Pyrosequencing Reveals Bacterial Diversity in the Rhizosphere of Three Phragmites australis Ecotypes

Abstract

Here we present the use of high-throughput DNA pyrosequencing to assess bacterial diversity in the rhizosphere of three Phragmites australis ecotypes from the Hexi Corridor, China. In total, 43404 sequences were obtained for the three ecotypes, representing 31 phyla and a small amount of unclassified bacteria. The predominant bacterial groups in the rhizosphere of P. australis were Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Gemmatimonadetes and Planctomycetes. The bacterial community structure varied with the different degrees of wetland degradation, which were exhibited by the three P. australis ecotypes in the study area. At the phylum level, the Caldiserica, Chlamydiae, Deferribacteres, Lentisphaerae, and candidate division WS3 were only detected in the swamp reed (SR) sample. Then, δ-proteobacteria, Acidobacteria, Cyanobacteria and Fusobacteria decreased, the Actinobacteria increased with the degree of degradation from SR through salt meadow reed (SMR) to dune reed (DR). The functional bacterial genera also varied with wetland degradation. The sulfur and sulfate-reducing, nitrifying and nitrogen-fixing bacteria were more abundant in the rhizosphere of the SR sample. Methane-oxidizing bacteria were abundant in the SR and DR samples but less so in the SMR. In our study, pyrosequencing of different P. australis ecotypes provided insight into the structural variation of the rhizosphere bacterial community. This study gave a database for the use of bacteria in the protection and ecological restoration of wetland.