Chlortetracycline Detoxification in Maize via Induction of Glutathione S-Transferases after Antibiotic Exposure

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• 作者：Michael H. Farkas ; James O. Berry ; Diana S. Aga
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：February 15, 2007
• 年：2007
• 卷：41
• 期：4
• 页码：1450 - 1456
• 全文大小：190K
• 年卷期：v.41,no.4(February 15, 2007)
• ISSN：1520-5851

文摘

Soil contamination with nonmetabolized antibiotics is anemerging environmental concern, especially on agriculturalcroplands that receive animal manure as fertilizer. Inthis study, phytotoxicity of chlortetracycline (CTC) antibioticson pinto beans (Phaseolus vulgaris) and maize (Zeamays) was investigated under controlled conditions. Whengrown in CTC-treated soil, a significant increase in theactivities of the plant stress proteins glutathione S-transferases (GST) and peroxidases (POX) were observedin maize plants, but not in pinto beans. In vitro conjugationreactions demonstrated that the induced GST in maizecatalyzed the conjugation of glutathione (GSH) with CTC,producing stable conjugates that were structurallycharacterized using liquid chromatography/mass spectrometry. The antibiotic-induced GST produced CTC-glutathioneconjugate at relative concentrations 2-fold higher thanthat produced by constitutively expressed GST extractedfrom untreated maize. On the other hand, GST extracted frompinto beans (both treated and untreated) did not efficientlycatalyze glutathione conjugation with CTC. These resultssuggest that maize is able to detoxify chlortetracycline viathe glutathione pathway, whereas pinto beans cannot.This may explain the observed stunted growth of pinto beansafter antibiotic treatment. This study demonstrates theimportance of plant uptake in determining the fate of antibioticsin soil and their potential phytotoxicity to susceptibleplants.