Analysis Of Bacterial Community Diversity And Water Viral Diversity In Different Types Of Wetlands Of Northeast China

Wetlands are one of the major ecosystems on the earth.Wetlands microorganisms play a vital role in wetland ecosystem,which take part in a variety of biogeochemical cycles.Northeast China is one of the main wetland distribution regions in China,with a variety of wetland resources.Although lots of researchers studied the microbial communities in various environments,such as soil,river and ocean ecosystems,studies related to the microbial communities in wetlands with aquatic and terrestrial characteristics have been limited.In this study,sediment and water samples were synchronously collected from six typical wetlands in northeast China,including three different types of wetlands:coastal wetlands?Liaohekou and Yalujiangkou?,swamp wetlands?Nanwenghe,Honghe and Zhalong?and lake wetland?Xingkaihu?.In order to reveal the diversity and distribution of bacterial and viral communities in different types of wetlands of northeast China,Illumina Mi Seq sequencing method were applied to detect the similarities and differences of bacterial community composition between sediment and water;Randomly Amplified Polymorphic DNA PCR?RAPD-PCR?were used to analyze the viral assemblages in different types of wetlands water;metagenomic techniques were involved in the investigation of viral communities structures and function prediction in different types of wetlands water.The results were showed as follows:1.The bacterial community compositions of sediment and water in different types of wetlands of northeast China was detected by the Illumina Mi Seq sequencing method.The results revealed that the composition of bacterial communities in the two coastal wetlands was similar to that in the other four freshwater wetlands.The dominant phyla?relative abundance>5%?across all sediment samples were Proteobacteria and Chloroflexi,while those across all water samples were Proteobacteria,Actinobacteria and Bacteroidetes.Bacterial community composition was distinctly different among wetlands at the phylum and genus levels.The indicator species for different sediment and water samples also varied greatly according to the wetland types.The alpha diversity of bacterial community was higher in sediment samples than in water samples,and the lowest alpha diversity was detected in two coastal wetlands,both in sediment and in water samples.All bacterial communities in sediment or in water samples were separated into distinct groups according to wetland type,and the communities in two coastal wetlands were highly similar to each other both in sediment and water samples,respectively.Bacterial communities in sediment and water were driven by different environmental factors,bacterial communities in sediment were mainly affected by the available K content,while in water,the communities were mainly affected by total P and total K.2.The virial community compositions of water in different types of wetlands of northeast China was detected by the randomly amplified polymorphic DNA PCR.Viral community compositions distinctly differed among different water samples,the composition of viral communities in the two coastal wetlands was similar to that in the other four freshwater wetlands.Mantel test revealed that the structure of viral communities in wetlands water was most closely related to the water NH₄⁺-N content,followed to inorganic C,total K,total P,total C and NO₃^–-N.167 bands were randomly cut and cloned,and 87 positive clones were sequenced.The results showed that these sequences were annotated as viruses,bacteria and eukaryotes at the amino acid level,of which the proportion of virus sequences was 39.08%,and the majority of viral sequences belonged to Microviridae?38.24%?viral families among the hit viral homologs.Based on the analysis of bacterial and viral community structure of wetland water,the results showed that the structure of bacterial and viral community in water has both similarities and differences,and both the bacterial and viral community structure of Nanwenghe were similar with that of Honghe,and the bacterial community structure of Zhalong was similar with that of Xingkaihu,while the viral community structure were distinctly different of Zhalong and Xingkaihu.3.The virial metagenomic compositions and function of water in different types of wetlands of northeast China was detected by the metagenomic technique.In this study,22,523,7,467,12,043,12,353,13,250 and 17,146 assembled sequences?contigs?in viral metagenomes of wetlands waters from Liaohekou,Yalujiangkou,Zhalong,Nanwenghe,Xingkaihu and Honghe,respectively.Most of the sequences in the six viromes of different types of wetlands water belonged to single-stranded DNA?ss DNA?viruses,which were Microviridae and Circoviridae.There were 28,28,27,28,28 and 27 categories of functional genes being assigned to Liaohekou,Yalujiangkou,Zhalong,Nanwenghe,Xingkaihu and Honghe,respectively.Among the categories of functional genes,“Phages,Prophages,Transposable elements,Plasmids”was the most abundant category,and the viruses contain functional genes related to metabolism.