Community Structure And Abundance Of Methanogens,Sulfate-reducing Bacteria In Tidal Marsh Soil In The Min River Estuary

The community structure, abundance and vertical profile characteristics of methanogens and sulfate-reducing bacteria were determined using PCR-RFLP technology, sequencing and real-time qPCR in three different vegetation type marshes in the Min River estuarine marsh. The relationships between diversity of the functional microbial groups and methane production rates and soil physicochemical factors were also analysised. Methanobacteriales, Methanomirobiales, Methanosarcinales and Methanococcales were detected at a soil depth of0-30cm in the Phragmites australis marsh, Cyperus malaccensis marsh, Spartina alterniflora marsh. Methanomirobiales was the dominant groups at a soil depth of0-30cm in the Min River estuarine marsh. It indicated that the main pathway of methane production at a depth of0-30cm in the Min River estuarine marsh was H2/CO2because Methanomirobiales was belonged to hydrogenotrophic methanogens. The main genera of methanogen varied with different vegetation types. In addition,the distribution of methanogen communities also presented the vertical change at different soil depth in the same vegetation types marsh. Methanoregula was dominant genus in the three vegetation types marsh. The average abundance of methanogen in the P. australis marsh, C. malaccensis marsh,S. alterniflora marsh determined by real-time quantitative PCR technology were3.72×108copies g-’dws,3.39×107copies g-1dws,5.68×107copies g-1dws, respectively. The average abundance of methanogen at a depth of0-30cm in P. australis marsh soil was significantly higher than that of C. malaccensis marsh(F (1,16)=20.581, P<0.001), and also significantly higher than that of S. alterniflora marsh (F (1,16)=17.751, P<0.001). The abundance of methanogen in the same vegetation type marsh has vertical variation characteristics at different soil depth. Desulfovibrionales, Desulfobacterales, Syntrophobacterales and Clostridiales were detected at a soil depth of0-30cm in the P. australis marsh, C. malaccensis ma.S. alterniflora marsh. Desulfobacterales was the dominant group at a soil depth of0-30cm in the Min River estuarine marsh. The mam genera of sulfate-reducing bacteria varied from different vegetation types marsh soils. The distribution of sulfate-reducing bacteria communities also presents the vertical change at different soil depth in the same vegetation types marsh. Desulfobacterium and Desulfosarcina were the predominant genera of sulfate-reducing bacteria in the Min River estuarine marsh. The average number of sulfate-reducing bacteria in the P. australis marsh, C. malaccensis marsh, S. alterniflora marsh determined by real-time quantitative PCR technology were8.95×107copies g-1dws,1.55×107copies g-1dws, 2.40×107copies g-1dws, respectively. The average abundance of sulfate-reducing bacteria at a depth of0-30cm in the P. australis marsh was significantly higher than that of C. malaccensis marsh(F (1,16)=26.449, P<0.001), and also significantly higher than that of S. alterniflora marsh (F (1,16)=19.013, P=0.001). The abundance of sulfate-reducing bacteria showed vertical variation characteristics at the different soil depth in same vegetation type marsh zone. It showed that the abundance of methanogens and sulfate-reducing bacteria have a remarkable regression relationship with soil organic carbon content, but no significant correlation with other soil physicochemical factors. The relationship between soil physicochemical factors and community composition of methanogen and sulfate-reducing bacteria were analysised based on RDA and CCA. It showed that the composition of methanogen community and salinity had a highly significant correlation (P=0.002). It also had a significant correlation with pH (P=0.036) and no significant correlation with SOC, TN, SOC/TN (P>0.05). The composition of sulfate-reducing bacteria community had a highly significant correlation with pH (P=0.004). It also had a significant correlation with soil moisture content (P=0.022) and no significant correlation with SMC, SOC, TN, SOC/TN, salinity(P>0.05).The regression analysis showed that the rate of methane production significantly linearly increased with the abundances of both methanogens and sulfate-reducing bacteria for the three vegetation zones together. When regression analysis was carried out for single vegetation zone, methane production rate only significantly linearly increased with the abundance of methanogens in the C. malaccensis marsh(y=0.196x-0.008, R2=0.6671, P=0.007, n=9). The rate of methane production did not correlate with the abundance of sulfate-reducing bacteria in each marsh zone (P>0.05, n=9).