Allelochemicals from Alexandrium minutum induce rapid inhibition of metabolism and modify the membranes from Chaetoceros muelleri

Long, Marc; Tallec, Kévin; Soudant, Philippe; Grand, Fabienne Le; Donval, Anne; Lambert, Christophe; Sarthou, Géraldine; Jolley, Dianne F.; Hégaret, Hélène

doi:10.1016/j.algal.2018.09.023

Cited by 31 publications

(30 citation statements)

References 72 publications

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“…External stresses, including allelopathic stressors, can alter the algal energy flux of PSII by reducing the photosynthetic efficiency [67][68][69], and by enhancing non-photochemical quenching (NPQ) [65]. The maximum quantum yield (Fv/Fm) is an effective indicator of the efficiency of photochemical stress.…”

Section: Discussionmentioning

confidence: 99%

“…Significant declines in Fv/Fm (Figure 5b), growth rate ( Figure 2), and Chl a and b (Figure 5a) were shown after 192 h exposure to high concentrations of B. cereus BE23 filtrate, suggesting disruption of the PSII reaction centers' (RCs) complexes [67] including the electron transport chain [74]. Reduced rETR and Y(II) indicate a reduction in the electron transport rate and CO 2 assimilative capacity [75].…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, one mechanism by which U. prolifera responds to allelopathic stress is a lowering of the photosynthetic performance, which directly impacts carbon fixation and therefore the growth rate [76]. The significant decreases in the Chl a and b concentrations in the HC treatments may also be considered as an adaptive strategy which decreases the absorption of photons, thereby leading to less ROS production [67].…”

Section: Discussionmentioning

confidence: 99%

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Allelopathic Inhibition by the Bacteria Bacillus cereus BE23 on Growth and Photosynthesis of the Macroalga Ulva prolifera

Zhang

Zhao

et al. 2020

JMSE

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Bacteria-derived allelopathic effects on microalgae blooms have been studied with an aim to develop algicidal products that may have field applications. However, few such studies have been conducted on macroalgae. Therefore, a series of experiments was conducted to investigate the impacts of different concentrations of cell-free filtrate of the bacteria Bacillus cereus BE23 on Ulva prolifera. Excessive reactive oxygen species (ROS) were produced when these cells were exposed to high concentrations of filtrate relative to f/2 medium. In such conditions, the antioxidative defense system of the macroalga was activated as shown by activities of the enzymes superoxide dismutase (SOD) and catalase (CAT) and upregulation of the associated genes upMnSOD and upCAT. High concentrations of filtrate also inhibited growth of U. prolifera, and reduced chlorophyll a and b, the photosynthetic efficiency (Fv/Fm), and the electron transport rate (rETR). Non-photochemical quenching (NPQ) was also inhibited, as evidenced by the downregulation of the photoprotective genes PsbS and LhcSR. Collectively, this evidence indicates that the alteration of energy dissipation caused excess cellular ROS accumulation that further induced oxidative damage on the photosynthesis apparatus of the D1 protein. The potential allelochemicals were further isolated by five steps of extraction and insolation (solid phase–liquid phase–open column–UPLC–preHPLC) and identified as N-phenethylacetamide, cyclo (L-Pro-L-Val), and cyclo (L-Pro-L-Pro) by HR-ESI-MS and NMR spectra. The diketopiperazines derivative, cyclo (L-Pro-L-Pro), exhibited the highest inhibition on U. prolifera and may be a good candidate as an algicidal product for green algae bloom control.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Allelopathic Inhibition by the Bacteria Bacillus cereus BE23 on Growth and Photosynthesis of the Macroalga Ulva prolifera

Zhang

Zhao

et al. 2020

JMSE

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“…While the nature of allelochemicals remains unknown (Ma et al, 2011b(Ma et al, , 2009, they disrupt biological membranes of target cells (Long et al, 2018b;Ma et al, 2011a). The environmental modulation of Alexandrium spp.…”

Section: A C C E P T E D M Amentioning

confidence: 99%

“…minutum were grown in natural seawater (Cronulla, Australia) supplemented with F/2 media (Guillard, 1975). The A. minutum strain CCMI1002, isolated from a bloom in Gearhies (Bantry Bay in Ireland), was selected according to its allelochemical potency (Borcier et al, 2017;Long et al, 2018bLong et al, , 2018a. Cultures of A. minutum were kept under exponential growth phase through weekly culturing and were maintained at 17 ± 1°C under white light (Sylvania premium extra F18W/840 cool white and Lumilux OSRAM L 36W/840 cool white) with a 12/12 day/night light cycle (150 -210 µmol photon m -² s -1 ).…”

Section: Microalgal Stock Culturementioning

confidence: 99%

Effects of copper on the dinoflagellate Alexandrium minutum and its allelochemical potency

et al. 2019

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The dinoflagellate Alexandrium minutum produces toxic compounds, including paralytic shellfish toxins, but also some unknown extracellular toxins. Although copper (Cu) is an essential element, it can impair microalgal physiology and increase their toxic potency. This study investigated the effect of different concentrations of dissolved Cu (7 nM, 79 nM and 164 nM) on A. minutum allelochemical potency, here defined as negative effects of a protist on competing protists through the release of chemicals. This was studied in relation to its physiology. The effects of Cu were assessed on A. minutum growth, reactive oxygen species level, photosynthesis proxies, lipid metabolism, exudation of dissolved organic compounds, allelochemical potency and on the associate free bacterial community of A. minutum. Only the highest Cu exposure (164 nM) inhibited and delayed the growth of A. minutum, and only in this treatment did the allelochemical potency significantly increase, when the dissolved Cu concentration was still toxic. Within the first 7 days of the high Cu treatment, the physiology of A. minutum was severely impaired with decreased growth and photosynthesis, and increased stress responses and free bacterial density per algal cell. After 15 days, A. minutum partially recovered from Cu stress as highlighted by the growth rate, reactive oxygen species level and photosystem II yields. This recovery could be attributed to the apparent decrease in background dissolved Cu concentration to a non-toxic level, suggesting that the release of exudates may have partially decreased the bioavailable Cu fraction. Overall, A. minutum appeared quite tolerant to Cu, and this work suggests that the modifications in the physiology and in the exudates help the algae to cope with Cu exposure. Moreover, this study shows the complex interplay between abiotic and biotic factors that can influence the dynamic of A. minutum blooms. Modulation in allelochemical potency of A. minutum by Cu may have ecological implications with an increased competitiveness of this species in environments contaminated with Cu. Highlights ► Cu stress significantly increased allelochemical potency of A. minutum. ► The increase in allelochemical potency was linked to a physiological stress. ► Cu stress modified A. minutum growth, photosynthesis, ROS, lipids and bacteria. ► Cells of A. minutum coped with Cu stress after 7 days.

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Assessment of the allelochemical activity of Ostreopsis cf. ovata and the ovatoxins towards competitive benthic microalgae

Ternon

Pavaux

Peltekis³

et al. 2022

Aquat Ecol

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Recurrent blooms of the toxic dinoflagellate Ostreopsis cf. ovata are frequently reported in the Northwestern Mediterranean Sea. The impact of these proliferations on other microalgal species inhabiting the same habitats is of interest from an ecological prospective. In vitro experiments were carried out to investigate the influence of O. cf. ovata on the growth of the co-occurring benthic diatoms Licmophora paradoxa, Navicula arenaria and the benthic dinoflagellates Prorocentrum lima and Coolia monotis. Overall, O. cf. ovata exhibited weak allelopathic effects towards these microalgal species, with a reduction in the cell abundance for L. paradoxa and P. lima only. Interestingly, dead cells of L. paradoxa and N. arenaria were observed embedded in the thick mucus surrounding O. cf. ovata cells, suggesting that the mucous layer could act as a toxic phycosphere, especially for non-motile cells. All competitors were further exposed for 24 h to ovatoxins, the major toxins produced by O. cf. ovata, and the maximum quantum yield efficiency of L. paradoxa, N. arenaria and P. lima was affected at a minimum concentration of 10 µg mL−1. We then hypothesized that the diffusion of solubilized ovatoxins in the culture medium affects only moderately the competitors' growth, whereas their accumulation in the mucus would yield deleterious effects. More precisely, the competitors' sensitivity to ovatoxins was enhanced in their stationary phase of growth and resulted from a rapid inhibition of an uncharacterized photosynthetic step downstream photosystem II. Altogether, these results emphasize the predominant role of the O. cf. ovata's mucus in driving ecological interactions and suggest that it can affect the growth of several benthic microalgae by accumulating the potent ovatoxins.Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

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Allelochemicals from Alexandrium minutum induce rapid inhibition of metabolism and modify the membranes from Chaetoceros muelleri

Abstract: Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Cited by 31 publications

References 72 publications

Allelopathic Inhibition by the Bacteria Bacillus cereus BE23 on Growth and Photosynthesis of the Macroalga Ulva prolifera

Allelopathic Inhibition by the Bacteria Bacillus cereus BE23 on Growth and Photosynthesis of the Macroalga Ulva prolifera

Effects of copper on the dinoflagellate Alexandrium minutum and its allelochemical potency

Assessment of the allelochemical activity of Ostreopsis cf. ovata and the ovatoxins towards competitive benthic microalgae

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