Hatamoto Masashi, Kimura Masafumi, Sato Takafumi, Koizumi Masato, Takahashi Masanobu, Kawakami Shuji, Araki Nobuo, Yamaguchi Takashi
Department of Civil and Environmental Engineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan.
Department of Civil and Environmental Engineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan; Department of Civil and Environmental Engineering, Tohoku University, Sendai, Miyagi, 980-8579, Japan.
PLoS One. 2014 Dec 29;9(12):e115823. doi: 10.1371/journal.pone.0115823. eCollection 2014.
Denitrifying anaerobic methane oxidizing (DAMO) microorganisms were enriched from paddy field soils using continuous-flow and batch cultures fed with nitrate or nitrite as a sole electron acceptor. After several months of cultivation, the continuous-flow cultures using nitrite showed remarkable simultaneous methane oxidation and nitrite reduction and DAMO bacteria belonging to phylum NC10 were enriched. A maximum volumetric nitrite consumption rate of 70.4±3.4 mg-N·L(-1)·day(-1) was achieved with very short hydraulic retention time of 2.1 hour. In the culture, about 68% of total microbial cells were bacteria and no archaeal cells were detected by fluorescence in situ hybridization. In the nitrate-fed continuous-flow cultures, 58% of total microbial cells were bacteria while archaeal cells accounted for 7% of total cell numbers. Phylogenetic analysis of pmoA gene sequence showed that enriched DAMO bacteria in the continuous-flow cultivation had over 98% sequence similarity to DAMO bacteria in the inoculum. In contrast, for batch culture, the enriched pmoA gene sequences had 89-91% sequence similarity to DAMO bacteria in the inoculum. These results indicate that electron acceptor and cultivation method strongly affect the microbial community structures of DAMO consortia.
利用以硝酸盐或亚硝酸盐作为唯一电子受体的连续流培养和批次培养，从稻田土壤中富集了反硝化厌氧甲烷氧化（DAMO）微生物。经过数月培养，使用亚硝酸盐的连续流培养表现出显著的同步甲烷氧化和亚硝酸盐还原，且属于NC10门的DAMO细菌得到了富集。在水力停留时间仅为2.1小时的情况下，实现了最大体积亚硝酸盐消耗速率70.4±3.4 mg-N·L⁻¹·天⁻¹。在该培养物中，约68%的微生物细胞为细菌，通过荧光原位杂交未检测到古菌细胞。在以硝酸盐为电子受体的连续流培养中，58%的微生物细胞为细菌，而古菌细胞占细胞总数的7%。对pmoA基因序列的系统发育分析表明，连续流培养中富集的DAMO细菌与接种物中的DAMO细菌具有超过98%的序列相似性。相比之下，对于批次培养，富集的pmoA基因序列与接种物中的DAMO细菌具有89 - 91%的序列相似性。这些结果表明，电子受体和培养方法强烈影响DAMO菌群的微生物群落结构。
