Exploring metal effects and synergistic interactions of ferric stimulation on azo-dye decolorization by new indigenous Acinetobacter guillouiae Ax-9 and Rahnella aquatilis DX2b
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The first-attempt study deciphered metal-interacting effects on dye-decolorizing capabilities of indigenous bioelectricity-generating strains, Acinetobacter guillouiae Ax-9 and Rahnella aquatilis DX2b. Most of the metallic ions were inhibitory to color removal capabilities of these strains. However, with supplementation of 5 mM ferric chloride, specific decolorization rate (SDR) of Ax-9 increased by 55.48 % compared to Fe3+-free conditions. In contrast, SDR of DX2b decreased 75.35 % due to the inhibition of ferric chloride. On the other hand, ferric citrate could stimulate SDR of DX2b for 21.5 % at same dosage. Enzymatic assay indicated that Fe reductase activity was consistent with synergistic effects of ferric chloride on Ax-9, and ferric citrate on DX2b. Protein analysis via SDS-PAGE and identification of Tandem MS/MS afterwards showed that outer membrane protein (Omp) primarily deals with decolorization as a channeling regulation. Moreover, molecular modeling and bioinformatics data also provided detailed evidences to confirm the biological significance of Omp.
KeywordsAcinetobacter guillouiae Rahnella aquatilis Decolorization Metal effect Ferric synergism
The authors are grateful to the financial support by the Fundamental Research Funds for the Central Universities (2011121017), the Chinese National Natural Science Foundation (21206141) and the Fujian Provincial Department of Science & Technology (2012I0009). The authors also sincerely appreciate the academic connection program between Xiamen University (China) and National I-Lan University (Taiwan) in this study.
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