Research Of Effects On Characteristics Of Rhamnolipid Fermented By Carbon Sources And The Mechanism Of Promoting Hydrocarbon Degradation By P. Aeruginosa NY3

Compared with chemical surfactants, rhamnolipid as a hot area of research and development, can be easily biodegradable, non-toxic for most microorganisms, and can improve the microbial utilization of petroleum hydrocarbon pollution. Our research group previous obtained a Pseudomonas aeruginosa NY3 could produce rhamnolipid and degrade different kind of hydrophobic organic pollutants. Study the effects on the composition and structure of rhamnolipid fermented by carbon sources and the mechanism of promting hydrocarbon degradation by P. aeruginosa NY3 is important for understanding the action and application of rhamnolipid in the process of hydrophobic environmental remediation.In this paper, using thin layer chromatography, infrared spectroscopy, LCMS-ITYOF, and so on, to analysis the composition and structure of rhamnolipid and study the mechanism of promting hydrocarbon degradation by P. aeruginosa NY3, the results as followed:(1) The main long-chain fatty acid in grease had an important effect on the composition and structure of rhamnolipid composited by P. aeruginosa NY3. The main structures of rhamnolipid fermented by colza oil were Rha-C14-C15:1, Rha-C15-C16, Rha-Rha-C10-C10, Rha-Rha-C9:1-C9:1. The main structures of rhamnolipid fermented by olive oil were Rha-Rha-C10-C10, Rha-Rha-C9:1-C9:1, Rha-Rha-C11-C11, Rha-C15-C16, and had more unsaturated bonds. The main structures of rhamnolipid fermented by illegal cooking oil were Rha-C15-C16, Rha-Rha-C10-C10. Rhamnolipid fermented by olive oil had the best surface activity and could improve the emulsifying property of hydrocarbon degradation more effectively hydrophobic pollutants, which had the lowest critical micelle concentration, 35 mg/L.(2) Rhamnolipid had more disaccharides could promote degradation of petroleum hydrocarbons obviously. When 1.11 g/L hexadecane was added respectively, after 48 h, the degradation rate of hexadecane could be 70.66% with adding 200 mg/L rhamnolipid fermented by olive oil, increased 9.7%, 21.1%, 37.6% respectively compared with rhamnolipid fermented by colza oil and illegal cooking oil. For 5 g/L dosage of crude oil, the average degradation rate of straight-chain alkanes could be about 88%, increased about 20%、16% respectively.(3) Rhamnolipid promoted the degradation of hydrocarbon, mainly through accelerating hydrocarbon mass transfer. Dosing concentration of 200 mg/L rhamnolipid, the degradation rate of hexadecane could reach about 98.82% after 90 h, increased 49.36% than non-dosing rhamnolipid. The content of extracellular protein in the system increased with adding dosage of rhamnolipid, and had significant role in promoting for degrading alkanes by P. aeruginosa NY3.(4) Acidic substances(mostly hydrocarbon oxidation products) accumulated in the system could be utilized by P. aeruginosa NY3 as carbon source to grow rapidly, which stored into cell in the form of protein and lipopolysaccharide and made the cell size becomes large.