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Transcriptome Analysis Reveals the Effect of Low NaCl Concentration on Osmotic Stress and Type III Secretion System

Youkun Zhang1,2,3, Xiaotong Tan1,2,3, Mingzhu Li1,2,3

  • 1Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.

International Journal of Molecular Sciences
|February 11, 2023
PubMed

Insights

Low salinity (0.5% NaCl) enhances the fitness and virulence of Vibrio parahaemolyticus by altering gene expression. This adaptation may facilitate the foodborne pathogen

Area of Science:

  • Microbiology
  • Food Safety
  • Pathogen Adaptation

Background:

  • Vibrio parahaemolyticus is a significant foodborne pathogen found in marine and freshwater environments.
  • The pathogen's transition between aquatic ecosystems and hosts is crucial for infection, occurring in low-salinity conditions.
  • Understanding how low salinity affects V. parahaemolyticus is key to controlling its spread and pathogenicity.

Purpose of the Study:

  • To investigate the impact of low salinity (0.5% NaCl) on the fitness and virulence of V. parahaemolyticus.
  • To identify specific genes and pathways affected by low-salinity conditions.
  • To elucidate the mechanisms by which low salinity enhances pathogenicity.

Main Methods:

  • Culturing V. parahaemolyticus in media with varying NaCl concentrations (0.5% and 3%).
  • Comparing cell densities during the stationary phase.
  • Performing RNA-sequencing (RNA-seq) to analyze differential gene expression between low (0.5% NaCl) and moderate (3% NaCl) salinity conditions.
  • Assessing cytotoxicity to HeLa cells and secretion of T3SS2 translocon protein VPA1361.

Main Results:

  • V. parahaemolyticus exhibited higher cell density in M9 medium with 0.5% NaCl during the stationary phase.
  • RNA-seq analysis revealed 658 differentially expressed genes at 0.5% NaCl, including regulators, osmotic adaptation systems, and virulence factors (T3SS1, T6SS1).
  • Low salinity induced T3SS1 expression, increasing cytotoxicity to HeLa cells, and also induced secretion of VPA1361 (T3SS2).

Conclusions:

  • Low salinity (0.5% NaCl) significantly affects V. parahaemolyticus gene expression, enhancing both fitness and virulence.
  • The observed changes in gene expression, particularly the induction of T3SS1 and T3SS2 components, contribute to increased pathogenicity in low-salinity environments.
  • These findings suggest that low salinity plays a critical role in the adaptation and transition of V. parahaemolyticus between aquatic environments and hosts.
Keywords:
RNA-seqT3SSVibrio parahaemolyticuslow NaClosmotic stress

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