Phloretin Inhibits Quorum Sensing and Biofilm Formation in Serratia marcescens

Area of Science:

• Microbiology
• Food Science
• Biochemistry

Background:

• Serratia marcescens is a bacterium that causes vegetable spoilage.
• Quorum sensing (QS) is a cell-to-cell communication system bacteria use to coordinate virulence.
• Phloretin is a natural compound found in apple skins.

Purpose of the Study:

• To investigate the antivirulence effects of phloretin against S. marcescens.
• To elucidate the mechanism by which phloretin inhibits S. marcescens.

Main Methods:

• Bacterial cultures of S. marcescens NJ01 were treated with phloretin at varying concentrations.
• Acyl homoserine lactone (AHL) secretion was measured to assess QS inhibition.
• Biofilm formation, protease production, prodigiosin, motility, and oxidative stress were evaluated.
• Membrane permeability and susceptibility to antibiotics were assessed.
• Metabolic pathways (amino acid, energy, nucleic acid) were analyzed.

Main Results:

• Phloretin (0.5-2 mg/mL) inhibited AHL secretion, disrupting QS in S. marcescens.
• QS disruption led to reduced biofilms, protease, prodigiosin, and motility.
• Antioxidant enzyme activity decreased, increasing oxidative injury and membrane damage.
• Enhanced oxidative stress increased susceptibility to amikacin, netilmicin, and imipenem.
• Disrupted QS and oxidative stress disordered key metabolic pathways, reducing spoilage ability.

Conclusions:

• Phloretin effectively inhibits S. marcescens virulence by disrupting QS.
• Phloretin's mechanism involves increased oxidative stress and metabolic disruption.
• Phloretin shows potential as a natural agent to prevent S. marcescens-induced spoilage.