Potent Antimicrobial Activity of Aspergillus oryzae Fermentate Against Toxigenic Strains of Clostridioides difficile.

2025-03-22
Antibiotics (Basel, Switzerland) 14(4)

PubMed: 40298462
DOI: 10.3390/antibiotics14040333

Study Design

Population: toxigenic strains of C. difficile
Methods: The ethyl acetate extract of A. oryzae fermentate (fungal extract) was tested for antimicrobial activity; zone of inhibition, time kill assays, scanning electron microscopy (SEM), and flow cytometry were used

Background:Clostridioides difficile infection (CDI) remains a significant public health challenge in the United States, with limited treatment options currently available. Objectives: This study investigated the antimicrobial efficacy of a fungal-based fermentate derived from Aspergillus oryzae, cultivated in a proprietary food-grade medium, against toxigenic strains of C. difficile. Methods and Results: The ethyl acetate extract of A. oryzae fermentate (fungal extract) exhibited potent bactericidal activity, producing a significant zone of inhibition across all tested C. difficile strains, including hypervirulent Ribotype 027. Notably, 80% of the tested strains (four out of five) exhibited greater susceptibility to the fungal extract than to 5 µg vancomycin discs. Inner colony formation within the zone of inhibition was observed for all strains treated with vancomycin but only one strain was exposed to fungal extract. Time kill assays further confirmed the rapid bactericidal effect of the fungal extract, achieving complete C. difficile eradication within six hours. Mechanistic studies using scanning electron microscopy (SEM) and flow cytometry revealed that the fungal extract induced severe membrane disruption, leading to intracellular leakage and complete lysis. Flow cytometry analysis confirmed membrane depolarization and permeability loss on C. difficile cells. Conclusions: These findings highlight that the fungal extract of A. oryzae exhibits a promising antimicrobial activity against C. difficile. Future studies will focus on identifying its active components, evaluating its efficacy in vivo, and assessing its impact on gut microbiota to establish its potential clinical application in managing CDI.

Research Insights

Supplement	Dose	Health Outcome	Effect Type	Effect Size	Source
Saccharomyces cerevisiae	—	Disrupted Bacterial Cell Membranes	Beneficial	Large	View source Mechanistic studies using scanning electron microscopy (SEM) and flow cytometry revealed that the fungal extract induced severe membrane disruption, leading to intracellular leakage and complete lysis. Flow cytometry analysis confirmed membrane depolarization and permeability loss on C. difficile cells.
Saccharomyces cerevisiae	—	Reduced Clostridium Difficile Growth	Beneficial	Large	View source The ethyl acetate extract of A. oryzae fermentate (fungal extract) exhibited potent bactericidal activity, producing a significant zone of inhibition across all tested C. difficile strains... Time kill assays further confirmed the rapid bactericidal effect of the fungal extract, achieving complete C. difficile eradication within six hours.