四氯双酚A和四溴双酚A的生物降解及基于16S rRNA基因高通量测序的菌群分析

发布时间：2018-10-29 14:17

【摘要】：四氯双酚A(TCBPA)和四溴双酚A(TBBPA)是广泛用于电子产品、涂料、塑料和建材等制品中的阻燃剂,由于其内分泌干扰特性等毒作用,备受关注。TCBPA和TBBPA的化学性质稳定、疏水性强,易富集在土壤/底泥中,尤以电子垃圾拆解区最为突出。本课题研究了电子垃圾拆解区附近河流底泥中TCBPA和TBBPA的厌氧生物降解,考察不同厌氧条件对脱卤效果的影响;通过16S rRNA基因高通量测序,分析和比较脱卤过程中菌群的变化;最后对脱卤终产物BPA进行了好氧降解研究。河流底泥对TCBPA和TBBPA的厌氧降解发现,相同条件下TBBPA的脱溴速率比脱氯速率高,添加电子供体可以促进脱卤效率。不同强化条件对TCBPA和TBBPA脱卤速率的促进效果一致:产甲烷条件电子供体条件硫酸盐还原条件。其中,低浓度硫酸盐更利于TCBPA脱氯,而高浓度硫酸盐更利于TBBPA脱溴。菌群的多样性分析发现,TCBPA或TBBPA的加入导致菌群数量先增后降,菌群多样性降低,相同时间和厌氧条件中菌群组成相似。分类学分析表明,厌氧底泥中的主要菌群为Proteobacteria,Chloroflexi,Firmicutes,Bacteroidetes,Actinobacteria,Planctomycetes和Nitrospirae。培养过程过程中,潜在脱卤菌Chloroflexi,Firmicutes和Bacteroidetes相对丰度明显增加。优势菌属unclassified Anaerolineaceae,Longilinea,Leptolinea,Anaerolinea,Bellilinea,Clostridium,Fastidiosipila,vadinBC27wastewater-sludge group和unclassified Porphyromonadaceae等相对丰度增大,可能参与TCBPA的脱氯和TBBPA的脱溴过程。硫酸盐还原条件中,硫酸盐还原菌Geobacter、Desulfuromonas、Desulfobulbus与目标污染物脱卤滞后期延长和脱卤速率减缓有关。添加TBBPA和TCBPA样品菌群的差异主要在于产甲烷条件,相对丰度较高的Longilinea、Leptolinea、Bellilinea、Clostridium、Fastidiosipila、unclassified Porphyromonadaceae、Sphingopyxis和Sphingobium,是该条件下脱卤速率较高的原因。脱卤终产物BPA好氧矿化可由驯化微生物代谢实现。当接种量10%、温度34oC和pH 8时,40 mg·L-1 BPA可在6 d内完全降解,具有最优的降解效果。BPA依次代谢为对羟基苯乙酮、乳酸,最终被转化为CO2和水,部分积累中间产物毒性大大降低。
[Abstract]:Tetrachlorobisphenol A (TCBPA) and tetrabromobisphenol A (TBBPA) are widely used as flame retardants in electronic products, coatings, plastics and building materials. Due to their toxic effects such as endocrine disruptions, the chemical properties of TCBPA and TBBPA are stable. Strong hydrophobicity, easy to be enriched in soil / sediment, especially in the electronic waste dismantling area. In this paper, the anaerobic biodegradation of TCBPA and TBBPA in the river sediment near the electronic waste dismantling area was studied, and the effects of different anaerobic conditions on the dehalogenation effect were investigated, and the changes of the flora in the dehalogenation process were analyzed and compared by high throughput sequencing of the 16s rRNA gene. Finally, aerobic degradation of dehalogenated end product BPA was studied. The anaerobic degradation of TCBPA and TBBPA by river sediment showed that the debromination rate of TBBPA was higher than that of dechlorination under the same conditions, and the dehalogenation efficiency could be promoted by adding electron donor. The effect of different strengthening conditions on the dehalogenation rate of TCBPA and TBBPA is the same: methanogenic condition electron donor condition sulfate reduction condition. Among them, low concentration sulfate is more favorable for TCBPA dechlorination, and high concentration sulfate is more favorable for TBBPA debromination. The diversity analysis showed that the addition of TCBPA or TBBPA led to the first increase in the number of bacteria and then the decrease of the diversity of the flora, and the composition of the flora was similar in the same time and anaerobic conditions. Taxonomic analysis showed that the main flora in anaerobic sediment was Proteobacteria,Chloroflexi,Firmicutes,Bacteroidetes,Actinobacteria,Planctomycetes and Nitrospirae.. During culture, the relative abundance of Chloroflexi,Firmicutes and Bacteroidetes increased significantly. The relative abundance of unclassified Anaerolineaceae,Longilinea,Leptolinea,Anaerolinea,Bellilinea,Clostridium,Fastidiosipila,vadinBC27wastewater-sludge group and unclassified Porphyromonadaceae increased, which may be involved in the dechlorination of TCBPA and the debromination of TBBPA. In sulfate reduction conditions, Geobacter,Desulfuromonas,Desulfobulbus of sulfate reducing bacteria is related to prolonged dehalogenation delay and slow down of dehalogenation rate of target pollutants. The difference between the sample populations of TBBPA and TCBPA was mainly due to the methanogenic conditions, and Longilinea,Leptolinea,Bellilinea,Clostridium,Fastidiosipila,unclassified Porphyromonadaceae,Sphingopyxis and Sphingobium, which had higher relative abundance, were the reasons for the higher dehalogenation rate under these conditions. Aerobic mineralization of dehalogenated end product BPA can be achieved by the metabolism of domesticated microorganisms. 40 mg L-1 BPA could be completely degraded within 6 days at the inoculation amount of 10: 10 and temperature 34oC and pH 8. BPA was metabolized as p-hydroxyacetophenone, lactic acid, and was converted to CO2 and water in turn. The toxicity of some accumulated intermediates was greatly reduced.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X172

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