Structure and function of the bacterial communities during rhizoremediation of hexachlorobenzene in constructed wetlands.
Vertical flow constructed wetlands (VF CWs) are considered to be effective for treating organic pollutants. The rhizosphere of macrophytes such as Phragmites sp., Typha sp. serves as an active and dynamic zone for the microbial degradation of organic pollutants. However, it is still not clear how soil bacterial communities respond to macrophytes and pollutants during the process. For this purpose, the seedlings of Phragmites australis and Typha angustifolia were planted respectively in the VF CWs added with HCB at a dose of 2 mg/kg. During 96 days of cultivation, we monitored hexachlorobenzene (HCB) removal efficiency by GC/MS and the structure of the rhizosphere bacterial communities in the different VF CWs by denaturing gradient gel electrophoresis (DGGE), and constructed bacterial clone library based on PCR-amplified 16S rRNA gene. As expected, the rhizosphere bacterial communities also remained insensitive to HCB exposure in the wetland soil. The diversity of these microbes presented two stages, from the varied up and down to equilibrium in the entire experimental period. Molecular analysis revealed that the phylum Firmicutes dominated over the bacterial communities. The genera that increased under HCB stress included the well-known HCB-degrading bacteria (Pseudomonas sp. and Alcaligenes sp.) and other common bacteria found in contaminated soil but with lesser known practical functions (Burkholderia sp., Lysinibacillus fusiformis, and Bacillus cereus). Furthermore, there was a certain variance in the relative abundances of the bacterial phyla and HCB removal efficiency among different VF CW treatments. The degradation of HCB in T. angustifolia microcosms was faster than that in P. australis and unvegetated wetlands, and the highest bacterial diversity and richness was found in the VF CWs comprising T. angustifolia.
Research Center for Pollution Control and Ecological Restoration, Yuxi Normal University, Yuxi, 653100, People's Republic of China.
Cuiping
C
Zhang
Research Center for Pollution Control and Ecological Restoration, Yuxi Normal University, Yuxi, 653100, People's Republic of China.|Institute of Ecology and Geobotany, Yunnan University, Kunming, 650091, People's Republic of China.
Bei
B
Wang
Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China.
Xiaoyan
X
Dai
Research Center for Pollution Control and Ecological Restoration, Yuxi Normal University, Yuxi, 653100, People's Republic of China.
Shuying
S
Li
Research Center for Pollution Control and Ecological Restoration, Yuxi Normal University, Yuxi, 653100, People's Republic of China.
Guangqiu
G
Lu
Research Center for Pollution Control and Ecological Restoration, Yuxi Normal University, Yuxi, 653100, People's Republic of China. yqzhou@yxnu.net.
Yuanqing
Y
Zhou
D001419:Bacteria / Q000145:classification*; D001673:Biodegradation, Environmental; D006581:Hexachlorobenzene / Q000302:isolation & purification*; D006109:Poaceae / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D058441:Rhizosphere; D032401:Typhaceae / Q000378:metabolism; D014871:Water Microbiology; D053833:Wetlands
D012336:RNA, Ribosomal, 16S; D006581:Hexachlorobenzene
Bacterial communities; Hexachlorobenzene; Macrophytes species; PCR-DGGE; Rhizoremediation; Vertical flow constructed wetlands