Harmful Algae最新文献

{"title":"Extracellular polymeric substances enhanced photosynthesis over respiration in Microcystis aeruginosa","authors":"Kaikai Deng ,&nbsp;Rui Yang ,&nbsp;Shirong Zhang ,&nbsp;Fang Fang ,&nbsp;Yuanchen Huo ,&nbsp;Peng Yan ,&nbsp;Youpeng Chen ,&nbsp;Jinsong Guo","doi":"10.1016/j.hal.2025.102843","DOIUrl":"10.1016/j.hal.2025.102843","url":null,"abstract":"<div><div>Extracellular polymeric substances (EPS) play a critical role in <em>Microcystis</em>-dominated freshwater cyanobacterial blooms. However, the mechanisms through which EPS affects <em>Microcystis</em> photosynthesis, respiration, and further affects its growth are not understood completely. To address this, we investigated the effects of varying EPS concentrations on the physiological processes of <em>Microcystis aeruginosa</em>. The results demonstrated that increasing EPS concentrations significantly enhanced both cell density and energy fixation efficiency, accompanied by a reduction in CO₂ emission flux. Specifically, compared with the control group, the addition of 20 mg·L^-¹ EPS increased respiratory rates by 2.14 μmol·mg·h^-¹ and photosynthetic rates by 2.48 μmol·mg·h^-¹, suggesting that EPS stimulated both respiration and photosynthesis, with a more pronounced effect on photosynthesis, thereby leading to a substantial increase in algal growth. Further analysis indicated that EPS enhanced respiration by retaining hydrolases capable of breaking down macromolecules into bioavailable micromolecular substrates, which elevated acetyl-CoA concentrations and citrate synthase activity, thus improving respiratory efficiency. In terms of photosynthesis, EPS enhanced light utilization, as indicated by an increase in F_V/F_M, and improved the efficiency of inorganic carbon supply by enriching CO₂ and creating extracellular inorganic carbon gradients. Moreover, EPS enhanced the activities of carbonic anhydrase and ribulose bisphosphate carboxylase/oxygenase. These findings emphasize the essential role of EPS in promoting algal growth and its potential impact on CO₂ fixation. Future research should incorporate the role of EPS in reducing carbon limitation into discussions of algal growth mechanisms and develop technologies that use algal blooms to harvest high-value carbon products such as ethanol, astaxanthin, lipids, and other valuable compounds.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"145 ","pages":"Article 102843"},"PeriodicalIF":5.5,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mixotrophic flagellate Ochromonas gloeopara promotes heterocyst production in cyanobacteria with altered filament length","authors":"Wenting Zhong ,&nbsp;Yulin Wang ,&nbsp;Yao Wang ,&nbsp;Junjun Wei ,&nbsp;Yuan Huang ,&nbsp;Zhou Yang","doi":"10.1016/j.hal.2025.102844","DOIUrl":"10.1016/j.hal.2025.102844","url":null,"abstract":"<div><div>Heterocystous cyanobacteria can adapt to environmental fluctuations typically via the production of heterocyst, a specialized cell functioning dinitrogen-fixing. Responses of heterocyst production to abiotic stressors like nutrient availability have been widely studied. In natural environments cyanobacteria also face great pressures from a variety of organisms including mixotrophic protists<em>.</em> However, little is known about the impacts of mixotrophic protists on the filamentous cyanobacteria characterized by heterocyst production. Here, we explored the grazing of the flagellate <em>Ochromonas gloeopara</em> on two heterocystous cyanobacteria <em>Dolichospermum flos-aquae</em> and <em>Anabaena</em> sp., together with the cyanobacterial responses in terms of population growth, heterocyst production, filament length and photosynthesis. Results showed that <em>O. gloeopara</em> preyed on short filaments of both cyanobacteria, reducing the population growth rate of <em>D. flos-aquae</em> but not the <em>Anabaena</em> sp. The average filament length of the two species was generally increased by <em>O. gloeopara</em> grazing at the initial cultivation, whereas reversed phenomenon was observed in <em>Anabaena</em> sp. at late cultivation. <em>O. gloeopara</em> presence promoted the heterocyst production in both the cyanobacteria, with heterocyst abundance showing a rapid increase followed by decrease dynamic with cultivation. Heterocyst placement pattern was also changed with the number of vegetative cells between heterocysts increased in <em>Anabaena</em> sp. At the peak phase of heterocyst production, the maximum quantum efficiency of photosynthesis in <em>D. flos-aquae</em> enhanced as response to <em>O. gloeopara</em> presence. These findings reveal a phenotypic adaptation of heterocystous cyanobacteria to pressures from mixotrophic protists, providing a new perspective for understanding the role of biotic interactions in cyanobacterial blooms.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"145 ","pages":"Article 102844"},"PeriodicalIF":5.5,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phosphorus rather than nitrogen driving biosynthesis of diarrhetic shellfish toxins in Prorocentrum caipirignum via ATP","authors":"Heng Chen ,&nbsp;Zehui Huang ,&nbsp;Wanchun Guan ,&nbsp;Kaixuan Huang ,&nbsp;Lei Cui ,&nbsp;Hua Zhang ,&nbsp;Songhui Lu","doi":"10.1016/j.hal.2025.102842","DOIUrl":"10.1016/j.hal.2025.102842","url":null,"abstract":"<div><div>Okadaic acid and its analogues such as dinophysisitoxins-1, -2 (DTX-1, -2) are potent inhibitors of protein phosphatase and causative toxins of diarrhetic shellfish poisoning (DSP). These toxins are produced by dinoflagellate genera <em>Dinophysis</em> and <em>Prorocentrum</em>. Numerous studies have reported that the cellular content of these toxins increased under macronutrient limitation or other stress conditions in genus <em>Prorocentrum</em>. However, our recent study demonstrated positive linear or exponential relationships between toxin production rate (<em>R</em>_tox) and phosphate consumption rate in five strains of <em>P. lima</em> complex/<em>P. caipirignum</em>. To further clarify macronutrients roles in OA production, <em>P. caipirignum</em> SE10 selected for its extremely low DTX-1 content due to potential competitive relationship with OA, was exposed to nitrogen (N) or phosphorus (P) limitation via batch or semi-batch cultures, after which the depleted nutrients were replenished to assess OA production dynamics. The <em>R</em>_tox of OA peaked initially before declining under both N and P-limited treatments. Notably, <em>R</em>_tox increased only upon P replenishment rather than N replenishment, confirming phosphorus's critical role in OA production. In P-addition experiments, <em>R</em>_tox stagnated in the P-deficient condition but rose proportionally with increasing P concentration. Meanwhile, ATP and NADPH levels surged 7.5-fold and 1.5-fold, respectively, within 1 h of P-addition compared to P-deficient treatment. To probe how P affects OA production, inhibitors targeting ATP and NADPH synthesis were applied. OA production was specifically suppressed by ATP inhibitors, such as N, N-dicyclohexylcarbodiimid (DCCD), rotenone (ROT), and 2,4-dintrophenol (DNP). The highest inhibition occurred with 20 μM DCCD, reducing OA cellular content by 90 % after 48 h. Moreover, increasing ATP inhibitor concentration shift <em>R</em>_tox from positive to negative values. These finding demonstrated that phosphorus drives OA production primarily by modulating ATP levels, which directly regulate toxin synthesis.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"145 ","pages":"Article 102842"},"PeriodicalIF":5.5,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143767509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"World's largest oligotrophic Lake Baikal: Concerns about cyanobacterial blooms and potential microcystin producers along the littoral zone","authors":"Xi Li ,&nbsp;Irina V. Tikhonova ,&nbsp;Sergey A. Potapov ,&nbsp;Andrey Yu. Krasnopeev ,&nbsp;Natalya A. Zhuchenko ,&nbsp;Xin Niao ,&nbsp;Lin Wang ,&nbsp;Ekaterina G. Sorokovikova ,&nbsp;Weixuan Wang ,&nbsp;Olga I. Belykh","doi":"10.1016/j.hal.2025.102841","DOIUrl":"10.1016/j.hal.2025.102841","url":null,"abstract":"<div><div>Toxic cyanobacterial blooms are great challenge for water safety globally. Previous studies mainly focused on this issue in eutrophic lakes, but associated knowledge in oligotrophic lakes is quite scarce. Lake Baikal is the world's largest oligotrophic lake, containing about 20 % of world's available freshwater. In this study, sites grouped in the east (E1-E2), west (W1-W6), and southwest (SW1-SW3) located in the littoral zone of Lake Baikal, were sampled. The target genes of <em>16S rRNA</em> and <em>mcyE</em> in cyanobacteria, potential microcystin producers, microcystin-producing <em>Microcystis</em> and <em>Dolichospermum</em>, were quantitatively detected in collected surface water samples, and the highest target gene abundance was observed at the site where the highest water temperature (WT) and total nitrogen (TN) were recorded <em>(P</em> <em>&lt;</em> <em>0.05).</em> The WT showed a strong positive correlation with the target gene abundance, possibly via promoting the growth of cyanobacteria, potential microcystin producers or toxic strain proportion. The strong positive correlation between TN and absolute <em>mcyE</em> gene abundance of potential microcystin producers was also shown, and it was likely that its production is related to N availability. These findings suggested that the potential risk of cyanobacterial blooms and microcystin producers for water safety should not be ignored in the world's largest oligotrophic Lake Baikal, and WT and TN could be as pivotal factors to affect the potential risk. Consequently, it is vitally necessary for water authorities to take suitable action to cope with this challenge in hot spot littoral region of increased water temperature and nitrogen in a large oligotrophic lake.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"144 ","pages":"Article 102841"},"PeriodicalIF":5.5,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143698103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monitoring pelagic Sargassum in the Atlantic Ocean from space: Principles and practices","authors":"Chuanmin Hu ,&nbsp;Brian B. Barnes ,&nbsp;Lin Qi ,&nbsp;James F.R. Gower ,&nbsp;Junnan Jiao ,&nbsp;Yuyuan Xie","doi":"10.1016/j.hal.2025.102840","DOIUrl":"10.1016/j.hal.2025.102840","url":null,"abstract":"<div><div>While pelagic <em>Sargassum</em> as a critical habitat to marine animals is known to be abundant in the Sargasso Sea, Gulf of Mexico, and the Caribbean Sea, attempts to detect this brown macroalgae from space did not start until 2006 when the proof of concept was demonstrated with medium-resolution satellite sensors. The annually recurrent Great Atlantic <em>Sargassum</em> Belt (GASB) since 2011 motivated efforts to develop new algorithms and approaches to detect and quantify <em>Sargassum</em> using data collected by various satellite sensors. This is mainly because of this macroalgae's harmful impacts on the coastal environments. Here, we review the principles and practices of using satellite remote sensing to map, quantify, and monitor pelagic <em>Sargassum</em> in the Atlantic Ocean. We first present the concept of how <em>Sargassum</em> can be detected, discriminated (against look-alikes), and quantified, where four types of data products are defined to meet the various needs. Then, we present the various published approaches in realizing such a concept using data collected by different satellite sensors. Following this concept and using recently developed algorithms and medium-resolution satellite data, we show the spatial distribution patterns and temporal changes of the GASB as well as a near real-time system to monitor <em>Sargassum</em> in the GASB. Finally, we discuss the gaps in the current technology and propose pathways forward to fill these gaps.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"144 ","pages":"Article 102840"},"PeriodicalIF":5.5,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmental-level antibiotics disrupt Microcystis stoichiometry: An overlooked risk in the context of cyanobacterial harmful algal blooms","authors":"Ganyu Feng ,&nbsp;Zhipeng Duan ,&nbsp;Liang Wu ,&nbsp;Yunze Gao ,&nbsp;Yuan Zhang ,&nbsp;Fang Li ,&nbsp;Xiang-Zhou Meng","doi":"10.1016/j.hal.2025.102839","DOIUrl":"10.1016/j.hal.2025.102839","url":null,"abstract":"<div><div>At trace levels (nanograms to micrograms per liter, ng L^-1 – μg L^-1), antibiotics exert stimulatory effects on cyanobacteria, potentially posing a threat to aquatic ecosystems. Here, environmentally relevant concentrations of antibiotics were firstly observed to disrupt the stoichiometry of cyanobacterium <em>Microcystis</em> (<em>i.e.</em>, the quota and allocation patterns of carbon (C), nitrogen (N), and phosphorus (P)). In scenarios where the doses of antibiotics ranged from 50 to 200 ng L^-1, cyanobacteria displayed a complex response – a reduction of their intracellular P pools by 22% to 24% and an adjustment of elemental allocation patterns, such as by a 51% increase in the ratio of C:P. Furthermore, at these doses, antibiotics significantly impacted the physiology of cyanobacteria, resulting in increased production of extracellular polymeric substances (EPS), a substantial rise in maximum biomass (169% to 219% increase), and an enlargement of colony size (22% to 37% increase). Transcriptomic analyses revealed that these changes were linked to the downregulation of ABC transporters and the upregulation of photosynthetic and ribosomal processes. This research offers novel insights into the hormesis effects on cyanobacteria and bloom formation, highlighting the necessity of using a multidimensional evaluation framework that integrates comprehensive bloom factors (biomass, colony size, and EPS) and elemental profiles (C, N, and P quotas and ratios) for accurate assessment.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"144 ","pages":"Article 102839"},"PeriodicalIF":5.5,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Great Atlantic Sargassum Belt: Impacts on the Central and Western Caribbean–A review","authors":"R.E. Rodríguez-Martínez ,&nbsp;E.G. Torres-Conde ,&nbsp;J. Rosellón-Druker ,&nbsp;N. Cabanillas-Terán ,&nbsp;U. Jáuregui-Haza","doi":"10.1016/j.hal.2025.102838","DOIUrl":"10.1016/j.hal.2025.102838","url":null,"abstract":"<div><div>Pelagic <em>Sargassum</em> spp. blooms pose a complex challenge to the Caribbean coast, affecting ecological, economic, and social dimensions. Since the formation of the Great Atlantic <em>Sargassum</em> Belt in 2011, these blooms have become an annual occurrence, lasting up to nine months each year. The <em>Sargassum</em> that washes ashore in the Western and Central Caribbean can reach tens of thousands of cubic meters per kilometer annually. These algae can carry pollutants, pathogens, and exotic species to coastal zones. As the algae decay, toxic gases and leachates are released, posing significant health risks to humans and other species. Ecologically, <em>Sargassum</em> landings contribute to beach erosion, nearshore waters eutrophication and transition from sandy to muddy sediments, and oxygen depletion, leading to losses in seagrass meadows flora and fauna. Mangrove ecosystems, inlets, and bays face disruptions in their biochemistry, hydrodynamics, and ecology, potentially shifting from carbon sinks to sources of greenhouse gases. Economically, the impact is severe, threatening the tourism and fishing industries crucial to the affected countries' economies. Socially, the blooms affect various aspects of well-being, including health, job quality, and connections to nature. Although progress has been made in understanding the impacts of <em>Sargassum</em>, much of the research has been concentrated in Mexico, primarily focusing on the ecological effects on coastal and beach environments. However, considerable knowledge gaps remain regarding the impacts of <em>Sargassum</em> on the ecosystems, economies, and social well-being of many other countries and territories in the region.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"144 ","pages":"Article 102838"},"PeriodicalIF":5.5,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143679978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel hybrid cyanobacteria mapping approach for inland reservoirs using Sentinel-3 imagery","authors":"Thainara M.A. de Lima ,&nbsp;Claudio C.F. Barbosa ,&nbsp;Cristina S.F. Nordi ,&nbsp;Felipe N. Begliomini ,&nbsp;Vitor S. Martins ,&nbsp;Fernanda S.Y. Watanabe ,&nbsp;Raianny L.N. Wanderley ,&nbsp;Rejane S. Paulino","doi":"10.1016/j.hal.2025.102836","DOIUrl":"10.1016/j.hal.2025.102836","url":null,"abstract":"<div><div>Detecting and quantifying cyanobacteria algal bloom occurrence plays an important role in preventing public health risks and understanding aquatic ecosystem dynamics. Satellite remote sensing has been used as an important data source to estimate cyanobacteria biomass based on pigment concentration. Phycocyanin (PC) is a unique pigment of inland water cyanobacteria and has been widely used as a proxy for cyanobacteria algal biomass. Based on the PC absorption feature around 620 nm, scientific efforts have been made to develop bio-optical models for orbital satellite observations, but proposed PC models limit the retrievals at different concentration ranges and depend on empirical models calibrated for specific aquatic environments. This study proposes a hybrid machine learning approach for PC retrieval that efficiently adopts the optimal algorithm for specific PC concentration ranges. An <em>in-situ</em> dataset of 165 samples was collected between November 2020 and December 2021 to support full training and validation of the proposed method. First, a Random Forest algorithm was applied to classify PC-low-concentration waters (0 – ∼14 mg.m⁻³) and PC-high-concentration waters (∼14.1 – 300 mg.m⁻³). Then, for each defined class, an individual PC estimation algorithm was calibrated. The final PC-hybrid model was applied to atmospherically corrected Sentinel-3/OLCI imagery derived by three approaches (L2-WFR, 6SV, and ACOLITE). The PC hybrid-model performance was evaluated by comparing the estimated PC concentration from satellite and in situ measurements. The hybrid PC model estimates (median symmetric accuracy (ζ) = 25.35%) outperformed the individual PC algorithms calibrated for the entire range of PC concentration, proving the practical applicability for quantifying PC concentration in optically dynamic waters.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"144 ","pages":"Article 102836"},"PeriodicalIF":5.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benthic cyanobacterial accumulations and associated cyanotoxins in coastal urban stormwater pond networks","authors":"Avery O. Tatters ,&nbsp;Courtney Clevenger ,&nbsp;Wendy K. Strangman ,&nbsp;Stuart Oehrle ,&nbsp;Raphael M. Kudela ,&nbsp;Jessica Aukamp ,&nbsp;Yongshan Wan","doi":"10.1016/j.hal.2025.102833","DOIUrl":"10.1016/j.hal.2025.102833","url":null,"abstract":"<div><div>Extensive cyanobacteria-dominated mats were observed during late summer of 2021 within coastal urban stormwater retention pond networks in northwest Florida. Common in residential communities across the region, such ponds may be routinely visited by humans, domestic and wild animals, and often contain a variety of aquatic life. To begin examining correlations between environmental factors and mat characteristics, we investigated the temporal heterogeneity of these networks with regards to presence of potentially toxic cyanobacteria, associated toxins, and other putative cyanobacterial compounds throughout the fall at several sites within the networks. Multiple toxin classes were detected in whole water and passive SPATT samples using targeted analysis including levels of cylindrospermopsin that exceeded national recreational guidelines. Non-targeted analysis also revealed a collection of potential cyanobacteria-associated compounds. Our results suggest that the benthic proliferations may be, at least in part, correlated with the intended functions of the stormwater treatment networks, which are nutrient and sediment removal. Furthermore, these retention ponds may serve as an episodic source of cyanotoxins to estuarine waters.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"144 ","pages":"Article 102833"},"PeriodicalIF":5.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Growth and anatoxin-a production of Microcoleus (Cyanobacteria) strains from streams in California, USA","authors":"Sydney M. Brown ,&nbsp;Joanna R. Blaszczak ,&nbsp;Robert K. Shriver ,&nbsp;R.Christian Jones ,&nbsp;Abeer Sohrab ,&nbsp;Ramesh Goel ,&nbsp;Gregory L. Boyer ,&nbsp;Bofan Wei ,&nbsp;Kalina M. Manoylov ,&nbsp;T.Reid Nelson ,&nbsp;Jordan M. Zabrecky ,&nbsp;Rosalina Stancheva","doi":"10.1016/j.hal.2025.102834","DOIUrl":"10.1016/j.hal.2025.102834","url":null,"abstract":"<div><div>Benthic cyanobacterial proliferations are an emerging concern globally due to their potential for toxin production and subsequent negative environmental and health impacts. <em>Microcoleus</em> is a common mat-forming genus reported to produce potent neurotoxin, anatoxin-a, ingestion of which has been associated with animal mortalities. Six different unialgal monoclonal strains of <em>Microcoleus</em> were isolated from streams in California and grown in batch culture for 49 days. The four toxic strains were identified using a polyphasic approach as belonging to the species <em>Microcoleus anatoxicus</em>, which expands its known distribution throughout the Klamath River and Rock Creek watersheds in northern California. The non-toxic strains from the Eel River belonged to <em>Microcoleus</em> sp. 1. Maximum toxin production occurred during the exponential growth phase, and peaked 6–13 days later in more toxic strains, with a persistently higher fraction of extracellular toxins compared to less toxic strains, which had maximum toxin concentrations at day 13. The proposed mechanism of toxin release into culture medium was through damage to the cell walls of unhealthy filaments. Peak toxin production was energetically expensive for all <em>M. anatoxicus</em> strains, evidenced by reduced specific growth rates at the time of peak toxin production, followed by quick recovery of cell division. Despite this, more toxic strains achieved faster maximum growth rates than the less toxic and non-toxic strains under luxurious nutrient culture conditions. Differential toxin and growth rate responses of <em>M. anatoxicus</em> strains from wide geographical ranges under the same laboratory-controlled conditions suggest high intraspecific variation, which may represent challenges for harmful algal blooms mitigation. More toxic strains have the potential to proliferate and consistently release extracellular anatoxins into the environment. This study provides a baseline to understanding the growth and toxin kinetics of two commonly occurring <em>Microcoleus</em> species in northern California which may help benthic harmful cyanobacteria management.</div></div>","PeriodicalId":12897,"journal":{"name":"Harmful Algae","volume":"144 ","pages":"Article 102834"},"PeriodicalIF":5.5,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}