Potential of yeasts isolated from dry-cured ham to control ochratoxin A production in meat models

The environmental conditions reached during the ripening of dry-cured meat products favour the proliferation of moulds on their surface. Some of these moulds are hazardous to consumers because of their ability to produce ochratoxin A (OTA). Biocontrol using Debaryomyces hansenii could be a suitable strategy to prevent the growth of ochratoxigenic moulds and OTA accumulation in dry-cured meat products. The aim of this work was to evaluate the ability of two strains of D. hansenii to control the growth and OTA production of Penicillium verrucosum in a meat model under water activities (a_w) values commonly reached during the dry-cured meat product ripening. The presence of D. hansenii strains triggered a lengthening of the lag phase and a decrease of the growth rate of P. verrucosum in meat-based media at 0.97 and 0.92 a_w. Both D. hansenii strains significantly reduced OTA production (between 85.16 and 92.63%) by P. verrucosum in the meat-based medium at 0.92 a_w. Neither absorption nor detoxification of OTA by D. hansenii strains seems to be involved. However, a repression of the expression of the non-ribosomal peptide synthetase (otanpsPN) gene linked to the OTA biosynthetic pathway was observed in the presence of D. hansenii. To confirm the protective role of D. hansenii strains, they were inoculated together with P. verrucosum Pv45 in dry-fermented sausage and dry-cured ham slices. Although P. verrucosum Pv45 counts were not affected by the presence of D. hansenii in both meat matrices, a reduction of OTA amount was observed. Therefore, the effect of D. hansenii strains on OTA accumulation should be attributed to a reduction at transcriptional level. Consequently, native D. hansenii can be useful as biocontrol agent in dry-cured meat products for preventing the hazard associated with the presence of OTA.