Rugosity in Grimontia hollisae

Area of Science:

• Microbiology
• Bacteriology
• Cell Biology

Background:

• Grimontia hollisae (formerly Vibrio hollisae) presents distinct colonial phenotypes: smooth and rugose.
• The rugose phenotype is associated with wrinkled colonies and abundant exopolysaccharide production.

Purpose of the Study:

• To characterize the rugose colonial phenotype of Grimontia hollisae.
• To investigate the influence of growth temperature on colony morphology and exopolysaccharide expression.
• To assess the stress response and biofilm formation capabilities of rugose versus smooth variants.

Main Methods:

• Colony morphology observation and characterization.
• Flow cytometry for cell clumping and lectin binding analysis (wheat germ agglutinin, Galanthus nivalis lectin).
• Biofilm assays and ultrastructural analysis using electron microscopy.
• Stress survival assays (bleach exposure) and suckling mouse infection models.

Main Results:

• Rugose colonies exhibit temperature-dependent morphology changes, forming rugose colonies at 30°C and smooth colonies at 37°C.
• Rugose cells showed increased resistance to bleach stress, greater clumping, and higher binding of specific lectins (WGA, GNL), indicating N-acetylglucosamine and mannose in exopolysaccharide.
• Rugose colonies produced significantly more biofilm material than smooth colonies, with higher production at 30°C.
• Ultrastructural analysis revealed distinct cellular differentiation and matrix production in rugose colonies, absent in smooth colonies.

Conclusions:

• This study provides the first detailed characterization of rugosity in G. hollisae.
• Exopolysaccharide production and rugose phenotype expression are influenced by growth temperature.
• The rugose phenotype confers advantages in stress resistance and biofilm formation.