PDF(Pubmed)
Abstract：
Karst caves have recently been demonstrated to act as a sink for atmospheric methane, due in part to consumption by microbes residing in caves that can oxidize methane at atmospheric levels. However, our knowledge about the responsible atmospheric methane-oxidizing bacteria (atmMOB) in this vast habitat remains limited to date. To address this issue, weathered rock samples from three karst caves were collected in Guilin City and subjected to high-throughput sequencing of pmoA and 16S rRNA genes. The results showed that members of the high-affinity upland soil cluster (USC), especially upland soil cluster gamma (USCγ), with absolute abundances of 104 to 109 copies · g-1 dry sample, dominated the atmMOB communities, while Proteobacteria and Actinobacteria dominated the overall bacterial communities. Moreover, USCγ was a keystone taxon in cooccurrence networks of both the atmMOB and the total bacterial community, whereas keystone taxa in the bacterial network also included Gaiella and Aciditerrimonas. Positive links overwhelmingly dominated the cooccurrence networks of both atmMOB and the total bacterial community, indicating a consistent response to environmental disturbances. Our study shed new insights on the diversity and abundances underlining atmMOB and total bacterial communities and on microbial interactions in subterranean karst caves, which increased our understanding about USC and supported karst caves as a methane sink. IMPORTANCE Karst caves have recently been demonstrated to be a potential atmospheric methane sink, presumably due to consumption by methane-oxidizing bacteria. However, the sparse knowledge about the diversity, distribution, and community interactions of methanotrophs requires us to seek further understanding of the ecological significance of methane oxidation in these ecosystems. Our pmoA high-throughput results from weathered rock samples from three karst caves in Guilin City confirm the wide occurrence of atmospheric methane-oxidizing bacteria in this habitat, especially those affiliated with the upland soil cluster, with a gene copy number of 104 to 109 copies per gram dry sample. Methanotrophs and the total bacterial communities had more positive than negative interactions with each other as indicated by the cooccurrence network, suggesting their consistent response to environmental disturbance. Our results solidly support caves as an atmospheric methane sink, and they contribute to a comprehensive understanding of the diversity, distribution, and interactions of microbial communities in subsurface karst caves.
摘要：
岩溶洞穴最近被证明是大气甲烷的汇，部分原因是居住在洞穴中的微生物消耗，这些微生物可以在大气水平上氧化甲烷。然而,迄今为止，我们对这个广阔栖息地中负责任的大气甲烷氧化细菌（atmMOB）的了解仍然有限。为了解决这个问题，采集桂林市三个岩溶洞穴的风化岩石样品，并对pmoA和16SrRNA基因进行高通量测序。结果表明，高亲和力旱地土壤簇(USC)的成员，特别是旱地土壤团簇伽马(USCγ)，绝对丰度为104至109拷贝·g-1干样品，主导了atmMOB社区，而变形杆菌和放线菌主导了整个细菌群落。此外，USCγ是atmMOB和总细菌群落共生网络中的基石分类单元，而细菌网络中的梯形分类群还包括Gaiella和Aciditerrimonas。正联系压倒性地主导了atmMOB和总细菌群落的共生网络，表明对环境干扰的反应一致。我们的研究对atmMOB和总细菌群落的多样性和丰度以及地下岩溶洞穴中的微生物相互作用提供了新的见解，这增加了我们对南加州大学的了解，并支持岩溶洞穴作为甲烷汇。重要性岩溶洞穴最近被证明是潜在的大气甲烷汇，大概是由于甲烷氧化细菌的消耗。然而,关于多样性的稀疏知识，分布，甲烷氧化菌的群落相互作用要求我们进一步了解甲烷氧化在这些生态系统中的生态意义。我们从桂林市三个岩溶洞穴的风化岩石样品中获得的pmoA高通量结果证实了该生境中大气甲烷氧化细菌的广泛存在，特别是那些与陆地土壤集群有联系的地方，基因拷贝数为每克干样品104到109个拷贝。如共生网络所示，甲烷营养生物和总细菌群落彼此之间的积极相互作用多于消极相互作用，表明它们对环境干扰的一致反应。我们的结果坚定地支持洞穴作为大气甲烷汇，它们有助于全面理解多样性，分布，地下岩溶洞穴中微生物群落的相互作用。
