Biocontrol activity optimization of low-fermenting yeast isolates against Aspergillus niger to remove toxin from grape juice

Grapes infected with Aspergillus can produce ochratoxin A (OTA) in the processing of beverages such as wine or grape juice. This study aimed to evaluate the antifungal biological potential of two low-fermenting native yeast isolates (A01 G01) and three standards (Saccharomyces cerevisiae, Candida guilliermondii, Metschnikowia agaves) yeast isolates against Aspergillus niger and their ability to remove OTA in grape juice and its products, without any considerable alcohol production during the process.

Two native yeast isolates (A01 and G01) were obtained from Malayer apples and grapes, respectively, and inoculated on the PDA culture medium. Native isolates were identified by sequencing D1 and D2 and ITS 1 and ITS2 regions of the ribosomal DNA gene.

The results of DNA sequencing identified both native isolates as Saccharomyces. All strains showed a significant ability in inhibition of A. niger growth both on grape berries and in culture media. Meanwhile, yeast isolates produced a trace amount of alcohol.

Biological control of A. niger and OTA-decontamination using yeast is proposed as an approach to meet the Islamic dietary laws regarding the absence of alcohol in halal beverages.