Abstract: In this paper, high-throughput sequencing was used to analyze the diversity of water flora in the biofloc system during nitrogen transformation. A control group and a test group were set in the test. The control group had clean and disinfected seawater, and the test group was a biofloc group. The test period was 30 days. The results show that in the test group, the mass concentration of ammonia nitrogen reached its maximum (2.99 mg/L) on day 5 and then decreased to 0 mg/L; in the control group, the mass concentration reached its maximum (7.51 mg/L) on day 9 and then decreased to 0 mg/L. In the test group, the mass concentration of nitrite nitrogen reached its maximum (12.54 mg/L) on day 17 and then decreased to 0 mg/L; in the control group, it showed a rising trend during the test period and reached 13.42 mg/L on day 30. The mass concentration of nitrate nitrogen in the test group was higher than that in the control group, reaching 19.56 and 6.31 mg/L respectively on day 30. The biofloc system was obviously able to remove ammonia nitrogen and nitrite nitrogen, and the nitrogen transformation rate of the test group was higher than that of the control group. High-throughput sequencing showed that the flora abundance and diversity index of the microorganisms in the biofloc system increased significantly with the increase of the breeding cycle, and the differences were significant in different periods. During the test period, a total of 23 phylum and 549 genera were identified. At the phylum level, the relative abundance of Proteobacteria decreased with time (from 67.72% to 44.45%), while that of Bacteroidetes and Chloroflexi increased with time (respectively from 5.99% and 6.68% to 16.06% and 19.02%). The main bacteria related to nitrogen transformation included Ardenscatena and Nitrospiraceae, whose relative abundance increased with time (respectively from 0.34% and 0.07% to 12.69% and 0.2%), while that of Nitrosopumilus decreased with time. The function and microbial diversity of the biofloc system showed significant changes during the breeding cycle. This study has reference value for improving the utilization efficiency of the biofloc system breeding mode.

Key words:  , biofloc, nitrogen transformation, microbial community, succession

摘要： 通过高通量测序分析生物絮团系统在氮转化过程中的水体菌群多样性变化。试验设置对照组和试验组，对照组水体为清洁的消毒海水，试验组为生物絮团组，试验周期30 d。结果显示：试验组氨氮在第5 天达到最大质量浓度（2.99 mg/L），降低至趋于0 mg/L；对照组在第9 天达到最大质量浓度（7.51 mg/L），之后降低至趋于0 mg/L。试验组亚硝酸盐氮在第17天达到最大质量浓度（12.54 mg/L），之后降低至趋于0 mg/L；对照组在试验周期内呈不断升高的趋势，在第30 天达到13.42 mg/L。试验组的硝酸氮质量浓度高于对照组，在第30 天两组分别达到19.56和6.31 mg/L。生物絮团系统具有明显的消除氨氮和亚硝酸盐氮的能力，试验组的氮转化速率快于对照组。高通量测序显示，生物絮团系统微生物的菌群丰度和多样性指数随养殖周期的增加均显著增加，不同时期差异显著。试验共鉴定出23个门549个属，在门水平上，变形菌门(Proteobacteria)相对丰度随时间增加而降低（从67.72%降至44.45%），拟杆菌门(Bacteroidetes)和绿弯菌门(Chloroflexi)随时间增加而增加（分别从5.99%和6.68%增至16.06%和19.02%）。与氮转化有关的主要的菌有Ardenscatena和硝化螺旋菌(Nitrospiraceae)，相对丰度随时间增加而增加（分别从0.34%和0.07%增加至12.69%和0.2%）；Nitrosopumilus随时间增加而降低。生物絮团系统的功能与微生物多样性在养殖周期中呈显著变化。本研究对提高生物絮团系统养殖模式的利用效率具有参考价值。

关键词: 生物絮团, 氮转化, 微生物群落, 演替