外加碳源及固定化对荧蒽降解菌降解性能的强化作用

Increasing the Effectiveness of a Fluoranthene-Degrading Microorganism by Immobilization and Adding a Carbon Source

从受PAHs污染的河道底泥中筛选分离出一株荧蒽降解菌,经16S rDNA序列分析确定为青霉素菌DTQ-HK1。试验研究了外加碳源和菌种固定化对DTQ-HK1降解荧蒽的影响。结果表明,经连续42 d培养后,单独DTQ-HK1对水相中荧蒽的降解率达到52.22%;按照体系中C荧蒽∶C麦芽糖=5∶3投加麦芽糖后,荧蒽的降解率提高到81.75%。在此基础上,采用粒径10目的玉米芯对DTQ-HK1进行吸附固定化,并投加在菖蒲根际圈进行强化修复试验。90 d的降解试验结果证明,在菖蒲根际投加吸附固定化菌的荧蒽降解效率比直接投加悬浮菌液略有提高;外加碳源麦芽糖能明显提高固定化菌对荧蒽的降解效果,90 d的荧蒽去除率可达100%。降解动力学及产物分析表明,对DTQ-HK1菌株进行固定化处理能在一定程度上提高该菌种对荧蒽的降解速率,尤其是外加碳源辅助可使DTQ-HK1对荧蒽的降解速率增加1.3倍,而且降解过程更加彻底,产物以开链化合物为主。

Polycyclic aromatic hydrocarbon(PAH)pollution of sediments in rivers and lakes is widespread in China,particularly the high molecular weight polycyclic aromatic hydrocarbons(H-PAHs).To date,few studies have been conducted on use of the plant rhizosphere to promote respiration in river sediments with H-PAH pollution.In our study,fluoranthene was selected as the target pollutant.A typical fluoran-thene degrading strain was screened from the rhizosphere of calamus growing in the river sediment contaminated by fluoranthene.The strain labeled as DTQ-HK1 was identified as Penicillium purpurogenum through morphological observation and 16SrDNA sequence homology analysis.The strain was adsorbed and immobilized on pulverized corn cob and the effect of adding an external carbon source on fluoranthene degradation by DTQ-HK1and plant-microorganism remediation of fluoranthene contaminated river sedi-ment were studied.Degradation products were identified and degradation kinetics were analyzed.After being cultured in a liquid medium for 42days,52.22%of the fluoranthene was degraded.When maltose was added as an external carbon source(fluoranthene:maltose=5∶3),the extent of fluoranthene degradation increased to 81.75%.The degradation performance of the plant-microorganism combination then studied in a 90-day experiment.DTQ-HK1was immobilized on pulverized corn cob passed through a 10mesh sieve and added to sediment near calamus roots.The degradation efficiency of immobilized DTQ-HK1in sediment near calamus roots was slightly higher than for free DTQ-HK1and the degradation efficiency was significantly improved by adding maltose,reaching 100%at 90days.Analysis of degradation kinetics and products showed that the degradation rate of fluoranthene by DTQ-HK1was enhanced by immobilization and the degradation rate with an external carbon source was 1.3times that of DTQ-HK1alone.The degradation process was more complete and the degradation products were mainly open-chain substances.The results show that immobilization and addition of an external carbon source can enhance PAH degradation when using aplant-microorganism system for remediation.