Molecular identification of arsenic-resistant estuarine bacteria and characterization of their ars genotype

Abstract

In the present study, 44 arsenic-resistant bacteria were isolated through serial dilutions on agar plate with concentrations ≥0.05 mM of sodium arsenite and ≥10 mM of sodium arsenate from Mandovi and Zuari--estuarine water systems. The ars genotype characterization in 36 bacterial isolates (resistant to 100 mM of sodium arsenate) revealed that only 17 isolates harboured the arsA (ATPase), B (arsenite permease) and C (arsenate reductase) genes on the plasmid DNA. The arsA, B and C genes were individually detected using PCR in 16, 9 and 13 bacterial isolates respectively. Molecular identification of the 17 isolates bearing the ars genotype was carried using 16S rDNA sequencing. A 1300 bp full length arsB gene encoding arsenite efflux pump and a 409 bp fragment of arsC gene coding for arsenate reductase were isolated from the genera Halomonas and Acinetobacter. Phylogenetic analysis of arsB and arsC genes indicated their close genetic relationship with plasmid borne ars genes of E. coli and arsenate reductase of plant origin. The putative arsenate reductase gene isolated from Acinetobacter species complemented arsenate resistance in E. coli WC3110 and JM109 validating its function. This study dealing with isolation of native arsenic-resistant bacteria and characterization of their ars genes might be useful to develop efficient arsenic detoxification strategies for arsenic contaminated aquifers.

Arsenic Response of Three Altiplanic Exiguobacterium Strains With Different Tolerance Levels Against the Metalloid Species: A Proteomics Study

“…The As(V) and As(III) tolerance levels shown for our three strains contrast with those previously reported for this genus: strains WK6 (Anderson and Cook, 2004), KM05 (Sunita et al, 2012), S17 (Belfiore et al, 2013), PS NCIM 5463 (Sacheti et al, 2014), AS-9 (Pandey and Bhatt, 2015), antarcticum B7 (da Costa et al, 2018), and profundum PT2 (Andreasen et al, 2018). We highlight the ability of SH0S7 strain, isolated from H0 site, to tolerate 20 mM of As(III), one of the highest concentrations reported so far.…”

Bacterial isolates harboring antibiotics and heavy-metal resistance genes co-existing with mobile genetic elements in natural aquatic water bodies

“…Our results corroborate with the previous study carried out among isolates from municipal wastewater in Italy, where co-occurrence of antibiotic resistance and ars C gene was observed ( Di Cesare et al, 2016 ). Reports from Kaur et al, 2009 , Sunita et al, 2012 also showed the presence of ars C gene among the bacterial isolates from freshwater bodies in India. The association of mobile elements with blaTEM gene was also studied where positive amplification for IntI 81, SulI 63, ISecp1 54, TN3 45, and TN21 63% isolates was achieved.…”

“…The amplified products were tested for the possible amalgamations of ESBLs ( blaTEM ) and sil genes besides the determinants mer B, mer P, and mer T genes, that confer the resistance against mercury. Arsenic resistant ( arsC ) gene was also amplified using the primer sequence from previously available literature ( Sunita et al, 2012 ).…”

Plasmid-Mediated Ampicillin, Quinolone, and Heavy Metal Co-Resistance among ESBL-Producing Isolates from the Yamuna River, New Delhi, India

“…The maintenance of heavy metals like mercury and arsenic in aquatic environments could help bacteria in acquisition of metal resistance determinants located on the chromosome or plasmids [22]. Reports from the United States, the Netherlands, India, and Australia suggested the occurrence of heavy metal resistance among bacterial isolates [23][24][25][26]. Different resistance determinants are responsible for conferring resistance to heavy metals, e.g., mer and ars operon genes are responsible for resistance against mercury and arsenic, respectively [27].…”