2.2. CMC Determination

The critical micelle concentration (CMC) was determined by measuring the surface tension of the rhamnolipids containing aqueous solutions at room temperature (approximately 22 °C) using a K11 tensiometer (KRÜSS, Hamburg, Germany). Rhamnolipids concentration range was from 10⁻³ to 10⁶ mg/m³. Each measurement was conducted in triplicate, and the average was calculated. Afterwards, a surface tension curve versus the decimal logarithm of the biosurfactant concentration (γ = f(logc)) were made, from which the CMC value in water was determined [42]. CMC is the point beyond which a further increase in the biosurfactant concentration does not reduce the surface tension of the water [43].