Algal Growth Research Articles

Evaluation of ten plant-derived biocides for the inhibition of photosynthetic organisms on the karst surfaces of heritage buildings

Biodeterioration is a significant problem in the conservation of stone heritage buildings. In this study, 10 plant essential oils were assessed for their effectiveness in biofilm inhibition on stone heritage building surfaces under laboratory and in situ conditions, and were compared with traditional biocides such as benzalkonium chloride. The plant extracts were tested against algae and mosses. The effect on algae removal was evaluated by measuring the color of the surface before treatment, after 24 h and after 1 month of treatment. The effect on mosses was assessed by measuring the photosynthetic pigment content of mosses after 24 h of treatment. The results showed that the different plant extracts exhibited different levels of antibiotic activity. Benzalkonium chloride, S. aromaticum and C. cassia extracts showed strong antibiotic activity against all algae and mosses tested. T. mongolicus extracts showed antibiotic activity against only some of the algae and mosses, while the application of P. cablin extracts increased chlorophyll b content in the mosses. The other plant extracts were less effective at inhibiting the growth of algae and mosses. GC–MS compositional analysis further indicated that the higher antibiotic activity of S. aromaticum and C. cassia extracts was related to the high content of eugenol and cinnamaldehyde.

Robust Natural Light-Absorbable and -Degradable AIE Photosensitizers for Fluorescence Labeling and Efficient Photodynamic Eradication of Algal Pollutants.

Current water pollution caused by the excessive proliferation of harmful algae urges green methods that can efficiently utilize natural light to treat algal pollution. Herein, a series of aggregation-induced emission (AIE) photosensitizers that can efficiently harness sunshine were synthesized for the environmentally friendly and biocompatible treatment of algal pollution. By tuning the number of thiophene units and the electron conjugation degree, the photosensitizers' absorptions were broadened to cover the whole visible light range. The positive charges guided photosensitizers to aggregate on algal cell surfaces, resulting in a turn-on fluorescence signal and robust reactive oxygen species generation under sunshine, thereby achieving fluorescence labeling and photodynamic eradication of algae. The eradication outcomes demonstrated that the AIE photosensitizers significantly outperformed the commercial algaecide ALG. At 20 ppm photosensitizers, 90.4% and 94.2% killing rates were achieved for C. reinhardtii and C. vulgaris, respectively, 2.8- and 3.6-fold higher than those from the same concentration of ALG. Excellent performances in inhibiting algae growth were also verified with efficiency superior to that of ALG. Importantly, the photosensitizers can self-degrade into biocompatible fragments under irradiation to avoid secondary pollution. The developed photosensitizers that possess sunshine convertibility and degradability provide an efficient tool for algal treatment, showing broad research and application prospects.

The growth and nitrogen utilization strategies in two dominant Symbiodiniaceae species facing nitrogen deficiency and enrichment

Symbiodiniaceae, a diverse group of unicellular dinoflagellates, are well known as endosymbionts of marine invertebrates (e.g., corals, giant clams and foraminiferans). Currently, how in vitro cultured Symbiodiniaceae cope with nitrogen (N) deficiency and enhancement remain largely unexplored. To address this knowledge gap, this study investigated the dynamics of growth, photosynthesis and crystalline guanine formation in response to differential N supplies in two dominant Symbiodiniaceae species: Durusdinium trenchii and Cladocopium goreaui. The results indicated growth rate and photosynthesis were closely related to N sources and concentrations. Under N deficiency, cell growth was inhibited. As N concentration increased, both D. trenchii and C. goreaui exhibited flexible strategies for utilizing different N sources. When provided with nitrate (NO3−), C. goreaui and D. trenchii showed an enhancement in the algal growth and photosynthetic efficiency (Fv/Fm). When ammonium (NH4+) was supplied, a moderate increase of NH4+ can benefit cell growth and photosynthesis, but excessive enrichment adversely affected algal growth. Additionally, Raman microscopy demonstrated that cellular crystalline guanine was formed by C. goreaui when exposed to N supply, but gradually decreased as N was consumed in medium. A similar phenomenon was observed in D. trenchii. We proposed that crystalline guanine may serve as an important N storage and utilization strategy. This study delved into the growth strategies and adaptability of Symbiodiniaceae to varying N nutritional environments, which contributes to understanding the symbiotic relationship between Symbiodiniaceae and corals.

Understanding the fouling characteristics in ultrafiltration membrane for marine algae-laden seawater pretreatment: Focus on the role of algal extracellular organic matter

The increasing frequency and extent of harmful algal blooms (HABs) due to global warming and environmental pollution pose significant challenges to the ultrafiltration (UF)-seawater reverse osmosis (SWRO) desalination process. The UF process is a dominant pretreatment method to reduce HAB fouling potential in subsequent SWRO processes. Herein, we systematically evaluate the UF membrane fouling characteristics at different growth phases of HAB algae in terms of reversible/irreversible fouling and pinpoint the fouling mechanisms on UF membranes in the real seawater matrix. We employed Prorocentrum donghaiense as a model marine HAB specie to characterize algal derivatives, including extracellular organic matter (EOM) and granule particles. LC-OCD, MFIs, 3D-EEM, and GPC were used to analyze algae-derived matters. Results from the multiple fouling model revealed that algal solution in both stationary and decline phases exhibit severe membrane fouling, characterized by rapid cake layer formation, swift flux decline, and high membrane resistance. Soluble EOM (S-EOM) was the primary contributor to membrane fouling, linked to its elevated concentrations of dissolved organic matters, polysaccharides, proteins, and humic substances, which are predominantly hydrophobic. Additionally, granule particles mitigated organic membrane fouling, as evidenced by the smaller permeate volume required for S-EOM cake layer formation (<5 mL), resulting in a faster initial flux decline. These results revealed a shift in released organic matter from protein-centric to humic substance-centric during the transition from exponential growth to the decline phase, with correlation analysis further underscoring the substantial contribution of humic substances to membrane resistance. This research highlights the distinct UF membrane fouling characteristics at different marine algal growth stages, offering theoretical support for predicting and managing HABs.

Enhancing nutrient bioavailability in distillery wastewater through electrochemical oxidation for microalgal growth: Insights on biomass yield, nutrient utilisation, and VFA-assisted carbon capture

Two-stage treatment of distillery wastewater (DWW) via electrochemical oxidation (EO) using Ti-RuO2 anodes (35 cm2 area) followed by mixotrophic microalgal treatment was investigated. In the first-stage, EO of DWW has improved the bioavailability of nitrogen and phosphorus at 3.95–5.14 mg/Ah and 0.43–1.02 mg/Ah, respectively, which had strong correlation with current density. EO also reduced ∼30 % TOC, 53 % COD and ∼44 % TN. In the second-stage, the ability of a novel microalgae, Asterarsys quadricellulare to mitigate the toxicity of electrochemically oxidised DWW (EO-DWW) while utilising the nutrients effectively was investigated. The mixotrophic algal growth effectively utilised 85 % phosphate and 91 % nitrate present in EO-DWW at a corresponding growth rate of 0.73 d−1. The algal biomass was found to have ∼15 % carbohydrates, ∼12 % lipids and ∼33 % proteins. Subsequently, a bench-scale bubble column photobioreactor investigation was carried out to understand the carbon dynamics during the growth of Asterarsys quadricellulare. The metabolic uptake of monocarboxylic volatile fatty acids (VFA) and nitrate were found to release OH− ions, which eventually helped in dissolving CO2 in the reactor through a diffusion-limited process. The total energy spent in bench-scale EO system was 840 kWh (3024 kJ) per L of DWW, and the energy recovery potential of second-stage algal reactor was ∼8.7 %. The microtoxicity experiments with Alivibrio fischeri revealed that two-stage treated DWW was found to be safe for reuse as the microalgal growth has abated the toxicity of EO-DWW.

UV-B light (radiation) affects the metabolism of pigments and fatty acids in green algae Edaphochlorella mirabilis and Klebsormidium flaccidum in vitro

Algae offer a rich source of bioactive compounds suitable for food products and bioenergy. Environmental challenges such as nutrient scarcity, extreme pH and temperature, high light intensity, and UV radiation usually trigger algae to produce excess of lipids, antioxidants, and other bioprotective molecules as part of their adaptations for survival. Algal cultivation provides proteins, lipids, carbohydrates, vitamins, antioxidants, and trace elements. This study focused on understanding how UV-B irradiance, as an abiotic stressor, can influence the growth and metabolite production of two green algal species, Edaphochlorella mirabilis (Chlorophyta) and Klebsormidium flaccidum (Charophyta). Using a temporary immersion system bioreactor for in-vitro algal growth, the results showed no significant difference in biomass for both algal species after the exposure to UV-B rays. However, the assessment of malondialdehyde levels revealed a significantly higher tendency towards lipid peroxidation in treated E. mirabilis (+ 90 %) compared to control. Conversely, K. flaccidum did not display significant differences, thereby highlighting a more advanced adaptive capacity against UV-B radiation. Overall, both algal species treated with UV-B showed increased pigment accumulation. K. flaccidum exhibited an average pigment increase of over 53 %, while E. mirabilis showed a lower increase, over 30 % on average. The notable rise in antioxidant compounds (lutein, β-carotene, and chlorophyll a) in UV-B exposed K. flaccidum samples also suggested a more suitable adaptive strategy to mitigate oxidative stress in Charophyta. In K. flaccidum, the increase in polyunsaturated fatty acids can be associated with increased production of antioxidant compounds. Conversely, E. mirabilis appeared to protect itself by decreasing polyunsaturated fatty acids in favor of saturated ones. In both algal species, the increase in secondary metabolites under UV stress highlighted potential as a novel food source for human consumption, deserving further investigation.

Straightforward electroanalytical sensing of nitrate in cyanobacteria growth media at electrified liquid-liquid interface

Nitrate is one among the necessary substance in the biosphere as its presence is pivotal to ensuring healthy vegetation and human health while its excess causes serious adversities. In this work, we utilized the electrified liquid-liquid interface (eLLI) and voltammetry to develop an alternative approach that enables onsite periodic monitoring of nitrate ions in cyanobacteria growth medium. The signal attributed to nitrate detection was directly related to its interfacial ion transfer behavior and not the redox properties. The ion transfer voltammograms of nitrate at eLLI delivered useful analytical parameters of linear detection range from 20 to 500 μM paired with detection and quantification limits of 1.5 and 14.6 μM, respectively. Further, the influence of chloride ions, and other anionic species present in the algae grow media were studied towards the determination of nitrates. We also optimized an in-situ chemical precipitation strategy to eliminate the influence of chloride ions that significantly improved the accuracy of the eLLI-based nitrate sensor. eLLI-based nitrate sensor delivered a remarkable analytical performance to determine nitrate levels in Z8 medium composed of nitrate and other nutrients (medium serving as the optimal environment for algae growth). eLLI based nitrate sensor was successful towards periodic monitoring of nitrate levels in Microcystis aeruginosa cyanobacteria samples cultured in Z8 medium.

SEMANTIC SEGMENTATION OF ALGAL BLOOMS ON THE OCEAN SURFACE USING SENTINEL 3 CHL_NN BAND IMAGERY

Satellite imagery plays an important role in detecting algal blooms because of its ability to cover larger geographical regions. Excess growth of Sea surface algae, characterized by the presence of Chlorophyll-a (Chl-a), is considered to be harmful. The detection of algal growth at an earlier stage may prevent hazardous effects on the aquatic environment. Semantic segmentation of algal blooms is helpful in the quantization of algal blooms. A rule-based semantic segmentation approach for the segregation of sea surface algal blooms is proposed. Bloom concentrations are classified into three different concentrations, namely, low, medium, and high. The chl_nn band in the Sentinel-3 satellite images is used for experimentation. The chl_nn band has exclusive details of the presence of chlorophyll concentrations. A dataset is proposed for the semantic segmentation of algal blooms. The devised rule-based semantic segmentation approach has produced an average accuracy of 98%. A set of 100 images is randomly selected for testing. The tests are repeated on 5 different image sets. The results are validated by the pixel comparison method. The proposed work is compared with other relevant works. The Arabian Sea near the coastal districts of Udupi and Mangaluru has been considered as the area of study. The methodology can be adapted to monitor the life cycle of blooms and their hazardous effects on aquatic life.

Species‐specific stoichiometric effects of leaf litter on algal growth, production, and cell quotas

AbstractDissolved organic matter and nutrients released from leaf litter are important cross‐ecosystem resources supporting freshwater food webs. Dissolved organic matter supports heterotrophic organisms in freshwater communities. However, the role of nutrients released from leaf litter in the autochthonous production in aquatic ecosystems is not well understood. Therefore, we investigated how dissolved nutrients released from leaf litter affect algal growth, biomass production, and cellular elemental ratios. Specifically, we experimentally examined the response of green algae to nitrogen (N) and phosphorus (P) released from leaf litter of 11 temperate tree species and the degree of deficiency of nutrient elements other than N and P relative to algal demand in these litter leachates by supplementing these elements. We found that algal growth did not significantly increase with dissolved N or P in the leaf leachates. In contrast, algal biomass production increased with dissolved N concentration, regardless of amendment. Algal growth and production limitation by deficiency of elements other than N and P was found only in the leachate of Japanese hemlock, indicating that the concentrations or release efficiencies of these elements in this leaf litter were lower than those of N and P relative to algal requirements. More importantly, leaf litter leachates from different tree species altered algal cell quotas and C:N:P ratios, which would affect secondary production. These results suggest that variations in leaf litter leachate stoichiometry caused by vegetation change would affect the abundance and chemical composition of phytoplankton, and thus the trophic transfer efficiency between phytoplankton and herbivorous zooplankton.

Records of Burdigalian sea level and paleoclimate in the Maldives carbonate system

Tropical carbonate systems are valuable archives of paleoenvironments, as the carbonate growth is intimately affected by water depth and climatic conditions. Geochemical data from the Burdigalian interval in IODP Site U1468 in the Maldives, northern Indian Ocean, were integrated with sedimentological and paleontological data for a more detailed reconstruction of depositional history. Generally, the Sr/Ca values of slope sediments record highstand progradation in both sequence unit and whole Burdigalian interval, while the absence of higher Sr/Ca ratio close to the sequence boundary during the early Burdigalian could be related to the erosion of deeper-water sediments due to the activity of bottom current. From 20.5 to 19.1 Ma and from 17.9 to 17.2 Ma, nutrient level and productivity were moderately elevated due to the terrigenous input by the intensified South Asian Proto-Monsoon, which also helped cause more reducing conditions in the distal slope. Moreover, increased nutrient level facilitated the growths of calcareous algae and sponges, while it was not favorable for coral development. The elevated nutrient level, higher sea level, and monsoon-induced current contributed to the backstepping of the outer margin during the late Burdigalian. Our study shows an example on how a tropical carbonate platform evolved in response to the interplay of sea-level and paleoclimatic conditions. Findings are expected to be applicable to other tropical carbonate platforms.

Impact of Neurotransmitters on the Fatty Acid Composition and the Pigments of the Green Microalga Scenedesmus quadricauda

Apart from their functions in the nervous system of animals, neurotransmitters operate as regulatory agents and signals in diverse kingdoms of life. Some neurotransmitters have recently been revealed to exert specific effects on microalgae, predominantly functioning as algal growth stimulators. This article presents new data on the effects of such neurotransmitters as serotonin, norepinephrine, dopamine, histamine, and acetylcholine on the fatty acid and pigment composition of the green microalga Scenedesmus quadricauda (Turp.) Breb. K-1149. It was established that acetylcholine and, to a lesser extent, histamine increased the total fatty acid content of S. quadricauda cells, whereas serotonin and dopamine decreased the fatty acid content. Acetylcholine, histamine, and norepinephrine elevated the percentage of polyunsaturated fatty acids; in contrast, serotonin and dopamine increased the share of saturated fatty acids. Acetylcholine and, to a lesser extent, norepinephrine increased the total chlorophyll content per gram of dry weight in S. quadricauda, while histamine decreased the chlorophyll content. Histamine also increased the chlorophyll a/chlorophyll b and carotenoid/chlorophyll ratios, which were decreased by dopamine. The data obtained are of biotechnological and ecological interest. The stimulation of fatty acid accumulation and the increase in the percentage of polyunsaturated species was caused by the neurotransmitters acetylcholine and histamine at low (1–10 μM) concentrations, which potentially enables facilitating the biotechnological production of health-promoting preparations for therapeutic and cosmetic purposes. However, other neurotransmitters (dopamine and serotonin) tested increased the relative content of saturated fatty acids; therefore, they apparently can be used to stimulate biofuel production, since saturated fatty acid-rich lipids are advantageous raw materials for biodiesel production. The impact of neurotransmitters on microalgal fatty acid composition and photosystem components may be considered in terms of ongoing chemical interaction between microalgae and other aquatic ecosystem components that are known to produce neurotransmitters.

Physiological and transcriptomic analyses to determine the responses of the harmful algae Akashiwo sanguinea to phosphorus utilization

Phosphorus (P) is an essential nutrient driving algal growth in aquatic ecosystems. Dissolved inorganic and organic P (DIP and DOP) are the main components in the marine P pools and are closely related to harmful algal blooms. The dinoflagellate Akashiwo sanguinea is a cosmopolitan species which frequently causes dense blooms in estuaries and coasts worldwide, while the availability of P to A. sanguinea still remain unclear. Herein, the physiological and transcriptomic responses of A. sanguinea grown under P-deficient, DIP-replete and DOP-replete conditions were compared. P-deficient adversely suppressed the growth and photosynthesis of A. sanguinea, while genes associated with P transport, DOP utilization, sulfolipid synthesis, and energy production, were markedly elevated. Three forms of DOP, namely, glucose-6-phosphate (G-6-P), adenosine 5-triphosphate (ATP), and β-Glycerol phosphate (SG-P), supported A. sanguinea growth as efficiently as DIP (NaH2PO4), and no significant difference was observed in biochemical compositions and photosynthesis of A. sanguinea between the DIP and DOP treatments. While the genes related to P transporter were markedly suppressed in DOP groups compared with the DIP group. Our results indicated that A. sanguinea is a good growth strategist under P-deficient/replete conditions, and this species had evolved a comprehensive strategy to cope with P deficiency, which might be a crucial factor driving bloom formation in a low inorganic P environment.

Emissions and transport of urban biocides from facades to topsoil at the district-scale

Urban biocides used in facade paints and renders to prevent algae and fungal growth are released into the environment during rainfall, subsequently contaminating groundwater. However, quantitative data on the emission, transport and infiltration of urban biocides at the district scale are generally lacking. In this study, we quantified the fluxes of the urban biocide terbutryn and its major transformation product, terbutryn-sulfoxide, from building facades into stormwater, sediment, soil, and vegetation within a seven-year-old district employing sustainable stormwater management such as infiltration trenches and ponds. Combining four months of field observations with district scale modeling, we estimated initial concentrations of terbutryn in facade paint, quantified the emissions of terbutryn and terbutryn-sulfoxide from facades to soil, and evaluated terbutryn storage in soil under various painting scenarios. Terbutryn concentrations in sustainable stormwater management systems ranging from 2 to 67 ng L−1, frequently exceeding predicted no-effect concentrations. The constant release of terbutryn and its transformation products in runoff highlighted the chronic exposure of non-target organisms to urban biocides. Terbutryn concentrations in topsoil and pond sediment indicated accumulation, while concentrations exceeding 1 μg g−1 in the vegetation suggested plant uptake. Model results revealed that a substantial portion (27 to 73 %) of biocides infiltrated near facades through permeable surfaces like gravel, while a smaller portion (7 to 39 %) reached the stormwater management systems. Additionally, significant biocide leaching in the topsoil (30 cm below the surface) underscored the potential for biocide contamination in groundwater. Overall, this district-scale study and modeling approach provide a comprehensive framework for evaluating scenarios and measures for sustainable stormwater management to mitigate the infiltration of urban biocides into groundwater.

The phagotrophic growth of algae on bacteria and its potential for wastewater and waste sludge treatment

Algae exhibit diverse growth strategies, including phototrophy, osmotrophy, and phagotrophy. While phototrophic and osmotrophic growths have been extensively studied, phagotrophic growth remains relatively unexplored. This research delves into the phagotrophic growth of Ochromonas danica on bacteria, evaluating its potential for wastewater and waste sludge treatment. The study reveals that O. danica was able to grow on bacteria without light or additional nutrients, achieving a doubling time of 3.5–3.9 hours and converting 41–45 % of bacterial organic matter into algal biomass. The resultant O. danica cells were lipid-rich, containing 35–46 % lipids by dry weight. The efficiency of O. danica in treating waste sludge was highlighted, achieving a 43 % reduction in organic matter within 36 hours, outperforming conventional aerobic digestion. The study also highlights the potential of O. danica in wastewater treatment. An approach was developed to reclaim organic matter from wastewater through a two-stage process, in which bacteria were first grown on wastewater organic matter and then the grown bacteria were fed to O. danica for growth. Results show that a total of 78.2 % of the initial wastewater organic matter was removed through this approach and 27.3 % of the removed organic matter was converted into lipid-rich algal biomass. The findings underscore the potential of phagotrophic growth for waste treatment and lipid production. The simplicity of the phagotrophic process, independent of light or complex nutrient supplementation, positions it as a promising strategy for industrial applications in waste sludge and wastewater treatment.

Winter Season Outdoor Cultivation of an Autochthonous Chlorella-Strain in a Pilot-Scale Prototype for Urban Wastewater Treatment

The global population increase during the last century has significantly amplified freshwater demand, leading to higher wastewater (WW) production. European regulations necessitate treating WW before environmental. Microalgae have gained attention for wastewater treatment (WWT) due to their efficiency in remediating nutrients and pollutants, alongside producing valuable biomass. This study investigates the phycoremediation potential of a Chlorella-like strain isolated from urban WW in a 600L-scale system under winter conditions. Experiments in December 2021 and February 2022 tested the strain’s adaptability to varying environmental conditions, particularly temperatures (min-max temperature range: from −3.69 to 10.61 °C in December and −3.96 to 17.61 °C in February), and its ability to meet legal discharge limits. In December, low temperatures algal growth. Nitrates showed an RE of about 92%, while ammonia slightly decreased (RE, about 32%), and phosphorous remained unchanged. In February, mild temperatures increased algal density (33.3 × 106 cell mL−1) and, at the end of experiment, all nutrients were below legal limits with very high RE % (NH4+, 91.43; PO43− 97.32). Both trials showed an E. coli RE, % = 99%. The study highlights the potential of microalgae for WWT and the importance of considering seasonal variations when implementing these systems.

Promoting effects of ferric ions on Microcystis aeruginosa growth and arsenate accumulation and reduction at different phosphorus environments

The effects of different dissolved organic phosphorus (DOP) associated with distinct iron conditions (iron deficient (dFe), ferric ions (Fe3+), and colloidal iron (CFe)) on algal growth and arsenate (As(V)) metabolism were systematically evaluated and compared in Microcystis aeruginosa. Two chemical forms of DOP (D-glucose-6-phosphate (GP) and phytic acid (PA)), as well as dissolved inorganic phosphorus (DIP), were employed as distinct phosphorus environments. The results revealed that As(V) metabolism of M. aeruginosa was more influenced by different phosphorus forms than by different iron conditions. Conversely, the release of microcystins in the media was found to be significantly more affected by the different phosphorus forms than by the iron conditions. Moreover, DOP was observed to promote arsenic (As) biotransformation, particularly the efflux of methylated As from a single algal cell, whereas DIP was found to primarily facilitate As(V) accumulation in algae. The total As metabolism amount per algal cell under PA was observed to be five times that observed under DIP and GP. The influence of iron conditions on the synthesis of algal metabolites was notable, as evidenced by the metabolites identified in algae of aliphatic (δ 1.28–1.68), humic acid-like and aromatic protein-like substances through 1H-NMR spectra and three-dimensional excitation-emission matrix fluorescence spectroscopy analysis. This impact was particularly notable at Fe3+ conditions, due to the role of Fe3+ as a micronutrient with highly bioavailable forms, which enhanced the synthesis of organic compounds in algae and promoted algal growth. Consequently, Fe3+ could inhibit As accumulation under DIP but promote it under DOP. The obtained results facilitate a more comprehensive understanding of the combined role of different phosphorus forms and iron conditions in algal bloom outbreaks and As(V) metabolism.

The Allelopathic Effects of Persicaria salicifolia on the Growth and Antioxidant Enzymes of Synechocystis pevalekii and Tetradesmus bernardii

In recent years, there has been an increasing focus on the prospect of exploiting macrophytes as an alternative strategy to control undesired algal growth. The present research was conducted to study the effect of different concentrations of an aqueous stem extract of Persicaria salicifolia on the growth, some metabolites and antioxidant enzymes of the green microalgae Synechocystis pevalekii and Tetradesmus bernardii. Chlorophyll a, dry weight, total protein, total carbohydrate and proline contents of the tested algae decreased with increasing the crude extract concentrations of P. salicifolia. In general, catalase, superoxide dismutase and lipoxygenase activity of T. bernardii increased with increasing the aqueous extract of P. salicifolia. The identification of phytochemical components of the plant extract by gas chromatograph-mass spectrometry (GC-MS) revealed the presence of various biologically active compounds such as 11-Octadecenoic acid, methyl ester (18.03%) and 9,12-Octadecadienoic acid methyl ester (15.03%) that are capable of inhibiting the growth of S. pevalekii and T. bernardii. Therefore, P. salicifolia may provide a cheap and environmentally friendly alternative for controlling microalgae in aquatic ecosystems.

Potansiyel bisphenol-A ikameleri sucul yaşam için gerçekten güvenli mi? Birincil üreticiler üzerindeki etkisi

Bisphenol A threat to environmental health and human health and has been added to the Candidate List as Very High Concern Substances by the European Chemicals Agency. This led to the replacement of bisphenol A (BPA) with bisphenol analogues, which were considered "safer". However, there are very few scientific studies on the impact of BPA analogues on the environment. In this study, three analogues bisphenol B (BPB), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE) were selected to investigate their ecotoxicological effects on the marine phytoplankton species Phaeodactylum tricornutum, which is representative of primary producers. Phaeodactylum tricornutum was exposed to different concentrations (0.5, 0.8, 1.0, 1.5, 2.0 mg/L) of BPB, BADGE and BFDGE analogues for 72 hours and the toxicity values of three BPA analogues were calculated by OECD 201 algal growth inhibition assay (IC50/EC50). In the light of the data obtained, algal growth inhibition (IC50/EC50) values for marine phytoplankton Phaeodactylum tricornutum were determined as 3.91 mg-BPA/L, 7.83 mg-BPB/L, 5.69 mg-BFDGE/L, 11.71 mg-BADGE/L. The results revealed that BPB, BFDGE and BADGE showed lower toxicity to Phaeodactylum tricornutum compared to BPA algal growth inhibition (3.91 mg-BPA/L). Therefore, it is necessary to share the results of the adverse effects of BPA analogues on aquatic organisms and to conduct ecotoxicological risk assessments.

Sporelings and growth of the marine red alga, Gelidium elegans (Gelidiaceae), from Northern Taiwan

Sporelings and growth of the marine red alga, Gelidium elegans (Gelidiaceae), from Northern Taiwan

Unraveling the toxicity mechanisms of nanoplastics with various surface modifications on Skeletonema costatum: Cellular and molecular perspectives

Nanoplastics are ubiquitous in marine environments, exhibiting high bioavailability and potential toxicity to marine organisms. However, the impacts of nanoplastics with various surface modifications on marine microalgae remain largely unexplored. This study explored the toxicity mechanisms of two nanoplastic types-polystyrene (PS) and polymethyl methacrylate (PMMA)-with distinct surface modifications on Skeletonema costatum at cellular and molecular levels. Results showed that nanoplastics significantly impaired the growth of microalgae, particularly PS-NH2, which caused the most pronounced growth inhibition, reaching 56.99 % after a 96-h exposure at 50 mg/L. Transcriptomic profiling revealed that nanoplastics disrupted the expression of genes predominantly involved in ribosome biogenesis, aminoacyl-tRNA biosynthesis, amino acid metabolism, and carbohydrate metabolism pathways. The integrated biochemical and transcriptomic evidence highlighted that PS-NH2 nanoplastics had the most adverse impact on microalgae, affecting fundamental pathways such as ribosome biogenesis, energy metabolism, photosynthesis, and oxidative stress. Our findings underscore the influence of surface-modified nanoplastics on algal growth and contribute new understanding to the toxicity mechanisms of these nanoplastics in marine microalgae, offering critical information for assessing the risks of emerging pollutants.