The coupling of the plant and microbial catabolisms of phenanthrene in the rhizosphere of Medicago sativa
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- 作者：Anna Muratova ; amuratova@yahoo.com" class="auth_mail" title="E-mail the corresponding author ; ecbio@ibppm.sgu.ru" class="auth_mail" title="E-mail the corresponding author ; Ekaterina Dubrovskaya ; Sergey Golubev ; Vyacheslav Grinev ; Marina Chernyshova ; Olga Turkovskaya
- 关键词：Medicago sativa ; Root exudates ; Rhizobacteria ; Phenanthrene ; Biodegradation pathways
- 刊名：Journal of Plant Physiology
- 出版年：2015
- 出版时间：1 September 2015
- 年：2015
- 卷：188
- 期：Complete
- 页码：1-8
- 全文大小：1046 K
文摘
We studied the catabolism of the polycyclic aromatic hydrocarbon phenanthrene by four rhizobacterial strains and the possibility of enzymatic oxidation of this compound and its microbial metabolites by the root exudates of alfalfa (Medicago sativa L.) in order to detect the possible coupling of the plant and microbial metabolisms under the rhizospheric degradation of the organic pollutant. A comparative study of phenanthrene degradation pathways in the PAH-degrading rhizobacteria Ensifer meliloti, Pseudomonas kunmingensis, Rhizobium petrolearium, and Stenotrophomonas sp. allowed us to identify the key metabolites from the microbial transformation of phenanthrene, including 9,10-phenanthrenequinone, 2-carboxybenzaldehyde, and 1-hydroxy-2-naphthoic, salicylic, and o-phthalic acids. Sterile alfalfa plants were grown in the presence and absence of phenanthrene (0.03 g kg−1) in quartz sand under controlled environmental conditions to obtain plant root exudates. The root exudates were collected, concentrated by ultrafiltration, and the activity of oxidoreductases was detected spectrophotometrically by the oxidation rate for various substrates. The most marked activity was that of peroxidase, whereas the presence of oxidase and tyrosinase was detected on the verge of the assay sensitivity. Using alfalfa root exudates as a crude enzyme preparation, we found that in the presence of the synthetic mediator, the plant peroxidase could oxidize phenanthrene and its microbial metabolites. The results indicate the possibility of active participation of plants in the rhizospheric degradation of polycyclic aromatic hydrocarbons and their microbial metabolites, which makes it possible to speak about the coupling of the plant and microbial catabolisms of these contaminants in the rhizosphere.