Microcystin biosynthesis in Microcystis aeruginosa: Indirect regulation by iron variation

Wang, Xun; Wang, Peifang; Wang, Chao; Hu, Bin; Ren, Lingxiao; Yang, Yangyang

doi:10.1016/j.ecoenv.2017.11.059

Cited by 16 publications

(10 citation statements)

References 65 publications

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“…Recent studies indicated that the production of ROS in M. aeruginosa cells can induce various antioxidant responses such as increasing the activities of the antioxidant enzymes superoxide dismutase, peroxidase and catalase (Hua et al ., 2018; Sun et al ., 2018; Wang et al ., 2018b; Hou et al ., 2019; Gao et al ., 2020; Kang et al ., 2020; Li et al ., 2020). In general, SOD acts as the first defence line of cell’s antioxidant responses against ROS by converting superoxide O 2 ‐ to oxygen and H 2 O 2 , which is further eliminated by CAT (Hua et al ., 2018; Sun et al ., 2018; Wang et al ., 2018b; Hou et al ., 2019; Gao et al ., 2020; Kang et al ., 2020; Li et al ., 2020). However, CAT is an important enzyme promoting the conversion of H 2 O 2 to ground state oxygen and water (Hua et al ., 2018; Sun et al ., 2018; Wang et al ., 2018b; Hou et al ., 2019; Gao et al ., 2020; Kang et al ., 2020; Li et al ., 2020).…”

Section: Discussionmentioning

confidence: 99%

“…3). The observed increase in SOD and CAT activities suggests that enzymes are involved to eliminate oxidative stress (Hua et al ., 2018; Sun et al ., 2018; Wang et al ., 2018b; Hou et al ., 2019; Gao et al ., 2020; Kang et al ., 2020; Li et al ., 2020).…”

Section: Discussionmentioning

confidence: 99%

“…In general, SOD acts as the first defence line of cell's antioxidant responses against ROS by converting superoxide O 2 -to oxygen and H 2 O 2 , which is further eliminated by CAT (Hua et al, 2018;Sun et al, 2018;Wang et al, 2018b;Hou et al, 2019;Gao et al, 2020;Kang et al, 2020;Li et al, 2020). However, CAT is an important enzyme promoting the conversion of H 2 O 2 to ground state oxygen and water (Hua et al, 2018;Sun et al, 2018;Wang et al, 2018b;Hou et al, 2019;Gao et al, 2020;Kang et al, 2020;Li et al, 2020). In our study, the SOD and CAT activities of M. aeruginosa cells were significantly increased (P < 0.05) by the different concentrations of the three MEA extracts tested (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Inhibitory effect and mechanism of three macrophytes extract on Microcystis aeruginosa growth and physiology

Tazart

Caldeira

Douma

et al. 2020

Water & Environment J

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Macrophytes are a promising source of bioactive compounds with potential applications in the biocontrol of harmful cyanobacteria blooms. In this study, we investigated the inhibitory effects of extracts from three macrophytes (Nasturtium officinale, Potamogeton natans and Ranunculus aquatilis) on Microcystis aeruginosa. We assessed physiological indicators of inhibition on M. aeruginosa, including lipid peroxidation, protein content, superoxide dismutase activity, catalase activity and growth. The chemical composition of the macrophyte extracts and their specific allelochemicals were analysed using high‐performance liquid chromatography (HPLC). Results showed that M. aeruginosa growth was significantly inhibited after 8 days of exposure, with inhibitory rate varying from 96.98% to 99.01%. The macrophyte extracts caused cyanobacterial cell membrane and antioxidant defence system damage. Thirteen different compounds were identified as allelochemical compounds that could be responsible for M. aeruginosa growth inhibition and oxidative stress. Our findings suggest that allelopathic compounds from macrophytes may be used to effectively control cyanobacteria blooms and promote the restoration of aquatic ecosystems.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Inhibitory effect and mechanism of three macrophytes extract on Microcystis aeruginosa growth and physiology

Tazart

Caldeira

Douma

et al. 2020

Water & Environment J

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“…The regulation of mcy gene expression in a response to external biotic and abiotic factors has been investigated recently [33]. An indirect downregulation of MC synthesis was observed in response to iron limitation [34], probably as a result of a lower photosynthetic activity. The light intensity is also known as an important abiotic factor influencing mcy expression and MC production [35].…”

Section: Monitoringmentioning

confidence: 99%

Occurrence of a single-species cyanobacterial bloom in a lake in Cyprus: monitoring and treatment with hydrogen peroxide-releasing granules

et al. 2021

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Background Excess loads of nutrients finding their way into waterbodies can cause rapid and excessive growth of phytoplankton species and lead to the formation of cyanobacterial harmful algal blooms (cyano-HABs). Toxic cyanobacteria produce a broad range of bioactive metabolites, some of which are known as cyanotoxins. These metabolites can negatively impact the ecosystem, and human and animal health, thus their presence needs to be closely monitored and mitigated. This study aimed to monitor St. George Lake (Athalassa National Forest Park, Cyprus) for its water quality characteristics, and initiate a new methodology to control the bloom that occurred in the lake during summer 2019, by comparing hydrogen peroxide treatment with novel metallic peroxide granules as source of hydrogen peroxide. Results Lake monitoring showed that pH, salinity, total dissolved solids and conductivity varied throughout the year, and nutrients concentration was high, indicating a eutrophic lake. The cyanobacterium Merismopedia sp. bloomed in the lake between June and September 2019, comprising up to 99% of the phytoplankton biovolume. The presence of microcystin synthase encoding gene (mcyB, mcyE) was documented, however microcystins were not detected by tandem mass spectroscopy. Treatment with liquid hydrogen peroxide in concentrations 1 to 5 mg L−1 had no effect on the phycocyanin fluorescence (Ft) and quantum yield of PSII (Fv/Fm) indicating an ineffective treatment for the dense Merismopedia bloom (1 million cells mL−1 ± 20%). Metallic peroxide granules tested for their H2O2 releasing capacity in St. George Lake water, showing that CaO2 released higher H2O2 concentration and therefore have better mitigation efficiency than MgO2 granules. Conclusion The present study highlights the importance of monitoring several water parameters to conclude on the different actions to be taken to limit eutrophication in the catchment area. The findings demonstrated that testing for the presence of genes involved in cyanotoxin production may not be sufficient to follow cyanotoxins in the water, therefore it should be accompanied with analytical confirmation. Treatment experiments indicated that slow release of H2O2 from peroxide granules may be an alternative to liquid hydrogen peroxide when applied in appropriate doses, but further investigation is needed before it is applied at the field. Graphic Abstract

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“…The presence of mcyB only in 3 samples and mcyE in 8 samples suggest that the genetic machinery for MC synthesis may be de cient. Furthermore, an indirect downregulation of MC synthesis was observed in response to iron limitation [40], probably as a result of a lower photosynthetic activity, therefore it was suggested that this parameter (iron level) may be helpful in predicting bloom toxicity. The light intensity is also known as an important abiotic factor in uencing mcy expression and MC production [41].…”

Section: Treatmentsmentioning

confidence: 99%

First report on the occurrence of a single species cyanobacterial bloom in a lake in Cyprus: Monitoring and treatment with hydrogen peroxide releasing granules

Keliri¹,

Paraskeva²,

Sofokleous³

et al. 2020

Preprint

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Background: Cyanobacteria are phytoplankton microorganisms, also known as blue-green algae, and an essential component of the food web in all aquatic ecosystems. Excess loads of nutrients into waterbodies can cause their rapid and excessive growth which leads to the formation of cyanobacterial harmful algal blooms (cyano-HABs). Toxic species of cyanobacteria genera excrete into the water a broad range of bioactive metabolites, some of which are known as cyanotoxins. These metabolites can negatively affect the ecosystem, and human and animal health in various ways, thus their presence needs to be closely monitored. This study aimed to monitor a lake at the Athalassa National Forest Park in Cyprus, in order to correlate its trophic condition with its water quality characteristics and identify the key environmental variables driving cyanobacteria blooming and their toxicity. In addition, surface water during the blooming period was collected and used in bench-scale experiments in order to test novel hydrogen peroxide releasing granules as mitigation processes for cyano-HABs.Results: The monitoring lasted throughout 2019 with ten sampling events taking place during this period. Samples were mainly analyzed for phytoplankton community, and various physicochemical parameters: pH, conductivity, salinity, total and dissolved nutrients. Obtained data indicated that cyanobacteria blooming lasted for four months (June – September), while microscopic observation of preserved samples showed that 99% of the phytoplankton biovolume was attributed to a single picocyanobacterial species, the Merismopedia sp. Select samples were analysed for the presence of toxins genes with positive results mainly for mcyB and mcyE genes. Further analysis with HPLC MS/MS, revealed that cyanotoxins’ concentration was lower than the method detection limit - MDL (<2-6 ng/L). Conclusion: The present study highlights the importance of monitoring several water characteristics to conclude on the main drivers of a bloom and its toxicity. The findings demonstrated that it is not enough to test cyanotoxin genes as indicator of their presence since, in case of mono-domination, cyanobacteria may not be active on producing the toxins. Treatment experiments of contaminated water indicated that slow realizing peroxide granules may be an alternative to hydrogen peroxide. Treatment with CaO2 granules outperformed MgO2 granules due to higher H2O2 releasing capacity.

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Microcystin biosynthesis in Microcystis aeruginosa: Indirect regulation by iron variation

Cited by 16 publications

References 65 publications

Inhibitory effect and mechanism of three macrophytes extract on Microcystis aeruginosa growth and physiology

Inhibitory effect and mechanism of three macrophytes extract on Microcystis aeruginosa growth and physiology

Occurrence of a single-species cyanobacterial bloom in a lake in Cyprus: monitoring and treatment with hydrogen peroxide-releasing granules

First report on the occurrence of a single species cyanobacterial bloom in a lake in Cyprus: Monitoring and treatment with hydrogen peroxide releasing granules

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