Novel thermophilic genera Geochorda gen. nov. and Carboxydochorda gen. nov. from the deep terrestrial subsurface reveal the ecophysiological diversity in the class Limnochordia

作者：Olga V. Karnachuk, Anastasia P. Lukina, Marat R. Avakyan, Vitaly V. Kadnikov, Shahjahon Begmatov, Alexey V. Beletsky, Ksenia G Vlasova, А. А. Новиков, V. A. Shcherbakova, Andrey V. Mardanov, Nikolai V. Ravin · 发表于：Frontiers in Microbiology · 年份：2024 · DOI：10.3389/fmicb.2024.1441865 · 被引用次数：16 · 研究领域：Microbial Community Ecology and Physiology、Genomics and Phylogenetic Studies、Wastewater Treatment and Nitrogen Removal

The class Limnochordia harbors a single cultivated member, the mesophilic Limnochorda pilosa , which was isolated from a meromictic lake. Despite numerous molecular signatures reported in various ecosystems, the ecophysiological versatility of this deeply branched lineage of Firmicutes (Bacillota) remains poorly understood. The objective of this study was to use targeted cultivation, based on metagenome-assembled genomes from a deep terrestrial aquifer in Western Siberia, to isolate two new thermophilic members of the class. These isolates, described as Geochorda subterranea gen. nov. sp. nov. and Carboxydochorda subterranea gen. nov. sp. nov. within the Geochordaceae fam. nov., were capable of both anaerobic and aerobic respiration using fumarate and O 2 , respectively, with simple sugars as electron donors. The cultivated Geochordaceae have demonstrated fermentative growth and degradation of various polymers, including starch, maltose, maltodextrin, xylan, and chitin. The carboxydotrophic C. subterranea sp. nov. exhibited autotrophic growth via the Calvin–Benson–Bassham cycle, using CO, H 2 , and formate as electron donors and O 2 as an electron acceptor, adding metabolic flexibility to the bacterium in the nutrient-depleted “deep biosphere” and supporting the possibility of aerobic metabolism in the deep subsurface. The broad physiological potential deciphered from physiological experiments and comparative genomic data explains the widespread distribution of uncultivated m...