Green Catanionic Gemini Surfactant-Lichenysin Mixture: Improved Surface, Antimicrobial, and Physiological Properties

Area of Science:

• Biochemistry
• Microbiology
• Materials Science

Background:

• Catanionic surfactant mixtures form organized assemblies with enhanced properties.
• Investigating synergistic antimicrobial effects and mechanisms of novel surfactant formulations is crucial for developing new therapeutic agents.

Purpose of the Study:

• To evaluate the antimicrobial synergy and biological properties of a green catanionic mixture composed of NαNω-Bis(Nαcaproylarginine) α,ω-propyldiamide (C3(CA)2) and Lichenysin.
• To elucidate the mechanism of action, including the induction of the viable but nonculturable (VBNC) state and cell selectivity.

Main Methods:

• Antimicrobial susceptibility testing against Yersinia enterocolitica, Bacillus subtilis, Escherichia coli O157:H7, and Candida albicans.
• Flow cytometry and viability assays to assess the VBNC state induction.
• Zeta potential measurements to analyze surfactant interactions.
• Isotherm studies for aggregate formation.
• Hemolysis assays and irritant potential characterization to determine cytotoxicity.

Main Results:

• The C3(CA)2:Lichenysin mixture (8:2 molar ratio) demonstrated significant antimicrobial synergy against tested pathogens.
• The mixture induced a viable but nonculturable (VBNC) state in Y. enterocolitica (38.2%) and B. subtilis (17.1%).
• Zeta potential and isotherm studies confirmed the formation of a stable, partially neutralized catanionic aggregate that interacts with bacterial phospholipids.
• The mixture exhibited low hemolysis (22.1 μM) and a favorable therapeutic index, indicating reduced toxicity to eukaryotic cells compared to individual components.

Conclusions:

• The C3(CA)2:Lichenysin catanionic mixture possesses potent antimicrobial properties with enhanced synergy.
• Partial neutralization of C3(CA)2 by Lichenysin alters the mode of action, promoting bacterial entry into the VBNC state and improving cell selectivity.
• This green formulation represents a promising candidate for antimicrobial applications with a favorable safety profile.