Bol’shie Vyazemy, Odintsovskii Region, Moscow Province, 143050 Russia, e-mail dzhavakhiya@yahoo.com, larisa@vniif.ru Acknowledgements: Supported financially by Russian Science Foundation (RSF project ¹ 14-16-00150) Received February 9, 2016 A b s t r a c t Aflatoxin B1-destroying activity and antagonistic potential of Gliocladium roseum GRZ7 and Trichoderma viride TV35 strains isolated from natural substrates colonized by aflatoxigenic Aspergillus flavus were studied in vitro. <...> Submerged cultures of G. roseum grown on liquid Czapek's medium with casein hydrolizate (Czapek-CasH) at 28 С and 200 rpm for 7 days were able to destroy 80-90 % of aflatoxin B1 (AFB1), which was added in the nutrient medium before inoculation. <...> T. viride grown under the same conditions destroyed only 48 % of initial AFB1 during the same time of cultivation. <...> The tested T. viride strain effectively suppressed the growth of toxigenic A. flavus strain A11 on Czapek-CasH agar. <...> Co-cultivation of A11 with T. viride TV35 resulted in 64 % diminution of the average colony diameter of the aflatoxigenic strain. <...> AFB1-destroyimg activity was detected in samples of high-molecular weight metabolites (> 5 kDa) isolated from culture liquid of G. roseum grown without AFB1. <...> In addition, T. viride ability to degrade the mycotoxin was shown to be inducible. <...> Obtained results were supposed to be of interest for further investigation on decontamination of feeds, which are contaminated with AFB1 or AFB1-producers. <...> Keywords: aflatoxin B1, biological decontamination, Gliocladium roseum, Trichoderma viride Contamination of forage grains and plant materials with aflatoxins, the secondary metabolites of aspergillus fungi, is a serious problem. <...> Feed contamination with aflatoxins can cause animal death or decreased production, and also lead to food stuff contamination [2]. <...> The biological method of decontamination [8-10] is based on the use of secondary metabolites of some plants toxic to A. flavus [11], and also on the search for natural inhibitors of aflatoxinogenesis or microorganism that could serve as a source of enzymes destroying aflatoxins or transform them to non-hazardous derivatives [12-16]. <...> For example, when some micromycetes colonizing natural substrates are grown together with the toxigenic isolates of A. flavus, aflatoxin B1 (AFB1 <...>