Biosurfactants are categorised as surface-active substances of natural origin, produced through microbial culture, and are composed of both hydrophilic and hydrophobic regions. On account of their capacity for reducing both surface and interfacial tension, and due to their simplicity of biodegradation and eco-friendly nature, biosurfactants are considered attractive alternatives to chemical surfactants. Biosurfactants find extensive applications in the following domains: bio-remediation, the food industry, the pharmaceutical industry, and the metal recovery processes of precious metals. As a part of the present study, biosurfactants obtained from Pseudomonas aeruginosa WARP_W2 were studied for pH sensitivity with a special focus on their use as biosurfactants in metal recovery/bioleaching technique based on the following methodology: Biosurfactants obtained from the microbial culture mentioned in the study were tested in varying acidic pH environments ranging from pH 2 and pH 7 using different acids H₂SO₄, HNO₃, HCl, and HCOOH. Results obtained revealed that varying biosurfactant pH values did indeed affect biosurfactant functionality and stability. Even though there is an increase in the biosurfactant emulsification activity in lower pH values, a decrease in the values of biosurfactant stability does provide information regarding the degradation of biosurfactants in lower pH con-ditions. Therefore, based on the above-discussed findings, it is concluded that pH values hold important positions in optimising biosurfactant properties, especially in environments where pH values are acidic in nature. In the metal recovery process, which involves biosurfactant-assisted bioleaching, where there is an involvement of the acidic environment, there is a major requirement to understand the properties of biosurfactants in relation to pH values in increasing the efficiency of solubilization.

pH Effect, Emulsification Efficiency, Surface Activity, Microbial Products, Environmental Applications