Degradation Characteristics Of Quinclorac Z2 Strain And Bioremediation By Z2

Quinclorac is a novel selective postemergence herbicides. And it is classified as a type of hormone quinolinecarboxylic acid herbicides. Quinclorac has low toxicity and a long period of residue. Besiaes, quinclorac can do harm to after crop. Along with the widely use of quincorac, there are some environment problems in recent years. Therefore, it has important significance to solve those problems by degradation bacteria.In the laboratory, through enriching, separating and screening from wastewater sludge around pesticide plant, we got quinclorac degradation bacteria strain. The bacterium, designated as Z2, was identified as Alcaligenes sp. In the single-factor test and orthogonal test, we measured the AOD600 of Z2.Finally we determined the optimal basal salt medium of degradation bacteria strain Z2. The results showed that optimal carbon and nitrogen sources were sodium citrate and yeast, and the optimal basal salt medium were sodium citrate 0.2%, yeast 0.7%, NaCl 2%, CaCl2 0.006%, FeCl3 0.0003%, K2HPO4 0.05%, KH2PO4 0.07%. Z2 could multiply in the optimal basal salt medium, which laid the foundation for its use in bio-remediation of contaminated soil.The rusults of study on the degradation characteristics of Z2 shows that: when the culture temperature is 30℃,pH7.0, substrate concentration is 100 mg L-1, inoculation quantity is 10%, after 7 days, the highest degradation rate of quinclorac reached 90%. Between 25℃and35℃, in the neutral and slightly acidic environment, the substrate concentration at 100 mg L-1 inoculation quantity at 10%, Z2 can grow fine and has a good degradation rate of quinclorac.Under certain conditions, in black soil, along with inoculation quantity raising, the degradation rate of quinclorac increases. When conditions were respectively changed at 30℃, pH7.0, the inoculation quantity per gram water-free soil 8.2×1011 CFU, the soil moisture content of 30%~40%, Z2 can grow fine and has a good degradation rate of quinclorac in black soil. Under certain conditions, in the non-sterilized black soil and inoculating Z2 stain, degradation rate of quinclorac is 88.6%,in cinnamon soil is 63.5%, in saline-alkali soil is 46.1%;In the sterilized soil and inoculating Z2 stain, degradation rate of quinclorac is respectively 81.5%, 66.8%, 45.3% in black soil, cinnamon soil, saline-alkali soil. That degradation rate of quinclorac is higher than treatments without Z2. Therefore, Z2 can obviously promote the degredation of quinclorac in soil. And the degradation rate of quinclorac in different soil is in turn from high to low: black soil, cinnamon soil, saline-alkali soil.