Biocontrol of Aspergillus flavus on Peanut Kernels Using Streptomyces yanglinensis 3-10

Area of Science:

• Agricultural Science
• Microbiology
• Mycology

Background:

• Phytopathogenic fungi like Aspergillus flavus cause significant postharvest losses in agricultural commodities.
• Aflatoxin AFB1, a toxic metabolite produced by A. flavus, poses a serious threat to food safety.
• Chemical fungicides are widely used but raise environmental and health concerns.

Purpose of the Study:

• To evaluate the antifungal activity of Streptomyces yanglinensis 3-10 and its derived substances against Aspergillus flavus.
• To assess the efficacy of these natural compounds in reducing fungal growth and aflatoxin AFB1 production.
• To investigate the potential of S. yanglinensis as a biocontrol agent for postharvest protection of peanut kernels.

Main Methods:

• Dual culture assays and agar plate inhibition tests were performed to evaluate mycelial growth inhibition.
• Liquid culture experiments assessed growth inhibition and aflatoxin AFB1 reduction using culture filtrate (CF3-10) and crude extracts (CE3-10).
• In vivo studies on peanut kernels and gene expression analysis (aflR, aflS) were conducted, alongside electron microscopy.

Main Results:

• S. yanglinensis inhibited A. flavus mycelial growth by 41% in dual culture.
• CF3-10 and CE3-10 completely inhibited A. flavus growth at specific concentrations and significantly reduced AFB1 production (up to 93.4%).
• In vivo application reduced postharvest decay and AFB1 by over 88%, while downregulating key AFB1 biosynthesis genes and causing cellular damage in A. flavus.

Conclusions:

• Streptomyces yanglinensis 3-10 and its antifungal substances (CF3-10, CE3-10) demonstrate potent activity against Aspergillus flavus.
• These natural compounds effectively inhibit fungal growth, reduce aflatoxin AFB1 production, and protect peanut kernels from postharvest decay.
• S. yanglinensis presents a promising biological control strategy as an alternative to synthetic fungicides.