August 12, 2025

Pseudomonas fluorescens from Lake Bogoria, Kenya: a promising biocontrol agent against Fusarium solani in Phaseolus vulgaris L.

Key Points

Pseudomonas fluorescens reduced wilt symptoms to less than 20% in bean plants contaminated with Fusarium solani, indicating its potential efficacy.
The study identified two strains of Pseudomonas fluorescens which showed mycelial inhibition rates ranging from 5.95% to 42.86% against Fusarium solani.
Enzyme assays revealed antifungal enzyme production, including chitinase and chitosanase, contributing to the biocontrol properties of the bacteria.
These findings emphasize the role of Lake Bogoria-derived Pseudomonas fluorescens in improving bean yield and reducing disease incidence.

Abstract

Common beans ( Phaseolus vulgaris L) are an important staple crop valued for their high protein content and dietary benefits. However, Fusarium wilt, caused by Fusarium solani , is responsible for up to an 84% yield loss in bean production. This study aimed to isolate and evaluate novel Pseudomonas fluorescens from Lake Bogoria as potential biocontrol agents against F. solani . Using serial dilution, 30 bacterial isolates were obtained; 10 showed varied mycelial inhibition rates (5.95–42.86%) through dual culture and confrontation assays. Molecular identification using 16S rDNA confirmed that two isolates were Pseudomonas fluorescens strains. Antibiosis gene screening revealed the presence of 2,4-diacetylphloroglucinol, pyrrolnitrin, pyoluteorin and hydrogen cyanide. Enzyme assays demonstrated chitinase (1.33–3,160 U ml −1 ) and chitosanase (12.67–29.00 mm) production, indicating antifungal capabilities. In vivo pot experiments with isolate TW17 + showed reduced wilt symptoms <20.0% and disease incidence (8.0–35.0%). These findings highlight the potential of soda lake-derived Pseudomonas fluorescens as an effective biocontrol agent against F. solani , with additional benefits for common bean growth and yield improvement.

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