Mangrove crab intestine and habitat sediment microbiomes cooperatively work on carbon and nitrogen cycling

Prasert Tongununui, Yuki Kuriya, Masahiro Murata, Hideki Sawada, Michihiro Araki, Mika Nomura, Katsuji Morioka, Tomoaki Ichie, Kou Ikejima, Kohsuke Adachi

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Mangrove ecosystems, where litter and organic components are degraded and converted into detrital materials, support rich coastal fisheries resources. Sesarmid (Grapsidae) crabs, which feed on mangrove litter, play a crucial role in material flow in carbon-rich and nitrogen-limited mangrove ecosystems; however, the process of assimilation and conversion into detritus has not been well studied. In this study, we performed microbiome analyses of intestinal bacteria from three species of mangrove crab and five sediment positions in the mud lobster mounds, including the crab burrow wall, to study the interactive roles of crabs and sediment in metabolism. Metagenome analysis revealed species-dependent intestinal profiles, especially in $\textit{Neosarmatium smithi}$, while the sediment microbiome was similar in all positions, albeit with some regional dependency. The microbiome profiles of crab intestines and sediments were significantly different in the MDS analysis based on OTU similarity; however, 579 OTUs (about 70% of reads in the crab intestinal microbiome) were identical between the intestinal and sediment bacteria. In the phenotype prediction, cellulose degradation was observed in the crab intestine. Cellulase activity was detected in both crab intestine and sediment. This could be mainly ascribed to $\textit{Demequinaceae}$, which was predominantly found in the crab intestines and burrow walls. Nitrogen fixation was also enriched in both the crab intestines and sediments, and was supported by the nitrogenase assay. Similar to earlier reports, sulfur-related families were highly enriched in the sediment, presumably degrading organic compounds as terminal electron acceptors under anaerobic conditions. These results suggest that mangrove crabs and habitat sediment both contribute to carbon and nitrogen cycling in the mangrove ecosystem via these two key reactions.
Original languageEnglish (US)
Pages (from-to)e0261654
Issue number12
StatePublished - Dec 31 2021
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2022-01-06
Acknowledgements: The authors thank Professor Kohei Ohnishi of the Research Institute of Molecular Genetics, Kochi University, for technical assistance with the metagenome analysis. The authors gratefully acknowledge Dr. Fujio Hyodo of the Research Core for Interdisciplinary Sciences, Okayama University, and Dr. Shuichi Igarashi of the Faculty of Agriculture and Marine Science, Kochi University, for stable isotope analysis. The authors also express special thanks to Mami Sugioka and Hikari Kamiichi for their general technical support. We would like to thank Editage ( for English language editing.

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences
  • General Biochemistry, Genetics and Molecular Biology
  • General Medicine


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