Serratamolide is a hemolytic factor produced by Serratia marcescens

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Ocular Infections

Background:

• Serratia marcescens is a frequent contaminant of contact lens cases and lenses.
• Hemolytic factors of S. marcescens are key virulence determinants for this opportunistic pathogen.

Purpose of the Study:

• To investigate the mechanisms underlying S. marcescens hemolysis, particularly in hyper-hemolytic crp mutants.
• To identify novel hemolysins contributing to S. marcescens virulence.

Main Methods:

• Genetic screening to identify genes involved in hyper-hemolysis.
• Analysis of swrW gene expression and serratamolide biosynthesis.
• In vitro testing of purified serratamolide's hemolytic and cytotoxic effects.
• Detection of the swrW gene in clinical contact lens isolates.

Main Results:

• The swrW gene was identified as essential for the hyper-hemolysis observed in crp mutants.
• Serratamolide, a biosurfactant produced by swrW, was confirmed as a hemolysin.
• Elevated swrW expression and serratamolide production were observed in crp mutants.
• Purified serratamolide demonstrated hemolytic activity against red blood cells and cytotoxicity towards human epithelial cells.

Conclusions:

• The biosurfactant serratamolide functions as a novel hemolysin in Serratia marcescens.
• Serratamolide likely contributes to ocular irritation and infections associated with contact lens use.
• The swrW gene, encoding serratamolide, is prevalent in contact lens-associated S. marcescens isolates.