{"title":"The denitrification ability and nitrogen metabolism pathway of aerobic denitrifier Marinobacter alkaliphilus SBY-1 under low C/N ratios.","authors":"Chao Pan, Yang-Guo Zhao, Progress Mupindu, Shuxue Zhao","doi":"10.1016/j.scitotenv.2024.177651","DOIUrl":null,"url":null,"abstract":"<p><p>Mariculture tail water is characterized as the low C/N ratios and thus blocks the conventional heterotrophic denitrification process due to insufficient carbon source. Therefore, oligotrophic marine bacteria with heterotrophic nitrification and aerobic denitrification (HN-AD) are urgently required to bioaugment aerobic biological filter. In this study, Marinobacter alkaliphilus SBY-1 was isolated and confirmed optimal nitrate removal capacity at a rate of 716 mg/L·d without ammonia production or nitrite accumulation under initial nitrate concentration of 800 mg/L, pH 7, salinity 20 ‰, sodium acetate as the carbon source, and low C/N ratios of 3.6. SBY-1 also demonstrated heterotrophic nitrification capability with a maximum ammonia removal rate reaching 69.21 % when ammonia was used as the nitrogen source. The enzymes involved in the HN-AD process including ammonia monooxygenase (AMO), nitrate reductase (NR), and nitrite reductase (NIR) were all detected in SBY-1 with superior activity observed for NR and NIR. Additionally, analysis of EPS and auto-aggregation revealed that SBY-1 exhibited excellent auto-aggregation ability under high influent nitrogen concentration conditions, making it more suitable for biofilm formation and further application in biofilm-based denitrification process. Genome analysis identified genes associated with Nar, Nap, Nas, Nir, Nif, Nrt, Nrf, Nor, Nos which confirmed that SBY-1 possessed a complete HN-AD pathway for nitrogen metabolism. The predicted nitrogen metabolism pathway of SBY-1 was NO<sub>3</sub><sup>-</sup>-N → NO<sub>2</sub><sup>-</sup>-N → NO→N<sub>2</sub>O → N<sub>2</sub>. These findings provide new insights into the efficient removal of nitrate by SBY-1 under lower C/N conditions.</p>","PeriodicalId":422,"journal":{"name":"Science of the Total Environment","volume":" ","pages":"177651"},"PeriodicalIF":8.2000,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Science of the Total Environment","FirstCategoryId":"93","ListUrlMain":"https://doi.org/10.1016/j.scitotenv.2024.177651","RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/11/24 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Mariculture tail water is characterized as the low C/N ratios and thus blocks the conventional heterotrophic denitrification process due to insufficient carbon source. Therefore, oligotrophic marine bacteria with heterotrophic nitrification and aerobic denitrification (HN-AD) are urgently required to bioaugment aerobic biological filter. In this study, Marinobacter alkaliphilus SBY-1 was isolated and confirmed optimal nitrate removal capacity at a rate of 716 mg/L·d without ammonia production or nitrite accumulation under initial nitrate concentration of 800 mg/L, pH 7, salinity 20 ‰, sodium acetate as the carbon source, and low C/N ratios of 3.6. SBY-1 also demonstrated heterotrophic nitrification capability with a maximum ammonia removal rate reaching 69.21 % when ammonia was used as the nitrogen source. The enzymes involved in the HN-AD process including ammonia monooxygenase (AMO), nitrate reductase (NR), and nitrite reductase (NIR) were all detected in SBY-1 with superior activity observed for NR and NIR. Additionally, analysis of EPS and auto-aggregation revealed that SBY-1 exhibited excellent auto-aggregation ability under high influent nitrogen concentration conditions, making it more suitable for biofilm formation and further application in biofilm-based denitrification process. Genome analysis identified genes associated with Nar, Nap, Nas, Nir, Nif, Nrt, Nrf, Nor, Nos which confirmed that SBY-1 possessed a complete HN-AD pathway for nitrogen metabolism. The predicted nitrogen metabolism pathway of SBY-1 was NO3--N → NO2--N → NO→N2O → N2. These findings provide new insights into the efficient removal of nitrate by SBY-1 under lower C/N conditions.
期刊介绍:
The Science of the Total Environment is an international journal dedicated to scientific research on the environment and its interaction with humanity. It covers a wide range of disciplines and seeks to publish innovative, hypothesis-driven, and impactful research that explores the entire environment, including the atmosphere, lithosphere, hydrosphere, biosphere, and anthroposphere.
The journal's updated Aims & Scope emphasizes the importance of interdisciplinary environmental research with broad impact. Priority is given to studies that advance fundamental understanding and explore the interconnectedness of multiple environmental spheres. Field studies are preferred, while laboratory experiments must demonstrate significant methodological advancements or mechanistic insights with direct relevance to the environment.