长链脂肪酸的厌氧共消化给频度影响协同发酵群落结构和生物动力学。
Long-chain fatty acid feeding frequency in anaerobic codigestion impacts syntrophic community structure and biokinetics.
机构信息
Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA; Department of Civil Engineering, University of British Columbia, Vancouver, Canada.
eScience Institute, University of Washington, Seattle, WA, USA; Department of Chemical Engineering, University of Washington, Seattle, WA, USA.
出版信息
Water Res. 2017 Jun 15;117:218-229. doi: 10.1016/j.watres.2017.03.060. Epub 2017 Mar 31.
This study investigated the impacts of long-chain fatty acid (LCFA) feeding frequencies on microbial community structure, bioconversion kinetics, and process stability during anaerobic codigestion. Parallel laboratory-scale anaerobic codigesters fed with dairy cattle manure were either pulse-fed every two days or continuously-fed daily, respectively, with oleate (C) in incremental step increases over 200 days up to 64% of the influent chemical oxygen demand (COD). The effluent acetate concentration exceeded 3000 mg/L in the continuous-fed codigester at the highest oleate loading rate, but remained below 100 mg/L in the pulse-fed codigester at the end of its 48-hr oleate feed cycle. Maximum substrate conversion rates of oleate (q) and acetate (q) were significantly higher in the pulse-fed codigester compared to the continuous-fed codigester. 16S rRNA gene amplicon sequencing showed that Bacteria and Archaea community profiles diverged based on the codigester LCFA feeding pattern and loading rate. LCFA-degrading Syntrophomonas bacteria were significantly enriched in both LCFA codigesters relative to the control digester. The pulse-fed codigester had the highest community fraction of Syntrophomonas 16S rRNA genes by the end of the experiment with 43% of Bacteria amplicon sequences. q and q values were both significantly correlated to absolute concentrations of Syntrophomonas and Methanosaeta 16S rRNA genes, respectively. Multiple-linear regression models based on the absolute abundance of Syntrophomonas and Methanosaeta taxa provided improved predictions of oleate and acetate bioconversion kinetics, respectively. These results collectively suggest that pulse feeding rather than continuous feeding LCFA during anaerobic codigestion selected for higher microbial bioconversion kinetics and functional stability, which were related to changes in the physiological diversity and adaptive capacity of syntrophic and methanogenic communities.
本研究考察了长链脂肪酸（LCFA）进料频率对微生物群落结构、生物转化动力学和厌氧共消化过程稳定性的影响。分别采用脉冲进料（每两天进料一次）和连续进料（每天进料）方式，以递增步长在 200 天内将橄榄油（C）进料浓度逐渐提高至进料化学需氧量（COD）的 64%，在实验室规模的平行厌氧共消化器中进料奶牛粪便。在最高橄榄油进料速率下，连续进料共消化器的出水中乙酸浓度超过 3000mg/L，但在脉冲进料共消化器中，在其 48 小时橄榄油进料周期结束时仍保持在 100mg/L 以下。与连续进料共消化器相比，脉冲进料共消化器中橄榄油（q）和乙酸（q）的最大基质转化速率明显更高。16S rRNA 基因扩增子测序结果表明，基于共消化器 LCFA 进料模式和进料速率，细菌和古菌群落图谱存在差异。与对照消化器相比，LCFA 降解菌Syntrophomonas 在两种 LCFA 共消化器中均显著富集。到实验结束时，脉冲进料共消化器的Syntrophomonas 16S rRNA 基因的群落分数最高，占细菌扩增子序列的 43%。q 和 q 值分别与 Syntrophomonas 和 Methanosaeta 16S rRNA 基因的绝对浓度显著相关。基于 Syntrophomonas 和 Methanosaeta 分类群的绝对丰度建立的多元线性回归模型分别为橄榄油和乙酸的生物转化动力学提供了更好的预测。这些结果共同表明，在厌氧共消化过程中，与连续进料 LCFA 相比，脉冲进料可选择更高的微生物生物转化动力学和功能稳定性，这与共消化物中同型产乙酸菌和产甲烷菌群落的生理多样性和适应性变化有关。
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