Inhibition of Aspergillus carbonarius growth and ochratoxin A production in vitro by beneficial Saccharomyces cerevisiae strains

ARMANDO, MR; DOGI C.A; POLONI, V.; DALCERO A.M.; CAVAGLIERI L.R.

Simposio; 7th Conference of The World Mycotoxin Forum® and the XIIIth IUPAC International Symposium on Mycotoxins and Phycotoxins; 2012

Mycotoxin contamination is a serious problem in developing countries where climatic conditions and agricultural and storage practices are conducive to fungal growth and toxin production. Ochratoxin A (OTA) is a mycotoxin with nephrotoxic, teratogenic, immunosuppressive, and carcinogenic properties that has been classified by the International Agency for Research on Cancer as a possible human carcinogen (group 2B). Among these species, Aspergillus carbonarius seems to be the most important source of OTA because of the high proportion of producing strains and high amounts produced. The effect of Saccharomyces cerevisiae RC008 and RC016, previously selected based on their aflatoxin B1 mycotoxins binding ability and beneficial properties, against Aspergillus carbonarius under different interacting environmental conditions was evaluated. Studies on the lag phase, growth rate and OTA production were carried out in vitro under different regimes of aw (0.95 and 0.99); pH (4 and 6); temperature (25 and 37°C) and oxygen availability (normal and reduced). Both yeast strains showed great antagonistic activity, decreasing growth rate compared to the control. The RC016 strain showed the greatest inhibitory activity at all assayed conditions. Aspergillus carbonarius was able to in vitro produce large amounts of OTA. A significant decrease of OTA levels in comparison with the control were observed with yeast interaction. The use of live strains with both beneficial and bio-control properties, able to prolong the safe storage of feedstuff and exert beneficial properties after animal consumption, are important to be included in a novel product to animal feed. This study demonstrated that selected S. cerevisiae strains exerted in vitro inhibition activity against A. carbonarius. The inhibition was effective against on both, fungal growth and OTA production, and was significantly influenced by environmental conditions. The use of S. cerevisiae RC008 and RC016 as additives of animal feed could be an alternative to control mycotoxigenic fungi in stored feedstuff.