关键词: 除草剂, 2, 4-D, 分离鉴定, 除草剂降解, 降解途径

Abstract: 2,4-dichlorophenoxyacetic acid (2,4-D) is a systemic and broad-spectrum foliar herbicide which can control  broadleaf weeds. But because of its frequent use, 2,4-D has resulted in considerable pollution to water and soil and thus threatened the ecological environment and human health. In this paper, 85 strains were isolated and screened from 2,4-D contaminated soil samples (inorganic salt medium with 2,4-D as the sole carbon source) by enrichment culture. 16S rDNA analysis showed that it belongs to Pseudomonas, Bacillus, Lysinibacillus, Paenibacillus, Brevibacillus, Serratia, Methylobacterium, Cupriavidus, Rhodococcus, Larender (Rahnella), Staphylococcus, Enterobacter and Mycobacterium. The strain herbicide tolerance test showed that Pseudomonas can tolerate a higher concentration of 2,4-D with a maximum tolerated concentration of 8 g/L. Some strains were selected to be cultured with 2,4-D as the sole carbon source. The degradation ability of the strain was determined by detecting 2,4-D degradation products (4-aminoantipyrine colorimetric measurement and high performance liquid chromatography), the LC/MS and LC-QTOF were used to detected its metabolites. A total of 11 strains were identified with highly 2,4-D degradation ability. The utilization rate of L1, L2, L4 and L6 cultured for 72 h was 17.3%, 28.07%, 38.97% and 49.02% respectively. The preliminary analysis and structural prediction of the metabolites of the above selected strains were carried out by LC/MS and LC-QTOF. The results showed that a total of 4 strains could convert 2,4-D de-chained groups into phenolic substances, presumably the product was 2,4-dichlorophenol (2,4-DCP).

Key words: herbicide, 2,4-D, isolation and identification of the strains, herbicide degradation, degradation pathway