The Potential of Bacilli-Derived Biosurfactants as an Additive for Biocontrol against Plant Pathogenic Fungi.

Fungal diseases caused by constitute a significant threat to the production and quality of a wide range of crops, including beans, fruits, vegetables, and grains. Traditional methods for controlling these diseases involve synthetic chemical pesticides, which can negatively impact the environment and human health. Biosurfactants are natural, biodegradable secondary metabolites of microorganisms that have also been shown to possibly have antifungal activity against plant pathogenic fungi, including being sustainable alternatives to synthetic pesticides. In this study, we investigated the potential of biosurfactants of three (, , and ) as a biocontrol agent against on beans as a model organism. For this fermentation, we describe using an biomass sensor monitoring both permittivity and conductivity, which are expected to correlate with cell concentration and products, respectively. After the fermentation of biosurfactants, we first characterised the properties of the biosurfactant, including their product yield, surface tension decrement capability, and emulsification index. Then, we evaluated the antifungal properties of the crude biosurfactant extracts against , both in vitro and in vivo, by analysing various plant growth and health parameters. Our results showed that bacterial biosurfactants effectively inhibited the growth and reproduction of in vitro and in vivo. manufactured the highest amount of biosurfactant (1.37 g/L) and demonstrated the fastest growth rate, while produced the least amount (1.28 g/L). The correlation study showed a strong positive relationship between viable cell density VCD and OD600, as well as a similarly good positive relationship between conductivity and pH. The poisoned food approach in vitro demonstrated that all three strains suppressed mycelial development by 70-80% when applied with the highest tested dosage of 30%. Regarding in vivo investigations, post-infection treatment decreased the disease severity to 30%, whereas and post-infection treatment reduced disease severity by 25% and 5%, respectively. The study also revealed that the plant's total height, root length, and stem length were unaffected by the treatment or the infection.