Year: 2026
Type: preprint
Abstract: Phagocytosis is considered energetically out of reach for prokaryotes. Mitochondria-first models of eukaryogenesis therefore suggest a non-phagocytic archaeal host. Yet two recently described planctomycetes lack mitochondria and engulf entire bacteria. Whether this mode of predation is an oddity of two isolates or the hallmark of a bacterial lineage remained unresolved. Here, we report eight additional predatory Planctomycetota from three aquatic habitats. The ten cultured strains now span two classes of the phylum Planctomycetota , ‘ Candidatus Uabimicrobiia’ and one newly proposed class. Using engineered fluorescent prey, we show that nine strains internalize prey into fully sealed compartments whereas one digests its prey externally, a non-engulfing predator for comparison. The strains additionally divide by two distinct modes, however, not correlating with their feeding behavior. Sequence- and structure-based searches detect no eukaryotic phagocytosis protein conserved across the engulfing strains. The actin homologue previously proposed to mediate uptake occurs only in three engulfing strains. Routine engulfment by aerobic bacteria without mitochondria thus unsettles a premise of mitochondria-first models and reopens the question of which cell plans could have hosted the mitochondrial endosymbiont.
Authors: Carmen E. Wurzbacher, Jonathan Hammer, Tom Haufschild, Begüm Serra Büyüktarakçı, Alejandro Jiménez González, Feriel Bouderka, André R. Soares, Julian M. Müller, Luis Felipe Muriel-Millan, María Leticia Ferrelli, Vivien Hotter, Martin Taubert, Kirsten Küsel, Damien Devos, Andreas Klingl, Alexander J. Probst, Siv G. E. Andersson, Nicolai Kallscheuer, Christian Jogler
Institutions: Friedrich Schiller University Jena, Uppsala University, University of Duisburg-Essen, Ludwig-Maximilians-Universität München, Centre National de la Recherche Scientifique, Inserm, Université de Lille, Institut Pasteur de Lille, Center for Infection and Immunity of Lille, Consejo Nacional de Investigaciones Científicas y Técnicas, Instituto de Biotecnología y Biología Molecular, Universidad Nacional de La Plata
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
Funders: Carl-Zeiss-Stiftung, Friedrich-Schiller-Universität Jena, Université de Lille, Freistaat Thüringen, Deutsche Forschungsgemeinschaft, Volkswagen Foundation, Knut och Alice Wallenbergs Stiftelse, Studienstiftung des Deutschen Volkes, Thüringer Ministerium für Bildung, Wissenschaft und Kultur, Thüringer Ministerium für Wirtschaft, Wissenschaft und Digitale Gesellschaft
OpenAlex ID: W7223957172