The diversification of bacterial populations in wetland habitats: studies on the upper course of Gum-Ho River and its tributary
Division of Biological Sciences, Daegu University, Rep. Korea
In order to determine how a wetland habitat affects bacterial diversity, sediment samples were collected from three sites with different degrees of pollution, one of which is a wetland (site 4) in the upper course of Gum-Ho River, and two sites in a tributary of Gum-Ho River. Of the two sites (sites 1 and 2) in the tributary, the water at site 2 is constantly contaminated by the discharge of effluent from a municipal wastewater treatment plant (WWTP). The metagenomic DNAs of the sediment samples were extracted and amplified with 27F/518R primers and then pyrosequenced with Roche 454 GS-FLX Titanium. The results were expressed as the ratio (%) of equivalent reads to total classifiable reads on the phylum level. The dominant bacterial phyla with more than 10% composition at all sites were Proteobacteria and Firmicutes. These were followed by Bacteroidetes, Actinobacteria, Chloroflexi Acidobacteria, Planctomycetes, Verrucomicrobia and Nitrospirae in varying proportions, depending on their ecological status of each site. Remarkably, Firmicutes which includes spore formers was the most dominant at site 3 where the tributary (loaded by effluent from WWTP) merges with Gum-Ho River and at site 5, near the recreational water zone. Based on diversity evaluations using Shannon (H) and Simpson-index, the bacterial diversity in the water zone of the wetland (site 4) showed the highest value, even surpassing the measured value at the pollution free site 1. These findings indicate that the wetland has the capability to restore its ecology. Therefore, wetlands must be protected to preserve the ecological stability and biodiversity of the surface water.
keywords:wetland ,bacterial diversity,pyrosequencing ,restoring effect,surface waater