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Mulec J, Skok S, Pašić L. Low Bacterial Diversity and Nitrate Levels in Cores from Deep Boreholes in Pristine Karst. Life (Basel) 2024; 14:677. [PMID: 38929661 PMCID: PMC11204850 DOI: 10.3390/life14060677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 05/09/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
This study investigates the nitrate gradients within the deep biosphere of karst carbonate rocks and their resident microbiota. Samples were taken from borehole cores at depths down to 350 m below the surface, collected during geological site investigations for proposed railway tunnels and analysed using 16S rRNA amplicon sequencing. 16S rRNA amplicon sequencing analysis revealed relatively low microbial diversity, which can serve as a reliable indicator of the pristine nature of deep karst. However, some local hotspots of diversity are independent of depth. Pseudomonadota dominated the samples, with Gammaproteobacteria dominating at the class level. The low nitrate content in deep karst, in contrast to higher values closer to the surface, serves as an additional marker of its undisturbed and unpolluted status. Based on the prediction of functional profiles from 16S rRNA sequencing data, nitrates remain low due to indigenous microbial denitrification and assimilatory nitrate reduction. Pathways related to nitrogen fixation, ammonia assimilation, and nitrification were not confirmed. When elevated nitrate levels are observed in karst, they are most probably related to anthropogenic activities. Environmental factors other than depth and nitrate content play an important role in shaping bacterial communities.
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Affiliation(s)
- Janez Mulec
- Karst Research Institute, Research Centre of the Slovenian Academy of Sciences and Arts, Titov trg 2, 6230 Postojna, Slovenia;
- UNESCO Chair on Karst Education, University of Nova Gorica, 5271 Vipava, Slovenia
| | - Sara Skok
- Karst Research Institute, Research Centre of the Slovenian Academy of Sciences and Arts, Titov trg 2, 6230 Postojna, Slovenia;
| | - Lejla Pašić
- Sarajevo Medical School, University Sarajevo School of Science and Technology, Hrasnička cesta 3a, 71000 Sarajevo, Bosnia and Herzegovina;
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Li Q, Cheng X, Liu X, Gao P, Wang H, Su C, Huang Q. Ammonia-oxidizing archaea adapted better to the dark, alkaline oligotrophic karst cave than their bacterial counterparts. Front Microbiol 2024; 15:1377721. [PMID: 38659982 PMCID: PMC11041041 DOI: 10.3389/fmicb.2024.1377721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 03/28/2024] [Indexed: 04/26/2024] Open
Abstract
Subsurface karst caves provide unique opportunities to study the deep biosphere, shedding light on microbial contribution to elemental cycling. Although ammonia oxidation driven by both ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) is well explored in soil and marine environments, our understanding in the subsurface biosphere still remained limited to date. To address this gap, weathered rock and sediment samples were collected from the Xincuntun Cave in Guilin City, an alkaline karst cave, and subjected to high-throughput sequencing and quantification of bacterial and archaeal amoA, along with determination of the potential nitrification rates (PNR). Results revealed that AOA dominated in ammonia oxidation, contributing 48-100% to the PNR, and AOA amoA gene copies outnumbered AOB by 2 to 6 orders. Nitrososphaera dominated in AOA communities, while Nitrosopira dominated AOB communities. AOA demonstrated significantly larger niche breadth than AOB. The development of AOA communities was influenced by deterministic processes (50.71%), while AOB communities were predominantly influenced by stochastic processes. TOC, NH4+, and Cl- played crucial roles in shaping the compositions of ammonia oxidizers at the OTU level. Cross-domain co-occurrence networks highlighted the dominance of AOA nodes in the networks and positive associations between AOA and AOB, especially in the inner zone, suggesting collaborative effort to thrive in extreme environments. Their high gene copies, dominance in the interaction with ammonia oxidizing bacteria, expansive niche breadth and substantial contribution to PNR collectively confirmed that AOA better adapted to alkaline, oligotrophic karst caves environments, and thus play a fundamental role in nitrogen cycling in subsurface biosphere.
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Affiliation(s)
- Qing Li
- School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Xiaoyu Cheng
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Xiaoyan Liu
- School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Pengfei Gao
- School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Hongmei Wang
- School of Environmental Studies, China University of Geosciences, Wuhan, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Chuntian Su
- Institute of Karst Geology, CAGS/Key Laboratory of Karst Dynamics, MNR & GZAR, Guilin, China
- Pingguo Guangxi, Karst Ecosystem, National Observation and Research Station, Pingguo, Guangxi, China
| | - Qibo Huang
- Institute of Karst Geology, CAGS/Key Laboratory of Karst Dynamics, MNR & GZAR, Guilin, China
- Pingguo Guangxi, Karst Ecosystem, National Observation and Research Station, Pingguo, Guangxi, China
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Man BY, Xiang X, Cheng XY, Wang HM, Su CT, Huang QB, Luo Y, Zhang C, Cheng G, Ni YY, Shao XH. Deconstructing the Dimensions of Mycobiome Fingerprints in Luohandu Cave, Guilin, Southern China. Microorganisms 2024; 12:211. [PMID: 38276196 PMCID: PMC10818497 DOI: 10.3390/microorganisms12010211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/14/2024] [Accepted: 01/18/2024] [Indexed: 01/27/2024] Open
Abstract
Subterranean karst caves are windows into the terrestrial subsurface to deconstruct the dimensions of mycobiome fingerprints. However, impeded by the constraints of remote locations, the inaccessibility of specimens and technical limitations, the mycobiome of subterranean karst caves has remained largely unknown. Weathered rock and sediment samples were collected from Luohandu cave (Guilin, Southern China) and subjected to Illumina Hiseq sequencing of ITS1 genes. A total of 267 known genera and 90 known orders in 15 phyla were revealed in the mycobiomes. Ascomycota dominated all samples, followed by Basidiomycota and Mortierellomycota. The sediments possessed the relatively highest alpha diversity and were significantly different from weathered rocks according to the diversity indices and richness metrics. Fifteen families and eight genera with significant differences were detected in the sediment samples. The Ca/Mg ratio appeared to significantly affect the structure of the mycobiome communities. Ascomycota appeared to exert a controlling influence on the mycobiome co-occurrence network of the sediments, while Ascomycota and Basidiomycota were found to be the main phyla in the mycobiome co-occurrence network of weathered rocks. Our results provide a more comprehensive dimension to the mycobiome fingerprints of Luohandu cave and a new window into the mycobiome communities and the ecology of subterranean karst cave ecosystems.
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Affiliation(s)
- Bai-Ying Man
- College of Life Science, Shangrao Normal University, Shangrao 334001, China; (X.X.); (Y.L.); (C.Z.); (G.C.); (Y.-Y.N.); (X.-H.S.)
- Key Laboratory for Regional Plants Conservation and Ecological Restoration of Northeast Jiangxi, Shangrao Normal University, Shangrao 334001, China
| | - Xing Xiang
- College of Life Science, Shangrao Normal University, Shangrao 334001, China; (X.X.); (Y.L.); (C.Z.); (G.C.); (Y.-Y.N.); (X.-H.S.)
- Key Laboratory for Regional Plants Conservation and Ecological Restoration of Northeast Jiangxi, Shangrao Normal University, Shangrao 334001, China
| | - Xiao-Yu Cheng
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China;
- State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences, Wuhan 430074, China
| | - Hong-Mei Wang
- School of Environmental Studies, China University of Geosciences, Wuhan 430074, China;
- State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences, Wuhan 430074, China
| | - Chun-Tian Su
- Institute of Karst Geology, CAGS/Key Laboratory of Karst Dynamics, MNR & GZAR, Guilin 541004, Guangxi, China; (C.-T.S.); (Q.-B.H.)
- Pingguo Guangxi, Karst Ecosystem, National Observation and Research Station, Pingguo 531406, Guangxi, China
| | - Qi-Bo Huang
- Institute of Karst Geology, CAGS/Key Laboratory of Karst Dynamics, MNR & GZAR, Guilin 541004, Guangxi, China; (C.-T.S.); (Q.-B.H.)
- Pingguo Guangxi, Karst Ecosystem, National Observation and Research Station, Pingguo 531406, Guangxi, China
| | - Yang Luo
- College of Life Science, Shangrao Normal University, Shangrao 334001, China; (X.X.); (Y.L.); (C.Z.); (G.C.); (Y.-Y.N.); (X.-H.S.)
- Key Laboratory for Regional Plants Conservation and Ecological Restoration of Northeast Jiangxi, Shangrao Normal University, Shangrao 334001, China
| | - Chao Zhang
- College of Life Science, Shangrao Normal University, Shangrao 334001, China; (X.X.); (Y.L.); (C.Z.); (G.C.); (Y.-Y.N.); (X.-H.S.)
- Key Laboratory for Regional Plants Conservation and Ecological Restoration of Northeast Jiangxi, Shangrao Normal University, Shangrao 334001, China
| | - Gang Cheng
- College of Life Science, Shangrao Normal University, Shangrao 334001, China; (X.X.); (Y.L.); (C.Z.); (G.C.); (Y.-Y.N.); (X.-H.S.)
- Key Laboratory for Regional Plants Conservation and Ecological Restoration of Northeast Jiangxi, Shangrao Normal University, Shangrao 334001, China
| | - Yu-Yang Ni
- College of Life Science, Shangrao Normal University, Shangrao 334001, China; (X.X.); (Y.L.); (C.Z.); (G.C.); (Y.-Y.N.); (X.-H.S.)
- Key Laboratory for Regional Plants Conservation and Ecological Restoration of Northeast Jiangxi, Shangrao Normal University, Shangrao 334001, China
| | - Xing-Hua Shao
- College of Life Science, Shangrao Normal University, Shangrao 334001, China; (X.X.); (Y.L.); (C.Z.); (G.C.); (Y.-Y.N.); (X.-H.S.)
- Key Laboratory for Regional Plants Conservation and Ecological Restoration of Northeast Jiangxi, Shangrao Normal University, Shangrao 334001, China
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