Salmonella promotes virulence by repressing cellulose production

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Molecular Biology

Background:

• Cellulose, the most abundant organic polymer, protects bacteria externally and forms biofilms.
• Bacteria utilize cellulose for protection against environmental stress and for biofilm formation on surfaces.

Purpose of the Study:

• To investigate the role of cellulose synthesis in Salmonella Typhimurium virulence within host macrophages.
• To explore the relationship between cellulose production, mgtC gene, and bacterial pathogenicity.

Main Methods:

• Analyzing cellulose synthesis in Salmonella Typhimurium inside macrophages.
• Generating and assessing the virulence of bacterial mutants with altered cellulose synthesis (e.g., mgtC and bcsA mutants).
• Measuring gene expression (bcsA) and cyclic diguanylate levels.

Main Results:

• Salmonella Typhimurium unexpectedly synthesizes cellulose within macrophages.
• Preventing cellulose synthesis enhanced bacterial virulence, while stimulating it decreased virulence.
• A mgtC mutant showed increased cellulose due to elevated bcsA expression and cyclic diguanylate; bcsA inactivation restored virulence.

Conclusions:

• Bacterial cellulose synthesis acts as an antivirulence trait within macrophages, contrary to its external protective role.
• Virulence determinants can repress antivirulence traits, impacting pathogen fitness and transmission strategies.
• Modulating bacterial antivirulence mechanisms offers insights into pathogen survival and evolution.