Growth Of Scenedesmus Obliquus Research Articles

Identifying potential toxic organic substances in leachates from tire wear particles and their mechanisms of toxicity to Scenedesmus obliquus

Tire wear particles (TWPs) are increasingly being found in the aquatic environment. However, there is limited information available on the environmental consequences of TWP constituents that may be release into water. In this study, TWP leachate samples were obtained by immersing TWPs in ultrapure water. Using high-resolution mass spectrometry and toxicity identification, we identified potentially toxic organic substances in the TWP leachates. Additionally, we investigated their toxicity and underlying mechanisms. Through our established workflow, we structurally identified 13 substances using reference standards. The median effective concentration (EC50) of TWP leachates on Scenedesmus obliquus growth was comparable to that of simulated TWP leachates prepared with consistent concentrations of the 13 identified substances, indicating their dominance in the toxicity of TWP leachates. Among these substances, cyclic amines (EC50: 1.04–3.65 mg/L) were found to be toxic to S. obliquus. We observed significant differential metabolites in TWP leachate-exposed S. obliquus, primarily associated with linoleic acid metabolism and purine metabolism. Oxidative stress was identified as a crucial factor in algal growth inhibition. Our findings shed light on the risk posed by TWP leachable substances to aquatic organisms.

Interspecific insights into direct and indirect effects of acetochlor on interactions between daphnids and microalgae: Toxic, trophic, and grazer-infochemical responses

As the herbicide acetochlor (ACT) affects the plankton food web, this study investigated the effects of ACT and exocrine infochemicals from daphnids (after ACT exposure and/or starvation) on Scenedesmus obliquus growth, as well as the effects of ACT and starvation on life-history traits of Daphnia magna. Filtered secretions from daphnids increased algal ACT tolerance, dependent on different ACT exposure histories and food intake. Endogenous and secretory metabolite profiles of daphnids following ACT and/or starvation appear to be regulated by the fatty acid synthesis pathway and sulfotransferases and were related to energy allocation trade-offs. Oleic acid (OA) and octyl sulfate (OS), screened by secreted and somatic metabolomics, affected algal growth and ACT behavior in the algal culture in opposite ways. Trophic and non-trophic interspecific effects caused by ACT were observed in microalgae-daphnid microcosms, including algal growth inhibition, daphnid starvation, OA down-regulation, and OS up-regulation. Based on these findings, risk assessment of ACT on the freshwater plankton communities should take species interactions into account.

Effects of Dissolved Organic Matter Fractions of Varying Molecular Weights and Cd2 + on Scenedesmus obliquus Growth

Effects of Dissolved Organic Matter Fractions of Varying Molecular Weights and Cd2 + on Scenedesmus obliquus Growth

Plasma-induced conversion of polystyrene nanoplastics in water: Intermediates release, toxicity, and disinfection byproducts formation

Widely distributed nanoplastics have become a threat to water environment. Information regarding their conversion behaviors and risks under oxidation conditions is still lacking. In this study, conversion of polystyrene nanoplastics (PSNPs) in water induced by electrical plasma was investigated, and its risks were evaluated in terms of Scenedesmus obliquus growth, Human alveolar cell A549 toxicity, and chlorinated disinfection byproducts (DBPs) formation. Attacks of 1O2 and ·OH resulted in rough surface, smaller particle size of PSNPs (particles larger than 200 nm disappeared, and it was in the range of 50–150 nm), sequence breakages in functional groups, and generation of hydroxylated and carboxylated intermediates. The plasma-treated PSNPs exhibited slightly weaker toxicity for Scenedesmus obliquus growth when PSNPs concentration was 30 mg L−1, but stronger toxicity for A549 (relative viability of A549 decreased from approximately 40% to 6.9% after 15 min treatment). The hydroxylated and carboxylated intermediates were important precursors of DBPs, and the formation potentials and toxicities of haloacetic acid DBPs increased with the plasma treatment. The relevant roadmaps among haloacetic acid DBPs and conversion intermediates were figured out. Overall, the conversion of PSNPs under oxidation exposure may pose a greater threat to DBPs formation, which deserved more attention.

Effects of Nitrogen Forms and Supply Mode on Lipid Production of Microalga Scenedesmus obliquus

Optimization of the microalgae culture conditions could significantly reduce the production costs of microalgae-derived biodiesel. In the current study, a new process of adding different forms using the multiple small-dose method was employed. The effects of different forms of nitrogen (NaNO3, NH4Cl, and CH4N2O) and their concentrations (0.1, 0.5, 1, and 2 mg L−1) on the growth and lipid production of Scenedesmus obliquus were studied. Algae density and lipid production increased with increasing nitrogen concentration for all different forms of nitrogen except NH4Cl. The Scenedesmus obliquus growth was promoted by adding NaNO3 and CH4N2O, but was inhibited by adding NH4Cl. Adding 2 mg N L−1 of CH4N2O daily yielded the highest cell density (1.7 × 107 cells mL−1) and lipid production (242.4 mg L−1). These conditions can thus maintain the biomass of Scenedesmus obliquus, increase its lipid accumulation, and decrease the costs of biodiesel production.

Effect of differently methyl-substituted ionic liquids on Scenedesmus obliquus growth, photosynthesis, respiration, and ultrastructure

Concerns have been raised regarding the ecotoxicity of ionic liquids (ILs) owing to their wide usage in numerous fields. Three imidazolium chloride ILs with different numbers of methyl substituents, 1-decyl-imidazolium chloride ([C10IM]Cl), 1-decyl-3-methylimidazolium chloride ([C10MIM]Cl), and 1-decyl-2,3-dimethylimidazolium chloride ([C10DMIM]Cl), were examined to assess their effects on growth, photosynthesis pigments content, chlorophyll fluorescence, photosynthetic and respiration rate, and cellular ultrastructure of Scenedesmus obliquus. The results showed that algal growth was significantly inhibited by ILs treatments. The observed IC50,48h doses were 0.10 mg/L [C10IM]Cl, 0.01 mg/L [C10MIM]Cl, and 0.02 mg/L [C10DMIM]Cl. The chlorophyll a, chlorophyll b, and total chlorophyll content declined, and the chlorophyll fluorescence parameters, minimal fluorescence yield (F0), maximal fluorescence yield (Fm), maximum quantum yield of PSII photochemistry (Fv/Fm), effective quantum yield of PSII [Y(II)], non-photochemical quenching (NPQ) and non-photosynthetic losses yield [Y(NO)] were notably affected by ILs in a dose-dependent manner. ILs affected the primary photosynthetic reaction, impaired heat dissipation capability, and diminished photosynthetic efficiency, indicating negative effects on photosystem II. The photosynthetic and respiration rates of algal cells were also reduced due to the ILs treatments. The adverse effects of ILs on plasmolysis and chloroplast deformation were examined using ultrastructural analyses; chloroplast swelling and lamellar structure almost disappeared after the [C10MIM]Cl treatment, and an increased number of starch grains and vacuoles was observed after all ILs treatments. The results indicated that one-methyl-substituted ILs were more toxic than non-methyl-substituted ILs, which were also more toxic than di-methyl-substituted ILs. The toxicity of the examined ILs showed the following order: [C10IM]Cl < [C10DMIM]Cl ≤ [C10MIM]Cl.

Uptake and toxic effects of triphenyl phosphate on freshwater microalgae Chlorella vulgaris and Scenedesmus obliquus: Insights from untargeted metabolomics

The flame retardant triphenyl phosphate (TPhP) has been widely detected in surface waters. Yet, little information is known regarding its impact on microalgae. We investigated the uptake and toxicity of TPhP on two freshwater microalgae Chlorella vulgaris (CV) and Scenedesmus obliquus (SO) after exposure to 10 μg/l–10 mg/l for 5 days. The presence of microalgae significantly enhanced TPhP degradation, with the final concentrations dropped to 5.5–35.1% of the original concentrations. Most of the medium TPhP were sorbed and transformed by microalgae in just one day. Growth of CV was inhibited in a concentration-dependent manner, whereas growth of SO were only inhibited significantly at 10 mg/l TPhP exposure. Mass spectrometry-based untargeted metabolomics revealed concentration- and species-dependent metabolic responses. Exposure to TPhP in CV resulted in enhanced respiration (increase of fumarate and malate) and osmoregulation (increase of sucrose and myo-inositol), synthesis of membrane lipids (accumulation of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), decrease of lysoglycerolipids, fatty acids, and glyceryl-glucoside). Exposure to TPhP in SO resulted in enhanced osmoregulation (increase of valine, proline, and raffinose) and lipolysis (decrease of MGDG, accumulation of fatty acids, lysophospholipids, and glycerol phosphate). Although chlorophyll a and b contents did not change significantly, decrease of chlorophyll derivatives was observed in both CV and SO at high exposure concentrations. Further bioassays confirmed that CV exhibited enhanced membrane integrity and decreased cellular reactive oxygen species (ROS) possibly as a defense strategy, whereas SO showed disruption of membrane integrity and induction of ROS at 10 mg/l exposure. This study demonstrated the potential of microalgae to remove TPhP in water, and offered new insights for the risk assessment of TPhP on freshwater microalgae using metabolomics.

Algae toxicological assessment and valorization of energetic-laden wastewater streams using Scenedesmus obliquus

The manufacturing of energetic compounds (explosives), such as 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and 3-nitro-1,2,4-triasol-5-one (NTO), generates large volumes of wastewater containing organic pollutants, which are also rich in nutrients, mainly nitrogen. These wastewaters are subject to regulatory compliance and require treatment prior to their release into local water bodies. An approach is proposed to recover nutrients and water from wastewaters prior to treatment by growing microalgae with the aim to reduce the energy footprint of the munitions production facility by producing algae-based biofuels. In order to assess the feasibility of implementation of the proposed approach, ten different fully characterized untreated wastewaters with various levels of organic and inorganic carbon and nitrogen content were assessed for microalgae toxicity using Scenedesmus obliquus ATCC® 11477 as target microorganism. Toxicity experiments were performed in microplates for six days at 25 °C, 120 rpm orbital mixing speed, under a 14:10 h light: dark photoperiod, and 68 μmol photons/m2s of light intensity. The results indicate that the majority of the wastewater streams assessed could be used as nutrient media with no pretreatment while only three of the streams required chemical treatment due to their high growth inhibition characteristics. From the toxicological results obtained, a site specific mixture prepared by blending of the different untreated waste streams was tested for Scenedesmus obliquus growth. It was observed that this microalga can reach 5 × 107 cells/mL over six days of incubation in the wastewater mixture containing up to 24 mg/L RDX and 28 mg/L NTO. This strain exhibited similar growth patterns in the wastewater mixture as compared to the control sample, suggesting the potential feasibility of using untreated, energetic-laden industrial wastewater along with carbon dioxide [CO2 (atmospheric or flue gases)] for microalgae biomass production.

Mixotrophic cultivation of green microalgae Scenedesmus obliquus on cheese whey permeate for biodiesel production

Microalgae mass cultivation for biodiesel production might very well become the next marketable biofuel. The main challenge to overcome however is the development of high efficiency strategies for the large-scale production of oleaginous microalgae at low costs. In the present work, the use of cheese whey permeate (WP) in mixotrophic microalgae cultures is proposed. Pure lactose, the main constituent of WP (>80% w/w of the total dissolved solids), can support Scenedesmus growth under heterotrophic culture conditions (absence of light). Substituting 40% (v/v) of the culture medium with WP significantly stimulates Scenedesmus obliquus growth under mixotrophic (μmax=1.083±0.030day−1) and heterotrophic (μmax=0.702±0.025day−1) conditions, compared to photoautotrophic control cultures (μmax=0.267±0.083day−1). As growth occurs in the presence of lactose, a significant reduction of its concentration is observed, while the galactose and glucose concentrations actually increase in the culture medium. Culture medium analyses showed complete exhaustion of extracellular nitrogen (nitrate and ammonium), while intracellular lipid analyses showed neutral lipid (NL) accumulation, particularly under conditions of high pH (>9.5). Photoautotrophic control cultures accumulated more lipids (per dry weight) than WP-supplemented cultures, an aspect which is discussed in the context of lipid enrichment strategies. A fast and simple method for NL cellular content estimation is also described.

Cultivation of Scenedesmus obliquus in Photobioreactors: Effects of Light Intensities and Light–Dark Cycles on Growth, Productivity, and Biochemical Composition

One of the main parameters influencing microalgae production is light, which provides energy to support metabolism but, if present in excess, can lead to oxidative stress and growth inhibition. In this work, the influence of illumination on Scenedesmus obliquus growth was assessed by cultivating cells at different light intensities in a flat plate photobioreactor. S. obliquus showed a maximum growth rate at 150 μmol photons m(-2) s(-1). Below this value, light was limiting for growth, while with more intense illumination photosaturation effects were observed, although cells still showed the ability to duplicate. Looking at the biochemical composition, light affected the pigment contents only while carbohydrate, lipid, and protein contents remained stable. By considering that in industrial photobioreactors microalgae cells are subjected to light-dark cycles due to mixing, algae were also grown under pulsed illumination (5, 10, and 15 Hz). Interestingly, the ability to exploit pulsed light with good efficiency required a pre-acclimation to the same conditions, suggesting the presence of a biological response to these conditions.

Allelopathic Activities of Exudates from Potamogeton Pectinatus on the Growth of Scenedesmus Obliquus and Toxic Microcystis Aeruginosa at Different Algal Cell Density

Allelopathic Activities of Exudates from Potamogeton Pectinatus on the Growth of Scenedesmus Obliquus and Toxic Microcystis Aeruginosa at Different Algal Cell Density

Influence of hydrodynamic stress in the growth of Scenedesmus obliquus using a culture medium based on olive-mill wastewater

The wastewater from olive oil elaboration (OMW) constitutes a major environmental problem in producing countries of olive oil. OMW from the three-phase system is harmful due to its high organic load and the presence of phytotoxic phenolic compounds. The culture medium was constituted with 5% OMW. The effects of mechanical agitation and aeration rates on the microalga Scenedesmus obliquus growth, in a batch photobioreactor were studied. A maximum specific growth rate, μ m = 0.031 h −1, was obtained using a rotational impeller speed around 350 rpm without aeration and was greater than that found in the absence of stirring 0.024 h −1. The chlorophyll contents were independent of the stress and light intensity in the cultures, but did boost the nutrient concentration in the medium. The stress induced by stirring or by aeration of the cultures did not alter the final cell-protein and carbohydrate content, 18% and 48% as mean value, respectively.

Toxic effects of leachate of water hyacinth decay on the growth of Scenedesmus obliquus (chlorophyta)

Effects of leachate of leaf and root litters of water hyacinth, collected after various periods of decay, on the growth of a green alga Scenedesmus obliquus (Turpin) Kuetzing were determined. Leachates of the leaf and root litters showed very similar effects on the growth of test alga. Higher concentrations of the leachate of 1-day decay considerably stimulated algal growth. Lower concentrations of the leachates of 10-, 35- and 60-day decay caused growth toxic effects in comparison with higher concentrations. The inhibition of algal growth was significantly higher by the leachate of 60-day decay relative to that by the leachates of 35- and 10-day decay. Short-term incubation of the test alga with the leachate recorded a greater inhibition of growth than long-term incubation.

Effect of hydrilla‐growth inhibiting extracts upon the growth of scenedesmus obliquus

Abstract The noxious, submersed aquatic plant Hydrilla verticillata has not thrived in certain lakes, including Lake Starvation, northwest Hillsborough County, Florida. Aqueous extracts of sediment from that lake were inhibiting the growth of hydrilla in the laboratory (Co, organic carbon, ca. 0.4 ppm). In contrast, similar concentrations of active fractions did not inhibit the growth of the freshwater alga S. obliquus, though at higher concentrations, cultures were stimulated (6–12 ppm, Co), and inhibition was noted for the highest concentration studied (18 ppm Co, 0.01 ppm Fe).