Fate of hexavalent chromium reduction by using Halomonas maridiana EA1

Abstract

The present study is focused on the reduction of hexavalent chromium by using the isolated bacterium Halomonas maridiana EA1. H. maridiana EA1 has shown a > 90 % reduction of 100 ppm hexavalent chromium on day 1 and a > 70 % reduction of 1200 ppm hexavalent chromium on day 4. ICP-OES analysis revealed that H. maridiana EA1 has efficiently reduced hexavalent chromium into trivalent chromium. The occurrence of the chrA gene in H. maridiana EA1, which regulates the ChrA (reductase) enzyme, may be associated with the reduction of hexavalent chromium into trivalent chromium. TEM images depicted the alteration in the morphology of H. maridiana EA1 under hexavalent chromium stress conditions. The LCMS result illustrates the role of metabolites in hexavalent chromium reduction by regulating two main pathways: cell wall strengthening and biofilm formation, which help to maintain the cell integrity. Hence, applications of such dynamic bacteria H. maridiana EA1 can be useful to minimize the burden of hexavalent chromium in the soil for the sustainability of the ecosystem.

Keywords

• Hexavalent chromium
• Halomonas maridiana
• Exopolymeric substances (EPS)
• TEM
• LCMS