不同方法提取PAHs高效降解菌EPS的特性

Characteristics of EPS extracted from a high efficient PAHs-degrading bacterium by different methods

采用阳离子交换树脂法、超声法、超声-阳离子交换树脂法、加热法4种方法提取一株PAHs高效降解菌的胞外聚合物(EPS),并结合红外光谱、三维荧光光谱、透射电子显微镜对不同方法提取的EPS进行特性分析。结果表明,加热法得到的EPS中蛋白质和多糖的总含量最大为328.36 mg·L-1;4种方法提取EPS的红外光谱谱线均出现C(N)═O、N—H(蛋白质)和O—H(多聚糖)强峰,其中加热法提取EPS谱图中C(N)═O和N—H基团的吸收峰最宽、强度最大;三维荧光光谱分析结果表明,加热法提取EPS的2个类蛋白峰强度最大,分别为13.8、118.2 a.u.,而其他3种方法提取EPS的类蛋白峰强度较弱、类腐殖酸和类富里酸峰较强;透射电子显微镜检测结果表明,加热法细胞体破坏程度最小且胞内物质没有溶出现象。综合考虑4种方法提取EPS特性,加热法提取效率较高且温和,是比较理想的EPS提取方法。

Extracellular polymeric substances （EPSs） of a high efficient PAHs-degrading bacterium strain were extracted by four methods including cation exchange resin method, ultrasonic method, ultrasoniccation exchange resin method and heating method, and the properties of EPSs extracted by the four methods were analyzed by infrared spectrum, threedimensional fluorescence spectrum and transmission electron microscope. The maximum total content of protein and polysaccharide in EPSs by the heating method was 328.36 mg·L-1. The adsorption peaks of C（N）═O, N―H （protein） and O―H （polysaccharides） were all present on the infrared spectrum of EPSs obtained by the four methods, and the peaks of C（N）═O and N―H on the spectra of EPSs extracted by the heating method were the widest and strongest. The threedimensional fluorescence spectrum analysis showed that the intensities of two proteinoid peaks in EPSs obtained by the heating method were maximum, being 13.8 and 118.2 a.u., respectively, while the proteinoid peak was weaker and the humiclike and fulviclike acids were stronger in EPSs obtained by the other three methods. Transmission electron microscopy analysis showed that the damage of bacterial cell was least and no intracellular substances dissolved out during the process of heating. According to the characteristics of the EPSs obtained by the four methods, the heating method was considered as the better EPS extraction method due to its highest efficiency and moderate impact on bacterial cell.