【作者】 张谦；

【导师】 沈超峰；

【作者基本信息】 浙江大学 ， 环境工程， 2015， 硕士

【摘要】 多氯联苯(polychlorianted biphenyls, PCBs)因具有持久性、远距离迁移性、生物富集性及高生物毒性,已经被列为全球首批优先控制的十二种持久性有机污染物之一,但仍有大量残留于土壤等环境中。土壤PCBs污染的微生物修复法成本低、二次污染小,但如何提高土壤中PCBs的生物有效性一直是研究难点。表面活性剂已被证实可有效提高土壤中PCBs的生物有效性,其中生物表面活性剂更具有绿色、安全等优点,但其可生物降解性使得修复过程中需不断补充。若添加产表面活性剂菌至土壤中就可持续分泌生物表面活性剂,修复操作更方便,运行成本更低。但将产表面活性剂菌直接应用于土壤有机污染生物修复的研究极少,值得探索。本论文首先对比了大豆卵磷脂、茶皂甙、鼠李糖脂、烷基糖苷、蔗糖酯这三类五种生物表面活性剂和一种类生物表面活性剂物质p-环糊精对土壤中PCBs微生物降解的影响；然后进一步探索水相体系中,铜绿假单胞菌Pseudomonas aeruginosa AB93066 (产鼠李糖脂菌)对赤红球菌Rhodococcus ruber SS1 (PCBs降解菌)降解PCBs过程中的促进作用及影响机制；并在此基础上考察了土壤泥浆体系中,铜绿假单胞菌与赤红球菌联合降解PCBs的效果。研究结果如下：(1)通过对比几种常见的生物表面活性剂和类表面活性剂物质对实际污染土壤中PCBs微生物降解的促进效果,发现植物源表面活性剂茶皂甙、微生物源表面活性剂鼠李糖脂、生物原料合成的表面活性剂烷基糖苷与蔗糖酯以及类表面活性剂物质β-环糊精,可分别将污染土壤中PCBs的30d消减率提高约39%、40%、22%、43%和42%。另外,烷基糖苷、蔗糖酯和β-环糊精对低氯代PCBs降解的促进作用优于高氯代PCBs。(2)将铜绿假单胞菌与赤红球菌在水相混合培养时,铜绿假单胞菌能将赤红球菌降解PCB8、 PCB28与PCB52的速率分别提高35.0%、5.1%和9.6%,并能将PCB28、PCB52的生物降解延滞期缩短。低氯代PCBs的添加使铜绿假单胞菌经历更长时间的调整期和对数期,但稳定期更短,进入衰亡期后铜绿假单胞菌的微生物量以及分泌的鼠李糖脂含量均高于无PCBs体系,说明低氯代PCBs对铜绿假单胞菌生长的影响由胁迫作用转为刺激作用。(3)通过对比鼠李糖脂和铜绿假单胞菌对泥浆体系中赤红球菌及土著菌降解PCBs的影响,发现铜绿假单胞菌对三氯联苯的微生物降解具有显著促进作用,且与鼠李糖脂的作用相当,对四氯联苯的降解具有一定的促进作用。此外,鼠李糖脂对五氯联苯降解的促进作用优于铜绿假单胞菌,而两者对六氯、七氯联苯的含量变化无影响。本论文从疏水性有机污染土壤的绿色修复角度出发,探讨了产表面活性剂菌对PCBs微生物降解的影响与作用机制,研究结果表明产表面活性剂菌有利于提高疏水性有毒有机物PCBs的微生物降解效率,为进一步研发土壤PCBs污染的微生物修复技术提供了理论依据。更多还原

【Abstract】 Since their persistence, long distance mobility, bioconcentration and biotoxicity, polychlorinated biphenyls (PCBs) have been listed as a category of the first twelve POPs (Persistent Organic Pollutants), which need to be controlled in precedence. Although lots of works have been done, PCBs still remain in the natural environment, especially in the soil. Microbial remediation technologies of PCBs-contaminated soil play significant roles because they can be operated simply with low cost and less secondary contamination. But how to increase the bioavailability of PCBs has always been one of the research challenges. It has been shown that some surfactants can improve the bioavailability of PCBs in the soil, especially the biosurfactants those are more environmentally friendly. But the biodegradation of biosurfactants makes it need to be constantly added throughout the process. Adding surfcant-producing bacterium to contaminated soil for sustainable production can make remediation more convenient and more economical. However, there have been few researches focused on the bioremediation of the organic contaminated soil by surfactant-producing bacterium directly.In this study, the different effects of soya bean lecithin, tea saponin, rhamnolipid, alkyl glycoside, sucrose esterto and P-cyclodextrin on the biodegradation of PCBs in soil were tested. The synergic biodegradation of PCBs by Pseudomonas aeruginosa AB93066 and Rhodococcus ruber SS1 was sudied with traditional methods. The mechanism of synergic biodegradation was explained from the growth of Pseudomonas aeruginosa AB93066, the concentration of the produced rhamnolipid and the degradation of PCBs by Rhodococcus ruber SS1. Then how to apply the synergic effects of Pseudomonas aeruginosa AB93066 and Rhodococcus ruber SS1 on hydrophobic organic-contaminated soil was discussed. The main results of this research are as follows:1) By comparing the influence of several common biosurfactants on the degradation rate of PCBs in the contaminated soil, tea rhamnolipid, saponin, alkyl glycoside, sucrose esterto and P-cyclodextrin were found to increase the degradation rate of total PCBs by approximately 40%,39%,22%,43% and 42% respectively after 30 days. Besides, more low-chlorinated PCBs were degraded with alkyl glycoside, sucrose esterto and β-cyclodextrin added when compared with high-chlorinated PCBs.2) Pseudomonas aenuginosa AB93066 promoted the degradation rates of PCB8, PCB28 and PCB52 by 35.0%,5.1% and 9.6% respectively after mixed cultivation with Rhodococcus ruber SS1. It was also proved that Pseudomonas aeruginosa AB93066 can reduce the lag phases of PCB28 and PCB52. The addition of low-chlorinated PCBs gave Pseudomonas aeruginosa AB93066 longer adjustment phase and logarithmic phase, with shorter stable phase. When it came to decline phase, there were more microbial biomass and rhamnolipid detected than the blank system (without PCBs), which indicates that low-chlorinated PCBs stimulated Pseudomonas aeruginosa AB93066 instead of stressing.3) Enhanced biodegradation of both trichlorodiphenyl and tetrachlorobiphenyl was revealed when comparing the influence of rhamnolipid and Pseudomonas aeruginosa AB93066 on Rhodococcus ruber SS1 and indigenous flora. Decreases of pentachlorodiphenyl were observed in slurry with the presence of rhamnolipid. Neither rhamnolipid nor Pseudomonas aeruginosa AB93066 has influence on the degradation rate of hexachlorodiphenyl or heptachlorodiphenyl.In conclusion, the influence of surfactant-producing bacterium on the biodegradation of PCBs was studied, which showed that surfactant-producing bacterium promoted the biodegradation rate of hydrophobic organic compound in soil. The results will help us to understand the PCBs-biodegradation mechanisms and also provide a new way of the remendiation of PCBs soil contamination.更多还原