title: [Identification of hexavalent chromium reducing bacteria Cr4-1 and optimization of its reduction conditions].
abstract: OBJECTIVE
  To identify the hexavalent chromium reduction Cr4-1, and to study the better conditions of the bacterial growth and its Cr(VI) reduction.
  
  
  METHODS
  The physiological and biochemical methods and 16s rDNA sequencing were used for identification of bacteria Cr4-1. The influence of temperature, pH, initial Cr (VI) concentration and shaking speed on bacterial growth and Cr (VI) reduction were studied. Mass balance analysis was used to analyze the end products of the reduction reaction.
  
  
  RESULTS
  A Cr(VI) reducing bacteria Cr4-1, screened from acclimated activated sludge, was identified as Bacillus cereus. The appropriate conditions of bacterial growth was 25 °C, pH 7 to 8, shaking speed 150 r/min, while the suitable conditions for Cr(VI) reduction was 35 °C, pH 8 to 9. When the initial Cr(VI) concentration increased from 20 mg/L to 60 mg/L, the reduction rate decreased gradually. Under the suitable reducing conditions, when the initial concentration of Cr (VI) was 30 mg/L, the reduction rate could up to 100% in 9 h. The end product was soluble trivalent chromium.
  
  
  CONCLUSIONS
  Strain Cr4-1 had a good effect on Cr (VI) reduction and the final product was soluble trivalent chromium.
authors.forename: Peilei
authors.initials: P
authors.lastname: Zhu
authors.forename: Shilin
authors.initials: S
authors.lastname: Jiao
authors.forename: Pu
authors.initials: P
authors.lastname: Jiang
authors.forename: Xin
authors.initials: X
authors.lastname: Zeng
authors.forename: Qifang
authors.initials: Q
authors.lastname: Luo
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
mesh_terms: D001419:Bacteria; D002857:Chromium / Q000378:metabolism*; D004275:DNA, Ribosomal; D005960:Glucosides; D012717:Sesquiterpenes; D012722:Sewage
chemical_list: D004275:DNA, Ribosomal; D005960:Glucosides; D012717:Sesquiterpenes; D012722:Sewage; C572717:cadin-2-en-1-ol-1-glucuronopyranoside; D002857:Chromium; C074702:chromium hexavalent ion