Cladophora blooms, exacerbated by climate change and littoral eutrophication, pose a significant ecological threat. Of particular concern is their potential to disrupt phytoplankton and bacterial assemblages, triggering a cascade of effects that may include shifts in nutrient cycling and the dissemination of resistomes. However, the mechanistic links between Cladophora’s life-stage-dependent dissolved organic matter (DOM) release, its role in restructuring epiphytic communities, and its promotion of resistome dissemination in natural, oligotrophic lakes remain poorly understood. To address this, this study integrates field and laboratory investigations of Cladophora qinghaiensis sp. nov.. The algal phycosphere functions as a dynamic “gene incubator”, driven by chemical shifts in algal‑derived DOM. During decay under low‑oxygen conditions, DOM composition transitions from tyrosine‑like proteins to recalcitrant fulvic‑acid‑like compounds, selectively enriching competitive, intrinsically resistant taxa such as Halomonas and Phacus. Microbes such as Acinetobacter drive nutrient cycling (e.g., nitrogen metabolism) and serve as hotspots for resistomes within the phycosphere. Contrary to the expectation that high cell density favors horizontal gene transfer (HGT), genomic analyses show that vertical gene transfer (VGT) dominates antibiotic resistance gene (ARG) proliferation in this niche, a pattern explained by strong DOM‑mediated host selection and subsequent propagation. In contrast, the resistome in the surrounding water is more diverse and primarily shaped by HGT via mobile genetic elements. These results establish a mechanistic link between life‑stage‑specific algal DOM components, selective epiphytic communities enrichment, and divergent pathways of resistome evolution, positioning the phycosphere as a key source of ARGs that amplifies ecological risk in nearshore environments.
{"title":"Cladophora drives the evolution of its epiphytic communities and antibiotic resistome in the littoral zone of Qinghai Lake","authors":"Jia Jia, Hongyi Ao, Xiong Xiong, Shuai Wang, Xiaoyan Xi, Kelong Chen, Chenxi Wu","doi":"10.1016/j.watres.2026.125530","DOIUrl":"https://doi.org/10.1016/j.watres.2026.125530","url":null,"abstract":"<em>Cladophora</em> blooms, exacerbated by climate change and littoral eutrophication, pose a significant ecological threat. Of particular concern is their potential to disrupt phytoplankton and bacterial assemblages, triggering a cascade of effects that may include shifts in nutrient cycling and the dissemination of resistomes. However, the mechanistic links between <em>Cladophora</em>’s life-stage-dependent dissolved organic matter (DOM) release, its role in restructuring epiphytic communities, and its promotion of resistome dissemination in natural, oligotrophic lakes remain poorly understood. To address this, this study integrates field and laboratory investigations of <em>Cladophora qinghaiensis</em> sp. nov.. The algal phycosphere functions as a dynamic “gene incubator”, driven by chemical shifts in algal‑derived DOM. During decay under low‑oxygen conditions, DOM composition transitions from tyrosine‑like proteins to recalcitrant fulvic‑acid‑like compounds, selectively enriching competitive, intrinsically resistant taxa such as <em>Halomonas</em> and <em>Phacus</em>. Microbes such as <em>Acinetobacter</em> drive nutrient cycling (e.g., nitrogen metabolism) and serve as hotspots for resistomes within the phycosphere. Contrary to the expectation that high cell density favors horizontal gene transfer (HGT), genomic analyses show that vertical gene transfer (VGT) dominates antibiotic resistance gene (ARG) proliferation in this niche, a pattern explained by strong DOM‑mediated host selection and subsequent propagation. In contrast, the resistome in the surrounding water is more diverse and primarily shaped by HGT via mobile genetic elements. These results establish a mechanistic link between life‑stage‑specific algal DOM components, selective epiphytic communities enrichment, and divergent pathways of resistome evolution, positioning the phycosphere as a key source of ARGs that amplifies ecological risk in nearshore environments.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"91 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146129689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1016/j.watres.2026.125517
Jianquan Peng, Siheng Zhao, Shengchao Zhao, Mingbin Chen, Kuo Chen, Q. Jason Niu
{"title":"Synthesis of Thin Film Composite Membranes via Acid-Assisted Interfacial Polymerization for Water Desalination","authors":"Jianquan Peng, Siheng Zhao, Shengchao Zhao, Mingbin Chen, Kuo Chen, Q. Jason Niu","doi":"10.1016/j.watres.2026.125517","DOIUrl":"https://doi.org/10.1016/j.watres.2026.125517","url":null,"abstract":"","PeriodicalId":443,"journal":{"name":"Water Research","volume":"89 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1016/j.watres.2026.125519
Lihua Niu, Yao Pan, Yi Li, Xuekai Chen, Xiaobo Liu, Yamei Chen, Longfei Wang, Wenming Zhang
As an important water replenishment measure for urban rivers, the input of wastewater treatment plant (WWTP) effluents can change both the nutrient loading and the microbial community diversity of receiving rivers. However, our knowledge of the characteristics of viral communities and virus-mediated nitrogen-cycling processes in WWTP effluents-receiving rivers remains very limited. In this study, the prokaryotic virus, host and non-host communities in sediments were detected via metagenome and virome methods, to explore the variation characteristics of viral communities, interactions with hosts and virus-mediated nitrogen-cycling processes along the upper reference reach (UR), middle receiving reach (MR) and lower recovery reach (LR) of a typical WWTP effluents-receiving river. The results showed that compared to the non-hosts, viruses and hosts were much more sensitive to the influence of WWTP effluents. Among the three reaches, viruses and hosts showed more obvious spatial variability in community diversity and structures than those of non-hosts. Compared to UR, viruses in MR displayed the highest community diversity and virus-to-host abundance ratio, while viruses in LR maintained the high abundance ratio. Co-occurrence network analysis indicated the more important central roles of viruses than those of prokaryotes in bridging species or groups within the virus-host-prokaryote communities, especially in MR and LR. Functional gene analyses revealed that viral communities might potentially regulate nitrogen cycles in MR and LR via two pathways: directly carrying more abundant nitrogen-related auxiliary metabolic genes (N-vAMGs) and indirectly regulating hosts involved in nitrogen transformations (N-hosts) via enriched viruses, which showed strong responses to nitrogen loadings (TN and NO3--N) in rivers. Both N-vAMGs and virus-enrichment N-hosts, dominantly involved in denitrification, dissimilatory nitrate reduction to ammonium, and organic degradation and synthesis processes, significantly increased in MR and LR, which highlighted a long-term regulation potential of viral communities to WWTP effluents-receiving rivers. Together, these findings provided a new insight into the nonnegligible ecological role of viruses in influencing biogeochemical cycles in WWTP effluents-receiving urban rivers.
{"title":"WWTP effluents influence prokaryotic viral diversity and interaction with hosts: regulating the virus-mediated nitrogen-cycling processes in river sediments","authors":"Lihua Niu, Yao Pan, Yi Li, Xuekai Chen, Xiaobo Liu, Yamei Chen, Longfei Wang, Wenming Zhang","doi":"10.1016/j.watres.2026.125519","DOIUrl":"https://doi.org/10.1016/j.watres.2026.125519","url":null,"abstract":"As an important water replenishment measure for urban rivers, the input of wastewater treatment plant (WWTP) effluents can change both the nutrient loading and the microbial community diversity of receiving rivers. However, our knowledge of the characteristics of viral communities and virus-mediated nitrogen-cycling processes in WWTP effluents-receiving rivers remains very limited. In this study, the prokaryotic virus, host and non-host communities in sediments were detected via metagenome and virome methods, to explore the variation characteristics of viral communities, interactions with hosts and virus-mediated nitrogen-cycling processes along the upper reference reach (UR), middle receiving reach (MR) and lower recovery reach (LR) of a typical WWTP effluents-receiving river. The results showed that compared to the non-hosts, viruses and hosts were much more sensitive to the influence of WWTP effluents. Among the three reaches, viruses and hosts showed more obvious spatial variability in community diversity and structures than those of non-hosts. Compared to UR, viruses in MR displayed the highest community diversity and virus-to-host abundance ratio, while viruses in LR maintained the high abundance ratio. Co-occurrence network analysis indicated the more important central roles of viruses than those of prokaryotes in bridging species or groups within the virus-host-prokaryote communities, especially in MR and LR. Functional gene analyses revealed that viral communities might potentially regulate nitrogen cycles in MR and LR via two pathways: directly carrying more abundant nitrogen-related auxiliary metabolic genes (N-vAMGs) and indirectly regulating hosts involved in nitrogen transformations (N-hosts) via enriched viruses, which showed strong responses to nitrogen loadings (TN and NO<sub>3</sub><sup>-</sup>-N) in rivers. Both N-vAMGs and virus-enrichment N-hosts, dominantly involved in denitrification, dissimilatory nitrate reduction to ammonium, and organic degradation and synthesis processes, significantly increased in MR and LR, which highlighted a long-term regulation potential of viral communities to WWTP effluents-receiving rivers. Together, these findings provided a new insight into the nonnegligible ecological role of viruses in influencing biogeochemical cycles in WWTP effluents-receiving urban rivers.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"9 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146129688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.watres.2026.125518
Yunxia Zu, Xueqi Chen, Zimeng Zhang, Aijie Wang, Zhiling Li
Organohalides and heavy metals often co-contaminate groundwater, however, the biotoxicity of heavy metal strongly inhibits microbial reductive dechlorination activity and existing bioremediation strategies seldom achieve simultaneous removal of both types of pollutants. Here, we demonstrated that cysteine amendment enabled synchronous reductive dechlorination and cadmium (Cd(II)) removal in an organohalide-respiring bacterium Pseudomonas sp. CP-1 through cysteine-mediated sulfide bioprecipitation. Batch experiments revealed that cysteine supplementation at a Cd(II):Cys molar ratio of 1:2 achieved an enhanced 2,4,6-trichlorophenol dechlorination kinetics (kd = 0.28 d-1) and 91.20% recovery of Cd(II) as nanocrystalline CdS deposited on the cell surface. In simulated continuous-flow biobarriers, the addition of cysteine sustained high removal efficiencies for both contaminants despite hydraulic fluctuations, with a highest dechlorination rate reaching 120 µM·(L·d)-1, 9.6 times higher than the pure dechlorination process. Multi-omics analysis revealed the potential coupled metabolic mechanism of dechlorination and Cd(II) removal in which the amendment of cysteine not only activated cysteine desulfurase to produce H2S for extracellular precipitation of CdS, but also generated alanine and pyruvate, which likely assimilated into the TCA cycle to augment NADH production and electron supply for reductive dechlorination. This work establishes a unique single-strain based strategy for synergistic remediation of organohalide and heavy metal ions in groundwater, highlighting the potential of cysteine-driven metabolism as an effective bioaugmentation tool for sustainable remediation of organohalide and heavy metal co-contaminated groundwater.
{"title":"Cysteine-induced sulfide bioprecipitation enables simultaneous efficient dechlorination and cadmium removal by Pseudomonas sp. CP-1","authors":"Yunxia Zu, Xueqi Chen, Zimeng Zhang, Aijie Wang, Zhiling Li","doi":"10.1016/j.watres.2026.125518","DOIUrl":"https://doi.org/10.1016/j.watres.2026.125518","url":null,"abstract":"Organohalides and heavy metals often co-contaminate groundwater, however, the biotoxicity of heavy metal strongly inhibits microbial reductive dechlorination activity and existing bioremediation strategies seldom achieve simultaneous removal of both types of pollutants. Here, we demonstrated that cysteine amendment enabled synchronous reductive dechlorination and cadmium (Cd(II)) removal in an organohalide-respiring bacterium <em>Pseudomonas</em> sp. CP-1 through cysteine-mediated sulfide bioprecipitation. Batch experiments revealed that cysteine supplementation at a Cd(II):Cys molar ratio of 1:2 achieved an enhanced 2,4,6-trichlorophenol dechlorination kinetics (<em>k<sub>d</sub></em> = 0.28 d<sup>-1</sup>) and 91.20% recovery of Cd(II) as nanocrystalline CdS deposited on the cell surface. In simulated continuous-flow biobarriers, the addition of cysteine sustained high removal efficiencies for both contaminants despite hydraulic fluctuations, with a highest dechlorination rate reaching 120 µM·(L·d)<sup>-1</sup>, 9.6 times higher than the pure dechlorination process. Multi-omics analysis revealed the potential coupled metabolic mechanism of dechlorination and Cd(II) removal in which the amendment of cysteine not only activated cysteine desulfurase to produce H<sub>2</sub>S for extracellular precipitation of CdS, but also generated alanine and pyruvate, which likely assimilated into the TCA cycle to augment NADH production and electron supply for reductive dechlorination. This work establishes a unique single-strain based strategy for synergistic remediation of organohalide and heavy metal ions in groundwater, highlighting the potential of cysteine-driven metabolism as an effective bioaugmentation tool for sustainable remediation of organohalide and heavy metal co-contaminated groundwater.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"303 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146129691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-05DOI: 10.1016/j.watres.2026.125516
Junyan Liu, Jinze Li, Li-ping He, Li Gu
{"title":"CFD-PBM-ASM2 Integrated Model Reveals the Influence Mechanisms of Bubble Size Distribution on Oxygen Mass Transfer and Pollutant Removal in a Full-Scale A²O Bioreactor","authors":"Junyan Liu, Jinze Li, Li-ping He, Li Gu","doi":"10.1016/j.watres.2026.125516","DOIUrl":"https://doi.org/10.1016/j.watres.2026.125516","url":null,"abstract":"","PeriodicalId":443,"journal":{"name":"Water Research","volume":"1 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Micro-particles (0.45-10 μm) containing substantial microbial populations in anaerobic membrane bioreactor (AnMBR) supernatants have recently been identified as critical foulants. However, the assembly processes and ecological roles of micro-particle–associated microbiota (MPM) remain largely unknown in AnMBRs. In this study, a long-term operated AnMBR under varying organic loading rates (OLRs), along with a series of batch experiments, was used to investigate the responses and functional roles of both MPM and sludge flocs microbiota (SFM). The results indicated that MPM significantly enhanced organic conversion rates and methane production (p < 0.01). Although MPM demonstrated significantly lower microbial diversity than SFM (p < 0.01), it showed greater stability and resilience under OLR fluctuations. Mantel tests revealed that the MPM, rather than the SFM, was more strongly correlated with organic transformation and methanogenesis (p < 0.001). Both null model and Sloan neutral model analyses demonstrated that stochastic processes dominated the overall assembly of both communities, while deterministic selection shaped the abundant taxa. The presence of MPM did not alter the cooperative dominance in microbial interaction patterns, but it enhanced the interaction intensity and shortened path distances within the community network, thereby facilitating more efficient organic transformation and methane production. Moreover, the involvement of the MPM enhanced the stability and resilience of the community network within the AnMBR. Overall, these findings uncover previously overlooked ecological functions of MPM and provide new insights and strategies for optimizing AnMBR performance.
{"title":"Overlooked ecological roles of micro-particle–associated microbiota in sustaining reactor performance in submerged anaerobic membrane bioreactors","authors":"Ronghua Xu, Yuan Gao, Yuanyuan Yao, Zongyue Chen, Zhongbo Zhou, Fangang Meng","doi":"10.1016/j.watres.2026.125509","DOIUrl":"https://doi.org/10.1016/j.watres.2026.125509","url":null,"abstract":"Micro-particles (0.45-10 <em>μ</em>m) containing substantial microbial populations in anaerobic membrane bioreactor (AnMBR) supernatants have recently been identified as critical foulants. However, the assembly processes and ecological roles of micro-particle–associated microbiota (MPM) remain largely unknown in AnMBRs. In this study, a long-term operated AnMBR under varying organic loading rates (OLRs), along with a series of batch experiments, was used to investigate the responses and functional roles of both MPM and sludge flocs microbiota (SFM). The results indicated that MPM significantly enhanced organic conversion rates and methane production (<em>p</em> < 0.01). Although MPM demonstrated significantly lower microbial diversity than SFM (<em>p</em> < 0.01), it showed greater stability and resilience under OLR fluctuations. Mantel tests revealed that the MPM, rather than the SFM, was more strongly correlated with organic transformation and methanogenesis (<em>p</em> < 0.001). Both null model and Sloan neutral model analyses demonstrated that stochastic processes dominated the overall assembly of both communities, while deterministic selection shaped the abundant taxa. The presence of MPM did not alter the cooperative dominance in microbial interaction patterns, but it enhanced the interaction intensity and shortened path distances within the community network, thereby facilitating more efficient organic transformation and methane production. Moreover, the involvement of the MPM enhanced the stability and resilience of the community network within the AnMBR. Overall, these findings uncover previously overlooked ecological functions of MPM and provide new insights and strategies for optimizing AnMBR performance.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"23 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146129690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-04DOI: 10.1016/j.watres.2026.125511
Baoxiang Fan, Haijun Peng, Jingcheng Ran, Hu Yao, Weijun Luo, Bing Hong
Lakes are increasingly recognized as hotspots for methane (CH₄) emissions, yet high-frequency (hourly-scale) measurements of CH₄ fluxes throughout all seasons and a clear understanding of their underlying environmental control mechanisms are still lacking. Here, we explore the dynamics of CH4 flux and its hydrological and biogeochemical mechanisms in a karst shallow lake ecosystem, based on eddy covariance (EC), sTable carbon isotope, and metagenomic sequencing techniques. Our 13-month EC monitoring shows that the lake was a CH4 source to the atmosphere, with average emission rate being 2.07 ± 1.20 mmol CH4 m⁻² d⁻¹, with the highest emissions in autumn (3.63 ± 0.5 mmol m-2 d-1), accounting for more than twice those of winter. Seasonal CH₄ flux variations were primarily driven by water temperature, water level, and electrical conductivity. Elevated temperature stimulated methanogenesis, water level changes altered redox gradients shaping methanogen activity, and conductivity regulated substrate availability favoring acetoclastic methanogens. At the diurnal scale, CH₄ emissions were higher at night than during the day, with diel flux variations were mainly controlled by water temperature, which enhanced methanogenesis while suppressing oxidation. These environmental controls on CH₄ flux are consistent with the structure of the methanogenic community and support the dominance of acetoclastic methanogenesis. Methanothrix was found to be the dominant (∼65%) methanogenic microbe in this carbonate-rich alkaline karst lake. Additionally, the dominant pathway of CH4 production in the lake was acetoclastic methanogenesis, with the apparent fractionation factor of δ¹³C-CH₄ being 1.041 ± 0.002. We emphasize the importance of integrating physicochemical variability with microbial functional potential to advance understanding of biogeochemical feedbacks in carbonate-rich karst systems and improve the accuracy of CH₄ emission estimates across scales.
{"title":"Environmental and Microbial Regulation of Multi-temporal Scale Methane Flux Dynamics in a Shallow Karst Lake","authors":"Baoxiang Fan, Haijun Peng, Jingcheng Ran, Hu Yao, Weijun Luo, Bing Hong","doi":"10.1016/j.watres.2026.125511","DOIUrl":"https://doi.org/10.1016/j.watres.2026.125511","url":null,"abstract":"Lakes are increasingly recognized as hotspots for methane (CH₄) emissions, yet high-frequency (hourly-scale) measurements of CH₄ fluxes throughout all seasons and a clear understanding of their underlying environmental control mechanisms are still lacking. Here, we explore the dynamics of CH<sub>4</sub> flux and its hydrological and biogeochemical mechanisms in a karst shallow lake ecosystem, based on eddy covariance (EC), sTable carbon isotope, and metagenomic sequencing techniques. Our 13-month EC monitoring shows that the lake was a CH<sub>4</sub> source to the atmosphere, with average emission rate being 2.07 ± 1.20 mmol CH<sub>4</sub> m⁻² d⁻¹, with the highest emissions in autumn (3.63 ± 0.5 mmol m<sup>-2</sup> d<sup>-1</sup>), accounting for more than twice those of winter. Seasonal CH₄ flux variations were primarily driven by water temperature, water level, and electrical conductivity. Elevated temperature stimulated methanogenesis, water level changes altered redox gradients shaping methanogen activity, and conductivity regulated substrate availability favoring acetoclastic methanogens. At the diurnal scale, CH₄ emissions were higher at night than during the day, with diel flux variations were mainly controlled by water temperature, which enhanced methanogenesis while suppressing oxidation. These environmental controls on CH₄ flux are consistent with the structure of the methanogenic community and support the dominance of acetoclastic methanogenesis. Methanothrix was found to be the dominant (∼65%) methanogenic microbe in this carbonate-rich alkaline karst lake. Additionally, the dominant pathway of CH<sub>4</sub> production in the lake was acetoclastic methanogenesis, with the apparent fractionation factor of δ¹³C-CH₄ being 1.041 ± 0.002. We emphasize the importance of integrating physicochemical variability with microbial functional potential to advance understanding of biogeochemical feedbacks in carbonate-rich karst systems and improve the accuracy of CH₄ emission estimates across scales.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"41 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146129694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eutrophication is generally considered as a major factor in the outbreak of cyanobacterial blooms, yet some species can thrive even bloom under low phosphorus (P) conditions. However, the underlying physiological and molecular mechanisms enabling cyanobacterial proliferation in P-limited environments remain poorly understood. This study identifies cyanophycin (CP) accumulation as a novel low-P response mechanism and compares the strategies of nitrogen-fixing Dolichospermum and non-nitrogen-fixing Microcystis. Dolichospermum adapts to low P stress via a "CP-gene synergy" pattern, with significant upregulation of the CP synthesis gene (cphA) and peak CP levels reaching 3.5% of dry weight. This nitrogen-storage polymer balances the carbon-to-nitrogen ratio within cells. In contrast, Microcystis showed limited CP production (peak: 0.6% DW) with 57% downregulation of cphA under low P. Beyond the CP accumulation strategy, the two cyanobacterial species additionally exhibited distinct P utilization strategies: Microcystis predominantly employed polyphosphate storage, while Dolichospermum obtained P through alkaline phosphatase secretion. These differential strategies resulted in species-specific photoregulatory responses under P-limited conditions. Dolichospermum enhances PSII efficiency to compensate for reduced light capture, while Microcystis increases light capture to relieve energy stress. These differentiated strategies provide both genera with a sustained competitive advantage in aquatic environments, allowing them to occupy ecological niches even in low-P conditions.
{"title":"From Cyanophycin Accumulation to Photoregulation: Divergent Phosphorus Stress Response Mechanisms in Dolichospermum and Microcystis","authors":"Zhenghan Liu, Meng Tan, Jingjie Zhang, Dong Bai, Lingling Wan, Xiaowen Li, Chunlei Song, Xiuyun Cao","doi":"10.1016/j.watres.2026.125513","DOIUrl":"https://doi.org/10.1016/j.watres.2026.125513","url":null,"abstract":"Eutrophication is generally considered as a major factor in the outbreak of cyanobacterial blooms, yet some species can thrive even bloom under low phosphorus (P) conditions. However, the underlying physiological and molecular mechanisms enabling cyanobacterial proliferation in P-limited environments remain poorly understood. This study identifies cyanophycin (CP) accumulation as a novel low-P response mechanism and compares the strategies of nitrogen-fixing <em>Dolichospermum</em> and non-nitrogen-fixing <em>Microcystis. Dolichospermum</em> adapts to low P stress via a \"CP-gene synergy\" pattern, with significant upregulation of the CP synthesis gene <em>(cph</em>A) and peak CP levels reaching 3.5% of dry weight. This nitrogen-storage polymer balances the carbon-to-nitrogen ratio within cells. In contrast, <em>Microcystis</em> showed limited CP production (peak: 0.6% DW) with 57% downregulation of <em>cph</em>A under low P. Beyond the CP accumulation strategy, the two cyanobacterial species additionally exhibited distinct P utilization strategies: <em>Microcystis</em> predominantly employed polyphosphate storage, while <em>Dolichospermum</em> obtained P through alkaline phosphatase secretion. These differential strategies resulted in species-specific photoregulatory responses under P-limited conditions. <em>Dolichospermum</em> enhances PSII efficiency to compensate for reduced light capture, while <em>Microcystis</em> increases light capture to relieve energy stress. These differentiated strategies provide both genera with a sustained competitive advantage in aquatic environments, allowing them to occupy ecological niches even in low-P conditions.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"104 1236 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146129692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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