2026/04/29 by Ivan Čepička, Ondřej Pomahač, Daniel Méndez-Sánchez +8 · 1 voice
Biochemistry, Genetics and Molecular Biology · Environmental Science · #Protist diversity and phylogeny #Legionella and Acanthamoeba research #Microbial Community Ecology and Physiology
paper · doi:10.21203/rs.3.rs-8743768/v1
Abstract Anaerobic single-celled eukaryotes illustrate the remarkable diversity of adaptations to life without oxygen, including multiple mitochondrial reductions and various symbiotic interactions with prokaryotes. However, rare lineages remain virtually unexplored. From 11 collected cells, we conducted an in-depth investigation of the ciliate Legendrea loyezae , a rare predator of microscopic animals. Using single-cell transcriptomics and metagenomics, we generated a high-completeness host transcriptome and macronuclear genome and characterized a novel type of mitochondrion-related organelle. By integrating omics data with microscopy and 3D imaging, we uncover an exceptionally complex endosymbiotic consortium with two methanogenic archaea and two bacteria, including the first strictly anaerobic member of Legionellales , and the most reduced member of Thermodesulfobacteriota , with a 0.5-Mb genome. We infer the metabolic potential and extensive complementarity within this pentapartite system and align it with spatial relationships. Our results expand the known complexity of anaerobic eukaryotes and demonstrate the feasibility of comprehensive analyses of rare protists.