S-Space College of Agriculture and Life Sciences (농업생명과학대학) Dept. of Agricultural Biotechnology (농생명공학부) Theses (Master's Degree_농생명공학부)
Isolation and Characterization of Butachlor-Degrading Bacteria from Paddy Soils
- 농업생명과학대학 농생명공학부
- Issue Date
- 서울대학교 대학원
- 학위논문 (석사)-- 서울대학교 대학원 : 농생명공학부, 2014. 2. 가종억.
- The chloroacetanilide herbicide butachlor, N-(butoxymethyl)-2-chloro-N-(2,6-diethylphenyl)-acetamide, is applied to agricultural soils to control pre-emergent weeds. Butachlor is one of the commonly applied herbicides in South America and Asia. Because of the extensive use of butachlor, the herbicide and its metabolites have been detected in agricultural soil and aquatic environment. Butachlor was shown to have toxicity to earthworm and affect microbial community structure and enzyme activities. In addition, butachlor caused stomach tumors in rat and oxidative DNA damage in human. Therefore, cleanup of butachlor residues from the environment is great concern. In this study, three butachlor-degrading bacteria and six syntrophic pairs of butachlor degraders were isolated from paddy soils. Based on repetitive extragenic palindromic PCR (REP-PCR) and 16S rRNA gene analysis, the isolates were related to members of the genera Sphingobium, Sphingomonas, Mycobacterium, and Rhodococcus. All isolates and syntrophic pairs were able to utilize butachlor as a sole source of carbon and energy. The butachlor-degrading isolates and the syntrophic pair appeared to degrade butachlor through 2-chloro-N-(2,6-diethylphenyl) acetamide (CDEPA), 2,6-diethylaniline (DEA), phenol, and 4-amino-3,5-diethyl (PADE) by gas chromatography-mass spectrometry (GC-MS) analysis. Four of the five representative isolates had 1 to 6 plasmids. Among the four plasmid-containing isolates, plasmid-cured strains were obtained from 2 strains. The cured strains could not degrade butachlor anymore, suggesting that the butachlor degradative genes were on the plasmid DNAs in these strains.