Abstract
Kerogen, insoluble macromolecular organic matter in sedimentary rocks, is the most abundant form of organic carbon on Earth and plays a role in deep biosphere processes. It is classified into four types (I–IV) based on origin and chemical composition, yet its influence on microbial communities and carbon cycling remains poorly understood. In this study, we examined how kerogen-rich shales and coals, each containing a distinct kerogen type, shape anaerobic microbial community development and activity. CFU counts showed that kerogen types I and II did not significantly alter overall microbial abundance, while type III-rich rocks inhibited growth, and type IV-rich rocks enhanced it. 16S rRNA gene sequencing revealed that type II-rich rocks selectively enriched for Burkholderiaceae, whereas type IV-rich rocks promoted the proliferation of Cellulomonadaceae and Pleomorphomonadaceae. Gas chromatography showed that CO2 production occurred only in the presence of type II-rich rocks, likely driven by Burkholderiaceae activity. These findings suggest that kerogen structure and geochemical properties drive microbial community assembly and organic matter mobilization in the deep subsurface. Beyond Earth, kerogen type IV-like material is widespread in extraterrestrial environments. Our results indicate the enhancement of the habitability of these environments, offering new insights into the potential for life.
Data availability
The genomic data for this study have been deposited in the Sequence Read Archive (SRA) at the National Center for Biotechnology Information (NCBI) under accession number PRJNA1425804 (https://www.ncbi.nlm.nih.gov/sra/PRJNA1425804).
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Acknowledgements
We thank Mark Sephton at Imperial College London for providing the kerogen samples, Toby Samuels at the Heriot-Watt University and Sophie Nixon at the University of Manchester for the information and advice on the kerogen samples and Jennifer Saito at the Advanced Studies in Genomics, Proteomics and Bioinformatics (ASGPB) at the University of Hawaii at Manoa for the analysis of the DNA samples.
Funding
This research was funded by the NERC Doctoral Training Partnership grant 363 (NE/L002558/1), Principal’s Career Development Scholarship (PCDS) and NWO GoSpace (R/010809). CSC was supported through the Science and Technologies Facilities Council (STFC) Grant Number ST/Y001788/1. MSR also acknowledges financial support from the Beatriz Galindo Senior Grant (No. BG23-00132) funded by the Spanish Ministry of Science, Innovation and Universities (MICIU).
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ACW, WW, JOE, JT and CC contributed to the conception and design of the study. ACW, WW and JOE carried out the experimental work. ACW performed data analysis and wrote the first draft of the manuscript. ACW, WW, MSR and CC contributed to the data analysis and interpretation. All authors contributed to the manuscript revision and read and approved the submitted version.
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Waajen, A.C., de Wit, W., Sánchez-Román, M. et al. Kerogen-rich rocks influence growth and composition of an anaerobic microbial community. Sci Rep (2026). https://doi.org/10.1038/s41598-026-42062-5
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DOI: https://doi.org/10.1038/s41598-026-42062-5
