Biology subjects

Jogler, C.

Publications and source records attributed to Jogler, C..

4 recordsLinked to original sources

bioRxiv2026

Phagocytosis without mitochondria is a lineage trait of planctomycetal bacteria of prey

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.

microbiology↗

bioRxiv2026

Conserved bacterial genes for biosynthesis of the algal morphogen thallusin span land and sea

Bacterial signals control the development of marine algae, yet the molecular basis of these cross-kingdom interactions remains largely unknown. Thallusin is the paradigmatic case: isolated in 2005, it induces rhizoid and cell wall formation in the green seaweed Ulva at picomolar concentrations, but its biosynthesis has remained elusive for two decades. Comparative genomics across five bacterial phyla identifies a conserved set of genes - the eustigmatophyte bacterial operon (ebo) - as determinants of thallusin biosynthesis. Isotope labeling, heterologous expression, and gene deletion in Stieleria maiorica show that the aromatic scaffold derives from a cyclitol precursor and L-aspartate, with subsequent prenylation and cyclization. Searching 124,295 prokaryotic genomes identifies producers in eleven bacterial lineages, including soil cyanobacteria, establishing thallusin as a widespread cross-kingdom signal reaching beyond the ocean.

microbiology↗

bioRxiv2025

The glycine betaine-cobalamin feedback loop drives cross-feeding between marine bacteria and algae

Heterotrophic bacteria supply cobalt-containing cobalamin (Cbl) to marine microalgae, which in return provide organic substrates. Such metabolic cross-feeding can regulate the species composition of prolific marine plankton and biofilms. Algal-produced glycine betaine (GB) can be catabolized by bacteria using a Cbl-dependent demethylase (MtgBCD). Yet, GBs impact on bacterial Cbl production during cross-feeding, and its control by cobalt scarcity remains elusive. Here, we demonstrate that Phaeobacter inhibens bacteria boost their Cbl production 25-fold when grown in monocultures with GB compared to glucose. During co-cultivation, P. inhibens satisfied the Cbl requirements of Gephyrocapsa huxleyi algae. Transcriptomic analysis of mono- and co-cultures revealed co-expression of mtgBCD and gbcAB genes encoding Cbl-dependent and -independent GB demethylases, respectively. Distinct growth defects of deletion mutants indicate that P. inhibens switches from Cbl-dependent to -independent GB demethylation under cobalt limitation, involving a Cbl riboswitch. Our findings suggest a positive feedback loop in which algal GB release stimulates the bacterial supply of Cbl. We predict the breakdown of this interaction under naturally occurring cobalt limitation which potentially contributes to the transient nature of algal blooms. Comparative genomics indicate that this mechanism is widespread in Rhodobacterales and other abundant marine Alphaproteobacteria, underscoring its pivotal role in global ocean productivity.

microbiology↗

bioRxiv2019

The novel shapeshifting bacterial phylum Saltatorellota

Our current understanding of a free-living bacterium - capable of withstanding a variety of environmental stresses-is represented by the image of a peptidoglycan-armored rigid casket. The making and breaking of peptidoglycan greatly determines cell shape. The cytoplasmic membrane follows this shape, pressed towards the cell wall by turgor pressure. Consequently, bacteria are morphologically static organisms, in contrast to eukaryotic cells that can facilitate shape changes. Here we report the discovery of the novel bacterial phylum Saltatorellota, that challenges this concept of a bacterial cell. Members of this phylum can change their shape, are capable of amoeba-like locomotion and trunk-formation through the creation of extensive pseudopodia-like structures. Two independent Saltatorellota cells can fuse, and they employ various forms of cell division from budding to canonical binary fission. Despite their polymorphisms, members of the Saltatorellota do possess a peptidoglycan cell wall. Their genomes encode flagella and type IV pili as well as a bacterial actin homolog, the saltatorellin. This protein is most similar to MamK, a dynamic filament-forming protein, that aligns and segregates magnetosome organelles via treadmilling. We found saltatorellin to form filaments in both, E. coli and Magnetospirillum gryphiswaldense, leading to the hypothesis that shapeshifting and pseudopodia formation might be driven by treadmilling of saltatorellin.

microbiology↗