期刊
BIODEGRADATION
卷 32, 期 4, 页码 419-433出版社
SPRINGER
DOI: 10.1007/s10532-021-09940-3
关键词
Pesticide; 2; 4-Dichlorophenoxyacetic acid; Methanogenic; Biodegradation; Soil; Microbial diversity
资金
- CoordenacAo de Aperfeicoamento de Pessoal de Nivel Superior-Brasil (CAPES) [001]
- Wageningen Institute for Environment and Climate Research (WIMEK), the Netherlands
The study found that methanogenic enrichment cultures obtained from Amazonian soil can biotransform 2,4-D to 4-chlorophenol and phenol, but degradation rate decreases and biotransformation halts at high 2,4-D concentrations. There was no enrichment of known organohalide-respiring bacteria in the microbial community.
2,4-Dichlorophenoxyacetic acid (2,4-D) is the third most applied pesticide in Brazil to control broadleaf weeds in crop cultivation and pastures. Due to 2,4-D's high mobility and long half-life under anoxic conditions, this herbicide has high probability for groundwater contamination. Bioremediation is an attractive solution for 2,4-D contaminated anoxic environments, but there is limited understanding of anaerobic 2,4-D biodegradation. In this study, methanogenic enrichment cultures were obtained from Amazonian top soil (0-40 cm) and deep soil (50 -80 cm below ground) that biotransform 2,4-D (5 mu M) to 4-chlorophenol and phenol. When these cultures were transferred (10% v/v) to fresh medium containing 40 mu M or 160 mu M 2,4-D, the rate of 2,4-D degradation decreased, and biotransformation did not proceed beyond 4-chlorophenol and 2,4-dichlorophenol in the top and deep soil cultures, respectively. 16S rRNA gene sequencing and qPCR of a selection of microbes revealed no significant enrichment of known organohalide-respiring bacteria. Furthermore, a member of the genus Cryptanaerobacter was identified as possibly responsible for phenol conversion to benzoate in the top soil inoculated culture. Overall, these results demonstrate the effect of 2,4-D concentration on biodegradation and microbial community composition, which are both important factors when developing pesticide bioremediation technologies.
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