Biosurfactants Production from Low Cost Substrate and Degradation of Diesel Oil by a Rhod ococcus Strain

摘要

Biosurfactants Production from Low Cost Substrate and Degradation of Diesel Oil by a Rhodococcus Strain-The ability of a Rhodococcus strain to produce surface-active agents from residual sunflower frying oil(RSFO)has been screened in batch cultures.During cultivation with RSFO at the concentration 3%(vol/vol),the strain has synthesized extra-cellular compounds which increase the E_(24)emulsion index of the culture medium up to 63%.In their crude form,these substances lower the surface tension of water until 31.9 mN m~(-1).The exponential growth with RSFO as the sole carbon source has developed at a specific growth rate mu = 0.55 d~(-1).The critical micelle concentration of the crude product reached the value 287 mg L~(-1)(gamma CMC = 31.9 mN m~(-1)).After methylesterification,the lipid fraction of biosurfactants has been analyzed by GC-MS in EI,which reveals the presence of fatty acid methyl esters.The microorganism was also cultivated with the diesel oil as the sole carbon source at the concentration 1%(vol/vol):the active growth phase has developed at rate mu = 0.02 d~(-1),without production of emulsifying substance:the microorganism seems to develop different modes of substrate uptake,according to the nature of the carbon source.The potential use of surface-active agents synthesized on RSFO by Rhodococcus erythropolis 16 LM.USTHB is in the oil industry with minimum purity specification,so that crude preparation could be used,at low cost,in clean-up of hydrocarbons contaminated sites and for enhanced oil recovery.