# Interaction Between Bacillus subtilis and Trichoderma citrinoviride: Synergistic Inhibition of Aspergillus flavus Growth and Aflatoxin B1 Production

## TL;DR

Combining two microbes, Bacillus subtilis and Trichoderma citrinoviride, effectively inhibits harmful mold growth and toxin production in food.

## Contribution

The study demonstrates a synergistic biocontrol strategy using combined metabolites from two microbial strains to inhibit A. flavus and aflatoxin B1.

## Key findings

- Combined treatment inhibited A. flavus radial growth by 69.59% and aflatoxin B1 production by 98.69%.
- Trichoderma citrinoviride GC-T20 alone inhibited A. flavus growth by 74%.
- Bacillus subtilis Bs92 alone inhibited A. flavus growth by 48.61%.

## Abstract

Aspergillus flavus (A. flavus) and its potent carcinogenic metabolite, aflatoxin B1 (AFB1), pose severe threats to food safety and public health. This study explored the biocontrol potential of Bacillus and Trichoderma strains and their interactions. Through dual-culture assays, Bacillus subtilis Bs92 and Trichoderma citrinoviride GC-T20 were identified as the most inhibitory among 15 isolates each, with their culture filtrates inhibiting A. flavus growth by 48.61% and 74%, respectively. Investigation of the inter-genus interaction revealed strong mutual inhibition: Trichoderma filtrate suppressed Bacillus growth by >90%, while Bacillus filtrate inhibited Trichoderma mycelial growth by 40–90%. To circumvent this antagonism and enhance efficacy, the culture filtrates of Bs92 and GC-T20 were combined. The combined treatment demonstrated superior performance, inhibiting A. flavus radial growth by 69.59% and AFB1 production by 98.69%, significantly outperforming individual applications. These results indicate that the antifungal and anti-aflatoxigenic metabolites produced by Bs92 and GC-T20 are complementary. Their combined use presents a promising synergistic strategy for the biocontrol of A. flavus and AFB1 contamination in food and agricultural products.