Phylogenetic Diversity of Aerobic Anoxygenic Phototrophic Bacteria in Eutrophic Zone of Lake Ulansuhai Based on Gene pufM

Abstract:

The diversity of aerobic anoxygenic phototrophic bacteria (AAPB) has been well examined in marine habitats, but that in eutrophic lake are little known. Gene pufM is related to biosynthesis of photosynthetic reaction center and is widely used in diversity analysis of AAPB. This study constructed and analyzed pufM gene library, to reveal the distribution and phylogenetic diversity of AAPB and discuss their role of AAPB in eutrophic zone of Lake Ulansuhai. 52 clones of the library were obtained, analyzed and clustered into 28 operational taxonomic units (OTUs). Coverage analysis showed that the library coverage value was of 71.4%, which indicated that the clone library could provide a fine inventory of AAPB diversity in the lake. Phylogenetic and statistical analysis of clone library revealed a higher AAPB diversity in the lake, which has a sharp contrast with lower total bacteria diversity of the same lake according to our previous study. Sequences obtained in this study belonged to seven subgroups, namely γ-Proteobacteria (44.2%, including Group-1, -2 and -3), β-Proteobacteria (21.2%), Rhodobacter-like (7.69%) and unknown Group-1 (21.2%) and Group-2 (5.77%). Higher proportion of γ-Proteobacteria in lower salinity lake like Ulansuhai, has not been reported before. Some unique AAPB ecotypes were probably related to eutrophic lake habitat. This suggested that AAPB play an important role in maintenance and stability of eutrophic lake ecosystems.