Enrichment, Isolation, and Characterization of High-Affinity N2O-Reducing Bacteria in a Gas-Permeable Membrane Reactor
Enrichment, Isolation, and Characterization of High-Affinity N2O-Reducing Bacteria in a Gas-Permeable Membrane Reactor
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DOI：
10.1021/acs.est.9b02237
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发表时间：
2019-10-15
影响因子：
11.4
通讯作者：
Terada, Akihiko
中科院分区：
文献类型：
--
作者：
Suenaga, Toshikazu;Hori, Tomoyuki;Terada, Akihiko
最近发现的一氧化二氮（N2 O）还原细菌表明，强效温室气体N2 O可能存在生物汇。对于N2 O减排应用，需要对更多分离株进行表征。在这里，我们描述了成功的富集和分离的高亲和力的N2 O-还原细菌使用N2 O-进料反应器（N2 OFR）。两个N（2）OFR，其中N2 O是连续和直接供应作为唯一的电子受体的生物膜上生长的气体渗透膜，操作与乙酸或混合物的胨为基础的有机底物作为电子供体。平行地，使用相同的接种物操作填充有非织造片材基质的NO3进料反应器（NO3 FR）。我们假设，供应N2 O与NO3-将提高不同的N2 O还原细菌的优势。在N（2）OFR中，进化枝II型nosZ细菌变得比进化枝I型nosZ细菌迅速富集，而在NO3 FR中则相反。16 S rRNA基因扩增子的高通量测序揭示了红环藻科在N（2）OFR中的优势。固氮螺菌属和脱氯单胞菌属的菌株是携带Glade II型nosZ的典型细菌，从N（2）OFR中以高频率分离到（152个分离物中的132个）。与来自NO3 FR的Glade I型nosZ分离物相比，来自N2 OFR的分离物表现出更高的N2 O吸收速率（V-max：4.23 x 10（-3）-1.80 x 10（-2）pmol/h/cell）和更低的N2 O半饱和系数（K-m，（N2 O）：1.55-2.10 μ M）。此外，Glade II型nosZ菌株在N2 O上的特定生长速率比作为电子受体的亚硝酸盐高。因此，在N2 OFR中连续且专门地供应N2 O允许富集和分离高亲和力N2 O还原菌株，其可用作生物强化努力中的N2 O汇。
The recent discovery of nitrous oxide (N2O)-reducing bacteria suggests a potential biological sink for the potent greenhouse gas N2O. For an application toward N2O mitigation, characterization of more isolates will be required. Here, we describe the successful enrichment and isolation of high-affinity N2O-reducing bacteria using a N2O-fed reactor (N2OFR). Two N(2)OFRs, where N2O was continuously and directly supplied as the sole electron acceptor to a biofilm grown on a gas-permeable membrane, were operated with acetate or a mixture of peptone-based organic substrates as an electron donor. In parallel, a NO3--fed reactor (NO3FR), filled with a nonwoven sheet substratum, was operated using the same inoculum. We hypothesized that supplying N2O vs NO3- would enhance the dominance of distinct N2O-reducing bacteria. Clade II type nosZ bacteria became rapidly enriched over Glade I type nosZ bacteria in the N(2)OFRs, whereas the opposite held in the NO3FR. High-throughput sequencing of 16S rRNA gene amplicons revealed the dominance of Rhodocyclaceae in the N(2)OFRs. Strains of the Azospira and Dechloromonas genera, canonical denitrifiers harboring Glade II type nosZ, were isolated with high frequency from the N(2)OFRs (132 out of 152 isolates). The isolates from the N2OFR demonstrated higher N2O uptake rates (V-max: 4.23 x 10(-3)-1.80 x 10(-2) pmol/h/cell) and lower N2O half-saturation coefficients (K-m,(N2O) : 1.55-2.10 mu M) than a Glade I type nosZ isolate from the NO3FR. Furthermore, the Glade II type nosZ isolates had higher specific growth rates on N2O than nitrite as an electron acceptor. Hence, continuously and exclusively supplying N2O in an N2OFR allows the enrichment and isolation of high-affinity N2O-reducing strains, which may be used as N2O sinks in bioaugmentation efforts.