TY - JOUR
T1 - Methanotrophs dominate methanogens and act as a methane sink in a subterranean karst cave
AU - Cheng, Xiaoyu
AU - Zeng, Zhilin
AU - Liu, Xiaoyan
AU - Li, Lu
AU - Wang, Hongmei
AU - Zhao, Rui
AU - Bodelier, Paul L.E.
AU - Wang, Weiqi
AU - Wang, Yiheng
AU - Tuovinen, Olli H.
N1 - Data archiving: on request
PY - 2023/9/20
Y1 - 2023/9/20
N2 - Karst caves are potential sinks of atmospheric methane due to microbial consumption. However, knowledge gaps on methanogens (methane producing microorganisms) and their interaction with methane-oxidizing bacteria (MOB) hinder our further understanding about methane dynamics in karst caves. Here we reported methanogenic community composition and their interaction with MOBs in the Heshang Cave to comprehensively understand methane cycling in subsurface biosphere. MOBs in karst cave were dominated by high-affinity MOB, upland soil cluster (USC), with USCγ pmoA gene abundance within the range of 1.34 × 104 to 1.8 × 107 copies·g−1 DW. In contrast, methanogens were dominated by Methanoregula and cluster ZC-I. The mcrA numbers were 7.21 × 103 to 8.31 × 104 copies·g−1 DW, 1–3 orders of magnitude lower than those of MOB. The inter-domain network analysis indicated that MOBs and methanogens cooperated more in the interior of the cave. Despite of the higher number of methanogenic nodes in the network, MOB dominated the keystone taxa, suggesting a leading functional role of MOB. MOB in caves showed a comparable with or higher potential methane oxidizing rate (PMOR, 0.63 ng CH4·g−1 DW·h−1 in sediment versus 11.02 ng CH4·g−1 DW·h−1 in weathered rock) than those in soils, whereas methane produced by methanogens was undetected. Collectively, high absolute abundances of MOB, high PMORs, the dominance of methanotrophic keystone taxa in the inter-domain network confirmed the superiority of MOBs over methanogens in the oligotrophic karst cave, mounting new evidence on caves as an important methane sink in terms of the interaction between methanogens and MOBs.
AB - Karst caves are potential sinks of atmospheric methane due to microbial consumption. However, knowledge gaps on methanogens (methane producing microorganisms) and their interaction with methane-oxidizing bacteria (MOB) hinder our further understanding about methane dynamics in karst caves. Here we reported methanogenic community composition and their interaction with MOBs in the Heshang Cave to comprehensively understand methane cycling in subsurface biosphere. MOBs in karst cave were dominated by high-affinity MOB, upland soil cluster (USC), with USCγ pmoA gene abundance within the range of 1.34 × 104 to 1.8 × 107 copies·g−1 DW. In contrast, methanogens were dominated by Methanoregula and cluster ZC-I. The mcrA numbers were 7.21 × 103 to 8.31 × 104 copies·g−1 DW, 1–3 orders of magnitude lower than those of MOB. The inter-domain network analysis indicated that MOBs and methanogens cooperated more in the interior of the cave. Despite of the higher number of methanogenic nodes in the network, MOB dominated the keystone taxa, suggesting a leading functional role of MOB. MOB in caves showed a comparable with or higher potential methane oxidizing rate (PMOR, 0.63 ng CH4·g−1 DW·h−1 in sediment versus 11.02 ng CH4·g−1 DW·h−1 in weathered rock) than those in soils, whereas methane produced by methanogens was undetected. Collectively, high absolute abundances of MOB, high PMORs, the dominance of methanotrophic keystone taxa in the inter-domain network confirmed the superiority of MOBs over methanogens in the oligotrophic karst cave, mounting new evidence on caves as an important methane sink in terms of the interaction between methanogens and MOBs.
U2 - 10.1016/j.scitotenv.2023.164562
DO - 10.1016/j.scitotenv.2023.164562
M3 - Article
SN - 0048-9697
VL - 892
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 164562
ER -