1
|
Lu J, Mu X, Zhang S, Song Y, Ma Y, Luo M, Duan R. Coupling of submerged macrophytes and epiphytic biofilms reduced methane emissions from wetlands: Evidenced by an antibiotic inhibition experiment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:166710. [PMID: 37652383 DOI: 10.1016/j.scitotenv.2023.166710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 08/24/2023] [Accepted: 08/28/2023] [Indexed: 09/02/2023]
Abstract
Wetlands are the largest natural methane source, but how submerged macrophytes affect methane emission remains controversial. In this study, the impacts of submerged macrophytes on methane fluxes, water purification, and epiphytic microbial community dynamics were investigated in simulated wetlands (with and without Hydrilla verticillata) treated with norfloxacin (NOR) for 24 days. Mean methane fluxes were significantly lower in treatments with Hydrilla verticillata (56.84-90.94 mg/m2/h) than bulks (65.96-113.21 mg/m2/h) (p < 0.05) during the experiment regardless of NOR. The relative conductivity (REC) values, H2O2, and malondialdehyde (MDA) contents increased in plant leaves, while water nutrients removal rates decreased with increasing NOR concentration at the same sampling time. The partial least squares path model analysis revealed that plant physiological indices and water nutrients positively affected methane fluxes (0.72 and 0.49, p < 0.001). According to illumina sequencing results of 16S rRNA and pmoA genes, α-proteobacteria (type II) and γ-proteobacteria (type I) were the dominant methanotroph classes in all epiphytic biofilms. The ratio of type I/type II methanotrophs and pmoA gene abundance in epiphytic biofilm was considerably lower in treatment with 16 mg/L NOR than without it (p < 0.05). pmoA gene abundance was negatively correlated with methane fluxes (p < 0.05). Additionally, the assembly of epiphytic bacterial community was mainly governed by deterministic processes, while stochastic dispersal limitation was the primary assembly process in the epiphytic methanotrophic community under NOR stress. The deterministic process gained more importance with time both in bacterial and methanotrophic community assembly. Network analysis revealed that relationships among bacteria in epiphytic biofilms weakened with time but associations among methanotrophic members were enhanced under NOR stress over time. It could be concluded that submerged macrophytes-epiphytic biofilms symbiotic system exhibited potential prospects to reduce methane emissions from wetlands under reasonable management.
Collapse
Affiliation(s)
- Jianhui Lu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Xiaoying Mu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Songhe Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Yingying Song
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Yu Ma
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Min Luo
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| | - Rufei Duan
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, PR China; College of Environment, Hohai University, Nanjing 210098, PR China
| |
Collapse
|
2
|
Yang L, Zhang S, Lv X, Liu Y, Guo S, Hu X, Manirakiza B. Vallisneria natans decreased CH 4 fluxes in wetlands: Interactions among plant physiological status, nutrients and epiphytic bacterial community. ENVIRONMENTAL RESEARCH 2023; 224:115547. [PMID: 36822529 DOI: 10.1016/j.envres.2023.115547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 02/13/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Submerged macrophytes provide niches for epiphytic microbes (including aerobic methanotrophs) growth. However, little is known about the impacts of submerged macrophytes growth status and nutrients loadings on methanotroph community and methane release in wetlands. In the present study, methane fluxes, bacterial and methanotroph community in epiphytic biofilm, and environmental parameters were investigated during Vallisneria natans senescence in wetlands under low (VnL) and high (VnH) nutrients for seven weeks. Relative conductivity and concentration of H2O2, total chlorophyll and malondialdehyde were higher in leaves of V. natans in VnH than VnL at the same sampling time. Nutrients loading increased methane fluxes in treatments with or without (Control) macrophytes, while healthy V. natans plants reduced the methane flux and nutrients concentration in water columns. CH4 fluxes were positively correlated to temperature and COD (p < 0.05). Methane oxidation rates were 3.04-31.68 μmol methane mg-1 fresh weight of V. natans leaves - epiphytic biofilm within 1 h. Proteobacteria, Cyanobacteria, Bacteroidetes, Verrucomicrobia, Planctomycetes, Actinobacteria and Acidobacteria were dominant phylum in all epiphytic biofilms. The mean abundances of pmoA/16S rRNA were higher in VnL than VnH. According to Illumina sequencing results of pmoA gene, γ-proteobacteria and α-proteobacteria were the dominant methanotroph class in epiphytic biofilm from VnH and VnL, respectively. Among seven detected methanotrophic genera, Methylomonas was significantly higher in VnH than VnL. Network analysis revealed that there were much closer relationships between the environmental parameters and epiphytic bacterial community in VnH than in VnL. COD and MDA were negatively correlated with Methyloglobulus, Methylosarcina, Methylobacter and Methylocystis, but positively correlated with Methylomonas and Methylosinus. This study highlights that methanotrophs in epiphytic biofilm play important roles in methane-oxidizing, which can be affected by plant physiological status and environmental parameters.
Collapse
Affiliation(s)
- Liu Yang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, PR China; College of Environment, Hohai University, Nanjing, 210098, PR China
| | - Songhe Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, PR China; College of Environment, Hohai University, Nanjing, 210098, PR China.
| | - Xin Lv
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, PR China; College of Environment, Hohai University, Nanjing, 210098, PR China
| | - Yuansi Liu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, PR China; College of Environment, Hohai University, Nanjing, 210098, PR China
| | - Shaozhuang Guo
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, PR China; College of Environment, Hohai University, Nanjing, 210098, PR China
| | - Xiuren Hu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, PR China; College of Environment, Hohai University, Nanjing, 210098, PR China
| | - Benjamin Manirakiza
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, PR China; College of Environment, Hohai University, Nanjing, 210098, PR China
| |
Collapse
|