[4S02e] 03. Fermentation Physiology/ Technology - Part 3

5:00 PM - 5:30 PM JST(8:00 AM - 8:30 AM UTC)

[4Ferm-11-KL] Fungal diversity and mycotoxin safety in Korean traditional fermented food, Meju

○Kap-Hoon Han¹, Sang-Cheol Jun¹, Yu-Kyung Kim¹ (1. Woosuk University (Korea))

Keywords:

Meju,mycotoxin control,Aspergillus oryzae,fungal diversity

Meju, a soybean brick serving as the primary starter for traditional Korean soybean paste (Doenjang), is often considered susceptible to mycotoxin contamination due to the uncontrolled nature of spontaneous fungal fermentation; however, actual contamination is not observed. In this study, we demonstrate that the underlying reasons for the low incidence of contamination can be elucidated through integrated metagenomic and culture-based analyses of fungal diversity and functional charateristics. A total of 30 species across seven genera, including Aspergillus, Penicillium, Cladosporium, and Mucor, were identified from Meju, and their mycotoxin-producing potential was evaluated. Metagenomic analysis revealed that fungal community composition and abundance varied significantly depending on production regions and fermentation conditions. Among the isolates, nonaflatoxigenic Aspergillus oryzae strains were assessed for key enzymatic activities, including peptidase, amylase, and lipase, and compared with commercially available yellow-koji strains. Notably, a nonaflatoxigenic A. oryzae strain AO3222 exhibited superior enzymatic activity, indicating its suitability for Meju fermentation. Whole-genome analysis further showed that commercial yellow-koji strains were highly similar, whereas AO3222 formed a distinct cluster within the A. oryzae group. In co-fermentation experiments with Aspergillus flavus, Mucor racemosus, and Rhizopus arrhizus, AO3222 effectively suppressed the growth of A. flavus and significantly reduced aflatoxin production, as supported by metagenomic profiling of microbial distribution. Collectively, these results highlight the potential of AO3222 as a novel starter culture for improving the safety and consistency of Meju fermentation.