Physiological and cellular responses of the 2,4-D degrading bacterium, Burkholderia cepacia YK-2, to the phenoxyherbicides 2,4-D and 2,4,5-T.
Our previous research has demonstrated that novel 43-kDa DnaK and 41-kDa GroEL proteins are synthesized in Burkholderia sp. YK-2 in response to sublethal concentrations of 2,4-D stress [Cho et al. (2000) Curr Microbiol 41:33-38]. In this study, we have extended this work to examine the cellular responses of strain YK-2 to stresses induced in response to the phenoxyherbicides 2,4-D or 2,4,5-T. Strain YK-2 exhibited a more sensitive response to 2,4,5-T stress than to 2,4-D stress, as shown in physiological and morphological changes, suggesting a greater cytotoxic effect of 2,4,5-T. SEM analyses revealed the presence of perforations and irregular rod forms with wrinkled surfaces for cells treated with either herbicide. These irregularities were found more frequently for 2,4,5-T-treated cells than for 2,4-D-treated cells. Analysis of cellular fatty acids showed similar effects in the shifts of total cellular fatty acid composition in response to 2,4-D and 2,4,5-T. Strain YK-2 could degrade 2.25 m M 2,4-D completely during 28 h of incubation with transient production of 2,4-dichlorophenol as a metabolite; however, 2,4,5-T was not catabolized at any of the concentrations tested. BIOLOG and 16S rDNA analyses revealed that strain YK-2 was 98% similar to the Burkholderia cepacia species cluster; therefore, we have designated this strain as B. cepacia YK-2.
Cho
Yun-Seok
YS
Department of Life Science, Soonchunhyang University, P.O. Box 97, Asan, Chung-Nam, 336-600, Korea.
Kahng
Hyung-Yeel
HY
Kim
Chi-Kyung
CK
Kukor
Jerome J
JJ
Oh
Kye-Heon
KH
D015085:2,4,5-Trichlorophenoxyacetic Acid / Q000378:metabolism / Q000633:toxicity*; D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism / Q000633:toxicity*; D001673:Biodegradation, Environmental; D016956:Burkholderia cepacia / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure*; D004275:DNA, Ribosomal / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis; D018869:Heat-Shock Response; D006540:Herbicides / Q000378:metabolism / Q000494:pharmacology / Q000633:toxicity*; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
D004275:DNA, Ribosomal; D005227:Fatty Acids; D006540:Herbicides; D012336:RNA, Ribosomal, 16S; D015084:2,4-Dichlorophenoxyacetic Acid; D015085:2,4,5-Trichlorophenoxyacetic Acid