Debaryomyces hansenii as potential biocontrol agent of Aspergillus westerdijkiae in cheese

Aspergillus westerdijkiae is a fungal species able to produce ochratoxin A (OTA), a mycotoxin with adverse effects on human and animal health, due to its nephrotoxic, immunotoxic and teratogenic properties, classified by the International Agency for Research on Cancer as group 2B metabolite, possible human carcinogen. OTA has been recognized as a contaminant in fruits, cereals, coffee, grapes, as well as in nuts, dried fruits, spices, and it has been reported often in processed meat and dairy products, such as cheese. Furthermore, it has been reported that the growth of uncontrolled moulds during ripening and ageing may occur causing spoilage and possibly mycotoxin production [1], therefore further monitoring is still needed to develop strategies to prevent fungal contamination and ensure food safety. Debaryomyces hansenii is a yeast that has been isolated from different environments, notable for its ability to grow in diverse conditions and considered to have a high biotechnological potential, particularly in the food industry. It is one of the prevalent yeast species isolated from cheese, exerting important metabolic activities in cheese ripening and in limiting the growth of deleterious spoiling bacteria. D.hansenii has been reported as effective in the containment of ochratoxigenic fungal species on fermented meat [2,3], but currently there is no evidence of such ability against A. westerdijkiae on ripened cheese. Therefore, the aim of this study was to investigate the effect of D. hansenii on the reduction of A. westerdijkiae growth and related OTA production on cheese. Our results indicated that the presence of D. hansenii at 20 days post-inoculation of A. westerdijkiae on cheese-like medium reduced fungal growth by 40% (ttest, p<0.001) and OTA production by 61% (ttest, p<0.001) as compared to the control, thus suggesting that D. hansenii is a promising candidate to be used as biocontrol agent during cheese ripening process.