Nitrogen Removal Characteristics and Constraints of an Alphaproteobacteria with Potential for High Nitrogen Content Heterotrophic Nitrification-Aerobic Denitrification

Abstract

The discovery of heterotrophic nitrification-aerobic denitrification (HN-AD) microorganisms has opened a new window for wastewater treatment. The underlying mechanism of HN-AD, however, is not fully understood because of the phylogenetic diversity of HN-AD microbes. The isolation and characterization of new HN-AD microorganisms are encouraging for furthering the understanding of this process. In this study, we found an Alphaproteobacteria isolate W30 from a historically polluted river in China through an HN-AD microbes screening process, which we identified as Pannonibacter sp. A potential HN-AD pathway for W30 was proposed based on N conversion analyses and the successful amplification of the entire denitrification gene series. The isolate exhibited high efficiency of aerobic inorganic nitrogen transformation, which accounted for 97.11% of NH4+-N, 100% of NO3−-N, and 99.98% of NO2−-N removal with a maximum linear rate of 10.21 mg/L/h, 10.46 mg/L/h, and 10.77 mg/L/h, respectively. Assimilation rather than denitrification was the main mechanism for the environmental nitrogen depletion mediated by W30. The effect of environmental constraints on aerobic NO3−-N removal were characterized, following a membrane bioreactor effluent test under an oxic condition. Compared to known Alphaproteobacterial HN-AD microbes, we showed that Pannonibacter sp. W30 could deplete nitrogen with no NO2−-N or NO3−-N accumulation in the HN-AD process. Therefore, the application of Pannonibacter sp. W30 has the potential for developing a felicitous HN-AD technology to treat N-laden wastewater at the full-scale level.

Thauera sp. in Hydrogen-Based Denitrification: Effects of Plentiful Bicarbonate Supplementation on Powerful Nitrite Reducer

“…strain Is13 were also explicitly higher than those performed by the other strains. The results also implied that each bacterial strain had its suitable and favorable conditions to perform denitrifying activities (NO 3 − and NO 2 − removals), as reported in previous studies [32,33,36,37,[43][44][45]. Moreover, the initial and final pH of the synthetic medium supplemented with plentiful HCO 3 − of the overall experiments were found to be 9.19 ± 0.05 and 9.47 ± 0.11, respectively, suggesting that HCO 3 − could also be utilized as a buffer for the solution to avoid the pH shift in the HD system, as also reported previously [9,14,46,47].…”

“…− and NO 2 − in saline water [36,37]. Moreover, the complete denitrification was achieved aerobically by Halomonas spp.…”

Denitrification Characteristics of the Low-Temperature Tolerant Denitrification Strain Achromobacter spiritinus HS2 and Its Application

“…The yield of N 2 by strain HS2 was similar to previous findings. Alphaproteobacteria W30 could convert 26.64% of the ammonium to N2 [ 29 ]. Pseudomonas fluorescens wsw-1001 could convert 32.99% of the ammonia nitrogen into gaseous nitrogen [ 30 ].…”

Denitrification Characteristics of the Low-Temperature Tolerant Denitrification Strain <em>Achromobacter spiritinus</em> HS2 and Its Application

“…Moreover, in the whole reaction system, most of the ammonia nitrogen was converted into intracellular nitrogen, which provides energy for the growth of the strain, suggesting that nitrogen removal by strain HS2 is primarily achieved through assimilation rather than the HN-AD process. Similarly, Alphaproteobacteria W30 could remove environmental nitrogen, which was primarily driven by assimilation [28]. In contrast, only 47.02% of the ammonia nitrogen was converted into intracellular nitrogen in the Pseudomonas stutzeri UFV5, while 52.98% was transformed into gaseous nitrogen [29].…”