Microbial synthesis of rhamnolipids by Pseudomonas aeruginosa (ATCC 10145) on waste frying oil as low cost carbon source.

Vegetable edible oils and fats are mainly used for frying purposes in households and the food industry. The oil undergoes degradation during frying and hence has to be replaced from time to time. Rhamnolipids are produced by microbial cultivation using refined vegetable oils as a carbon source and Pseudomonas aeruginosa (ATCC 10145). The raw material cost accounts for 10-30% of the overall cost of biosurfactant production and can be reduced by using low-cost substrates. In this research, attention was focused on the preparation of rhamnolipids, which are biosurfactants, using potential frying edible oils as a carbon source via a microbial fermentation technique. The use of low-cost substrates as a carbon source was emphasized to tilt the cost of production for rhamnolipids. The yield was 2.8 g/L and 7.5 g/L from waste frying oil before and after activated earth treatment, respectively. The crude product contained mainly dirhamnolipids, confirmed by thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), liquid chromatography-mass spectroscopy (LC-MS), and (1)H-nuclear magnetic resonance (NMR). Hence, the treatment can be used to convert waste frying oil as a low-cost substrate into a cost-effective carbon source.

Utilization of sweetwater as a cost-effective carbon source for sophorolipids production by Starmerella bombicola (ATCC 22214).

Biosurfactants are microbially synthesized surfactants that are environmental friendly due to low toxicity. Sophorolipid is one of the simplest biosurfactants with well-defined structure produced by Starmerella bombicola(ATCC 22214) on glucose and vegetable oil as the carbon source. The raw material cost accounts for 10-30% of the overall cost. Glycerol is readily available from a commercial fat-splitting process as sweetwater at a very low cost. Sophorolipids was synthesized using glycerol and sweetwater as a cost-effective carbon source. The glycerol was further replaced with sweetwater as a source of glycerol. Optimum glycerol concentration was 15% w/v with 10% w/v sunflower oil, giving 6.6 g/L of sophorolipids. The crude sophorolipid contains two major components; both of them were lactonic sophorolipids as analyzed by reverse-phase high-performance liquid chromatography (RP-HPLC), liquid chromatography-mass spectroscopy (LC-MS), and nuclear magnetic resonance ((1)H-NMR).