Enhancing spontaneous biosurfactant production through water steeping of olive mill waste

This study offers novel and valuable insights into the spontaneous production of biosurfactant extracts from olive mill waste (OMW) through a steeping process with water at 37 °C for 15 days, followed by extraction with ethyl acetate or phosphate-buffered saline (PBS). The results showed that steeping process significantly improves the extraction efficiency and produces biosurfactant extracts with more favorable critical micellar concentration (CMC) and wettability properties than those from non-steeped OMW. Under best conditions, it yielded 104.6 g/Kg of OMW. Elemental analysis and comparative ATR-FTIR spectroscopy revealed that ethyl acetate biosurfactant extracts is compatible with biosurfactant extracts that contains phospholipids and lipopeptides. It reduced water surface tension to 46.7 mN/m and exhibited a CMC of 0.22 g/L. Conversely, the biosurfactant extract obtained through solid-liquid extraction with PBS was more compatible with glycopeptides biosurfactants, reducing the water surface tension to 50.4 mN/m, similarly to the surface tension values achieved by biosurfactants produced by lactic acid bacteria, but achieving reduced CMC value (0.19 g/L). Therefore, this approach presents a sustainable method for valorizing OMW, promoting sustainability, and circular economy principles. These extracts could have potential applications in various fields, such as soil bioremediation, surface cleaning, and in cosmetic and agrochemical formulations.