Characteristics and mechanism of heterotrophic nitrification/aerobic denitrification in a novel Halomonas piezotolerans strain

Abstract

A strain was isolated from an activated sludge system and identified as Halomonas piezotolerans HN2 in this study, which is the first strain in H. piezotolerans with the capability of heterotrophic nitrification and aerobic denitrification. Strain HN2 showed the maximum nitrogen removal rate of 9.10 mg/L/h by utilizing ammonium at the salinity of 3.0%. Under saline environment, HN2 could remove nitrogen efficiently in neutral and slightly alkaline environments, with the carbon sources of sodium succinate and sodium citrate and the C/N ratio of 15-20, and the maximum removal efficiencies of ammonium, nitrite, and nitrate were 100%, 96.35%, and 99.7%, respectively.The genomic information revealed the presence of amoA, napA, and nosZ genes in strain HN2, and the target bands of nirS were obtained via a polymerase chain reaction. Therefore, we inferred that ammonium was mainly utilized for the growth of strain HN2 through assimilation, and another part of the initial ammonium was converted into nitrate through nitrification, and then into gaseous nitrogen through denitrification. This report indicated the potential application of strain HN2 and other nitrifying and denitrifying Halomonas strains in the removal of nitrogen pollution in marine-related environments and also implies the important role of Halomonas in the nitrogen cycle process of the ocean.

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

“…This indicated the critical importance of selecting suitable carbon sources for strain HS2 to achieve efficient denitrification at low temperatures. Previous studies on Halomonas piezotolerans HN2 [ 19 ] and Pseudomonas stutzeri sdu 10 [ 20 ] have also identified sodium succinate as the optimal carbon source. This may be attributed to the fact that succinate can enter the tricarboxylic acid (TCA) cycle directly without undergoing modification during aerobic metabolism [ 21 ].…”

Phylogenomic analysis of Citrobacter sp. strain AAK_AS5 and its metabolic capabilities to support nitrogen removal behavior

“…At 96 h, the NO 3 − ‐N concentration decreased rapidly, with a slight increase in NO 2 − ‐N that reached a maximum concentration of 6 mg/L in 48 h. Then, NO 3 − ‐N and NO 2 − ‐N further gradually decreased after 96 h (Figure 6a). It could be inferred that both nitrate reductase and nitrite reductase may exist in strain AAK_AS5 [95, 96].…”

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

“…This indicated the critical importance of selecting suitable carbon sources for strain HS2 to achieve efficient denitrification at low temperatures. Previous studies on Halomonas piezotolerans HN2 [18] and Pseudomonas stutzeri sdu10 [19] have also identified sodium succinate as the optimal carbon source. This may be attributed to the fact that succinate can enter the tricarboxylic acid (TCA) cycle directly without undergoing modification during aerobic metabolism [20].…”