Nitrospira sp. KM1 Genome sequencing

Nitrification is an important process in the biogeochemical nitrogen cycle and is widely exploited in biological wastewater treatment. Recently, Nitrospira has been recognized as the numerically dominant nitrite-oxidizing bacterial genus, and is primarily responsible for the second step of aerobic nitrification. Nevertheless, the physiological ad genomic properties of Nitrospira remain poorly understood because the organisms are difficult to isolate and culture. Here we report a novel cultivation strategy for obtaining members of the Nitrospira lineage II in pure culture. The method combines 1) selective enrichment of Nitrospira using a continuous feeding reactor, and 2) purification followed by sub-cultivation via a cell sorting system by focusing on the unique characteristics of Nitrospira forming spherical microcolonies. New insight into previously uncultured Nitrospira would accelerate the genomic and biochemical understandings of this important group of organisms.硝化作用（Nitrification）是生物地球化学氮循环中的重要过程，且被广泛应用于生物废水处理领域。近年来，硝化螺菌属（Nitrospira）被认定为数量上占优势的亚硝酸盐氧化细菌属，主要负责好氧硝化作用的第二步。然而，由于该类微生物难以分离培养，学界对硝化螺菌的生理及基因组特性仍知之甚少。本研究报道了一种可获取硝化螺菌属谱系II类群纯培养物的新型培养策略：该方法结合了两项核心操作，1）利用连续进料反应器实现硝化螺菌的选择性富集；2）依托硝化螺菌形成球形微菌落的独特特性，通过细胞分选系统完成纯化与继代培养。对此前未获纯培养的硝化螺菌的深入解析，将加速学界对这一重要微生物类群的基因组学与生物化学认知。