Procaryotic Diversity and Hydrogenotrophic Methanogenesis in an Alkaline Spring (La Crouen, New Caledonia)

Abstract

(1) Background: The geothermal spring of La Crouen (New Caledonia) discharges warm (42 °C) alkaline water (pH~9) enriched in dissolved nitrogen with traces of methane, but its microbial diversity has not yet been studied. (2) Methods: Cultivation-dependent and -independent methods (e.g., Illumina sequencing and quantitative PCR based on 16S rRNA gene) were used to describe the prokaryotic diversity of this spring. (3) Results: Prokaryotes were mainly represented by Proteobacteria (57% on average), followed by Cyanobacteria, Chlorofexi, and Candidatus Gracilibacteria (GN02/BD1-5) (each > 5%). Both potential aerobes and anaerobes, as well as mesophilic and thermophilic microorganisms, were identified. Some of them had previously been detected in continental hyperalkaline springs found in serpentinizing environments (The Cedars, Samail, Voltri, and Zambales ophiolites). Gammaproteobacteria, Ca. Gracilibacteria and Thermotogae were significantly more abundant in spring water than in sediments. Potential chemolithotrophs mainly included beta- and gammaproteobacterial genera of sulfate-reducers (Ca. Desulfobacillus), methylotrophs (Methyloversatilis), sulfur-oxidizers (Thiofaba, Thiovirga), or hydrogen-oxidizers (Hydrogenophaga). Methanogens (Methanobacteriales and Methanosarcinales) were the dominant Archaea, as found in serpentinization-driven and deep subsurface ecosystems. A novel alkaliphilic hydrogenotrophic methanogen (strain CAN) belonging to the genus Methanobacterium was isolated, suggesting that hydrogenotrophic methanogenesis occurs at La Crouen.

Aqueous Geochemical and Microbial Variation Across Discrete Depth Intervals in a Peridotite Aquifer Assessed Using a Packer System in the Samail Ophiolite, Oman

“…Aerobic oxidation by bacteria of the genus Hydrogenophaga has been identified as a particularly widespread process across many serpentinizing settings, including the Samail Ophiolite (W. J. Brazelton et al., 2017; Daae et al., 2013; Frouin et al., 2018; Marques et al., 2018; Mei et al., 2016; Neubeck et al., 2017; Quéméneur et al., 2015, 2021; Rempfert et al., 2017; Suzuki et al., 2014; Tiago & Veríssimo, 2013; Woycheese et al., 2015). Sequences affiliated with Hydrogenophaga were detected in both BA1A and BA1D in about half of our samples, but accounted for <1 of reads in all samples except BA1A_2019_0‐30, where it accounted for (Figure ).…”

“…Cultivation and genomic data from the literature and the presence of considerable () in our sample with the highest relative abundance of Meiothermus suggest heterotrophic denitrification as a possible operative metabolism for the population at BA1. To date, gene sequences affiliated with Meiothermus have been detected at three other serpentinizing sites: Manleluag in the Zambales Ophiolite, Philippines (Woycheese et al., 2015), Prony Bay, New Caledonia (Mei et al., 2016), and La Crouen, New Caledonia (Quéméneur et al., 2021). Sequences related to another member of Deinococcota phlyum, the genus Truepera , have been detected somewhat more widely in serpentinizing environments including Cabeço de Vide, Portugal (Tiago & Veríssimo, 2013), Prony Bay, New Caledonia (Frouin et al., 2018; Mei et al., 2016), the Coast Range Ophiolite, USA (Sabuda et al., 2020, 2021), Voltri, Italy (Quéméneur et al., 2015), and the Chimaera Seeps, Turkey (Neubeck et al., 2017).…”

“…Taxa related to Thermodesulfovibrionia have been identified in other serpentizing settings including the Coast Range Ophiolite, USA (Glombitza et al., 2021; Sabuda et al., 2020), Zambales Ophiolite, the Philippines (Woycheese et al., 2015), Lost City hydrothermal field, Mid‐Atlantic Ridge (W. J. Brazelton et al., 2006), La Crouen, New Caledonia (Quéméneur et al., 2021), Old City hydrothermal field, SW Indian Ridge (Quéméneur et al., 2021), and the Chimaera Seeps, Turkey (Neubeck et al., 2017). Bioenergetic, metagenomic, and metatranscriptomic evidence of bacterial reduction has been particularly strongly demonstrated at the Coast Range Ophiolite (Sabuda et al., 2020) and at Lost City (Lang et al., 2018).…”

“…Ridge (Quéméneur et al, 2021), and the Chimaera Seeps, Turkey (Neubeck et al, 2017). Bioenergetic, metagenomic, and metatranscriptomic evidence of bacterial  2 4 SO reduction has been particularly strongly demonstrated at the Coast Range Ophiolite (Sabuda et al, 2020) and at Lost City (Lang et al, 2018).…”

“…Taxa related to Thermodesulfovibrionia have been identified in other serpentizing settings including the Coast Range Ophiolite, USA (Glombitza et al, 2021;Sabuda et al, 2020), Zambales Ophiolite, the Philippines (Woycheese et al, 2015), Lost City hydrothermal field, Mid-Atlantic Ridge (W. J. Brazelton et al, 2006), La Crouen, New Caledonia (Quéméneur et al, 2021), Old City hydrothermal field, SW Indian NOTHAFT ET AL.…”