Endophytic and Epiphytic Hydrocarbon-Utilizing Bacteria Associated with Root Nodules of Legumes

摘要

Nodules of Viciafaba roots were found to contain Rhizobium strains that could utilize crude oil as a sole source of carbon and energy. Scanning electron microscopy also revealed the occurrence of huge numbers of bacteria associated with the nodule surfaces. Transmission electron microscopy showed that a few of these epiphytes succeeded in colonizing the outer cells of the nodule tissues. Those epiphytic bacteria comprized oil-utilizing strains. Eleven oil-utilizing strains were isolated and purified, they were found to belong to the genera Pseudomonas, Bacillus, Nocardia and Rhizobium. The individual strains could grow on a wide range of pure aliphatic and aromatic hydrocarbons as sole sources of carbon and energy. Most of the epiphytic isolates could in addition grow in a nitrogen free medium, indicating that they could fix nitrogen gas. These results demonstrate the high potential of legume crops for phytoremediating oily environments. The nitrogen fixed contributes to accelerating the microbial degradation of hydrocarbons.