Unraveling interaction networks of ammonia- and nitrite-oxidizing microorganisms

Informations

Funding country

Netherlands

Acronym

-

URL

-

Start date

2/1/2020

End date

-

Budget

250,000 EUR

Fundings

Abstract

Excess anthropogenic use of artificial nitrogen (N) fertilizers has altered the global N cycle with severe ecological consequences. To avoid additional N pollution, biological wastewater treatment is key for removal of excess N compounds. Here, N conversion is initiated by nitrifying microorganisms. Autotrophic nitrification represents a tight mutualistic interplay of two different functional groups, which together perform a key process in the biogeochemical N cycle. In their cross-feeding interaction, ammonia-oxidizing bacteria (AOB) convert ammonia to nitrite, which is further oxidized to nitrate by nitrite-oxidizing bacteria (NOB). Nitrifiers also interact with heterotrophic bacteria that feed on metabolites released by nitrifiers or attack them in predator-prey interactions. Despite the biotechnological importance of nitrification, the dynamics within nitrifying assemblages and the interplay between nitrifiers and heterotrophic bacteria are poorly understood. In this project, I aim to determine factors defining and stabilizing nitrifying interaction networks. Since such networks are very complex in nature, I will first investigate these interactions under controlled conditions using artificially mixed assemblages of biotechnologically relevant AOB and NOB. This simplified system will allow me to unravel the metabolic consequences of their tight interplay. For this, I will compare physiological key features of individual and mixed nitrifier cultures and determine their metabolic response to interaction. Additionally, I will identify novel interaction partners of uncultured nitrifiers by analyzing co-occurrence patterns within spatially structured environments. To gain further insights into interaction dynamics between nitrifying and heterotrophic microorganisms, I will investigate the overall metabolic activity of these assemblages and use 13C-labelling to trace the carbon flux through a microbial community, which contains nitrifiers as sole primary producers. Overall, this project will greatly expand our understanding of nitrification by unraveling the natural interaction partners and dynamics that shape process performance and stability, allowing a further optimization of biotechnological N removal.