Prospective role of indigenous <italic>Exiguobacterium profundum</italic> PT2 in arsenic biotransformation and biosorption by planktonic cultures and biofilms.

Abstract: Aims: The aim of this study was to analyse arsenic (As) transformation and biosorption by indigenous As‐resistant bacteria both in planktonic and biofilm modes of growth. Methods and Results: As‐resistant bacteria were isolated from industrial waste water and strain PT2, and identified as <italic>Exiguobacterium profundum</italic> through 16S rRNA gene sequencing was selected for further study. As transformation and biosorption by <italic>E. profundum</italic>PT2 was determined by HPLC‐ICP‐MS analysis. Planktonic cultures reduced 3·73 mmol l⁻¹ As⁵⁺ into As³⁺ from artificial waste water effluent after 48‐h incubation. In case of biosorption, planktonic cultures and biofilms exhibited 25·2 and 29·4 mg g⁻¹ biomass biosorption, respectively. As biosorption kinetics followed Freundlich isotherm and pseudo second‐order model. Biofilm formation peaked after 3 days of incubation, and in the presence of As stress, biofilm formation was significantly affected in contrast to control (<italic>P </italic><<italic> </italic>0·05). Homogeneous nature of mature biofilms with an increased demand of nutrients was revealed by minimum roughness and maximum surface to biovolume ratio measured through CLSM analysis. Conclusion: Indigenous As‐resistant <italic>E. profundum</italic>PT2 was found capable of As transformation and biosorption both in the form of planktonic cultures and biofilms. Significance and Impact of the Study: Indigenous biofilm forming <italic>E. profundum</italic> PT2 revealing As biosorption and biotransformation potential is presented an eco‐friendly and cost‐effective source for As remediation that can be implemented for waste water treatment. [ABSTRACT FROM AUTHOR]