{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T19:14:04Z","timestamp":1788981244129,"version":"build-2803163510"},"reference-count":46,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,5,14]],"date-time":"2025-05-14T00:00:00Z","timestamp":1747180800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:p><jats:italic>p<\/jats:italic>-Nitrophenol (PNP), a member of the nitroaromatic family, is widely used in the production of pesticides, dyes, pharmaceuticals, and petroleum products. As a toxic compound, PNP is highly resistance to degradation, posing a significant challenge in agricultural and industrial wastewater treatment. Conventional PNP wastewater treatment methods require complex operational conditions that incur high chemical and equipment costs, and potential secondary pollution. Therefore, this study developed an anoxic fluidized bed bioreactor (AFBBR) and an anaerobic-aerobic fluidized bed bioreactor (AAFBBR) to evaluate the biodegradation performance and underlying mechanisms of PNP over a period of 90\u202fdays. The effect of glucose to PNP co-substrate ratios and C\/N ratios have been systemically investigated. At an influent PNP concentration of 100\u202fmg\/L, a glucose to PNP co-substrate ratio of 6:1, and a C\/N ratio of 10:1, the degradation of PNP reached 88.8\u202f\u00b1\u202f1.0% in the AFBBR at an HRT of 8.5\u202fh and 95.3\u202f\u00b1\u202f0.3% in the AAFBBR at an HRT of 12.7\u202fh. Meanwhile, the mechanism of PNP biodegradation and microbial community were also studied. Results of the LC\u2013MS\/MS revealed the intermediate products and confirmed that PNP biodegradation in both reactors followed the hydroquinone as well as the hydroxyquinol pathways, with the hydroquinone pathway being dominant. Results of the 16S rRNA high throughput sequencing further revealed a predominant presence of <jats:italic>Proteobacteria<\/jats:italic> (34% in the AFBBR, 42 and 65% in the anaerobic as well as aerobic zones of the AAFBBR, respectively), <jats:italic>Firmicutes<\/jats:italic> (35, 40, and 4%), <jats:italic>Saccharibacteria<\/jats:italic> (14, 9, and 4%) and <jats:italic>Bacteroidetes<\/jats:italic> (5, 4, and 19%). In the AFBBR and the AAFBBR, the key bacterial genera responsible for PNP degradation include <jats:italic>Lactococcus<\/jats:italic>, <jats:italic>Escherichia-Shigella<\/jats:italic>, <jats:italic>Saccharibacteria_norank<\/jats:italic>, <jats:italic>Acinetobacter<\/jats:italic>, <jats:italic>Comamonas, Zoogloea<\/jats:italic>, and <jats:italic>Pseudomonas<\/jats:italic>. Notably, the hydroxyquinol pathway was observed only in the AFBBR and the aerobic zone of the AAFBBR, where <jats:italic>Pseudomonas<\/jats:italic> were identified as key PNP degrading bacteria. These phenomena can be attributed to the varying dissolved oxygen concentrations across different zones in the two reactors, offering valuable insights into optimizing PNP removal in pilot-scale bioreactors. This study highlights an efficient, sustainable and cost-effective approach for PNP removal from agricultural and industrial wastewater.<\/jats:p>","DOI":"10.3389\/fmicb.2025.1602768","type":"journal-article","created":{"date-parts":[[2025,5,14]],"date-time":"2025-05-14T05:37:08Z","timestamp":1747201028000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":10,"title":["Biodegradation mechanisms of p-nitrophenol and microflora dynamics in fluidized bed bioreactors"],"prefix":"10.3389","volume":"16","author":[{"given":"Xin","family":"Zheng","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yongjie","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhiheng","family":"Ye","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhiyan","family":"Pan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,5,14]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"101867","DOI":"10.1016\/j.scp.2024.101867","article-title":"A review of recent advances in green and sustainable technologies for removing 4-nitrophenol from the water and wastewater","volume":"43","author":"Badamasi","year":"2025","journal-title":"Sustain. Chem. Pharm."},{"key":"ref2","doi-asserted-by":"publisher","first-page":"11536","DOI":"10.1021\/acs.est.5b03293","article-title":"Accelerating quinoline biodegradation and oxidation with endogenous electron donors","volume":"49","author":"Bai","year":"2015","journal-title":"Environ. Sci. Technol."},{"key":"ref3","doi-asserted-by":"publisher","first-page":"18","DOI":"10.1371\/journal.pone.0155485","article-title":"The regulation of Para-Nitrophenol degradation in Pseudomonas putida DLL-E4","volume":"11","author":"Chen","year":"2016","journal-title":"PLoS One"},{"key":"ref4","doi-asserted-by":"publisher","first-page":"151373","DOI":"10.1016\/j.scitotenv.2021.151373","article-title":"Enhanced mainstream nitrogen removal from synthetic wastewater using gel-immobilized anammox in fluidized bed bioreactors: process performance and disintegration mechanisms","volume":"811","author":"Chowdhury","year":"2022","journal-title":"Sci. Total Environ."},{"key":"ref5","doi-asserted-by":"publisher","first-page":"102443","DOI":"10.1016\/j.eti.2022.102443","article-title":"The emission of volatile organic compounds during the initial decomposition stage of food waste and its relationship with the bacterial community","volume":"27","author":"Cui","year":"2022","journal-title":"Environ. Technol. Innov."},{"key":"ref6","doi-asserted-by":"publisher","first-page":"289","DOI":"10.1016\/j.jhazmat.2010.05.010","article-title":"Biological nutrient removal from leachate using a pilot liquid-solid circulating fluidized bed bioreactor (LSCFB)","volume":"181","author":"Eldyasti","year":"2010","journal-title":"J. Hazard. Mater."},{"key":"ref7","doi-asserted-by":"publisher","first-page":"205","DOI":"10.1016\/j.gce.2023.03.003","article-title":"Catalytic transformation of 4-nitrophenol into 4-aminophenol over ZnO nanowire array-decorated cu nanoparticles","volume":"5","author":"Feng","year":"2024","journal-title":"Green Chem. Eng."},{"key":"ref8","doi-asserted-by":"publisher","first-page":"269","DOI":"10.1007\/s10532-006-9061-y","article-title":"Biodegradation of oil tank bottom sludge using microbial consortia","volume":"18","author":"Gallego","year":"2007","journal-title":"Biodegradation"},{"key":"ref9","doi-asserted-by":"publisher","first-page":"124","DOI":"10.1016\/j.biortech.2014.05.120","article-title":"Enrichment of anodic biofilm inoculated with anaerobic or aerobic sludge in single chambered air-cathode microbial fuel cells","volume":"167","author":"Gao","year":"2014","journal-title":"Bioresour. Technol."},{"key":"ref10","doi-asserted-by":"publisher","first-page":"7249","DOI":"10.1016\/j.biortech.2011.04.098","article-title":"Transition of microbial communities during the adaption to anaerobic digestion of carrot waste","volume":"102","author":"Garcia","year":"2011","journal-title":"Bioresour. Technol."},{"key":"ref11","doi-asserted-by":"publisher","first-page":"543","DOI":"10.1016\/j.cclet.2019.08.031","article-title":"The performance and degradation mechanism of sulfamethazine from wastewater using IFAS-MBR","volume":"31","author":"Hou","year":"2020","journal-title":"Chinese Chem. Lett."},{"key":"ref12","doi-asserted-by":"publisher","first-page":"1222","DOI":"10.1061\/(ASCE)EE.1943-7870.0000728","article-title":"Biodegradation of TCP in a sequencing batch-fluidized bed bioreactor with waste coke particles as the carrier","volume":"139","author":"Hu","year":"2013","journal-title":"J. Environ. Eng."},{"key":"ref13","doi-asserted-by":"publisher","first-page":"117933","DOI":"10.1016\/j.envres.2023.117933","article-title":"Temporal differentiation in the adaptation of functional bacteria to low-temperature stress in partial denitrification and anammox system","volume":"244","author":"Huang","year":"2024","journal-title":"Environ. Res."},{"key":"ref14","doi-asserted-by":"publisher","first-page":"864","DOI":"10.1016\/j.cej.2016.05.142","article-title":"Correspondence analysis of bio-refractory compounds degradation and microbiological community distribution in anaerobic filter for coking wastewater treatment","volume":"304","author":"Huang","year":"2016","journal-title":"Chem. Eng. J."},{"key":"ref15","doi-asserted-by":"publisher","first-page":"185","DOI":"10.1016\/j.procbio.2017.07.033","article-title":"Microbial community dynamics in aerated biological fluidized bed (ABFB) with continuously increased p-nitrophenol loads","volume":"63","author":"Ji","year":"2017","journal-title":"Process Biochem."},{"key":"ref16","doi-asserted-by":"publisher","first-page":"262","DOI":"10.1016\/j.procbio.2014.11.005","article-title":"A review on anaerobic biofilm reactors for the treatment of dairy industry wastewater","volume":"50","author":"Karadag","year":"2015","journal-title":"Process Biochem."},{"key":"ref7001","doi-asserted-by":"publisher","first-page":"4898","DOI":"10.1128\/JB.186.15.4894-4902.2004","article-title":"A novel p-nitrophenol degradation gene cluster from a gram-positive bacterium, Rhodococcus opacus SAO101","volume":"186","author":"Kitagawa","year":"2004","journal-title":"J. Bacteriol."},{"key":"ref17","doi-asserted-by":"publisher","first-page":"1252","DOI":"10.1016\/j.jece.2017.01.043","article-title":"Oilfield wastewater biotreatment in a fluidized-bed bioreactor using co-immobilized Rhodococcus cultures","volume":"5","author":"Kuyukina","year":"2017","journal-title":"J. Environ. Chem. Eng."},{"key":"ref18","doi-asserted-by":"publisher","first-page":"0960","DOI":"10.1016\/j.biortech.2024.131636","article-title":"Exploring the effects of polyethylene and polyester microplastics on biofilm formation, membrane fouling, and microbial communities in modified ludzack-ettinger-reciprocation membrane bioreactors","volume":"414","author":"Li","year":"2024","journal-title":"Bioresour. Technol."},{"key":"ref19","doi-asserted-by":"publisher","first-page":"717","DOI":"10.1016\/S1001-0742(13)60479-9","article-title":"Performance and microbial diversity of an expanded granular sludge bed reactor for high sulfate and nitrate waste brine treatment","volume":"26","author":"Liao","year":"2014","journal-title":"J. Environ. Sci."},{"key":"ref20","doi-asserted-by":"publisher","first-page":"103984","DOI":"10.1016\/j.jece.2020.103984","article-title":"Partial nitrification-reactor configurations, and operational conditions: performance analysis","volume":"8","author":"Liu","year":"2020","journal-title":"J. Environ. Chem. Eng."},{"key":"ref21","doi-asserted-by":"publisher","first-page":"161656","DOI":"10.1016\/j.cej.2025.161656","article-title":"Microalgal biofilm cultivation on lignocellulosic based bio-carriers: effects of material physical characteristics on microalgal biomass production and composition","volume":"510","author":"Lu","year":"2025","journal-title":"Chem. Eng. J."},{"key":"ref22","doi-asserted-by":"publisher","first-page":"134","DOI":"10.1016\/j.jes.2021.02.017","article-title":"Coupled biodegradation of p-nitrophenol and p-aminophenol in bioelectrochemical system: mechanism and microbial functional diversity","volume":"108","author":"Luo","year":"2021","journal-title":"J. Environ. Sci."},{"key":"ref23","doi-asserted-by":"publisher","first-page":"104233","DOI":"10.1016\/j.jece.2020.104233","article-title":"A review on hydrodynamic parameters and biofilm characteristics of inverse fluidized bed bioreactors for treating industrial wastewater","volume":"8","author":"Mallikarjuna","year":"2020","journal-title":"J. Environ. Chem. Eng."},{"key":"ref24","doi-asserted-by":"publisher","first-page":"99","DOI":"10.1016\/j.jhazmat.2018.09.072","article-title":"Simultaneous p-nitrophenol and nitrogen removal in PNP wastewater treatment: comparison of two integrated membrane-aerated bioreactor systems","volume":"363","author":"Mei","year":"2019","journal-title":"J. Hazard. Mater."},{"key":"ref25","doi-asserted-by":"publisher","first-page":"789","DOI":"10.1016\/j.chemosphere.2003.10.023","article-title":"Reductive degradation of nitrobenzene in aqueous solution by zero-valent iron","volume":"54","author":"Mu","year":"2004","journal-title":"Chemosphere"},{"key":"ref26","doi-asserted-by":"publisher","first-page":"2228","DOI":"10.2166\/wst.2018.140","article-title":"Techno-economic evaluation of simultaneous production of extra-cellular polymeric substance (EPS) and lipids by Cloacibacterium normanense NK6 using crude glycerol and sludge as substrate","volume":"77","author":"Ram","year":"2018","journal-title":"Water Sci. Technol."},{"key":"ref7002","doi-asserted-by":"publisher","first-page":"562263","DOI":"10.3389\/fenvs.2020.562263","article-title":"The \u201cPlastisphere\u201d of biodegradable plastics is characterized by specific microbial taxa of alpine and arctic soils","volume":"8","author":"Ruthi","year":"2020","journal-title":"Env. Sci."},{"key":"ref27","doi-asserted-by":"publisher","first-page":"1187","DOI":"10.1016\/j.jhazmat.2010.10.030","article-title":"Relationships between acute toxicities of Para nitrophenol (p-NP) and nitrobenzene (NB) to Daphnia magna and Photobacterium phosphoreum: physicochemical properties and metabolites under anaerobic\/aerobic sequentials","volume":"185","author":"Sponza","year":"2011","journal-title":"J. Hazard. Mater."},{"key":"ref28","doi-asserted-by":"publisher","first-page":"e10823","DOI":"10.1002\/wer.10823","article-title":"Six complex microbial inoculants for removing ammonia nitrogen from waters","volume":"94","author":"Sun","year":"2022","journal-title":"Water Environ. Res."},{"key":"ref29","doi-asserted-by":"publisher","first-page":"136982","DOI":"10.1016\/j.jhazmat.2024.136982","article-title":"Enhanced printing and dyeing wastewater treatment using anaerobic-aerobic systems with bioaugmentation","volume":"486","author":"Sun","year":"2025","journal-title":"J. Hazard. Mater."},{"key":"ref30","doi-asserted-by":"publisher","first-page":"203","DOI":"10.1016\/j.cej.2012.08.089","article-title":"Degradation of p-nitrophenol by interior microelectrolysis of zero-valent iron\/copper-coated magnetic carbon galvanic couples in the intermittent magnetic field","volume":"210","author":"Tang","year":"2012","journal-title":"Chem. Eng. J."},{"key":"ref31","doi-asserted-by":"publisher","first-page":"108635","DOI":"10.1016\/j.jece.2022.108635","article-title":"Assessing the performance and microbial structure of biofilms in membrane aerated biofilm reactor for high p-nitrophenol concentration treatment","volume":"10","author":"Tong","year":"2022","journal-title":"J. Environ. Chem. Eng."},{"key":"ref32","doi-asserted-by":"publisher","first-page":"122877","DOI":"10.1016\/j.biortech.2020.122877","article-title":"Selective carbon sources and salinities enhance enzymes and extracellular polymeric substances extrusion of Chlorella sp. for potential co-metabolism","volume":"303","author":"Vo","year":"2020","journal-title":"Bioresour. Technol."},{"key":"ref33","doi-asserted-by":"publisher","first-page":"137288","DOI":"10.1016\/j.scitotenv.2020.137288","article-title":"Performance and bacterial community structure of a novel inverse fluidized bed bioreactor (IFBBR) treating synthetic municipal wastewater","volume":"718","author":"Wang","year":"2020","journal-title":"Sci. Total Environ."},{"key":"ref34","doi-asserted-by":"publisher","first-page":"127670","DOI":"10.1016\/j.biortech.2022.127670","article-title":"Cometabolic biodegradation system employed subculturing photosynthetic bacteria: a new degradation pathway of 4-chlorophenol in hypersaline wastewater","volume":"361","author":"Wang","year":"2022","journal-title":"Bioresour. Technol."},{"key":"ref35","doi-asserted-by":"publisher","first-page":"129394","DOI":"10.1016\/j.ijbiomac.2024.129394","article-title":"Green synthesis of chitosan\/glutamic acid\/agarose\/ag nanocomposite hydrogel as a new platform for colorimetric detection of cu ions and reduction of 4-nitrophenol","volume":"259","author":"Wang","year":"2024","journal-title":"Int. J. Biol. Macromol."},{"key":"ref36","doi-asserted-by":"publisher","first-page":"139734","DOI":"10.1016\/j.scitotenv.2020.139734","article-title":"Formation of anaerobic granules and microbial community structure analysis in anaerobic hydrolysis denitrification reactor","volume":"737","author":"Wang","year":"2020","journal-title":"Sci. Total Environ."},{"key":"ref37","doi-asserted-by":"publisher","first-page":"124","DOI":"10.1186\/s13568-021-01284-8","article-title":"Biodegradation of p-nitrophenol by engineered strain","volume":"11","author":"Xu","year":"2021","journal-title":"AMB Expr."},{"key":"ref38","doi-asserted-by":"publisher","first-page":"133993","DOI":"10.1016\/j.jhazmat.2024.133993","article-title":"Detoxification of copper and zinc from anaerobic digestate effluent by indigenous bacteria: mechanisms, pathways and metagenomic analysis","volume":"469","author":"Yan","year":"2024","journal-title":"J. Hazard. Mater."},{"key":"ref39","doi-asserted-by":"publisher","first-page":"127187","DOI":"10.1016\/j.biortech.2022.127187","article-title":"Development of microalgae-bacteria symbiosis system for enhanced treatment of biogas slurry","volume":"354","author":"Yan","year":"2022","journal-title":"Bioresour. Technol."},{"key":"ref40","doi-asserted-by":"publisher","first-page":"130638","DOI":"10.1016\/j.biortech.2024.130638","article-title":"Nitrite accumulation performance and microbial community of algal-bacterial symbiotic system constructed by Chlorella sp. and Navicula sp","volume":"399","author":"Yang","year":"2024","journal-title":"Bioresour. Technol."},{"key":"ref41","doi-asserted-by":"publisher","first-page":"37","DOI":"10.1016\/j.jhazmat.2011.01.043","article-title":"Effect of C\/N ratio on extracellular polymeric substances (EPS) and physicochemical properties of activated sludge flocs","volume":"188","author":"Ye","year":"2011","journal-title":"J. Hazard. Mater."},{"key":"ref42","doi-asserted-by":"publisher","first-page":"1471","DOI":"10.1186\/1471-2180-12-27","article-title":"Identification of the Para-nitrophenol catabolic pathway, and characterization of three enzymes involved in the hydroquinone pathway, in pseudomonas sp. 1-7","volume":"12","author":"Zhang","year":"2012","journal-title":"BMC Microbiol."},{"key":"ref43","doi-asserted-by":"publisher","first-page":"124451","DOI":"10.1016\/j.jclepro.2020.124451","article-title":"Robust removal of phenolic compounds from coal pyrolysis wastewater using anoxic carbon-based fluidized bed reactor","volume":"280","author":"Zheng","year":"2021","journal-title":"J. Clean. Prod."},{"key":"ref44","doi-asserted-by":"publisher","first-page":"1510","DOI":"10.1002\/elan.201501052","article-title":"Microbial electricity generation and isolation of exoelectrogenic bacteria based on petroleum hydrocarbon-contaminated soil","volume":"28","author":"Zhou","year":"2016","journal-title":"Electroanalysis"}],"container-title":["Frontiers in Microbiology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fmicb.2025.1602768\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,5,14]],"date-time":"2025-05-14T05:37:09Z","timestamp":1747201029000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fmicb.2025.1602768\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,5,14]]},"references-count":46,"alternative-id":["10.3389\/fmicb.2025.1602768"],"URL":"https:\/\/doi.org\/10.3389\/fmicb.2025.1602768","relation":{},"ISSN":["1664-302X"],"issn-type":[{"value":"1664-302X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,5,14]]},"article-number":"1602768"}}