污泥四环素含量对蚯蚓堆肥中氨氧化菌群的影响

Effects of Different Concentrations of Tetracycline in Sludge on Ammonia Oxidizers During Vermicomposting

抗生素常积聚于脱水污泥中,其含量可影响污泥蚯蚓粪的氮肥价值.本研究通过向城市污泥中添加不同浓度四环素(0、100、500和1 000 mg·kg^(-1)),比较四环素含量对污泥蚯蚓堆肥过程中的硝化速率、氨氧化菌种群结构和丰度的影响,揭示四环素对污泥蚯蚓堆肥体中氨氧化作用的影响机制.结果表明,高含量四环素(1 000 mg·kg^(-1))显著抑制污泥蚯蚓堆肥过程的硝化速率(P <0. 05),但低含量四环素对硝化速率的影响并不显著.相比于氨氧化细菌(AOB),污泥蚯蚓堆肥体中氨氧化古菌(AOA)为氨氧化作用的主导者.低含量四环素(100 mg·kg^(-1))能显著提升氨氧化菌群amoA基因的丰度(P <0. 05);但随着四环素剂量增加,其对amoA基因的丰度有显著的抑制作用(P <0. 05).高通量测序结果表明,添加四环素改变了AOA和AOB的种群多样性及其结构,且AOA的α多样性和四环素含量之间呈负相关关系.

Dewatered sludge often contains abundant antibiotics,and such contaminants can potentially affect the nitrogen fertilizer value of sludge-derived vermicompost. For this purpose,the aims of this study were to investigate the effects of different tetracycline concentrations in sludge on the nitrification rate and abundance and community characteristics of ammonia oxidizers during vermicomposting. Four sludge treatments with different concentrations of tetracycline(0,100,500,and 1 000 mg·kg-1) were used,and data were collected to reveal the mechanism regarding the ammonia oxidization of sludge in the vermicomposting system. The results showed that the high concentration of tetracycline(1 000 mg·kg-1) significantly inhibited the nitrification rate of vermicomposting(P < 0. 05),but no significant effect was observed in the low concentration treatments. Compared with ammoniaoxidizing bacteria(AOB),ammonia oxidizing archaea(AOA) were detected as the dominant microorganisms involved in the ammonia oxidation process during vermicomposting. In addition,the abundances of amo A genes were significantly elevated(P < 0. 05) in the treatments with 100 mg·kg^-1 tetracycline,but values significantly decreased with the further increments of tetracycline concentrations(P < 0. 05). The results obtained from high-throughput sequencing revealed that the community diversity and structure of AOA and AOB were strongly modified by tetracycline concentrations,and a negative correlation relationship was detected between the tetracycline concentrations and the α diversity of AOA.