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

Nine predatory Planctomycetota strains internalize engineered fluorescent prey into fully sealed compartments without mitochondria, extending a lineage trait beyond two isolates.

• Why it matters: Phagocytosis is thought energetically out of reach for prokaryotes, and mitochondria-first models imply a non-phagocytic archaeal host.
• What they did: The study cultured eight additional predatory Planctomycetota from three aquatic habitats (ten total) and used engineered fluorescent prey to test engulfment versus external digestion.
• The result: Sequence- and structure-based searches found no conserved eukaryotic phagocytosis protein across engulfing strains, and actin homologue presence occurred only in three engulfing strains.