Bacterial community shifts in depth profiles of Alaskan permafrost soil ecosystems

Abstract

Although thaw of permafrost soil contributes to the increase of microbial activity and consequently to the high emission of greenhouse gases, the study on the bacterial communities in this ecosystem has been neglected. In this study, we carried out the bacterial community composition in active layer soil from the Alaskan high Arctic on the basis of 16S rRNA genes using pyrosequencing. These bacterial habitats contained relatively low number of OTUs ranged from 397 to 1,725 compared to the temperate habitats. Although the bacterial diversity was relatively low, tweenty known divisions and 27 unknown divisions were detected. The phyla of Proteobacteria (35.2%), Actinobacteria (20.9%) and Acidobacteria (16.5%) were predominant. Community shifts were observed significantly along the soil depth profiles, which certain increase or decrease of relative abundance was detected in some phyla. The comparison between communities based on PCoA indicated that the bacterial composition was separated between 25 and 30 depth. This suggests that certain environmental parameters drive the structure of bacterial community in this habitat. This study provides new insight regarding the bacterial communities in the Alaskan high Arctic permafrost.