Study of aflatoxin B1-destroying activity of Gliocladium roseum and Trichoderma viride and their аntagonism toward toxigenic Aspergillus flavus

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. The strain GRZ7 of G. roseum was ineffective as an antagonist of A11. 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.