Affiliation:
1. Department of Earth, Environmental and Life Sciences (DiSTAV) University of Genoa Genoa Italy
2. National Biodiversity Future Center (NBFC) Palermo Italy
3. Department of Integrative Marine Ecology (EMI) Stazione Zoologica Anton Dohrn—National Institute of Marine Biology, Ecology and Biotechnology, Genoa Marine Centre (GMC) Genoa Italy
Abstract
AbstractBlue holes are vertical water‐filled openings in carbonate rock that exhibit complex morphology, ecology, and water chemistry. In this study, macroscopic microbial mat structures found in complete anoxic conditions in the Faanu Mudugau Blue Hole (Maldives) were studied by metagenomic methods. Such communities have likely been evolutionary isolated from the surrounding marine environment for more than 10,000 years since the Blue Hole formation during the last Ice Age. A total of 48 high‐quality metagenome‐assembled genomes (MAGs) were recovered, predominantly composed of the phyla Chloroflexota, Proteobacteria and Desulfobacterota. None of these MAGs have been classified to species level (<95% ANI), suggesting the discovery of several new microbial taxa. In particular, MAGs belonging to novel bacterial genera within the order Dehalococcoidales accounted for 20% of the macroscopic mat community. Genome‐resolved metabolic analysis of this dominant microbial fraction revealed a mixotrophic lifestyle based on energy conservation via fermentation, hydrogen metabolism and anaerobic CO2 fixation through the Wood–Ljungdahl pathway. Interestingly, these bacteria showed a high proportion of ancestral genes in their genomes providing intriguing perspectives on mechanisms driving microbial evolution in this peculiar environment. Overall, our results provide new knowledge for understanding microbial life under extreme conditions in blue hole environments.
Reference72 articles.
1. Evolutionary history of carbon monoxide dehydrogenase/acetyl‐CoA synthase, one of the oldest enzymatic complexes;Adam P.S.;Proceedings of the National Academy of Sciences USA,2018
2. Binning metagenomic contigs by coverage and composition;Alneberg J.;Nature Methods,2014
3. Microbial ecology across an oxic‐anoxic interface in a sulphidic blue hole;Azzola A.;Memorie dell'Istituto Italiano di Speleologia S II,2022
4. Bacterial enzymes for dissimilatory sulfate reduction in a marine microbial mat (Black Sea) mediating anaerobic oxidation of methane;Basen M.;Environmental Microbiology,2011
5. The leaking bucket of a Maldives atoll: implications for the understanding of carbonate platform drowning;Betzler C.;Marine Geology,2015