate inside the cell in presence of periplasmic arsenite oxidase (aioBA) enzyme and pumps it out form the cell using unknown efflux pump (Istiaq et al 26 ). We found the oxidation process of As (III) to As (V) by A. xylosoxidans BHW-15 was predominant.…”

“…), tannery and industrial effluent, agricultural soil, wastewater, hot spring. Our strain A. xylosoxidans BHW-15 was reported as a novel heterotrophic arsenite oxidizing bacteria 26 with a high MIC value isolated from the tube well water. To date, it showed the highest As transformation and accumulation ability compared to the other reported arsenite oxidizing strains in Bangladesh.…”

“…Diverse taxonomic classes of arsenic metabolizing microorganisms such as Lactobacillus sp ., Stenotrophomonas , Alcaligenes , Rhodococcus Bacillus sp ., Kocuria sp ., Herminiimonas sp ., Lysinibacillus sp ., Pseudomonas sp ., Aliihoeflea sp ., Achromobacter xylosoxidans , etc. have already been reported to resist high As concentrations and can contribute in bioremediation of As from groundwater 20 – 26 . Many bacterial species were found to be involved in both heterotrophic and autotrophic As (III) oxidation 6 , 27 – 29 .…”

Prevalence of antibiotic-resistant, toxic metal-tolerant and biofilm-forming bacteria in hospital surroundings

“…A study conducted by Resende et al [ 86 ] demonstrated that clinical isolates of C. davisae exhibiting tolerance towards Ni, Zn, Cr, Cu, Cd and Hg, acquires a selection pressure towards a group of antibiotics. In another study, Istiaq et al [ 87 ] reported that strains of A. xylosoxidans possess genes for Arsenic (As), Cu, Zn, and Cd resistance, which also display a broad range of resistance against antibiotics belonging to β-lactams, aminoglycosides, cephalosporins, monobactams and even macrolides. Genomic investigation of S. maltophilia SJTH1 isolated from the hospitalized patient of PGIMER, Chandigarh, India revealed diverse antibiotic resistance genes, efflux pumps, heavy metal resistance, various transcriptional regulators etc.…”