Ziels Ryan M, Sousa Diana Z, Stensel H David, Beck David A C
Department of Civil Engineering, University of British Columbia, Vancouver, British Columbia, Canada.
Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.
ISME J. 2018 Jan;12(1):112-123. doi: 10.1038/ismej.2017.143. Epub 2017 Sep 12.
Fats, oils and greases (FOG) are energy-dense wastes that can be added to anaerobic digesters to substantially increase biomethane recovery via their conversion through long-chain fatty acids (LCFAs). However, a better understanding of the ecophysiology of syntrophic LCFA-degrading microbial communities in anaerobic digesters is needed to develop operating strategies that mitigate inhibitory LCFA accumulation from FOG. In this research, DNA stable isotope probing (SIP) was coupled with metagenomic sequencing for a genome-centric comparison of oleate (C)-degrading populations in two anaerobic codigesters operated with either a pulse feeding or continuous-feeding strategy. The pulse-fed codigester microcosms converted oleate into methane at over 20% higher rates than the continuous-fed codigester microcosms. Differential coverage binning was demonstrated for the first time to recover population genome bins (GBs) from DNA-SIP metagenomes. About 70% of the C-enriched GBs were taxonomically assigned to the Syntrophomonas genus, thus substantiating the importance of Syntrophomonas species to LCFA degradation in anaerobic digesters. Phylogenetic comparisons of C-enriched GBs showed that phylogenetically distinct Syntrophomonas GBs were unique to each codigester. Overall, these results suggest that syntrophic populations in anaerobic digesters can have different adaptive capacities, and that selection for divergent populations may be achieved by adjusting reactor operating conditions to maximize biomethane recovery.
脂肪、油类和油脂（FOG）是能量密集型废物，可添加到厌氧消化池中，通过其经长链脂肪酸（LCFA）转化来大幅提高生物甲烷回收率。然而，需要更好地了解厌氧消化池中互营型LCFA降解微生物群落的生态生理学，以制定减轻FOG中抑制性LCFA积累的运行策略。在本研究中，DNA稳定同位素探测（SIP）与宏基因组测序相结合，以对采用脉冲进料或连续进料策略运行的两个厌氧消化池中油酸（C）降解菌群进行以基因组为中心的比较。脉冲进料消化池微宇宙将油酸转化为甲烷的速率比连续进料消化池微宇宙高出20%以上。首次证明了差异覆盖分箱可从DNA-SIP宏基因组中回收种群基因组箱（GB）。约70%的C富集GB在分类学上被归类为互营单胞菌属，从而证实了互营单胞菌属物种对厌氧消化池中LCFA降解的重要性。C富集GB的系统发育比较表明，每个消化池中系统发育不同的互营单胞菌GB都是独特的。总体而言，这些结果表明，厌氧消化池中的互营菌群可能具有不同的适应能力，并且通过调整反应器运行条件以最大化生物甲烷回收率，可能实现对不同菌群的选择。
