Urine nitrification with a synthetic microbial community

• Published in: Systematic and applied microbiology 2019-11, Vol.42 (6), p.126021-126021, Article 126021
• Main Authors: Christiaens, Marlies E.R., De Paepe, Jolien, Ilgrande, Chiara, De Vrieze, Jo, Barys, Justyna, Teirlinck, Pieter, Meerbergen, Ken, Lievens, Bart, Boon, Nico, Clauwaert, Peter, Vlaeminck, Siegfried E.
• Format: Article
• Language: English
• Subjects: Nitrification; Resource recovery; Space; Sterile Reactor; Synthetic Community; Urine
• ISSN: 0723-2020; 1618-0984
• DOI: 10.1016/j.syapm.2019.126021

[Display omitted] •A synthetic community reactor nitrified urine with salt, ureolysis, and organics.•N. europaea and N. winogradskyi adapted to 45mScm−1, undiluted nitrified urine.•The full community achieved 29±3mg NO3−–NL−1d−1 for 10% fresh real urine.•Organics removal in the reactor (69±15%) should be optimized.•D. acidovorans dominated the community, suppressing invasive strains. During long-term extra-terrestrial missions, food is limited and waste is generated. By recycling valuable nutrients from this waste via regenerative life support systems, food can be produced in space. Astronauts’ urine can, for instance, be nitrified by micro-organisms into a liquid nitrate fertilizer for plant growth in space. Due to stringent conditions in space, microbial communities need to be be defined (gnotobiotic); therefore, synthetic rather than mixed microbial communities are preferred. For urine nitrification, synthetic communities face challenges, such as from salinity, ureolysis, and organics. In this study, a synthetic microbial community containing an AOB (Nitrosomonas europaea), NOB (Nitrobacter winogradskyi), and three ureolytic heterotrophs (Pseudomonas fluorescens, Acidovorax delafieldii, and Delftia acidovorans) was compiled and evaluated for these challenges. In reactor 1, salt adaptation of the ammonium-fed AOB and NOB co-culture was possible up to 45mScm−1, which resembled undiluted nitrified urine, while maintaining a 44±10mgNH4+–NL−1d−1 removal rate. In reactor 2, the nitrifiers and ureolytic heterotrophs were fed with urine and achieved a 15±6mg NO3−–NL−1d−1 production rate for 1% and 10% synthetic and fresh real urine, respectively. Batch activity tests with this community using fresh real urine even reached 29±3mgNL−1d−1. Organics removal in the reactor (69±15%) should be optimized to generate a nitrate fertilizer for future space applications.