磁性纳米颗粒介导分离技术筛选土壤中多氯联苯降解菌及其降解特性

【背景】磁性纳米颗粒介导分离(magnetic nanoparticle-mediated isolation, MMI)技术是近年来发展起来的一种无须底物标记就能从复杂菌群中分离活性功能微生物的方法，目前尚无研究报道该技术应用于难降解污染物3,3′,4,4′-四氯联苯(3,3′,4,4′-tetrachlorobiphenyl, PCB77)。【目的】从土壤中筛选PCB77活性降解菌并研究其污染物降解特性。【方法】利用磁性纳米颗粒(magnetic nanoparticles, MNPs)富集原位活性PCB77降解菌群，通过高通量测序分析细菌群落变化，经平板筛选得到PCB77降解菌，并研究其对多氯联苯和多溴联苯醚的降解特性。【结果】基于MMI技术获取的富集培养液能够高效地转化PCB77，与对照组相比底物降解效率从6%提升至79.3%，同时该富集培养液中细菌物种多样性显著降低，群落组成发生明显变化。从对照组和MMI处理组中分别筛选到PCB77降解菌红球菌CT2和类芽孢杆菌MT2，发现红球菌为对照组中唯一的优势物种，而MMI处理组的优势物种由红球菌和类芽孢杆菌共同组成。菌株MT2对PCB...

Magnetic nanoparticle-mediated isolation and degradation characterization of a PCB-degrading strain

Background] Magnetic nanoparticle-mediated isolation (MMI) is a culture-independent approach for identifying active degraders from complex microbial communities. However, there are few studies about the MMI-based identification of active bacteria involved in the degradation of recalcitrant 3,3'',4,4''-tetrachlorobiphenyl (PCB77). Objective] To isolate active PCB77 degraders from soil and assess the pollutant degradation capacity. Methods] Magnetic nanoparticles (MNPs) were used to enrich the active PCB77 degraders in soil. The change in bacterial community composition was determined by high-throughput sequencing. A PCB77 degrader was isolated from MNP-enriched culture, and its performance of degrading polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) was assessed. Results] The MNP-enriched culture was capable of degrading PCB77 with high efficiency compared with the control, which increased from 6% to 79.3%. The treatment with MNPs decreased the bacterial diversity and changed the community composition. PCB-degrading Rhodococcus sp. CT2 and Paenibacillus sp. MT2 were isolated from the control and MMI culture, respectively. Rhodococcus was dominant in the control group, while the dominant degraders included both Rhodococcus and Paenibacillus in the MMI group. The strain MT2 degraded 65.2% of PCB77 serving as the sole carbon source, and this degradation rate was close to that in MNP-enriched culture and significantly higher than that (26.3%) of strain CT2 under the same condition. In addition, the performance of Paenibacillus sp. MT2 in degrading PCBs and PBDEs was better than that of Rhodococcus sp. CT2. Conclusion] MMI is a powerful approach to enrich active PCB77 degraders from complex microbial communities, with which Paenibacillus sp. MT2 having high PCB degradation efficiency was isolated. The study lays a theoretical basis for developing efficient approaches to remediate the soil contaminated by PCBs.