Distinct Microbial Community Performing Dissimilatory Nitrate Reduction to Ammonium (DNRA) in a High C/NO3− Reactor

• Published in: Microbes and Environments 2018, Vol.33(3), pp.264-271
• Main Authors: Chutivisut, Pokchat, Isobe, Kazuo, Powtongsook, Sorawit, Pungrasmi, Wiboonluk, Kurisu, Futoshi
• Format: Article
• Language: English
• Subjects: Activated carbon; Activated sludge; Ammonium; Ammonium compounds; Anoxia; Batch reactors; Bioreactors; C/NO3− ratio; Communities; Denitrification; dissimilatory nitrate reduction to ammonium (DNRA); Ecosystems; Illumina MiSeq 16S rRNA sequencing; Inoculum; Microbial activity; Microbiomes; Microorganisms; Municipal wastewater; Nitrate reduction; Nitrates; Nitrogen dioxide; Nitrogen oxides; Organic carbon; Oxides; Photochemicals; Populations; Reactors; Reduction; rRNA 16S; semi-continuous sequencing batch reactor; Sequencing; Sludge; Stable isotopes; stable-isotope tracer; Wastewater; Wastewater treatment; Wastewater treatment plants
• ISSN: 1342-6311; 1347-4405
• DOI: 10.1264/jsme2.ME17193

A dissimilatory nitrate reduction to ammonium (DNRA) microbial community was developed under a high organic carbon to nitrate (C/NO3−) ratio in an anoxic semi-continuous sequencing batch reactor (SBR) fed with glucose as the source of carbon and NO3− as the electron acceptor. Activated sludge collected from a municipal wastewater treatment plant with good denitrification efficiency was used as the inoculum to start the system. The aim of this study was to examine the microbial populations in a high C/NO3− ecosystem for potential DNRA microorganisms, which are the microbial group with the ability to reduce NO3− to ammonium (NH4+). A low C/NO3− reactor was operated in parallel for direct comparisons of the microbial communities that developed under different C/NO3− values. The occurrence of DNRA in the high C/NO3− SBR was evidenced by stable isotope-labeled nitrate and nitrite (15NO3− and 15NO2−), which proved the formation of NH4+ from dissimilatory NO3−/NO2− reduction, in which both nitrogen oxides induced DNRA activity in a similar manner. An analysis of sludge samples with Illumina MiSeq 16S rRNA sequencing showed that the predominant microorganisms in the high C/NO3− SBR were related to Sulfurospirillum and the family Lachnospiraceae, which were barely present in the low C/NO3− system. A comparison of the populations and activities of the two reactors indicated that these major taxa play important roles as DNRA microorganisms under the high C/NO3− condition. Additionally, a beta-diversity analysis revealed distinct microbial compositions between the low and high C/NO3− SBRs, which reflected the activities observed in the two systems.