# Ultrastructure Analysis by Cryo-Electron Tomography Revealed Mesosomes in the Gram-negative Delftia acidovorans

## TL;DR

This study used cryo-electron tomography to discover mesosome-like structures in Delftia acidovorans, a Gram-negative bacterium, providing new insights into its cellular structure and function.

## Contribution

The discovery of mesosome-like structures in a Gram-negative bacterium challenges previous assumptions about their occurrence and function.

## Key findings

- Delftia acidovorans exhibits cytoplasmic membrane invaginations resembling mesosomes.
- Flagellar filaments in Delftia acidovorans display a supercoiling pattern.
- Outer membrane projections in Delftia acidovorans show structural diversity.

## Abstract

Delftia acidovorans, a Gram-negative bacterium commonly found in diverse environments, can occasionally cause infections in immunocompromised individuals. Despite its environmental prevalence and clinical relevance, there is a notable lack of studies on the cellular ultrastructure of D. acidovorans. Characterizing this aspect is essential for understanding the bacterium aggregation behavior, which significantly influences biofilm formation, environmental adaptability, and potential pathogenicity in clinical contexts. This study employs cryo-electron tomography to investigate the cellular ultrastructure of Delftia acidovorans. Our observations of D. acidovorans revealed a supercoiling pattern in flagellar filaments and diverse outer membrane projections. Our major finding was the observation of cytoplasmic membrane invaginations resembling mesosomes seen in Gram-positive bacteria, offering new insights into the cellular architecture and potential functions of these structures in Gram-negative bacteria. Together, these ultrastructural insights reveal adaptations potentially linked to environmental persistence and interspecies aggregation.

The online version contains supplementary material available at 10.1007/s00248-026-02698-2.