PVA/ZnONPs活细胞固定化载体的构建及喹啉生物降解特性试验研究

利用ZnO纳米颗粒(ZnONPs)修饰聚乙烯醇(PVA)制备活细胞固定化载体,并将喹啉降解菌Ochrobactrum sp.LC-1固定。X射线衍射(XRD)和扫描电镜(SEM)分析结果表明,ZnONPs均匀地分布在PVA内部孔隙表面,强化了对细菌及喹啉的吸附效果,且载体内部有大量孔隙支持细菌生长。喹啉生物降解结果表明,固定化细胞喹啉氧化还原酶(Qor)活性是游离细胞的1.7倍,喹啉降解能力大大增强。固定化细胞经驯化后,在喹啉起始质量浓度500 mg/L的条件下,10 h后,固定化细胞喹啉降解率为99.8%,远高于游离细胞的43.2%。当喹啉质量浓度为600~800 mg/L时,固定化细胞对喹啉的降解率可稳定在95%以上,固定化细胞重复利用30次后,喹啉降解率仍维持在94.9%以上,表现出良好的机械耐受强度,可应用于实际生产。

Creating PVA/ZnONPs living cell immobilization carrier and tracing the biodegradation function of quinoline

The present paper is aimed at preparing for a novel bacterial cell immobilized carrier(short for PVA/ZnONPs),which is the polyvinyl alcohol(PVA)composite decorated with ZnO nano particles(ZnONPs)and the quinoline-degrading bacteria(Ochrobactrum sp.LC-1)immobilized for the test.And,then,the paper would like to analyze and characterize the properties of PVA/ZnONPs through X-ray diffracto-meter(XRD)and electronic microscopy scanning.The results of our study and analysis indicate that ZnONPs has been evenly distributed on the porous surface of the PVA/ZnONPs,which helps to enhance the adsorption of bacteria and quinoline.In addition,it would be possible for us to observe and range lots of porosities with diameters from 20μm to 100μm in the PVA/ZnONPs,which indicates that PVA/ZnONPs with multiple porosities is in a position to provide enough space to support the growth of bacteria,and greatly shorten the carrier through adsorption of good quinoline and biocompatibility in transferring the mass distance.What is more,in the process of quinoline degradation,quinoline 2-oxidoreductase(Qor)activity in the immobilized cells can be increased up to 1.7 times higher than that of the free ones.Particularly speaking,under the condition of the initial concentrations,quinoline was 500 mg/L,while the degradation rate of the quinoline by the immobilized cells can be so high as to 99.8%in a period of about 10 h,much higher than that of the free ones(43.2%).Such a kind of result demonstrates that quinoline’s degrading ability of strain Ochrobactrum sp.LC-1 can be enhanced drastically through immobilization.For example,when the initial concentration of quinoline is,say,800 mg/L,it should be possible for the immobilized cells to degrade completely within a short time of 16 h,whereas it can only be degraded by the free cells by about 36 h under the normal condition of the initial concentration of quinoline of 600 mg/L.This has clearly indicated that the immobilized cells have strong tolerance to the high concentrations of quinoline.Furthermore,if the initial concentrations of quinoline were set from 600 mg/L to 800 mg/L,its degradation rate could only be gone up to about 95%by the immobilized cells.And,in addition,the degradation rate of quinoline can still be kept up over 94.9%through 30 times of reuse.Thus,it can be said that the immobilized carrier prove to be endowed with nice mechanical tolerance in the production practice concerned.