Host Factors Modulating Ochratoxin A Biosynthesis during Fruit Colonization by Aspergillus carbonarius

Abstract

Aspergillus carbonarius is a strong and consistent ochratoxin A (OTA) producer and considered to be the main source of this toxic metabolite in grapes and grape products such as wine, grape juice and dried vine fruit. OTA is produced under certain growth conditions and its accumulation is affected by several environmental factors, such as growth phase, substrate, temperature, water activity and pH. In this study, we examined the impact of fruit host factors on regulation and accumulation of OTA in colonized grape berries, and assessed in vitro the impact of those factors on the transcriptional levels of the key genes and global regulators contributing to fungal colonization and mycotoxin synthesis. We found that limited sugar content, low pH levels and high malic acid concentrations activated OTA biosynthesis by A. carbonarius, both in synthetic media and during fruit colonization, through modulation of global regulator of secondary metabolism, laeA and OTA gene cluster expression. These findings indicate that fruit host factors may have a significant impact on the capability of A. carbonarius to produce and accumulate OTA in grapes.

Pathogenicity of entomopathogenic fungi isolated from Periplaneta americana against Dolichoderus sp.

“…The present finding supports this opinion that postharvest deterioration of numerous fruits and vegetables is usually caused by Aspergillus carbonarius. The acidity of the apple fruit environment as a host increases through the secretion of organic acids assisted by maceration and fruit colonization by Penicillium expansum (Maor et al 2020). Individual ant mortality was assumed to be high in treating the KIF 3 strain due to various factors, namely toxins and chitinase.…”