Related Experiment Video

Updated: Mar 21, 2026

Applying Live Cell Imaging and Cryo-Electron Tomography to Resolve Spatiotemporal Features of the Legionella pneumophila Dot/Icm Secretion System
09:12

Applying Live Cell Imaging and Cryo-Electron Tomography to Resolve Spatiotemporal Features of the Legionella pneumophila Dot/Icm Secretion System

Published on: March 10, 2020

7.8K

Colony types and virulence traits of Legionella feeleii determined by exopolysaccharide materials

Changle Wang1, Mitsumasa Saito2, Midori Ogawa2

  • 1Department of Bacteriology, Graduate school of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan wcl1986@bact.med.kyushu-u.ac.jp.

FEMS Microbiology Letters
|May 19, 2016
PubMed

Insights

Legionella feeleii exhibits distinct colony types, white rugose (WRLf) and brown translucent (BTLf), with WRLf showing increased virulence. Secreted ruthenium red-stained materials in WRLf are linked to enhanced pathogenicity and cellular interactions.

Area of Science:

  • Microbiology
  • Bacteriology
  • Pathogen Research

Background:

  • Legionella feeleii is a Gram-negative bacterium causing human illness.
  • Distinct colony morphologies observed in L. feeleii serogroup 1 suggest underlying variations.

Purpose of the Study:

  • To characterize the differences between two L. feeleii colony types: white rugose (WRLf) and brown translucent (BTLf).
  • To investigate the role of secreted materials in L. feeleii colony morphology and virulence.

Main Methods:

  • Culturing L. feeleii on BCYE agar to observe colony morphology.
  • Electron microscopy with ruthenium red staining to analyze secreted materials.
  • In vitro assays using U937 macrophages, HeLa cells, murine macrophages, and Acanthamoeba for internalization and intracellular growth.
  • Serum bactericidal assays and guinea pig inoculation to assess virulence and resistance.

Main Results:

  • Two colony types, WRLf (white rugose) and BTLf (brown translucent), were identified with differing characteristics.
  • WRLf demonstrated enhanced internalization by macrophages and HeLa cells, greater resistance to human serum, and ability to transform into BTLf.
  • Ruthenium red staining revealed secreted materials in WRLf, absent in BTLf, correlating with increased virulence traits.
  • Both WRLf and BTLf induced fever in guinea pigs, indicating pathogenicity.

Conclusions:

  • Secreted ruthenium red-stained materials are strongly associated with L. feeleii colony morphology and virulence.
  • WRLf exhibits higher virulence potential compared to BTLf due to differences in secreted substances.
  • Understanding these variations is crucial for comprehending Legionella pathogenesis and developing targeted interventions.
Keywords:
Legionella feeleiiPontiac feverbrown translucent colonycolony transformationexopolysaccharidewhite rugose colony

More Related Videos

Use of Galleria mellonella as a Model Organism to Study Legionella pneumophila Infection12:30

Use of Galleria mellonella as a Model Organism to Study Legionella pneumophila Infection

Published on: November 22, 2013

41.6K
Tractable Mammalian Cell Infections with Protozoan-primed Bacteria13:54

Tractable Mammalian Cell Infections with Protozoan-primed Bacteria

Published on: April 2, 2013

11.0K

Related Concept Videos

Colonisation of Pathogens01:25

Colonisation of Pathogens

Pathogen colonization of host tissues is a critical step in the development of infectious diseases. Various pathogenic microorganisms, including bacteria, fungi, viruses, and protozoa, have evolved complex strategies to attach to, invade, and persist within host environments. These mechanisms enable pathogens to establish infections, evade immune responses, and resist antimicrobial treatments.Attachment to Host CellsIn bacteria, colonization typically begins with adherence to host epithelial...
9
Atypical Pneumonia01:14

Atypical Pneumonia

Atypical pneumonia, often caused by Mycoplasma pneumoniae, is a form of pulmonary infection that differs from the classical presentation of bacterial pneumonia in both its cause and clinical symptoms. Mycoplasma pneumoniae is a pleomorphic bacterium notable for its lack of a rigid cell wall. This structural characteristic imparts resistance to beta-lactam antibiotics and significantly influences the bacterium’s behavior within the human host.Other pathogens responsible for the disease...
9
Outer Layers of the Cell Envelope01:18

Outer Layers of the Cell Envelope

The outermost layers of prokaryotic cells play a critical role in their survival, virulence, and interaction with the environment. These layers, often composed of polysaccharides, polypeptides, or proteins, form protective and adhesive structures that vary in organization and function.Capsules and Slime LayersCapsules are highly organized, tightly bound layers that firmly attach to the bacterial cell wall. Capsules are usually made of polysaccharides, though some are made of polypeptides. These...
1.5K
Bacterial Phylum Proteobacteria01:26

Bacterial Phylum Proteobacteria

Proteobacteria, one of the largest and most diverse bacterial phyla, encompasses a wide range of Gram-negative bacteria distinguished by their outer membrane composed of lipopolysaccharides. These microorganisms exhibit various metabolic capabilities, including phototrophy, chemolithotrophy, and heterotrophy, and thrive in diverse environments from soil to aquatic systems and host-associated niches. The phylum is divided into six classes: Alphaproteobacteria, Betaproteobacteria,...
1.1K
Formation of Lipopolysaccharides01:19

Formation of Lipopolysaccharides

Lipopolysaccharides (LPS) are crucial components of the outer membrane of Gram-negative bacteria, serving both structural and functional roles. It contributes to membrane stability and protects bacteria from host immune responses. LPS is composed of three major regions—lipid A, a core oligosaccharide, and an O antigen. The biosynthesis and assembly of LPS involve a highly coordinated set of enzymatic reactions and transport mechanisms. Additionally, LPS is recognized as an endotoxin,...
902
Regulation of Bacterial Virulence01:28

Regulation of Bacterial Virulence

Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
3