生态沟渠对农田排水中菌群组分、耐药基因谱及氮磷浓度的影响

Effects of the ecological ditches on bacterial community composition, antibiotic resistance gene profiles, nitrogen and phosphorus concentrations in farmland drainage

农田排水中的耐药基因能够以微生物为宿主在环境中富集与传播,而其中的氮磷则会导致自然水体富营养化.生态沟渠作为农田排水的末端处理系统,是控制农田中氮磷向自然环境中转移的关键,但其对农田排水中菌群和耐药基因的影响却鲜有研究.本研究对浙江省内20条生态沟渠的氮磷拦截效果进行了评价,然后利用宏基因组测序技术对其中效果较好的生态沟渠进行了菌群组分和耐药基因谱的分析.研究结果表明,浙江省内生态沟渠有效的拦截了农田排水中的氮磷,其中湖州市生态沟渠-1对农田排水中总氮和总磷拦截率均接近50%,相较于其他生态沟渠具有更好的氮磷拦截效果.同时,湖州市生态沟渠-1有效降低了农田排水中耐药基因的种类,并将主要耐药基因子类(mfd、dfrE和tetT)的丰度降低了12.0%—41.4%.此外,湖州市生态沟渠-1有效降低了农田排水中Proteobacteria门和Verrucomicrobia门的微生物丰度,并提高了其中Actinobacteria门的微生物丰度.综上可知,浙江省生态沟渠不仅能够拦截农田排水中的氮磷和耐药基因还能够影响其中细菌群落组分,但相关机制仍需进一步研究.

The antibiotic resistance genes(ARGs) in farmland drainage promote the increase and spread of antibiotic resistance among environmental microbe and the anthropogenic nutrient(nitrogen and phosphorus) accelerates the eutrophication of lakes and streams. The ecological ditches, as the end treatment system of farmland drainage, are vital to mitigate the transfer of nitrogen and phosphorus from farmland drainage into natural environment, but few studies focused on the influences of the ecological ditches on ARGs and bacterial community in farmland drainage. This study comprehensively evaluated the effects of 20 ecological ditches in Zhejiang province on nutrients removal, then further applied the technology of metagenomic sequencing to analyze ARG profiles and bacterial community composition in the ecological ditch with effective nutrients removal. The related results indicated that the ecological ditches are effective in nutrients removal from farmland drainage, and the average interception efficiency of total nitrogen and total phosphorus were both closed to 50% in the Huzhou ecological ditch-1, which is more efficient comparing with that of other ecological ditches. Meantime, the Huzhou ecological ditch-1 effectively reduced the diversity of ARG subtypes in farmland drainage, and reduced the abundances of main ARGs(mfd、dfr E and tet T)by 12.0%—41.4%. In addition, the abundance of bacteria belonging to the phylum of Proteobacteri and Verrucomicrobia has been reduced, while the abundance of bacteria belonging to the phylum of Actinobacteria has been increased after the treatment of Huzhou ecological ditch-1. In summary, the ecological ditches not only contribute to the removal of nitrogen,phosphorus and ARGs in farmland drainage but also influencing its bacterial community, but the related mechanism needs to be further investigated.