中文摘要：

以携带质粒pJP4[其上含编码2,4-二氯苯氧基乙酸（2,4-dichlorophenoxyacetic acid,2,4-D）降解功能的基因簇（tfd）]的基因工程菌Pseudomonas putida SM1443：：gfp2x（pJP4：：dsRed）为供体菌,以生物膜系统为对象,通过半连续流实验研究了质粒pJP4水平转移介导基因强化降解2,4-D效应,考察了目标基因在系统中存在状况及基因强化对系统菌群结构的影响.结果表明,以2,4-D（初始浓度为170 mg/L±10 mg/L）为唯一碳源,向生物膜系统加入携pJP4质粒的基因工程菌对2,4-D的降解具有促进作用,运行初期,促进作用较弱,随着半连续流反应的进行,促进作用显著增强,基因强化系统较对照系统对2,4-D的平均降解速率之差达13.3 mg/（L·h）.通过对基因强化系统功能基因片段tfdB基因及报告基因gfp的跟踪检测,证实了在pJP4质粒介导下生物膜系统基因水平转移的发生.PCR-DGGE结果表明基因强化的生物膜系统较对照系统在受到2,4-D冲击条件下保持了相对更加稳定的菌群结构.

英文摘要：

With plasmid pJP4 （which contains functional gene cluster （tfd） encoding 2,4-D degradation） carrying genetic microorganism Pseudomonas putida SM1443 ： ： gfp2x （pJP4 ： dsRed） as the donor strain, events of plasmid mediated gene horizontal transfer and its effect on 2,4-D degradation was investigated in a biofilm system operated under fed-batch mode. The surviving status of the functional gene element in the gene-augmented system and effects of gene-augmentation on microbial community structure were also investigated. Results showed that introduction of pJP4 carrying strain to the biofilm system with 2, 4-D （initial concentration at 170 mg/L± 10 mg/L） as the sole carbon source could enhance the degradation of 2, 4-D. Enhancement was slight during the initial stage of operation, but it increased with increasing of fed batch runs. Difference in 2, 4-D average degradation rate between gene-augmented system and the control system achieved up to 13.3 mg/（L·h） at most. Through detecting functional gene tfdB and reporter gene gfp, pJP4 mediated gene horizontal transfer to the bacteria on biofilm was further approved. Effects of gene augmentation on microbial community structure was analyzed by PCR-DGGE analysis, and results showed that relatively higher stability of microbial community was maintained for the gene-augmented biofilm system compared to the control system when facing 2,4-D shock loadings.