Bacterially mediated Mn(II) oxidation and reduction are reported from different econiches. With increase in manganese concentration in coastal regions due to anthropogenic activities, we envisage the interaction of halophilic microbes with the metal. As Haloarchaea, the extremely halophilic archaea, dominate the coastal intertidal crude salt production regions, we selected the Haloferax alexandrinus GUSF-1, an isolate from a salt pan of Goa, India to unveil the involvement of haloarchaea in Mn(II) conversions. Our study is a first report indicating the formation of rhodochrosite by the haloarchaeon Haloferax alexandrinus GUSF-1, during its growth with sodium acetate, wherein Mn(II) is accumulated intracellularly with the formation of extracellular dark brown MnO2 that turned pinkish brown as the culture attained its stationary phase. The XRD, TEM and SEM–EDX analysis exhibited, nanometer sized electron dense regions, with cubic shaped particles characteristic to that of the mineral rhodochrosite. This biogenic formation of nano sized rhodochrosite is cost effective in comparison to that formed by oxygenic eubacteria and anoxygenic hyperthermophilic archaea, Haloarchaeon Haloferax alexandrinus GUSF-1, therefore attracts commercial prospect.
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Authors are indebted to Dr. M. Shyamprasad and Mr.V. Khedekar, National Institute of Oceanography, Goa, India for extending the SEM–EDX facility and to Mr. G Prabhu for helping with XRD profiling. We also thank Indian Institute of Technology, Bombay for the TEM facility.
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Conflict of interest
The authors declare that they have no conflict of interest.
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