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Updated: May 11, 2026

Bioprospecting of Extremophilic Microorganisms to Address Environmental Pollution
Published on: December 30, 2021
Selective enrichment of two different types of Nitrospira-like nitrite-oxidizing bacteria from a wastewater treatment
Hirotsugu Fujitani1, Yoshiteru Aoi, Satoshi Tsuneda
1Department of Life Science and Medical Bioscience, Waseda University, 2–2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162–8480, Japan.
Abstract:
Nitrification is an important step in nitrogen removal in biological wastewater treatment processes. Recently, Nitrospira have been recognized as the numerically dominant nitrite-oxidizing bacterial genus primarily responsible for the second step of aerobic nitrification; however, Nitrospira usually resist cultivation under laboratory conditions and only one species enriched from activated sludge has been described. In this study, a novel enrichment method for Nitrospira was successfully developed using continuous feeding bioreactors. By controlling nitrite concentrations strictly in the bioreactor at low levels below 10 mg-N L(-1), coexisting members of sublineages I and II of the genus Nitrospira were enriched selectively. The maximum ratios of sublineages I and II to total microbial cells achieved 88.3% and 53.8%, respectively. This enrichment method is potentially applicable to other uncultured Nitrospira.
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