Assessing Acinetobacter junii MKVVM4 IITBHU Mediated Remediation for As(III) and As(V)

In the present work, an arsenic (As) resistant bacterium has been isolated from the Ganga River, Varanasi, Uttar Pradesh, India. The isolate was identified as Acinetobacter junii MKVVM4 IITBHU (NCBI accession no. ON248394). A. junii MKVVM4 IITBHU could grow in As(V) and As(III) up to 4000 and 3000 ppm, respectively. The isolated strain showed amplification of genes like arsC (As(V) reductase), aioA (As(III) Oxidase), arrA (As(V) respiratory reductase), and arsM (As(III) S adenosylmethionine methyltransferase) in targeted amplification. SEM images of A. junii MKVVM4 IITBHU showed that bacterial cells in the initial development phase had coccobacilli-like morphology having a tail. Elemental mapping and EDS spectrum confirmed the arsenic accumulation within the bacterial cells. There were peak shifts of negatively charged functional groups like amine, alkenes, carboxyl, and hydroxyl in As(III) and As(V) mediums compared to the control group on the cell surface. This work gives insight into the resistance mechanism of A. junii MKVVM4 IITBHU against arsenic. The present work also reports the metabolic requirements of A. junii MKVVM4 IITBHU for environmental persistence and its potential utility in the bioremediation of As(III) and As(V) from the contaminated sites. SUMMARY: The isolate can tolerate 4000 and 3000 ppm of As(V) and As(III), respectively. Bacterial arsenic-resistant gene amplification explains arsenic bioremediation. As(V) facilitated the rapid growth of the isolate as compared to the Control. The diauxic growth in the As(V) medium indicated towards the preferred substrate. Isolate in the early stage of growth showed a tailed structure.