High rate of aerobic nitrification and denitrification by Nitrosomonas eutropha grown in a fermentor with complete biomass retention in the presence of gaseous NO 2 or NO

Abstract

A pure culture of the obligately lithoautotrophic ammonia-oxidizer Nitrosomonas eutropha was grown in a laboratory-scale bioreactor with complete biomass retention. The air supply was supplemented with nitrogen dioxide (NO2; 25 or 50 ppm) or nitric oxide (NO; 25 or 50 ppm). Compared to cultures grown without these nitrogenous oxides, the addition of NO2 or NO to the culture resulted in a significant increase of the nitrification rate, specific activity of ammonia oxidation, growth rate, and maximum cell densities. In contrast, the growth yield slightly decreased in the presence of NO or NO2. Maximum cell densities of about 2 x 10(10) cells ml-1 and a maximum nitrification rate of about 221 mmol NH4+ l-1 day-1 were obtained after 3 weeks in the presence of 50 ppm NO2. Furthermore, in the stationary phase about 50% of the nitrite produced was aerobically denitrified to dinitrogen (N2) and traces of nitrous oxide (N2O). When cells were supplemented with NO, a high rate of aerobic denitrification occurred only during the first days of the exponential growth phase.

High-cell-density cultivation of <i>Nitrosomonas europaea</i> in a membrane bioreactor for performing protein purification and characterization studies

“…Moreover, the growth was not completely recovered after removing the cell culture, as described in previous studies (Chapman et al, 2006;Tappe et al, 1996). In the high-cell-density culture, the concentration of NH 3 was high (>39 mM), whereas that of NO 2 -was lower than its inhibitory concentration (Zart and Bock, 1998). Factor(s) deciding the upper limit of cell density in the MBR culture need to be examined in another study.…”

Physiologic and Proteomic Evidence for a Role of Nitric Oxide in Biofilm Formation by Nitrosomonas europaea and Other Ammonia Oxidizers

“…Although NO was not added to the reactor system, its concentration in the off-gas remained high at 35 ppm, which corresponds to the production of about 450 mol of NO day Ϫ1 . Release of high concentrations of NO during ammonia oxidation has been described previously for N. eutropha (34,48,49). Approximately 0.7% of the consumed ammonia was converted to NO.…”

“…Another reactor system was supplied with 3 mmol of 2,3-dimercapto-1-propane-sulfonic acid (DMPS) per day. DMPS is an NO binding compound that can be used to reduce the NO concentration in Nitrosomonas cell suspensions (48). As a result, the NO concentrations in the reactor system decreased to 0.5 to 3 ppm.…”

Emissions of Nitrous Oxide (N2O) and Di-Nitrogen (N2) from the Agricultural Landscapes, Sources, Sinks, and Factors Affecting N2O and N2 Ratios

“…Ammonia oxidizers consume relatively large amounts of molecular O 2 during this first stage, causing anaerobic conditions in the microsites, which then lead to a reduction of NO 2 -to N 2 O and N 2 (Poth & Focht, 1985;Firestone & Davidson, 1989;Zart & Bock, 1998;Colliver & Stephenson, 2000) as shown in Eq. 3.1.2.…”