Nitrogen and Oxygen Isotope Signatures of Nitrogen Compounds during Anammox in the Laboratory and a Wastewater Treatment Plant.

Isotopic fractionation factors against N and O during anammox (anaerobic ammonia oxidization by nitrite) are critical for evaluating the importance of this process in natural environments. We performed batch incubation experiments with an anammox-dominated biomass to investigate nitrogen (N) and oxygen (O) isotopic fractionation factors during anammox and also examined apparent isotope fractionation factors during anammox in an actual wastewater treatment plant. We conducted one incubation experiment with high δO of water to investigate the effects of water δO.

Genomic and Physiological Characteristics of a Novel Nitrite-Oxidizing Strain Isolated From a Drinking Water Treatment Plant.

Nitrite-oxidizing bacteria (NOB) catalyze the second step of nitrification, which is an important process of the biogeochemical nitrogen cycle and is exploited extensively as a biological nitrogen removal process. Members of the genus are often identified as the dominant NOB in a diverse range of natural and artificial environments. Additionally, a number of studies examining the distribution, abundance, and characterization of complete ammonia oxidation (comammox) support the ecological importance of the genus .

Genomic Analysis of Two Phylogenetically Distinct Species Reveals Their Genomic Plasticity and Functional Diversity.

The genus represents a dominant group of nitrite-oxidizing bacteria in natural and engineered ecosystems. This genus is phylogenetically divided into six lineages, for which vast phylogenetic and functional diversity has been revealed by recent molecular ecophysiological analyses. However, the genetic basis underlying these phenotypic differences remains largely unknown because of the lack of genome sequences representing their diversity.

Nitrite oxidation kinetics of two Nitrospira strains: The quest for competition and ecological niche differentiation.

Nitrite oxidation is an aerobic process of the nitrogen cycle in natural ecosystems, and is performed by nitrite-oxidizing bacteria (NOB). Also, nitrite oxidation is a rate-limiting step of nitrogen removal in wastewater treatment plants (WWTPs). Although Nitrospira is known as dominant NOB in WWTPs, information on their physiological properties and kinetic parameters is limited.

Ecophysiology and Comparative Genomics of Ms1 Isolated from Autotrophic Nitrifying Granules of Wastewater Treatment Bioreactor.

Ammonia-oxidizing bacteria (AOB), which oxidize ammonia to nitrite in the first step of nitrification, play an important role in biological wastewater treatment systems. is an important and dominant AOB in various wastewater treatment systems. However, the detailed physiological and genomic properties of have not been thoroughly investigated because of limited success isolating pure cultures.

A rapid collection of yet unknown ammonia oxidizers in pure culture from activated sludge.

Nitrification is an important reaction in the biological nitrogen removal process in wastewater treatment plants (WWTPs). As ammonia-oxidizing microbes are slow-growing and sensitive to environmental factors such as free ammonia, pure strains are hard to obtain, preventing our understanding of their physiological characteristics. To conquer this hurdle, we report a high-throughput isolation technique based on scattering signatures, which exploits the tendency of many ammonia-oxidizing bacteria (AOB) to form microcolonies in activated sludge.

Selective isolation of ammonia-oxidizing bacteria from autotrophic nitrifying granules by applying cell-sorting and sub-culturing of microcolonies.

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.

Isolation of sublineage I Nitrospira by a novel cultivation strategy.

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 properties of Nitrospira remain poorly understood because the organisms are difficult to isolate and culture.

Isolation of Nitrospira belonging to sublineage II from a wastewater treatment plant.

Nitrite oxidation is a key step in nitrogen removal in biological wastewater treatment plants. Recently, two phylogenetically different Nitrospira (sublineages I and II) have been recognized as the numerically dominant nitrite-oxidizing bacteria in wastewater treatment plants. However, Nitrospira sublineage II inhabiting activated sludge was not isolated and its detailed properties were unclear.