Bacteria are ubiquitous microscopic organisms with the ability to grow rapidly. While beneficial strains such as lactic acid bacteria (LAB) support gut health and food preservation, pathogenic bacteria like Escherichia coli and Staphylococcus aureus can cause serious infections. These harmful microbes produce toxins and enzymes that threaten health and are increasingly showing resistance to conventional antibiotics.
Bacteria are microscopic organisms found everywhere with the ability to multiply rapidly. Beneficial species such as lactic acid bacteria (LAB) support intestinal health and food preservation, while pathogenic bacteria like Escherichia coli and Staphylococcus aureus can cause serious infections. These harmful microbes produce toxins and enzymes that threaten health and increasingly show resistance to conventional antibiotics.
In recent years, scientists have been researching alternative approaches to combat pathogenic bacteria. Among these approaches, endolysins—enzymes that break down bacterial cell walls—stand out. These proteins, typically derived from bacteriophages or genetically modified microorganisms, offer specificity in targeting pathogens. However, their widespread use is limited by challenges such as high production costs, instability during storage or circulation, and sensitivity to enzymatic degradation.
To address this research gap, researchers from Pusan National University in Korea focused on extracellular vesicles (EVs)—membrane-bound nanoparticles released by cells that carry biologically active molecules such as proteins or nucleic acids. The researchers engineered EVs derived from LAB to carry pathogen-specific endolysins on their surfaces.
The research findings were published in Chemical Engineering Journal on 15 May 2025. The study describes the process of discovering and applying a novel surface protein found in EVs derived from Lacticaseibacillus paracasei.
In their study, scientists first cultured L. paracasei (LP) bacteria, a LAB species, in the laboratory and then collected EVs using high-speed centrifugation and isolation techniques. Subsequently, the protein fraction associated with EVs was subjected to comprehensive proteomic analysis. In experiments using advanced bioinformatics tools to map protein functions, the team identified 13 surface display proteins (SDP) associated with LP-derived EVs.
Explaining the significance of the study, Prof. Kim states: "To date, no SDP from EVs of LAB species had been characterized. Now, our group has for the first time identified a new SDP called LP-SDP3 derived from extracellular vesicles of L. paracasei. Furthermore, we observed that homologous proteins to SDP3 are also found in E. coli and other LAB species, and that SDP function is conserved across these species."
Inspired by their findings, the researchers went a step further and integrated an endolysin called PlyF307SQ-8C, which specifically targets S. aureus bacteria, into EVs with LP-SDP3. Notably, these EVs displaying PlyF307SQ-8C via the LP-SDP3 protein were able to selectively target and eliminate S. aureus. Additionally, these engineered EVs were resistant to temperature and pH changes, did not induce antimicrobial resistance, and exhibited a similar safety profile compared to the pure PlyF307SQ-8C endolysin.
"LAB-derived engineered EVs can be produced at large scale and reduce the need for expensive protein purification technologies," says Prof. Kim. "Within 5 to 10 years, this research could transform how we treat infections, preserve food, and produce biological therapies—moving away from antibiotics and toward safe, smart, and sustainable bioengineering alternatives."
In conclusion, the identification of the LP-SDP3 protein and its use in developing a new, safe, and effective EV-based platform could transform the future of antibacterial treatments.
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