Introduction
The accelerated biodegradation of 3-nitrophenol (3-NP) in the rhizosphere of giant duckweed (Spirodela polyrrhiza) was investigated.Materials and methods
Biodegradation of 3-nitrophenol in the rhizosphere of a floating aquatic plant, S. polyrrhiza, was investigated by using three river water samples supplemented with 10?mg?l?1 of 3-NP. Isolation and enrichment culture of 3-NP-degrading bacteria were performed in basal salts medium containing 3-NP (50?mg?l?1). The isolated strains were physiologically and phylogenetically characterized by using an API20NE kit and 16S rRNA gene sequencing.Results and discussion
Accelerated removal of 3-NP (100%) was observed in river water samples with S. polyrrhiza compared with their removal in plant-free river water. Also, 3-NP persisted in an autoclaved solution with aseptic plants, suggesting that the accelerated 3-NP removal resulted largely from degradation by bacteria inhabiting the plant rather than from adsorption and uptake by the plant. We successfully isolated six and four strains of 3-NP-degrading bacteria from the roots of S. polyrrhiza and plant-free river water, respectively. Phylogenetic analysis based on 16S rRNA gene divided the 3-NP-degrading bacteria into two taxonomic groups: the genera Pseudomonas and Cupriavidus. The strains belonging to the genus Cupriavidus were only isolated from the roots of duckweed. All strains isolated from the roots utilized 3-NP (0.5?mM) as a sole carbon and energy source, indicating that they could have contributed to the accelerated degradation of 3-NP in the rhizosphere of S. polyrrhiza.Conclusions
The rhizoremediation using S. polyrrhiza and its rhizosphere bacteria can be an effective strategy for cleaning up the 3-NP-contaminated surface waters. 相似文献Social interactions may shape brain development. In primitively eusocial insects, the mushroom body (MB), an area of the brain associated with sensory integration and learning, is larger in queens than in workers. This may reflect a strategy of neural investment in queens or it may be a plastic response to social interactions in the nest. Here, we show that nest foundresses—the reproductive females who will become queens but are solitary until their first workers are born—have larger MBs than workers in the primitively eusocial sweat bee Augochlorella aurata. Whole brain size and optic lobe size do not differ between the two groups, but foundresses also have larger antennal lobes than workers. This shows that increased neural investment in MBs precedes social group formation. Larger MBs among foundresses may reflect the increased larval nutrition provisioned to future queens and the lack of social aggression from a dominant queen upon adult emergence.
相似文献