Response of PAH-degrading genes to PAH bioavailability in the overlying water, suspended sediment, and deposited sediment of the Yangtze River.
The degrading genes of hydrophobic organic compounds (HOCs) serve as indicators of in situ HOC degradation potential, and the existing forms and bioavailability of HOCs might influence the distribution of HOC-degrading genes in natural waters. However, little research has been conducted to study the relationship between them. In the present study, nahAc and nidA genes, which act as biomarkers for naphthalene- and pyrene-degrading bacteria, were selected as model genotypes to investigate the response of polycyclic aromatic hydrocarbon (PAH)-degrading genes to PAH bioavailability in the overlying water, suspended sediment (SPS), and deposited sediment of the Yangtze River. The freely dissolved concentration, typically used to reflect HOC bioavailability, and total dissolved, as well as sorbed concentrations of PAHs were determined. Phylogenetic analysis showed that all the PAH-ring hydroxylating dioxygenase gene sequences of Gram-negative bacteria (PAH-RHD[GN]) were closely related to nahAc, nagAc, nidA, and uncultured PAH-RHD genes. The PAH-RHD[GN] gene diversity as well as nahAc and nidA gene copy numbers decreased in the following order: deposited sediment>SPS>overlying water. The nahAc and nidA gene abundance was not significantly correlated with environmental parameters but was significantly correlated with the bioavailable existing forms of naphthalene and pyrene in the three phases. The nahAc gene copy numbers in the overlying water and deposited sediment were positively correlated with freely dissolved naphthalene concentrations in the overlying and pore water phases, respectively, and so were nidA gene copy numbers. This study suggests that the distribution and abundance of HOC-degrading bacterial population depend on the HOC bioavailability in aquatic environments.
School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China. Electronic address: xiaxh@bnu.edu.cn.
Xinghui
X
Xia
School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China.
Na
N
Xia
Agricultural and Environmental Chemistry Graduate Group, University of California, Davis, One Shields Avenue, Davis 95616, CA, United States.
Yunjia
Y
Lai
School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China.
Jianwei
J
Dong
School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China.
Pujun
P
Zhao
School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China.
Baotong
B
Zhu
School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China.
Zhihuang
Z
Li
School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China.
Wan
W
Ye
School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China.
Yue
Y
Yuan
School of Environment, Beijing Normal University, State Key Laboratory of Water Environment Simulation, Beijing 100875, China.
Junxiong
J
Huang
D001673:Biodegradation, Environmental; D001682:Biological Availability; D015415:Biomarkers / Q000378:metabolism; D002681:China; D049308:Dioxygenases / Q000235:genetics; D004785:Environmental Pollutants / Q000032:analysis* / Q000378:metabolism; D005798:Genes, Bacterial / Q000235:genetics*; D014644:Genetic Variation; D019015:Geologic Sediments / Q000737:chemistry*; D006090:Gram-Negative Bacteria / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000378:metabolism; D011721:Pyrenes; D045483:Rivers / Q000737:chemistry*
D015415:Biomarkers; D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D011721:Pyrenes; C030984:pyrene; D049308:Dioxygenases
Bioavailability; Biodegradation; Freely dissolved concentration; PAH-ring hydroxylating dioxygenase genes; Suspended sediment; nahAc and nidA gene