Fujitani Hirotsugu, Kumagai Asami, Ushiki Norisuke, Momiuchi Kengo, Tsuneda Satoshi
Department of Life Science and Medical Bioscience, Waseda University Tokyo, Japan.
Front Microbiol. 2015 Oct 16;6:1159. doi: 10.3389/fmicb.2015.01159. eCollection 2015.
Nitrification is a key process in the biogeochemical nitrogen cycle and biological wastewater treatment that consists of two stepwise reactions, ammonia oxidation by ammonia-oxidizing bacteria (AOB) or archaea followed by nitrite oxidation by nitrite-oxidizing bacteria. One of the representatives of the AOB group is Nitrosomonas mobilis species. Although a few pure strains of this species have been isolated so far, approaches to their preservation in pure culture have not been established. Here, we report isolation of novel members of the N. mobilis species from autotrophic nitrifying granules used for ammonia-rich wastewater treatment. We developed an isolation method focusing on microcolonies formation of nitrifying bacteria. Two kinds of distinctive light scattering signatures in a cell-sorting system enabled to separate microcolonies from single cells and heterogeneous aggregates within granule samples. Inoculation of a pure microcolony into 96-well microtiter plates led to successful sub-culturing and increased probability of isolation. Obtained strain Ms1 is cultivated in the liquid culture with relatively high ammonia or nitrite concentration, not extremely slow growing. Considering environmental clones that were closely related to N. mobilis and detected in various environments, the availability of this novel strain would facilitate to reveal this member's ecophysiology in a variety of habitats.
硝化作用是生物地球化学氮循环和生物废水处理中的关键过程，它由两个逐步反应组成，先是氨氧化细菌（AOB）或古菌将氨氧化，随后亚硝酸盐氧化细菌将亚硝酸盐氧化。AOB群体的代表之一是运动亚硝化单胞菌。尽管到目前为止已经分离出该物种的一些纯菌株，但尚未建立在纯培养物中保存它们的方法。在此，我们报告了从用于处理高氨废水的自养硝化颗粒中分离出运动亚硝化单胞菌物种的新成员。我们开发了一种专注于硝化细菌微菌落形成的分离方法。细胞分选系统中的两种独特光散射特征能够将微菌落与颗粒样品中的单细胞和异质聚集体分离。将纯微菌落接种到96孔微量滴定板中可成功传代培养并提高分离概率。获得的菌株Ms1在氨或亚硝酸盐浓度相对较高的液体培养物中生长，并非生长极其缓慢。考虑到在各种环境中检测到的与运动亚硝化单胞菌密切相关的环境克隆，这种新菌株的可得性将有助于揭示该成员在各种栖息地中的生态生理学。
