Preliminary Study On Microbial Community Characteristics And Influencing Factors In A Degraded Wetland Of The Yellow River Delta

DAPI staining, FDA activity and dilute plate method were applied to study the microbial characteristics and the seasonality dynamics of the degraded wetland in YRD. The relationships of the microbial community with soil salinity and rhizosphere effects were studied. Base on the study, the seasonality dynamics and vertical distribution characters of microbial characteristics were explored. Halophilic microbes were seprated. This research gave theory support on the exploration of the wetland soil microbial resource and the foundation of plant-microorganism bioremediation system.1. There was a very significant negative linear relationship between the salinity and the total number of microorganisms, overall microbial activity, or diversity of culturally viable microbes(p<0.01) all of the year. Bacteria had a high content in the culturable microorganisms, more than 90%. Actinomycetes and fungi were fewer than bacteria. There were usually no fungi detected at A2 and A3. Halophilic bacteria were more than actinomycetes and fungi. Bacteria and actinomycetes had better ability to survive in the saline environment of the degraded wetland than fungi. There were more actinomycetes and fungi availabe in the halophilic tests. This results implied that most of the actinomycetes and fungi on YRD might be halophilic. 3 halophilic bacteria were seperated: Pseudomonas mendocina, Burkholderia gluma, Acinetobacter johnsonii through BIOLOG identification.2. The seasonality dynamics of microbial size and activity was summer> srping> autumn> winter. Microbial activity changed most along to the seasonality. The diversity's seasonality dynamics was different among different spots. A1, A2,A4 had obvious seasonality dynamics. The microbial diversity was influenced less by seaonality in A3 and A5.3. Microbial community had obvious vertical distribution. The decreasing trends in the size, activity and diversity were observed with increasing soil depth. The differences between 0~10 cm layer (upper layer) and 10~20 cm layer were tiny. But there were bigger differences between upper layer and 20~30 cm layer. This implied that aerobic microorganisms were dominant in the wetland microbial community.4. Five kinds of plants (Chinese Tamarisk, Reed, Lalang Grass and Capillary Wormwood Herb, Common Seepweed) had obvious positive effects on the microbial communities. Rhizosphere microbial community had higher values of size, activity and diversity than non-rhizosphere microbial community. The microbial characters were also affected by the seasonality. There were usually highest values in summer and lowest values in winter. Changes in spring and autumn were not the same. Microbial diversity changed little during summer, autumn and spring. The lowest value of micorbial diversity happened in winter. Compared to Chinese Tamarisk, Reed, Lalang Grass and Capillary Wormwood Herb, Common Seepweed had the stongest rhizosphere effect.