Enrichment of iron-dependent anaerobic ammonia oxidizer microbial communities from tropical forest soil and paddy field sediments

• Main Author: Noor Ezanna Khamidun
• Format: Undergraduate Final Project Report
• Published: 2016
• Online Access: http://discol.umk.edu.my/id/eprint/6580/

Utilitarian strains/consortia for experience ammonium oxidation coupled to iron reduction divergence, termed as Feammox incorporate unique bacterial strains that are not been reported previously. In the present study, anaerobic oxidation of ammonium to nitrite has been observed in wetland soils under iron-reducing conditions. In exploring the dynamics of iron and nitrogen cycling in tropical forest soils and paddy fields sediments, we had observed a redox reaction that has not been previously described. To dictate whether ammonium oxidation under iron reducing conditions, each ammonium sulphate concentration was manipulated ranging from 1mM, 5mM and 20mM and functioned as electron donor while FeOOH as final terminal of electron acceptor in the certain cytochrome of electron transport chain. Development of enrichment culture revealed that Fe (Ill) are reduced to Fe (ll) by employed color indicator appeared oranges to dark. During incubations of soil slurries under anaerobic conditions, we measured an unexpected total concentration ferrous iron, Fe (ll) via ferrozine method. From the manipulation the source of electron, we found that Fe (ll) productions by newly isolated EF/D1 strains after 20-30 days anaerobic incubation in serum bottle containing Westlake supplemented with 20mM HFO and 1mM NH₄⁺ showed the highest concentration amongst all. This indirect evidence, we conclude that under anoxic and limited oxygen sources conditions, there is a biological process that utilizes ferric iron Fe (III) as an electron acceptor while oxidizing ammonium (NH₄⁺), termed as Feammox. We believed that Feammox could trigger nitrogen losses in ecosystems rich in poorly crystalline iron minerals, with low or fluctuating redox reactions.