ANTIFUNGAL ACTIVITY OF REUTERIN AGAINST AFLATOXIGENIC ASPERGILLUS FLAVUS

Abstract

Reuterin is a secondary metabolite of the lactic acid bacteria Limosilactobacillus reuteri having broad antimicrobial activity. This study aimed to determine the antifungal activity of reuterin against aflatoxigenic Aspergillus flavus (A. flavus). The aflatoxigenic A. flavus BIO 33212 isolated from Indonesian nutmeg was used in this study. The minimum inhibitory concentration (MIC) of reuterin based on radial growth and colony-forming assays in solid and liquid fat-enriched media against A. flavus was determined. The effect of reuterin on the morphological structure of A. flavus was investigated by scanning electron microscopy (SEM). The aflatoxin B1 (AFB1) produced by A. flavus was evaluated by enzyme-linked immunosorbent assay. Reuterin effectively prolonged the lag phase and decreased the growth rate of A. flavus. At 2 and 4 mM, reuterin demonstrated radial growth inhibition by 5.59% and 35.40%, respectively, while the reductions in colony numbers were 18.36% and 69.51%, respectively. At higher concentrations (6 and 8 mM), the fungal growth was inhibited and reduced completely (100%). SEM revealed the disruption of hyphae and conidiophore development and conidial damage. However, a contradictory phenomenon was found when reuterin at < 6 mM triggered a higher production of AFB1.