Inhibition of Vibrio parahaemolyticus and Multi-Targeted Modes of Action of Extract from Endophytic Fungus Fusarium concentricum Isolated from Piper betle Linn.

Endophytic fungi (EF) are symbiotic fungi that reside within plant tissues without any symptoms and can produce bioactive compounds, particularly phenolic compounds with antimicrobial activity. Vibrio parahaemolyticus (VP) is a major concern in seafood contamination due to its potential to cause serious foodborne illnesses. This study aimed to investigate the antibacterial activity and mode of action of the ethyl acetate extract from the endophytic fungus Fusarium concentricum P2NS8 (EAE-P2NS8) isolated from the Piper betle plant against VP. The antibacterial activity of EAE-P2NS8, as determined in three independent biological replicates, against VP strain ATCC 17802 and VP strain PSU 3952, exhibited minimum inhibitory concentrations (MICs) of 0.256 and 0.128 mg/mL, respectively. Scanning electron microscopic (SEM) images revealed that EAE-P2NS8 could damage the cells of VP strain ATCC 17802, resulting in cell shrinkage along with modified cell structure. Pore formation led to the leakage of intracellular proteins. Additionally, the EAE-P2NS8 induced DNA degradation, indicating disruption of the bacterial genomic DNA. The EAE-P2NS8 at 1×MIC also inhibited biofilm formation of VP strain ATCC 17802 by 85.7 %. Furthermore, EAE-P2NS8 at 2×MIC completely inhibited bacterial motility and killed the VP strain ATCC 17802 within 2 h. The hemolytic property of VP strain PSU 3952 was reduced by EAE-P2NS8 at MIC/4, MIC/2 and 1×MIC. These results suggest that secondary metabolites from the endophytic fungus F. concentricum P2NS8 have the potential to serve as an antimicrobial agent against VP.