Isolation and characterization of an As(III) oxidizing bacterium, Acinetobacter sp. TMKU4 from paddy field for possible arsenic decontamination

•As(III)-oxidizing Acinetobacter sp., TMKU4 isolated from paddy soil.•The strain could oxidize As(III) by inducible As(III) oxidase encoded by aioA.•As(III) oxidase exhibited km of 73.38 μM and vmax of 0.3456 μM min−1 μg−1 protein.•TMKU4 exhibited plant growth promoting traits as well. During past few decades arsenic (As), a poisonous and carcinogenic water and soil contaminant, is perceived as a significant universal environmental snag. The exploration of As-resistant microorganisms for mitigation of As-contaminated environment has been proven to be both economical and ecologically favourable among the various techniques so far documented. Several As-resistant bacterial isolates were isolated from the soil sample of As affected area of Nadia, a district in West Bengal, India. On the basis of maximum As resistance ability, an arsenite [As(III)]-oxidizing bacterial strain, TMKU4, was selected, which could withstand 12.5 mM As(III) and 95 mM arsenate [As(V)]. The strain was noted to be closely linked to the genus Acinetobacter as per 16S rDNA sequence analysis and biochemical characterization. Within 14 h of incubation on minimal salts medium, this strain could convert ∼78% of As(III) to As(V). Kinetic evaluation of partially purified As(III) oxidase from the bacterial cells exhibited Km of 73.38 μM and Vmax of 0.3456 μM min−1 μg−1 protein. The existence of the As(III) oxidase gene was further confirmed through PCR with degenerate primers. TMKU4 exhibits potential plant growth-promoting attributes owing to which it could also be exploited as a promising As bioremediation strategy for sustainable agriculture. [Display omitted]