Microalga Phaeodactylum Tricornutum Research Articles

The 'Erlenmeter': a low-cost, open-source turbidimeter for no-sampling phenotyping of microorganism growth.

This work presents a low-cost, open-source turbidimeter, the 'Erlenmeter', designed to monitor the growth of microorganisms in batch cultures. It is easy to build, based exclusively on inexpensive off-the-shelf electronic components and 3D-printed parts. The Erlenmeter allows measuring the optical density of cultures on standard Erlenmeyer flasks without the need to open the flasks to collect aliquots, ensuring speed, minimal use of consumables, and elimination of the risk of contamination. These features make it particularly well-suited not just for routine research assays but also for experimental teaching. Here we illustrate the use of the Erlenmeter turbidimeter to record the growth of the microalga Phaeodactylum tricornutum, of the bacterium Escherichia coli, and of the yeast Saccharomyces cerevisiae, model organisms that are widely used in research and teaching. The Erlenmeter allows a detailed characterization of the growth curves of all organisms, confirming its usefulness for studying microbial populations dynamics both for research purposes and in classroom settings.

Ethanol Extract of the Microalga Phaeodactylum tricornutum Shows Hepatoprotective Effects against Acetaminophen-Induced Acute Liver Injury in Mice.

Acute liver failure is an infrequent yet fatal condition marked by rapid liver function decline, leading to abnormalities in blood clotting and cognitive impairment among individuals without prior liver ailments. The primary reasons for liver failure are infection with hepatitis virus or overdose of certain medicines, such as acetaminophen. Phaeodactylum tricornutum (PT), a type of microalgae known as a diatom species, has been reported to contain an active ingredient with anti-inflammatory and anti-obesity effects. In this study, we evaluated the preventive and therapeutic activities of PT extract in acute liver failure. To achieve our purpose, we used two different acute liver failure models: acetaminophen- and D-GalN/LPS-induced acute liver failure. PT extract showed protective activity against acetaminophen-induced acute liver failure through attenuation of the inflammatory response. However, we failed to demonstrate the protective effects of PT against acute liver injury in the D-GalN/LPS model. Although the PT extract did not show protective activity against two different acute liver failure animal models, this study clearly demonstrates the importance of considering the differences among animal models when selecting an acute liver failure model for evaluation.

The Biosorption Capacity of the Marine Microalga Phaeodactylum tricornutum for the Removal of Toluidine Blue from Seawater.

A wide variety of dyes, such as toluidine blue (TB), are used daily for a multitude of purposes. After use, many of these compounds end up in aqueous effluents, reaching natural environments, including marine environments. The removal of these pollutants from marine environments must be considered a priority problem. The search for natural techniques, such as biosorption, is a preferred option to eliminate pollution from natural environments. However, biosorption studies in seawater are scarce. For this reason, the living biomass of the marine microalga Phaeodactylum tricornutum was studied to determine its ability to remove TB from seawater. The kinetics of the biosorption process, the isotherms, and the effect of light and pH were determined. This biomass showed a maximum TB removal capacity of 45 ± 2 mg g-1 in the presence of light. Light had a positive effect on the TB removal capacity of this living biomass. The best fitting kinetics was the pseudo-second order kinetics. The efficiency of the removal process increased with increasing pH. This removal was more effective at alkaline pH values. The results demonstrated the efficacy of P. tricornutum living biomass for the efficient removal of toluidine blue dye from seawater both in the presence and absence of light.

Discoloration and biosorption of Brilliant green dye in seawater using living biomass of the microalga Phaeodactylum tricornutum

Pollution by dyes is a serious environmental problem. Marine waters receive pollutants from many sources, however, there are few studies that deal with the elimination of pollutants from these environments. The search for effective, cheap, and ecological procedures to remove dyes from seawater is a current challenge. Biosorption meets these requirements, but it is necessary to find the best biosorbent for the operating conditions. Since microalgal biomass is considered a good biosorbent, the efficiency of living biomass from the marine microalga Phaeodactylum tricornutum to remove the Brilliant green dye from seawater was evaluated in this work. This dye showed spontaneous discoloration in seawater, showing a decrease in the amount of dye measured spectrophotometrically but not when measured by HPLC. Consequently, the difference between discoloration and true removal should be considered. It is shown that the determination of the biomass efficiency as biosorbent through spectrophotometric measurements could be wrong in some cases. Batch experiments were performed varying operational parameters, such as initial concentration of dye, contact time, and pH of the solution. At the lowest concentration of the dye (5 mg L-1), the algal biomass (0.4 g L-1) achieved total decolorization and removal (through biosorption) within 7 h, while at the highest concentration (200 mg L-1), discoloration was 96.3%, but removal was 32.6%. The spontaneous discoloration followed a pseudo-second-order kinetics. Pseudo-first-order kinetics and Langmuir isotherm best described the removal process, predicting a maximum biosorption capacity of 161.52±5.95 mg g-1. This natural biomass had a higher efficiency than other more complex biosorbents.

A Standardized Extract of Microalgae Phaeodactylum tricornutum (Mi136) Inhibit D-Gal Induced Cognitive Dysfunction in Mice.

The microalgae Phaeodactylum tricornutum (PT) is distinguished by its rich nutrient profile, characterized by well-documented neuroprotective activities, including fucoxanthin (FX), a major carotenoid and polyunsaturated omega-3 fatty acids (n-3 PUFA). The current study aims to evaluate the protective effects of a standardized extract of PT (Mi136) containing 2% FX on cognitive function, oxidative stress, and inflammation parameters in a mouse model of accelerated aging. Seventy-two (72) male mice were randomly assigned to the blank control group (BC), negative control group (NC), and four similar microalgae extract of PT groups (branded as BrainPhyt™) with different human equivalent doses to evaluate potential dose-response effects. From day 01 to day 51, mice in the BC group were injected with a 0.9% normal saline solution, while mice in all other groups were subcutaneously injected with D-galactose (D-Gal) at a dose of 150 mg/kg once per day, five days per week. Results indicated that, for the three higher microalgae extract of PT dose groups, spatial cognitive function, swim latency, and step-through latency impairments induced by chronic D-Gal intoxication were significantly and fully inhibited, with mean values similar to those in the BC group during each day of testing. Similar benefits were observed in biochemical analysis, specifically regarding brain and plasma levels of lipid peroxidation, TNF-α, and IL-6 markers. These data underscore the positive effects of a standardized extract of PT containing 2% FX on cognitive function parameters such as spatial working memory, long-term memory, and short-term memory through the regulation of oxidative stress and inflammation pathways.

Different responses of marine microalgae Phaeodactylum tricornutum upon exposures to WAF and CEWAF of crude oil: A case study coupled with stable isotopic signatures

Increasing use of chemical dispersants for oil spills highlights the need to understand their adverse effects on marine microalgae and nutrient assimilation because the toxic components of crude oil can be more bioavailable. We employed the crude oil water-accommodated fraction (WAF) and chemically enhanced WAF (CEWAF) to compare different responses in marine microalgae (Phaeodactylum tricornutum) coupled with stable isotopic signatures. The concentration and proportion of high-molecular-weight polycyclic aromatic hydrocarbons (HMW PAHs), which are key toxic components in crude oil, increased after dispersant addition. CEWAF exposure caused higher percent growth inhibition and a lower chlorophyll-a level of microalgae than those after WAF exposure. Compared with WAF exposure, CEWAF led to an enhancement in the self-defense mechanism of P. tricornutum, accompanied by an increased content of extracellular polymeric substances. 13C-depletion and carbon assimilation were altered in P. tricornutum, suggesting more HMW PAHs could be utilized as carbon sources by microalgae under CEWAF. CEWAF had no significant effects on the isotopic fractionation or assimilation of nitrogen in P. tricornutum. Our study unveiled the impact on the growth, physiological response, and nutrient assimilation of microalgae upon WAF and CEWAF exposures. Our data provide new insights into the ecological effects of dispersant applications for coastal oil spills.

UDP-glucose pyrophosphorylase as a target for regulating carbon flux distribution and antioxidant capacity in Phaeodactylum tricornutum

UDP-glucose pyrophosphorylase (UGPase) is a key enzyme for polysaccharide synthesis, and its role in plants and bacteria is well established; however, its functions in unicellular microalgae remain ill-defined. Here, we perform bioinformatics, subcellular localization as well as in vitro and in vivo analyses to elucidate the functions of two UGPs (UGP1 and UGP2) in the model microalga Phaeodactylum tricornutum. Despite differences in amino acid sequence, substrate specificity, and subcellular localization between UGP1 and UGP2, both enzymes can efficiently increase the production of chrysolaminarin (Chrl) or lipids by regulating carbon flux distribution without impairing growth and photosynthesis in transgenic strains. Productivity evaluation indicate that UGP1 play a bigger role in regulating Chrl and lipid production than UGP2. In addition, UGP1 enhance antioxidant capacity, whereas UGP2 is involved in sulfoquinovosyldiacylglycerol (SQDG) synthesis in P. tricornutum. Taken together, the present results suggest that ideal microalgal strains can be developed for the industrial production of Chrl or lipids and lay the foundation for the development of methods to improve oxidative stress tolerance in diatoms.

Phaeodactylum tricornutum as Fucoxanthin Biofactory Model and Hepatoprotective Effect of Encapsulated Spirulina and Fucoxanthin

In recent decades, the worldwide production of microalgae has been carried out on an industrial scale. In recent years, the market for natural products has grown because of changes in consumer preferences for more natural products. The objective of this study was to demonstrate the hepatoprotective capacity of fucoxanthin extract obtained from an industrial culture of the microalgae Phaeodactylum tricornutum (Culture Collection of Alga and Protists in Scotland). The microalga was grown in an artificial and natural seawater mixture (1:9), using Walne’s culture medium in columns and raceway photobioreactors (RWP) inside a greenhouse. The carotenoid content in the tested systems continued to increase from day 5 of the culture, when the stationary phase was reached. The final biomass powder contained 4.9 mg (2.59%) of pure fucoxanthin. The possible hepatoprotective activity of fucoxanthin was then studied in the HepG2 cell line for 24 h in culture, and compared with the cytotoxicity of methotrexate (MTX). In conclusion, the active ingredient showed hepatoprotective activity against MTX in the human hepatocyte cell line HEPG-2 at a concentration of 0.25 mg/mL. The current results also suggest that it has beneficial properties for liver health and is a suitable ingredient for all types of nutraceutical products.

Safety of an ethanolic extract of the dried biomass of the microalga Phaeodactylum tricornutum as a novel food pursuant to Regulation (EU) 2015/2283.

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on an ethanolic extract of the dried biomass of the microalga Phaeodactylum tricornutum as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is an ethanolic extract of the dried biomass of the microalga P. tricornutum diluted in a medium-chain triglyceride oil carrier, with standardised fucoxanthin and tocopherol content. The main component of the NF is fat (78% on average), followed by crude protein (10% on average). The Panel is of the view that a consistent and safe production process has not been demonstrated. Additionally, the Panel considers that the information provided on the composition of the NF is not complete and may raise safety concerns. The applicant proposed to use the NF as a food supplement at the use level of 437 mg/day, with the target population being adults, excluding pregnant and breastfeeding women. There is no history of use of the NF or of its source, i.e. P. tricornutum. The Panel notes that the source of the NF, P. tricornutum, was not granted the qualified presumption of safety (QPS) status by the EFSA Panel on Biological Hazards (BIOHAZ), due to the lack of a safe history of use in the food chain and on its potential for production of bioactive compounds with toxic effects. There were no concerns regarding genotoxicity of the NF. In the 90-day study provided, a number of adverse effects were observed, some of them seen already at the lowest dose tested (750 mg/kg body weight (bw) day), which was identified by the Panel as the lowest-observed-adverse-effect-level (LOAEL). The potential phototoxicity of pheophorbide A and pyropheophorbide A in the NF was not addressed in this study. Although noting the uncertainties identified by the Panel regarding the analytical determination of these substances in the NF and the limitations in the publicly available toxicity data, a low margin of exposure (MoE) was calculated for these substances at the proposed use levels. The Panel concludes that the safety of the NF under the proposed uses and use levels has not been established.

Polyphenols modulate microalgae metabolism with a particular increment in lipid accumulation

The development of an affordable strategy to concurrently enhance microalgal biomass and biocomponents is warranted for commercial applications. Here, we reported that a cheap and natural polyphenol, tannic acid, regulated the metabolic and physiological properties of the oleaginous microalga Phaeodactylum tricornutum to overproduce biocompounds. Tannic acid provision regulated the key metabolic pathways to enhance algal biomass and lipids in a dose-dependent manner without having a direct impact on photosynthesis. It reduced oxidative stress and reallocated carbon precursors toward lipogenesis. Lipidomic analyses showed that tannic acid provision unprecedentedly regulated the key lipogenic pathways, enhancing glyco- and neutral-lipids by 1.29- and 1.54-fold, respectively, whereas phospholipids were significantly altered. Tannic acid facilitated polyunsaturated fatty acid overproduction with a specific increment of EPA and DHA of 1.18- and 2.25-fold, respectively. Transcriptomic analysis demonstrated that tannic acid upregulated the expression of multiple genes involved in lipogenesis. Here, we dissected the potential of tannic acid, a natural and cheaper polyphenol, for simultaneously enhancing lipids and PUFAs without impairing physiological properties in P. tricornutum. The findings provide novel insights into the mechanistic roles of polyphenols as potential chemical modulators.

COMPARATIVE ASSESSMENT OF THE EFFECT OF GIBBERELLIC AND SALICYLIC ACIDS ON THE GROWTH AND BIOCHEMICAL PARAMETERS OF Phaeodactylum tricornutum

The research of the effect of gibberellic (0.4 - 3.8x 10-8 mol.L-1) and salicylic (0.4 - 3.8 x 10-5 mol.L-1) acids, in a wide range of their concentrations, on the growth indicators and biochemical composition of the cumulative culture of the microalgae Phaeodactylum tricornutum was carried out. It was determined that salicylic acid in a concentration of 0.4 x 10-5 mol stimulated cell growth by 184.6%, and gibberellic acid at a concentration of 0.39 x 10-8 mol by 181%, compared to the control. The effect of gibberellic acid during the experiment was expressed in the inhibition of protein accumulation in the culture, compared with the control. The use of salicylic acid led to a greater accumulation of protein in the culture than when using gibberellic acid. It was shown that salicylic acid had a positive effect on the accumulation of carbohydrates on day 9 and gibberellic acid on day 14 of culture. Gibberellic acid had no effect on the accumulation of lipids in the culture of microalgae. Under the action of salicylic acid for 14 days of cultivation, the lipid content increased by 18.5%, compared with the control. There were no quantitative differences in the content of chlorophyll when using two phytohormones. In this study, the optimal concentrations of gibberellic and salicylic acids for linear growth rate and the highest production of protein and carbohydrates for Phaeodactylum tricornutum were determined. Position, depending on the stage of microalgae growth, is noted.

Antagonistic Toxic Effects of Surfactants Mixtures to Bacteria Pseudomonas putida and Marine Microalgae Phaeodactylum tricornutum.

Surfactants can be found in an ever-widening variety of products and applications, in which the combination of several types of surfactants is used to reinforce their properties, looking for synergistic effects between them. After use, they tend to be discarded into wastewater, ending up in aquatic bodies with concerning harmful and toxic effects. The aim of this study is the toxicological assessment of three anionic surfactants (ether carboxylic derivative, EC) and three amphoteric surfactants (amine-oxide-based, AO), individually and in binary mixtures of them (1:1 w/w), to bacteria Pseudomonas putida and marine microalgae Phaeodactylum tricornutum. Critical Micelle Concentration (CMC) was determined to demonstrate the capacity to reduce surface tension and the toxicity of the surfactants and mixtures. Zeta potential (ζ-potential) and micelle diameter (MD) were also determined to confirm the formation of mixed surfactant micelles. The Model of Toxic Units (MTUs) was used to quantify the interactions of surfactants in binary mixtures and to predict if the concentration addition or response addition principle can be assumed for each mixture. The results showed a higher sensitivity of microalgae P. tricornutum to the surfactants tested and their mixtures than bacteria P. putida. Antagonism toxic effects have been detected in the mixture of EC + AO and in one binary mixture of different AOs; this is to say, the mixtures showed lower toxicity than expected.

Sorption as a pre-concentration step for metal ions recovery in multi-elemental systems

Sorption is here proposed as a promising approach for metal pre-concentration and recovery from wastewater. A study was carried out on the simultaneous sorption of Co2+, Cu2+, Ni2+ and Zn2+ on macroalgae, microalgae and cyanobacteria. The effect of pH, initial metal concentration, metal competition and time of contact on metal sorption were evaluated. Metal competition hampers sorption at the studied metal concentration ranges. The metal counterion (sulfate, chloride or acetate) did not influence metal sorption. The brown algae Sargassum sp. was the most promising sorbent (qmax = 0.66 ± 0.03 mmol·g−1), followed by the microalgae Phaeodactylum tricornutum (qmax = 0.36 ± 0.02 mmol·g−1) and the cyanobacteria Spirulina sp. (qmax = 0.216 ± 0.007 mmol·g−1). All biomass samples showed preferential sorption of Cu2+. The experimental kinetic data were well described by Ho’s model, showing chemisorption to be the main sorption mechanism. Ion-exchange of Ca2+, K+ and H+ also played a significant role in metal sorption. After sorption, metal recovery was achieved resorting to incineration. The metal content of the obtained biochar was 4639-fold higher when compared to the initial aqueous solution concentration.

Modeling of the absorption spectrum of Phaeodactylum tricornutum Bohlin in the red area

Mathematical decomposition of the absorption spectrum of the culture of the red microalga Phaeodactylum tricornutum Bohlin was carried out in the spectral range from 550 to 750 nm. The culture spectra were recorded on a spectrophotometer with an integrating sphere. Using the literature data, mathematical models of the absorption spectra in the red area of the following pigments were compiled: chlorophyll a and chlorophyll с. The mathematical model of each pigment represented the sum of Gaussian curves. The resulting equations were taken as a basis for modeling the native spectrum. A general model of the absorption spectrum of culture in the region of 550–750 nm has been compiled, consisting of the sum of individual pigments. Using the model obtained in practice, it is possible to determine the concentrations of chlorophyll a and c directly from the absorption spectrum of the culture.

Okara Waste as a Substrate for the Microalgae Phaeodactylum tricornutum Enhances the Production of Algal Biomass, Fucoxanthin, and Polyunsaturated Fatty Acids

Despite the rich nutritional content of okara, the majority remains underutilized and discarded as food waste. In this study, solid-state fermentation of okara with food-grade fungi was performed to extract and solubilize any remnant nutrients locked within the lignocellulosic matrix to produce a nutrient-rich okara fermentate. Fermented okara media (FOM) was used as the sole nutrient source for growing marine diatom, Phaeodactylum tricornutum. Results have shown a two-fold increase in biomass production when grown on FOM (0.52 g L−1) as compared with conventional Guillard’s F/2 media (0.25 g L−1). Furthermore, cellular fucoxanthin content was enhanced significantly by two-fold to reach a final concentration of 15.3 mg g−1 compared to 7.3 mg g−1. Additionally, a significantly higher amount of polyunsaturated fatty acid (PUFA) was produced, particularly eicosapentaenoic acid (EPA) which yield has increased by nearly three-fold. Metabolomics analysis of intracellular contents in fermented okara culture revealed a significantly enhanced accumulation of nitrogenous metabolites, alongside the decrease in sugar metabolites as compared to F/2 culture, thus indicating metabolic flux towards pathways involved in cellular growth. This study demonstrated an innovative and low-cost strategy of using fermented okara as a nutritious substrate for achieving a sustainable media replacement for high density algal growth with a simultaneous enhancement of production in highly valued nutraceuticals, including fucoxanthin and EPA.

Assessment of Small Cellular Particles from Four Different Natural Sources and Liposomes by Interferometric Light Microscopy

Small particles in natural sources are a subject of interest for their potential role in intercellular, inter-organism, and inter-species interactions, but their harvesting and assessment present a challenge due to their small size and transient identity. We applied a recently developed interferometric light microscopy (ILM) to assess the number density and hydrodynamic radius (Rh) of isolated small cellular particles (SCPs) from blood preparations (plasma and washed erythrocytes) (B), spruce needle homogenate (S), suspension of flagellae of microalgae Tetraselmis chuii (T), conditioned culture media of microalgae Phaeodactylum tricornutum (P), and liposomes (L). The aliquots were also assessed by flow cytometry (FCM), dynamic light scattering (DLS), ultraviolet-visible spectrometry (UV-vis), and imaging by cryogenic transmission electron microscopy (cryo-TEM). In Rh, ILM showed agreement with DLS within the measurement error in 10 out of 13 samples and was the only method used here that yielded particle density. Cryo-TEM revealed that representative SCPs from Tetraselmis chuii flagella (T) did not have a globular shape, so the interpretation by Rh of the batch methods was biased. Cryo-TEM showed the presence of thin filaments in isolates from Phaeodactylum tricornutum conditioned culture media (P), which provides an explanation for the considerably larger Rh obtained by batch methods than the sizes of particles observed by cryo-TEM images. ILM proved convenient for assessment of number density and Rh of SCPs in blood preparations (e.g., plasma); therefore, its use in population and clinical studies is indicated.

A scalable model for EPA and fatty acid production by Phaeodactylum tricornutum.

Large-scale photoautotrophic production of microalgae has the potential to provide a sustainable supply of omega-3 fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) for human and animal nutrition. This study presents a kinetic model for the EPA-producing microalga Phaeodactylum tricornutum in photoautotrophic conditions, with light and nitrogen being the growth limiting factors. The model was developed using a dataset obtained from bench-scale (5 L) cultures and was successfully validated against pilot-scale (50 L) cultures. This model is the first to predict the biomass and total fatty acid accumulation along with the EPA concentrations in the biomass and total fatty acid fraction for microalgae. The model was used to develop an optimized repeated-batch strategy; implementation of this led to increases in the biomass and EPA productivities of 50 and 20% respectively. This clearly indicates the potential of the model to be used as a tool in the design, optimization and scale-up of microalgal systems for EPA production.

Nanoencapsulation enhances the bioavailability of fucoxanthin in microalga Phaeodactylum tricornutum extract

The marine carotenoid fucoxanthin (FX) has various health benefits but suffers from poor bioavailability. We hypothesize that the bioavailability of FX in microalga Phaeodactylum tricornutum extract (PE) could be improved through nanoencapsulation. Here, we developed two types of nanoparticles: one consisting of alginate and casein (A-C-PE, 246 nm diameter, 79.6% encapsulation efficiency) and the other A-C-PE coated with chitosan (CS-A-C-PE, 258 nm, 78.1%). Both types of nanoparticles incorporating PE showed controlled FX release during simulated gastrointestinal digestion, as well as 1.8-fold improvement of membrane permeability in Caco-2/TC7 cells compared to non-encapsulated PE. Pharmacokinetic behavior of two FX metabolites (fucoxanthinol and amarouciaxanthin A) in mouse plasma was monitored after oral administration. The results showed that 31.8–332.1% more FX metabolites from the nanoparticles were absorbed into plasma than those from PE. In conclusion, encapsulation of PE in both types of nanoparticles significantly promoted the bioavailability of FX.

A first attempt to evaluate the toxicity to Phaeodactylum tricornutum Bohlin exposed to rare earth elements

The increasing use and demand of rare earth elements in many emerging technologies is leading to a potentially higher input to the marine environment. This study compared for the first time the effect of lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), dysprosium (Dy), and erbium (Er) to the microalga Phaeodactylum tricornutum Bohlin. The algal growth inhibition was investigated after 72 h of exposure. The median effect concentrations (EC50) ranged from 0.98 mg/L to 13.21 mg/L and elements were ranked as follows: Gd > Ce > Er > La > Eu > Nd > Dy > Sm. The comparison of predicted no effect concentrations (PNEC) for hazard and risk assessment with measured environmental concentrations showed that ecological risks deriving from REEs could be present, but limited to specific environments like estuarine waters. The results support evidence of actions to manage the REE impact in seawater environments, looking to improve the monitoring tailored to the different and dynamic nature of ecosystems.

ROS-mediated time-varying cytotoxic effects on Phaeodactylum tricornutum under the stress of commercial naphthenic acids

The aquatic toxicity and ecological risks of naphthenic acids (NAs) in marine environments have attracted an increasing amount of attention. However, there remains a lack of methodologies for the long-term risk assessment of NAs on marine ecosystems after high acid crude oil spill accidents. In this study, using the model microalgae Phaeodactylum tricornutum as the target object, the time-effect manner under NAs stress is investigated for a continuous 24–144 h. We found that: 1) NAs caused photosynthetic damage and persistent oxidative stress that slowed the growth rate and limited the maximum growth of P. tricornutum population within 24 h to 144 h of exposure, especially under the high concentration treatment; 2) Within 144 h, NAs can cause oxidative stress to P. tricornutum. The damage to cell membrane and radical oxidative species (ROS) accumulation of P. tricornutum were observed as obvious time-effect; 3) Under NAs stress, the two types of cell death (accidental cell death and regulated cell death) of P. tricornutum cell mediated by ROS played different roles in the population growth inhibition of P. tricornutum. Moreover, regulated cell death of the P. tricornutum cell was accompanied by PS externalization, DNA fragment and the G2/M phase stagnation acted as an adaptive regulatory mechanism under NAs stress. This explained the dose-time-effects of NAs on the population growth of P. tricornutum. Overall, the results suggested that NAs have a lasting effect on marine phytoplankton populations, and long-term risk assessments are required after high acid crude oil spill accidents. This is the first attempt to identify the different types of death at the cellular level to explain the time-effect toxicity at the population level of marine microalgae when exposed to NAs. This research will provide a new approach to facilitate further risk assessments for NAs and related contaminants in marine ecosystems.