title: Profiling bacterial diversity in a limestone cave of the western Loess Plateau of China.
abstract: Bacteria and archaea sustain subsurface cave ecosystems by dominating primary production and fueling biogeochemical cyclings, despite the permanent darkness and shortage of nutrients. However, the heterogeneity and underlying mechanism of microbial diversity in caves, in particular those well connect to surface environment are largely unexplored. In this study, we examined the bacterial abundance and composition in Jinjia Cave, a small and shallow limestone cave located on the western Loess Plateau of China, by enumerating and pyrosequencing small subunit rRNA genes. The results clearly reveal the contrasting bacterial community compositions in relation to cave habitat types, i.e., rock wall deposit, aquatic sediment, and sinkhole soil, which are differentially connected to the surface environment. The deposits on the cave walls were dominated by putative cave-specific bacterial lineages within the γ-Proteobacteria or Actinobacteria that are routinely found on cave rocks around the world. In addition, sequence identity with known functional groups suggests enrichments of chemolithotrophic bacteria potentially involved in autotrophic C fixation and inorganic N transformation on rock surfaces. By contrast, bacterial communities in aquatic sediments were more closely related to those in the overlying soils. This is consistent with the similarity in elemental composition between the cave sediment and the overlying soil, implicating the influence of mineral chemistry on cave microhabitat and bacterial composition. These findings provide compelling molecular evidence of the bacterial community heterogeneity in an East Asian cave, which might be controlled by both subsurface and surface environments.
authors: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science - Chinese Academy of Sciences, Nanjing China.
authors: Yucheng
authors: Y
authors: Wu
authors: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment - Chinese Academy of Sciences, Xi'an China ; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment - Chinese Academy of Sciences, Xi'an China.
authors: Liangcheng
authors: L
authors: Tan
authors: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science - Chinese Academy of Sciences, Nanjing China.
authors: Wuxing
authors: W
authors: Liu
authors: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science - Chinese Academy of Sciences, Nanjing China.
authors: Baozhan
authors: B
authors: Wang
authors: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology - Chinese Academy of Sciences, Nanjing China.
authors: Jianjun
authors: J
authors: Wang
authors: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment - Chinese Academy of Sciences, Xi'an China.
authors: Yanjun
authors: Y
authors: Cai
authors: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science - Chinese Academy of Sciences, Nanjing China.
authors: Xiangui
authors: X
authors: Lin
keywords: 16S rRNA; bacterial diversity; cave; elemental composition; pyrosequencing; rock surface