Yeast Pseudozyma hubeiensis potential for aflatoxin B1 decontamination and its genetic properties

Aflatoxin B1 (AFB1) is a toxic and carcinogenic secondary metabolite produced by Aspergillus species, particularly A. flavus and A. parasiticus, which often contaminates food. One promising strategy to control AFB1 toxicity and inhibit the growth of A. flavus is to use non-pathogenic yeasts. This study aimed to isolate yeasts from fruits and nutmeg (Myristica fragrans) seeds and to evaluate their ability to reduce AFB1 levels and inhibit A. flavus. We also conducted whole-genome analysis on selected yeast isolates to identify genes potentially involved in AFB1 reduction and fungal inhibition. We successfully obtained three yeast isolates, among which Pseudozyma hubeiensis BUP reduced AFB1 contamination by 53.03%, as detected by HPLC analysis. Based on a hemolysis assay, the BUP isolate was also confirmed to be non-pathogenic. In addition, BUP inhibited the growth of A. flavus by 46.1% in a dual-culture assay. Genome sequencing using the DNBSEQ platform produced an assembly of 18,648,523 base pairs segmented into 33 scaffolds comprising 38 contigs. Putative genes in the BUP genome potentially involved in AFB1 reduction include lactonase, cutinase, peroxidase, and aflatoxin B1 aldehyde reductase (AKR7). These results suggest that P. hubeiensis BUP has strong potential to decontaminate AFB1 and inhibit the growth of A. flavus. Further research will focus on elucidating AFB1 degradation pathways using LC-MS/MS and evaluating the in vivo efficacy of BUP in controlling A. flavus contamination in nutmeg seeds.