Related Experiment Video
Updated: Jun 15, 2026

A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Heterotrophic nitrogen removal by a newly isolated Acinetobacter calcoaceticus HNR
Bin Zhao1, Yi Liang He, Joseph Hughes
1School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Abstract:
Strain HNR, isolated from a Membrane Bioreactor (MBR), demonstrates a surprising ability to convert ammonium to nitrogen gas under aerobic conditions while growing heterotrophically. On the basis of phylogenetic analysis of the 16S rRNA gene sequence, strain HNR was related to Acinetobacter calcoaceticus (98.9% identity). Nitrogen balance during heterotrophic growth with 120mg/l of NH(4)(+)-N showed that 40.2% of NH(4)(+)-N was in the form of N(2) and 52.1% was found in biomass. Only a trace production was either nitrite or nitrate. Further tests demonstrated that nitrite and nitrate were not reduced by strain HNR under aerobic conditions. Neither nitrate reductase (NR) nor nitrite reductase (NiR) activity was detectable in the aerobic reaction mixtures. However, a 0.051 U activity of hydroxylamine oxidase (HAO) was observed. The nitrogen removal was speculated to be via a hydroxylamine intermediate instead of nitrite, which was different from the conventional nitrogen removal pathway.
More Related Videos
08:05Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
09:47Selective Cleaning of Wild Caenorhabditis Nematodes to Enrich for Intestinal Microbiome Bacteria
Published on: August 13, 2021
Related Concept Videos
Overview of Nitrogen Metabolism
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this nitrogen...
Microbes and the Nitrogen Cycle
Metabolism of Chemolithotrophs
Inorganic Nitrogen Assimilation
Microbial Nutrition
Microbial Bioremediation of Hydrocarbons