Abstract:

In order to explore the mechanism and species of microorganism, which was from wastewater and had possessed cross-resistance of heavy metals and antibiotic, bacteria were isolated from the selective culture mediums prepared by breeding wastewater, and based on the experimental design, their characteristics growing on the K-B agar mediums containing the heavy metals (33.33 mg/L Pb2+, 34.67 mg/L Cr6+, 16.67 mg/L Hg2+, 33.33 mg/L Cu2+) and the drug sensitivity papers (3.33 mg/L Amoxicillin, 2.67 mg/L Norfloxacin, 4.17 mg/L Cefradine) were observed. 7 strains were isolated from the breeding wastewater, and the numbers of rod-shaped Gram-positive and Gram-negative bacteria were 3 and 4, respectively. The resistance of the Gram-negative bacteria was stronger than the Gram positive bacteria. In which, strain 1# had 6 kinds of cross resistance (Pb+A, Cr+N, Hg+N, Hg+C, Cu+A, Cu+C), while both strain 4# and 7# had only one kind of cross resistance to Cu+N and Cr+C, respectively. 4 strains could grow on the culture medium containing Hg+N, and only one strain could grow on the culture medium containing Cr+N, Pb+C, Cu+C or Cr+C. The results of the cross resistance experiments also showed that the resistance of 7 strains to antibiotics was stronger than those to heavy metals. Therefore, a potential risk for public health due to discharge of the breeding wastewater might caused by the microorganism with cross resistance to heavy metals and antibiotics.