Research Of Rhamnolipid On The Physiological Property Of Strain Pseudomonas Aeruginosa NY3 In The Metabolic Process Of Hydrocarbon

It is generally accepted that rhamnolipid is biodegradable, and it can promote biodegradation because of its ability to emulsify solubilizing hydrophobic organics. But it is not yet very clear that rhamnolipid improve the efficiency of hydrocarbon degradation for the change of physiological characteristics of bacterial cells, This paper aims to reveal the mechanism of promoting microbial metabolism of alkanes by studing the influence of rhamnolipid on the physiological characteristics of bacterial cells, which is important for understanding the action and application of rhamnolipid in the process of hydrophobic environmental remediation.In this paper, P. aeruginosa strain NY3 and its hydroxylase mutant strains NB1 D, NB2 D, NB12 DD as the test strains, UV spectroscopy, infrared spectroscopy, gas chromatography and thin layer chromatography as the analysis tools, the hydrocarbons and crude oil as the research object for the study, the results as followed:(1)The carbon source had a greater impact on the composition and properties of rhamnolipids by strain NY3. Rhamnolipid were brown oily liquid and solid(and granular crystals), and mainly were single and double glycolipids.When olive oil and rapeseed oil as carbon source. The solid rhamnolipids had a good emulsifying properties and prompt the growth of bacterial, when 60,100,140mg/L of the solid rhamnolipids was added respectively, the degradation rate of hexadecane increased 9.7%, 21.1%, 37.6% respectively. Compared with non-dosing of rhamnolipid, the degradation efficiency of n-alkanes C25-C32 was increased more than 40% by NY3, NB1 D, NB2 D, NB12 DD during the degradation of mixing paraffin oil, which improved the bioavailability of long-chain alkanes significantly.(2)Rhamnolipid promoted the degradation of hydrocarbon, mainly through accelerating hydrocarbon mass transfer, promoting bacterial cell uptake and improving hydrocarbon oxidizing bacteria in vivo activity and accelerating electron transfer and other means. When 100,140 mg/L rhamnolipids was added, the accumulation of cetane in intracellular increased 12.5% and 37.69% respectively. For strains NY3 and NB1 D, the hydrocarbon oxidase specific activity could increased 3.38 times and 2.40 times respectively by adding rhamnolipid.(3)Rhamnolipids could increase the contant of hydrophobic functional group, the total protein in the composition of bacterial when hydrocarbon as carbon source, at the same time, it could increase the loss of cell surface lipopolysaccharide. When 60,100,140,200mg/L of rhamnolipid was added respectively, after 72 h, the content of LPS reduced 45.65%, 58.13%, 45.61%, 59.44% and the content of total protein increased 48.4%, 34.6 %, 78.3 % and 90.3%, respectively.The results of this paper aim to be a foundation of understanding the mechanism of promoting biodegradation of hydrophobic organic compounds by rhamnolipids deeply.