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Enhancement of Mycelial Growth and Antifungal Activity by Combining Fermentation Optimization and Genetic Engineering in Streptomyces pratensis S10

Summary

Researchers improved a naturally occurring bacteria called Streptomyces pratensis S10 that kills harmful wheat fungi causing crop disease. Using scientific optimization of growth conditions and genetic modification, they increased the bacteria’s disease-fighting power by about 22% and its growth by nearly four-fold. This advancement could help farmers control wheat diseases more sustainably without relying heavily on chemical fungicides.

Background

Streptomyces pratensis S10 is a biocontrol strain isolated from tomato leaf mold that exhibits antifungal activity against Fusarium graminearum, which causes Fusarium head blight (FHB) in wheat. However, the practical application of S10 has been limited by low biomass yield and prolonged fermentation periods, hindering large-scale commercialization.

Objective

This study aimed to enhance the antifungal activity and mycelial biomass of S. pratensis S10 by integrating fermentation optimization using statistical design methods with genetic engineering approaches to improve biocontrol efficacy against FHB.

Results

Optimization identified corn flour, yeast extract, and ZnSO₄·7H₂O as critical variables. The optimized medium increased mycelial dry weight from 2.13 g/L to 8.12 g/L and antifungal activity from 67.36% to 82.2% against F. graminearum. The ΔtetR mutant showed enhanced growth and antifungal activity, with mycelial biomass reaching 11.53 g/L in the optimized medium.

Conclusion

The integration of fermentation optimization and genetic engineering successfully enhanced S. pratensis S10’s biocontrol efficacy against FHB. The tetR gene acts as a negative regulator of bioactive compound biosynthesis, and the optimized medium provides favorable conditions for metabolite production, establishing a foundation for large-scale industrial application.
  • Published in:Microorganisms,
  • Study Type:Experimental Research,
  • Source: PMC12388169, PMID: 40871447
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