Regulation of the cytotoxic effects of Pseudomonas fluorescens by growth temperature

Related Experiment Video

Updated: Aug 29, 2026

Metabolic Profiling to Determine Bactericidal or Bacteriostatic Effects of New Natural Products using Isothermal Microcalorimetry
07:28

Metabolic Profiling to Determine Bactericidal or Bacteriostatic Effects of New Natural Products using Isothermal Microcalorimetry

Published on: October 29, 2020

Laurent Picot1, Sana Mezghani-Abdelmoula, Sylvie Chevalier

  • 1Laboratory of Cold Microbiology, UPRES2123, University of Rouen, 55, rue Saint Germain, 27000 Evreux, France.

Research in Microbiology
|February 5, 2004
PubMed

Insights

Pseudomonas fluorescens growth temperature affects its infectious potential. Low temperatures enhance bacterial adherence and apoptotic effects, while higher temperatures alter necrotic activity.

Area of Science:

  • Microbiology
  • Cell Biology
  • Bacterial Pathogenesis

Background:

  • Psychrotrophic bacterium Pseudomonas fluorescens previously identified as a pathogen.
  • P. fluorescens induces apoptosis and necrosis in neuronal and glial cells.

Purpose of the Study:

  • Investigate the influence of Pseudomonas fluorescens growth temperature on its infectious potential.
  • Determine the relationship between bacterial growth temperature, adherence, motility, and cytotoxic effects (apoptosis and necrosis).

Main Methods:

  • Culturing P. fluorescens at various temperatures (8, 19, 28, 32 degrees C).
  • Assessing bacterial adherence to glial cells.
  • Measuring bacterial motility.
  • Evaluating apoptotic effects via morphological and biochemical indicators (nitric oxide synthase activity).
  • Quantifying necrotic effects by lactate dehydrogenase release.
  • Analyzing lipopolysaccharide (LPS) structure using capillary electrophoresis.

Main Results:

  • Bacterial adherence to glial cells was maximal at 8 degrees C and decreased significantly at higher temperatures.
  • Apoptotic effects correlated with bacterial adherence, peaking at low growth temperatures.
  • Necrotic effects showed a dissociation from adherence, with maximal necrosis observed at 19 degrees C.
  • Capillary electrophoresis suggested temperature-dependent variations in LPS structure influencing apoptosis.
  • Necrotic effects appeared linked to exoenzyme secretion and metabolic activity at optimal temperatures.

Conclusions:

  • Growth temperature significantly modulates Pseudomonas fluorescens infectious potential.
  • Low temperatures enhance bacterial adherence and apoptotic cell death induction.
  • Higher temperatures alter the balance between apoptosis and necrosis, potentially via changes in LPS structure and metabolic activity.

More Related Videos

Bacteriophage Effectiveness for Biocontrol of Foodborne Pathogens Evaluated via High-Throughput Settings07:22

Bacteriophage Effectiveness for Biocontrol of Foodborne Pathogens Evaluated via High-Throughput Settings

Published on: August 19, 2021

Tools for the Real-Time Assessment of a Pseudomonas aeruginosa Infection Model07:39

Tools for the Real-Time Assessment of a Pseudomonas aeruginosa Infection Model

Published on: April 6, 2021

Related Concept Videos

Factors Influencing Microbial Growth: Temperature01:27

Factors Influencing Microbial Growth: Temperature

Microorganisms display remarkable adaptations, enabling them to thrive in diverse ecological niches across a wide range of temperatures. Temperature profoundly influences microbial growth by affecting enzymatic activity, membrane fluidity, and other cellular processes.Each microorganism operates within a specific temperature range defined by three cardinal points: minimum, optimum, and maximum. Below the minimum temperature, membranes lose fluidity, halting transport processes. Above the...
Gene Regulation in Microbial Communities: Quorum Sensing01:28

Gene Regulation in Microbial Communities: Quorum Sensing

Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
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...
Physical Methods for Controlling Microbial Growth: Temperature01:23

Physical Methods for Controlling Microbial Growth: Temperature

Heat is a widely used method to control microbial growth by targeting and denaturing cellular proteins, thereby killing or inactivating microbes. This method's effectiveness is quantified using parameters such as the thermal death point (TDP), thermal death time (TDT), and decimal reduction time (D value). TDP represents the lowest temperature at which all microorganisms in a liquid suspension are eliminated within 10 minutes, whereas TDT is the time necessary to achieve sterilization at a...
Stringent Response in E. coli01:23

Stringent Response in E. coli

Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
Other Stress Responses in Bacteria01:30

Other Stress Responses in Bacteria

Bacteria have global regulatory systems that control several types of stress mechanisms. These include Pho regulon and the heat shock response, which are essential systems for environmental adaptation, such as nutrient limitation and proteotoxic stress. The Pho regulon and the heat shock response exemplify bacterial resilience, enabling rapid adaptation to fluctuating environmental conditions.Pho RegulonBacteria require phosphorus for essential cellular processes, including nucleic acid...