鼠李糖脂对铜绿假单胞菌NY3表面特性及其烃降解效率的影响

研究了鼠李糖脂对NY3菌表面特性及其降解烃类物质的影响作用.结果表明,与未加鼠李糖脂相比,原油含量为1000 mg·L-1,鼠李糖脂100 mg·L-1时,生长24和48 h,NY3菌细胞净生长量分别提高8.60和6.68倍,且产酸明显,原油中正二十六烷至正三十三烷降解效率可提高约60%.分别以LB培养基和十六烷为唯一碳源的无机盐培养基生长的NY3菌体(OD400nm=1.68±0.08),与100 mg·L-1的鼠李糖脂作用1.5h,菌体表面疏水性分别增加32%、6%;且以LB培养基生长的NY3菌细胞,在鼠李糖脂和十六烷存在下作用90 min,菌细胞所积聚的正十六烷量比未加鼠李糖脂时增加了1.10 nmol·mg-1干菌,说明鼠李糖脂能加快疏水性有机物的传质速度.红外光谱分析结果表明,与未加鼠李糖脂相比,鼠李糖脂使菌体细胞中疏水性脂肪链的相对含量明显增加.因此,鼠李糖脂能增加菌体的表面疏水性,加快烃类的传质速率,从而促进NY3菌对烃的降解.

Effects of rhamnolipid on the properties of cell surface of strain Pseudomonas aeruginosa NY3 and its degradation efficiency of hydrocarbons

The effects of biosurfactant rhamnolipid on the surface properties of Pseudomonas aeruginosa NY3 and its degradation efficiency of hydrocarbons were studied.The results showed that rhamnolipid could increase the crude oil bioavailability.Compared with the rhamnolipid-free conditions,when the concentration of crude oil was 1000 mg·L^-1,the net accumulated biomass of NY3 strain cells increased by 8.60 times at 24 h with the existence of 100 mg·L^-1 rhamnolipid.Faster growth resulted in quicker declining of the pH values of the culture.The degradation rates of the alkanes ranging from hexacosane to tritriacontane in the crude oil were promoted to about 60% by the rhamnolipid.The hydrophobicity of the NY3 cells (OD_400nm=1.68±0.08) harvested from LB medium enhanced 32% after 1.5 h interaction with rhamnolipid (100 mg·L^-1) and that of the cells harvested from minimal medium with hexadecane as the sole carbon source enhanced only 6%.Cells harvested from LB medium accumulated and were intaken 1.10 nmol·mg^-1 dry cell more hexadecane with the assistance of rhamnolipid.The results indicated that rhamnolipid could accelerate mass transfer rate of hydrophobic organic compounds onto cells.The analysis of FT-IR suggested that the ratio of the hydrophilic functional groups contained in cells harvested from both medium reduced obviously after interaction with rhamnolipid.We may therefore conclude that rhamnolipid could enhance the hydrophobicity of NY3 cell surfaces,accelerate mass transfer rate of hydrocarbons,and promote the degradation rate of hydrocarbons by strain NY3.