Effect of Acclimatization in Elevated CO 2 on Growth and Aflatoxin B 1 Production by Aspergillus flavus Strains on Pistachio Nuts.

There is little knowledge of the effect of acclimatization of Aspergillus flavus strains to climate-related abiotic factors and the subsequent effects on growth and aflatoxin B 1 (AFB 1 ) production. In this study, two strains of A. flavus (AB3, AB10) were acclimatized for five generations in elevated CO 2 (1000 ppm × 37 °C) on a milled pistachio-based medium. A comparison was made of the effects of non-acclimatized strains and those that were acclimatized when colonizing layers of pistachio nuts exposed to 35 or 37 °C, 400 or 1000 ppm CO 2 , and 0.93 or 0.98 water activity (a w ), respectively. Acclimatization influenced the fitness in terms of the growth of one strain, while there was no significant effect on the other strain when colonizing pistachio nuts. AFB 1 , production was significantly stimulated after ten days colonization when comparing the non-acclimatized and the acclimatized AB3 strain. However, there was no significant increase when comparing these for strain AB10. This suggests that there may be inter-strain differences in the effects of acclimatization and this could have a differential influence on the mycotoxin contamination of such commodities.