The Influence of Different Carbon Sources on Denitrification Rate and Community Structure of Denitrifying Bacteria
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摘要: 为探究碳源类型在反硝化过程中对氮素转化和微生物群落组成的影响,分别建立R1(以C6H12O6为碳源)和R2(以CH3COONa为碳源)反应器,通过分析R1和R2反应器中反硝化过程的氮素转化情况,评价C6H12O6和CH3COONa对脱氮效果的影响,并运用动力学模型对R1和R2反应器中反硝化能力进行评价;同时,采用高通量测序技术表征2种碳源对反应器中微生物群落结构和多样性的影响.结果表明:①运行后期的R1、R2反应器中单位生物量的反硝化速率(以NO3--N计,下同)分别为8.56、11.26 mg/(g·h),R1反应器中NO2--N累积平均值为11.34 mg/L,显著高于R2反应器(0.20 mg/L),且R1反应器中NH4+-N累积平均值为6.58 mg/L,是R2反应器(0.65 mg/L)的10.11倍.②反应器中NO3--N还原过程均符合Haldane模型,其中R1、R2反应器中单位生物量的rmax(最大降解速率)分别为35.61、47.79 mg/(g·h),表明R2反应器中的反硝化能力强于R1反应器.③微生物经过富集后,其细菌多样性和物种丰度下降,但发挥反硝化作用的微生物相对丰度逐渐增加.R1和R2反应器中共同的优势菌门有Proteobacterias、Bacteroidetes、Firmicutes和Gracilibacters,其在R1反应器中的相对丰度依次为96.14%、2.06%、0.66%和0.47%,在R2反应器中依次为79.75%、6.88%、9.47%和2.13%,优势菌门在不同运行时间的丰度表达上存在消长变化状态.研究显示,C6H12O6和CH3COONa在反硝化过程的氮素转化上存在明显差异,对各类优势菌群的相对丰度有明显影响.Abstract: In order to investigate the influence of carbon sources on nitrogen change and microorganism community structure in the denitrification process, R1 (C6H12O6) and R2 (CH3COONa) continuous-flowing reactors were set up for comparison of nitrogen conversion, which can be used to evaluate the removal effect of C6H12O6 and CH3COONa. The NO3--N removal kinetics for the denitrification capacity of R1 and R2 were conducted, and the high-throughput sequencing was utilized to characterize and compare the community structure and diversity. The results showed that: (1) The denitrification rate per unit biomass of R1 was 8.56 mg/(g·h) when the denitrification rate per unit biomass of R2 was 11.26 mg/(g·h). The average accumulation value of NO2--N in R1 was 11.34 mg/L, which was significantly higher than that in R2 (0.20 mg/L). The average value of NH4+-N accumulation in R1 was 6.58 mg/L, which was 10.11 times of the cumulative amount of NH4+-N in R2. (2) The Haldane model fit the experimental data in the NO3--N reduction process well, in which the rmax (the maximum degradation rate) value per unit biomass of R1 was 35.61 mg/(g·h), and the rmax value per unit biomass of R2 was 47.79 mg/(g·h), indicating that the denitrification ability of R2 is stronger than the denitrification ability of R1. (3) High-throughput sequencing analysis showed that the bacterial diversity and the species abundance were decreased after a period, but the relative abundance of denitrifying bacteria was raised. Proteobacterias, Bacteroidetes, Firmicutes and Gracilibacters were the dominant groups on the phylum level in the R1 and R2. And the relative proportions of the groups in R1 were 96.14%, 2.06%, 0.66% and 0.47%, respectively, and the relative abundance of the groups in R2 were 79.75%. 6.88%, 9.47% and 2.13%. The abundance of the dominant bacteria experienced changing state of growth and decline during the operation time. It showed that C6H12O6 and CH3COONa have significant differences in nitrogen conversion in the process of denitrification, and have a significant impact on the relative abundance of various prevailing species.
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表 1 微生物样本多样性指数
Table 1. Diversity index of microbial samples
样品编号 序列数/条 OTUs/个 Chao 1指数 ACE指数 Shannon-Wiener指数 Simpson指数 覆盖值/% GS0 36 690 1 321 1 423.64 1 408.78 5.97 0.01 99.60 G5 47 870 562 970.86 1 135.95 3.79 0.04 99.50 G10 55 157 506 886.91 1 071.84 2.74 0.14 99.50 S5 46 768 549 1 064.68 965.55 2.53 0.16 99.40 S10 41 748 399 698.52 881.13 2.85 0.20 99.50 -
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