The Effect Of S. Alterniflora Invasion On Aerobic Methane Oxidizing Bacteria In Wetlands Along The Beach

Methane is one of the important greenhouse gases.The atmospheric methane content is only 1/27 of the carbon dioxide,but it caused 25 times greenhouse effect than the same quality of carbon dioxide.Methane has significant influence on global warming.Wetland is one of the world’s largest sources of methane emissions,accounting for 32%of global methane emissions.of wetlands can and they play an extremely important role in the process of methane oxidation.Plant invasion is one of bigest environment problems.Plant invasion causes changes of microbial community structure,which influence soil carbon and nitrogen cycle and greenhouse gas emissions.In 1982,in order to consolidate the beach,foreign species Spartina alterniflor was introduced to the coastal wetlands of Yancheng in Jiangsu Province.Spartina alterniflor grow quickly and soon occupy native plant growth environment.We want to study the influence of Spartina alterniflor invasion on the wetland soil properties and methanotrophic community structure.In order to illustrate the influence of Spartina alterniflora invision on the methanotrophic activity and community structure in coastal wetlands.We selected Yancheng coastal wetland as our study site.We measured the soil methane oxidation potential of the native Phragmites australis,Suaeda salsa and Spartina alterniflora.We detected the variation characteristics of soil organic carbon,total nitrogen,available phosphorus and salinity.Using qPCR、T-RFLP,Sanger sequencing,DNA-SIP and Miseq sequencing,we studied the abundance and relative abundance of methanotrophic community.The main results are as follows:1.The invasion of Spartina alterniflora significantly changed the soil properties of Yancheng wetland,including the increase of the soil organic carbon,total nitrogen and available phosphorus content.Spartina alterniflora invasion affected the methanotrophic community.The relative abundance of Type II methanotrophs Methylocystis decreases after the Spartina alterniflora invision.Meantimes,Type I methanotrophs increases after the invision of Spartina alterniflora,and the longer time invision,the more Type I methanotrophs were detected.2.Spartina alteniflora invasion significantly increased the carbon,nitrogen and phosphorus fixation in the Yancheng wetland,but these trends become weaker with the increase of soil depth.Spartina alterniflora invasion changes the community structure of methanotrophs in wetlands.Be different from methanotrophs of Type II in the Phragmites australis wetland and Type Ib(76 bp)in the Suaeda salsa wetland.Methanotrophs in Spartina alterniflora wetland is major in 438 bp of T-RF and 510 bp of Type Ia.The relative abundance of these groups changed in different soil depths.T-RFLP results showed different patterns of methanotrophs in these two different seasons(June 2015 and September 2014).3.Different vegetation soil types in Yancheng wetland had different methane oxidation capacities and different active methanotrophic groups mediate these differences.Using DNA-SIP method,we found Spartina alterniflora invasion had effects on the community structure of these "active" methanotrophs.Type I methanotrophs Methylomicrobium is the main active methanotrophic group in Phragmites australis soils and Suaeda sasaa soils.One unclassified group belong to Methylococcaceae is the main group consuming methane in Mud flat soils.Compared with these three native soils,methanotrophs in Spartina alterniflora soils belonged to more groups,such as Methylomicrobium,Methylomonas and Methylobacter.In addition to methanotrophs,some methylotrophs that can use intermediate products produced by methanotrophs were also detected by SIP.The methylotrophs in Yancheng coastal soils included Methylotenera,Methylophaga and unclassified methylotrophic groups from Marine.This study fills the blank of research on the effects of Spartina alterniflora invision on aerobic methanotrophs in the coastal wetland.It has an important significance to interpret the changes of methane cycle after exotic species invasion in Chinese coastal wetland,and to understand the regional and global carbon cycle and climate change.