Inhibition studies on isolated Aspergillus flavus using solvent extract from Trichoderma viride and Bacillus subtilis

Abstract

Aflatoxins are a group of the most toxic microbial metabolites found in foods and feeds. This study was conducted to obtain solvent extract from Bacillus subtilis and Trichoderma viride cultures and to assess the level of inhibition against the growth of Aspergillus flavus in vitro. Methanol (70%) was used to extract 7-day old (T. viridae) and 2-day old (B. subtilis) cultures. Filter paper impregnated disc method was used to determine the extract efficacy in inhibiting A. flavus growth on potato dextrose agar media using the extracts singly and in combination at varying doses. Analysis of variance was performed on all data with the general linear model. Least significant difference test was performed to compare treatment means at the 5% level. The result demonstrated a significant antagonistic effect of the solvent extracts against the growth of A. flavus indicating the presence of bioactive compounds which mitigates A. flavus growth at various doses of application. The highest level of inhibition individually was observed in the assay of solvent extract from B. subtilis at double dose compared to T. viride at double dose. The mixture of B. subtilis and T. viride solvent extract at double dose demonstrated the highest level of inhibition of A. flavus than individual extract at various doses. The relatively high level of inhibition confirms the presence antifungal substances in the solvent extract obtained from Bacillus subtilis and Trichoderma viride which could be used as bio-fungicides; an ideal alternative to synthetic fungicides in the control of Aspergillus flavus.