RESUMO
Although less toxic than hexavalent chromium, Cr (â ¢) species still pose a threat to human health. The Cr (â ¥) should be converted to Cr (0) instead of Cr (â ¢), which is still involved in biological detoxification filed. Herein, for the first time, it was found that Cr(â ¥) can be reduced into Cr(0) by Bacillus cereus FNXJ1-2-3, a way to completely harmless treatment of Cr(â ¥). The bacterial strain exhibited excellent performance in the reduction, sorption, and accumulation of Cr(â ¥) and Cr (â ¢). XPS etching characterization inferred that the transformation of Cr(â ¥) into Cr(0) followed a reduction pathway of Cr(â ¥)âCr (â ¢)âmetallic Cr(0), in which at least two secretory chromium reductases (ECrâ ¥ââ ¢ and ECrâ ¢â0) worked. Under the optimum condition, the yield ratio of Cr(0)/Cr (â ¢) reached 33.90%. In addition, the interfacial interactions, ion channels, chromium reductases, and external electron donors also contributed to the Cr(â ¥)/Cr(0) transformation. Findings of this study indicate that Bacillus cereus FNXJ1-2-3 is a promising bioremediation agent for Cr(â ¥) pollution control.