Denitrification-Potential Evaluation and Nitrate-Removal-Pathway Analysis of Aerobic Denitrifier Strain Marinobacter hydrocarbonoclasticus RAD-2

Abstract

An aerobic denitrifier was isolated from a long-term poly (3-hydroxybutyrate-co-3hydroxyvalerate) PHBV-supported denitrification reactor that operated under alternate aerobic/anoxic conditions. The strain was identified as Marinobacter hydrocarbonoclasticus RAD-2 based on 16S rRNA-sequence phylogenetic analysis. Morphology was observed by scanning electron microscopy (SEM), and phylogenetic characteristics were analyzed with the API 20NE test. Strain RAD-2 showed efficient aerobic denitrification ability when using NO 3 − -N or NO 2 − -N as its only nitrogen source, while heterotrophic nitrification was not detected. The average NO 3 − -N and NO 2 − -N removal rates were 6.47 mg/(L·h)and 6.32 mg/(L·h), respectively. Single-factor experiments indicated that a 5:10 C/N ratio, 25-40 • C temperature, and 100-150 rpm rotation speed were the optimal conditions for aerobic denitrification. Furthermore, the denitrifying gene napA had the highest expression on a transcriptional level, followed by the denitrifying genes nirS and nosZ. The norB gene was found to have significantly low expression during the experiment. Overall, great aerobic denitrification ability makes the RAD-2 strain a potential alternative in enhancing nitrate management for marine recirculating aquaculture system (RAS) practices.

Nitrogen Removal Performance and Metabolic Pathways Analysis of a Novel Aerobic Denitrifying Halotolerant Pseudomonas balearica Strain RAD-17

“…DO was measured using a DO meter (SG9-FK2, Mettler Toledo, Zurich, Switzerland). Physiological and biochemical characteristics were tested using API 20NE kits (BioMérieux Shanghai Co. Limited, Shanghai, China), and test strips were checked after incubation for 24 h [23]. Nitrogen balance analysis was done according to the previous study.…”

“…The culture media used in this study were according to our previous study [23]. The LB (Luria-Bertani) media was prepared by using 5.0 g/L yeast extract, 10.0 g/L peptone, 25.0 g/L NaCl, and 1.5% (w/v) agar.…”

“…Until now, many aerobic denitrifies were reported in plenty of genera including Pseudomonas stutzeri YZN-001 [20], Acinetobacter sp. HA2 [21], Pseudomonas stutzeri T13 [22], Marinobacter hydrocarbonoclasticus RAD-2 [23], Pseudomonas stutzeri C3 [24], etc. In addition, several strains were also found to have aerobic ammonium removal ability, which show potential through heterotrophic nitrification or assimilation pathways [22,[24][25][26].…”

Adsorption of Nitrate by a Novel Polyacrylic Anion Exchange Resin from Water with Dissolved Organic Matters: Batch and Column Study

“…Conventional heterotrophic denitrification techniques are severely restricted by the low C/N ratio of wastewater, thereby causing the high NO3 − -N content in STWW [33,34]. To further assess the practical application of AEE-3, the dynamic column test of NO3 − -N uptake onto AEE-3 was performed using a real STWW effluent which was collected from a local sewage treatment plant, containing the following quality parameters: pH, 6.54; NO3 − -N, 20 mg/L; COD, 39 mg/L; TDS, 436 mg/L.…”

Feed Types Driven Differentiation of Microbial Community and Functionality in Marine Integrated Multitrophic Aquaculture System

“…Oxygen and ammonia concentration are the two main factors determining the productivity of pond aquaculture. In ponds, autotrophic nitrifier and sulphur bacteria oxidize ammonium, nitrite and sulphite through an aerobic process in the water and denitrifying and sulphate-reducing bacteria perform anaerobic processes in the sediment [12][13][14]. Through the activity of heterotrophic decomposers, nitrogen and phosphorous are released to stimulate primary production of phytoplankton.…”