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Enrichment of Nitrogen-Fixing Bacteria in a Nitrogen-Deficient Wastewater Treatment System

Lookup NU author(s): Carolina Ospina Betancourth, Dr Kishor AcharyaORCiD, Dr Ben Allen, Jim Entwistle, Professor Ian Head, Professor Thomas CurtisORCiD


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Copyright © 2020 American Chemical Society.Anthropogenic nitrogen fixation is essential to sustain a global population of 7.7 billion. However, there has been a long-standing desire to find cheaper and more environmentally friendly alternatives to the Haber-Bosch process. In this study, we developed a new strategy of nitrogen fixation by enriching free-living N2-fixing bacteria (NFB) in reactors fed with low nitrogen wastewater, analogous to those usually found in certain industrial effluents such as paper mills. Our reactors fixed appreciable quantities of nitrogen with a rate of 11.8 mg N L-1 day-1. This rate is comparable to recent "breakthrough" nitrogen-fixing technologies and far higher than observed in low C/N reactors (fed with organic matter and nitrogen). NFB were quantified using quantitative polymerase chain reaction (qPCR) of the nifH (marker gene used to identify biological nitrogen fixation) and 16S rRNA genes. The nifH gene was enriched by a factor of 10 in the nitrogen-fixing reactors (compared to controls) attaining 13% of the bacterial population (1:4.2 copies of nifH to 16S rRNA). The Illumina MiSeq 16S rRNA gene amplicon sequencing of reactors showed that the microbial community was dominated (19%) by Clostridium pasteurianum. We envisage that nitrogen-enriched biomass could potentially be used as a biofertilizer and that the treated wastewater could be released to the environment with very little post-treatment.

Publication metadata

Author(s): Ospina-Betancourth C, Acharya K, Allen B, Entwistle J, Head IM, Sanabria J, Curtis TP

Publication type: Article

Publication status: Published

Journal: Environmental Science and Technology

Year: 2020

Volume: 54

Issue: 6

Pages: 3539-3548

Print publication date: 17/03/2020

Online publication date: 21/02/2020

Acceptance date: 21/02/2020

Date deposited: 05/05/2020

ISSN (print): 0013-936X

ISSN (electronic): 1520-5851

Publisher: American Chemical Society


DOI: 10.1021/acs.est.9b05322

PubMed id: 32083474


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