Gujarathi Ninad P, Haney Bryan J, Park Heidi J, Wickramasinghe S Ranil, Linden James C
Department of Chemical Engineering, Colorado State University, Fort Collins, Colorado 80523, USA.
Biotechnol Prog. 2005 May-Jun;21(3):775-80. doi: 10.1021/bp0496225.
The release of antibiotics to the environment has to be controlled because of serious threats to human health. Hairy root cultures of Helianthus annuus (sunflower), along with their inherent rhizospheric activity, provide a fast growing, microbe-free environment for understanding plant-pollutant interactions. The root system catalyzes rapid disappearance of tetracycline (TC) and oxytetracycline (OTC) from aqueous media, which suggests roots have potential for phytoremediation of the two antibiotics in vivo. In addition, in vitro modifications of the two antibiotics by filtered, cell- and microbe-free root exudates suggest involvement of root-secreted compounds. The modification is confirmed from changes observed in UV spectra of exudate-treated OTC. Modification appears to be more dominant at the BCD chromophore of the antibiotic molecule. Kinetic analyses dismiss direct enzyme catalysis; the modification rates decrease with increasing OTC concentrations. The rates increase with increasing age of cultures from which root exudates are prepared. The decrease in modification rates upon addition of the antioxidant ascorbic acid (AA) suggests involvement of reactive oxygen species (ROS) in the antibiotic modification process.
由于对人类健康构成严重威胁，必须控制抗生素向环境中的释放。向日葵的毛状根培养物及其固有的根际活性，为理解植物与污染物的相互作用提供了一个快速生长、无微生物的环境。根系能催化四环素（TC）和土霉素（OTC）在水介质中迅速消失，这表明根系在体内对这两种抗生素具有植物修复潜力。此外，经过过滤、无细胞和无微生物的根系分泌物对这两种抗生素的体外修饰表明，根系分泌的化合物参与其中。从经分泌物处理的OTC的紫外光谱变化可证实这种修饰。修饰似乎在抗生素分子的BCD发色团处更为显著。动力学分析排除了直接的酶催化作用；修饰速率随OTC浓度的增加而降低。修饰速率随制备根系分泌物的培养物年龄增加而增加。添加抗氧化剂抗坏血酸（AA）后修饰速率降低，这表明活性氧（ROS）参与了抗生素修饰过程。
