Production of cost-effective rhamnolipid from Halopseudomonas sabulinigri OZK5 using waste frying oil

The major barrier to the wide-range application of biosurfactants is their high cost of production and low yield. In this study, waste frying oil (WFO) was used as the sole carbon source to produce cost-effective and eco-friendly rhamnolipids by Halopseudomonas sabulinigri OZK5 isolated from crude oil–contaminated soil samples. The optimal culture conditions for rhamnolipid production were determined as 30 ml/l waste frying oil, 37 °C temperature, pH 8, and 72 h incubation time. Under the optimized conditions 2.97 g/l rhamnolipid production was achieved. With a critical micelle concentration of 50 mg/l, the rhamnolipids could reduce the surface tension of water to 37.5 mN/m and demonstrate strong emulsifying activity (E24 = 67.3%). As a result of FTIR analyses, major peaks were obtained at 2924, 2854, 1720, 1570, 1396, 1051, and 981 cm^–1. In conclusion, rhamnolipid production by non-pathogenic Halopseudomonas sabulinigri OZK5 using a low-cost fermentation medium has been shown to be biotechnologically promising.