Search

Chemical-based carotenoids have large implications to health as they may cause adverse side effects. Naturally occurring carotenoids mainly from microalgal sources are emerging as excellent substitute to combat cancer diseases. Astaxanthin is the most powerful antioxidant that derived from selected established microalgae with limited yield. Microalgal bioprospecting may provide the high-yielding sources for astaxanthin production. Hence, in the present research, freshwater microalgae Monoraphidium sp. (NCM no. 5585) and Scenedesmus obliquus (NCM no. 5586) were chosen to explore the unique potential of producing astaxanthin. Identification of bioactive metabolites in extracted carotenoid was analyzed through HPLC. Astaxanthin is identified as a major bioactive metabolite in both carotenoid fraction and β carotene only in Scenedesmus obliquus. Antioxidant potential of microalgal carotenoids was obtained by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric-reducing antioxidant power (FRAP) assay. The anti-proliferation activity of the extracted carotenoid from Monoraphidium sp. and Scenedesmus obliquus was evaluated against hepatocellular liver carcinoma cell line HUH7 by 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) colorimetric assay. Higher astaxanthin in Monoraphidium sp. leads to boosted antioxidant and anti-proliferation activity contrary to Scenedesmus obliquus that possess both astaxanthin and β carotene. Though freshwater microalgae have a huge potential to create beneficial metabolites like carotenoids, they are rarely studied in the pharmaceutical industry. This work was the first to investigate the anti-proliferative activity of Monoraphidium sp. and Scenedesmus obliquus carotenoid fraction on the HUH7 hepatocarcinoma cell line. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS 2) nanomaterials have attracted considerable attention due to their unique physicochemical properties and promising applications, and subsequent risks to the environment and human health. However, the toxicological investigations of MoS 2 nanosheets in aquatic environments are still limited. Herein, their aquatic toxic effects and involved mechanisms were explored using a freshwater green microalgae model, Selenastrum capricornutum. Several endpoints, including algal growth, photosynthetic pigment and macromolecular substances synthesis, were investigated after exposure to 0.02–50.0 mg/L MoS 2 nanosheets. Furthermore, oxidative stress, membrane damage, lipid oxidation, and secretion of extracellular polymeric substances were elucidated as well. The results showed that single-layer MoS 2 (SLMoS 2) nanosheets at low concentrations (≤ 1.0 mg/L) stimulated the synthesis of chlorophyll and primary macromolecules, and they slightly promoted the growth of S. capricornutum. In contrast, higher concentrations of SLMoS 2 (> 1.0 mg/L) inhibited algae growth through ROS-mediated membrane destruction and oxidative damage. Surprisingly, SLMoS 2 accelerated extracellular polymeric substances (EPS) secretion and changed their fluorescent components, thus influencing algal growth. Taken together, MoS 2 nanomaterials exerted bidirectional effects on S. capricornutum at the cellular, histological and organismal levels. These results provide considerable support regarding the adverse effects of MoS 2 nanomaterials on freshwater microalgae. [Display omitted] • SLMoS 2 nanosheets exert bidirectional effects in Selenastrum capricornutum microalgae. • SLMoS 2 at low concentrations (≤ 1.0 mg/L) promotes algal growth, otherwise, the opposite was true. • Low concentrations of SLMoS 2 enhance microalgae photosynthesis and metabolism to accelerate algal growth. • SLMoS 2 at low high concentrations (> 1.0 mg/L) induces ROS-mediated oxidative damage and membrane destruction on microalgae. • Algal EPS changes in both contents and components are involved in SLMoS 2 's effects on algal growth. [ABSTRACT FROM AUTHOR]

The increase in heatwave intensity and duration is challenging microalgal photosynthesis in shallow waters. In particular, the extent of photosynthesis impairment or limitation due to short extreme heat stress events occurring during a heatwave remains unknown.In this study, we investigated the importance of microalgal diversity and thermal history in response of phototrophic biofilms to severe heat stress. We exposed isolated microalgal strains, synthetic communities previously acclimated at three temperatures, and natural phototrophic biofilms sampled at different seasons to several temperature/duration pairs (from 31 to 44°C for 30, 60, 120 or 180 min). Microalgal photosynthetic activity (FV/FM) was measured after each heat stress and was shown to be a function of thermal dose, defined as the product of time and an exponential function of temperature.It appeared that the thermal history plays an important role in tolerance to heat stress, with synthetic communities acclimated at highest temperature being more tolerant. However, the responsiveness (i.e. the strength of the response) to heat stress was driven by the microalgal diversity of the community.Synthesis. Our analysis showed that although photosynthetic activity was negatively impacted by heat stress, gross primary productivity was even more strongly and rapidly impacted, highlighting the fact that in situ, even moderate heat stress can significantly impair primary productivity in shallow waters. [ABSTRACT FROM AUTHOR]

Microalgae are prokaryotic or eukaryotic organisms that have photosynthetic anabolic activity. This anabolic photosynthesis is related to the abiotic factor of light. Therefore, this study aimed to identify the morphological diversity level of microalgae based on their environment, especially light intensity. We collected samples based on two types of environment, namely high light community (HL-1D and HL-2D) and low light community (LL-1D and LL-2D). The Data were analyzed using Species Richness Indices (Menhinick and Margalef indices), Species Diversity (Shannon-Wiener and Simpson Indices), and Eveness Index. Based on the results of morphological identification, we found the presence of algae from the divisions Cyanophyta, Chlorophyta, and Euglenophyta in both communities. The most dominant species found in the HL environment were Cyanophyta (Chroococcus sp., Microcystis sp., Nostoc sp., Oscilatoria sp.), Chlorophyta (Actinastrum sp., Ankistrodesmus sp., Centritractus belanophorus, Coelastrum sp., Closterium sp., Gleocapsa sp., Mougeutia sp., Pediastrum sp., Scenedesmus sp., Selenastrum sp., Sphaeroplea sp., Tetraspora cylindrica, Ulothrix sp., and Volvox sp.), Euglenophyta (Cryptoglena sp. and Lepocinclis sp.). Species found in the LL environment were Cyanophyta (Bulbochaeta sp.) and Chlorophyta (Pleurotaenium sp., Uronema elongasi, and Zygnema sp.). Microalgae communities in high light communities have higher diversity than low light communities. This study can be used as a reference for the diversity of microalgae in two different types of environments, especially in the tropics and in freshwater microalgae communities. This diversity data could be a reference for researchers and provide preliminary information of microalgae potency as alternative biofuels in the future. [ABSTRACT FROM AUTHOR]

Taxonomy and classification of freshwater algae is highly dependent on morpho-taxonomic characterization and molecular genetic techniques. However, these methods are considered timeconsuming and tedious. This study was conducted to integrate the latest technological innovations of digital image processing and machine learning in developing an automated detection, recognition, and identification of selected algal species from the divisions of Chlorophyta and Cyanobacteria. OpenCV and Tensorflow (convolutional neural networks or CNN) were used in the development of a digital image identification system of common freshwater algal species (Chlorococcum infusionum, Chlorella vulgaris, Nostoc commune, Leptolyngbya lagerheimii, Desmodesmus abundans, Acutodesmus dimorphus, Oscillatoria proboscidea, and Oscillatoria limosa). Using OpenCV, digital microalgae images were subjected to image enhancement techniques for the removal of noise and other unwanted objects that minimizes image identification errors. TensorFlow classified these pre-processed images using CNN and gives the percentage results for the algal species in which it identifies each image. The developed automated image identification system correctly identified 75 images from a total of 80 selected freshwater algae images yielding a final test accuracy of 93.75%. This study exhibited for the first time in the Philippines the use of a CNN-based automated image identification system in the recognition and classification of freshwater algae. The developed system is applicable to algal culture collections and taxonomists for fast and easy identification of algal taxa and improved storage of algal images in the database. [ABSTRACT FROM AUTHOR]

Microalgae feasibility as food ingredients or source of nutrients and/or bioactive compounds and their health effects have been widely studied. This review aims to provide an overview of the use of microalgae biomass in food products, the technological effects of its incorporation, and their use as a source of health-promoting bioactive compounds. In addition, it presents the regulatory aspects of commercialization and consumption, and the main trends and market challenges Microalgae have stood out as sources of nutritional compounds (polysaccharides, proteins, lipids, vitamins, minerals, and dietary fiber) and biologically active compounds (asthaxanthin, β-carotene, omega-3 fatty acids). The consumption of microalgae biomass proved to have several health effects, such as hypoglycemic activity, gastroprotective and anti-steatotic properties, improvements in neurobehavioral and cognitive dysfunction, and hypolipidemic properties. Its addition to food products can improve the nutritional value, aroma profile, and technological properties, with important alterations on the syneresis of yogurts, meltability in cheeses, overrun values and melting point in ice creams, physical properties and mechanical characteristics in crisps, and texture, cooking and color characteristics in pastas. However, more studies are needed to prove the health effects in humans, expand the market size, reduce the cost of production, and tighter constraints related to regulations. [ABSTRACT FROM AUTHOR]

Simple Summary: The natural astaxanthin from algae (marketed only 5%) is the most powerful antioxidant for health compared to the synthetic that shares about 95% of the market. Therefore, there is a huge demand for natural astaxanthin from algae, which can accumulate significantly higher astaxanthin. We have isolated a new algal strain from the Himalayan region, Northern India, which was identified as Dysmorphococcus globosus-HI based on morphological and molecular analysis. Its growth conditions were optimized in the laboratory. Among the seven different tested culture media, MBBM and 3N-BBM provided the maximum growth and astaxanthin production. The highest biomass production (1.14 g L−1) was observed in the modified BBM medium. It is an excellent source of producing natural astaxanthin, to a tune of 391 mg L−1, which is greater than any other known algal species. The productivity of astaxanthin was about 15.6 mg L−1 d−1 under normal conditions, which is higher than the commercially used H. pluvialis species. It is the first report of natural astaxanthin production from D. globosus-HI that has great potential for commercial application. Synthesized astaxanthin (ASX), stereoisomers of 3S,3′R, 3R,3′R, and 3S,3′S, have over 95% market share and have relatively poor antioxidant and bioactivity properties, with persistent issues in terms of biological functions, health benefits, and biosafety if compared to natural ASX. Bioprospecting of new microalgal strains could be vital for a new source of powerful antioxidant (ASX). In this study, a new algal strain was isolated from the Indian foothills of the Himalayas. Its identity was discerned by morphological and DNA barcode studies. It is a unicellular spheroidal cell-shaped alga with 100–200 μm diameter. The isolate has 93.4% similarity to Dysmorphococcus globosus species based on 18S-rDNA phylogenetic analysis and named as D. globosus-HI (HI stands for Himalayan India). Its growth and major cellular components (carotenoids, carbohydrates, protein, lipids, fatty acid profile, and ASX) were optimized using the seven different culture media. The highest biomass (1.14 g L−1) was observed in the MBBM medium, with a specific growth rate (0.087 day−1), division/day (0.125), and cellular yield (6.16 x 106 cells/mL). The highest carotenoids (1.56 mg g−1), lipids (32.5 mg L−1), and carbohydrates (135.62 mg L−1) were recorded in the 3N-BBM medium. The maximum ω3-FAs (17.78%), ω6-FAs (23.11%), and ω9-FAs (7.06%) were observed in MBBM, JW, and BG-11 medium respectively. The highest amount of antioxidant ASX was accumulated in the 3N-BBM medium (391 mg L−1). It is more than any other known algal species used in the production of natural ASX. The optimized biochemical studies on the D. globosus-HI strain should fulfill the increasing demand for natural ASX for commercial application. [ABSTRACT FROM AUTHOR]

River ecosystems are widespread across the landscape through series of channels ultimately draining into the sea. Several theoretical models have provided coalescing concepts about ecosystem and biodiversity. Yet, a comparative study of phytoplankton community between the rivers is far limited and challenging. The present exploration embarks on comprehending the seasonal succession of phytoplankton community from the four major rivers such as Thenpennai, Gadilam, Vellar and Kollidam of Cuddalore district, Tamil Nadu, India. A total of 298 microalgal cultures belonging to 13 orders were isolated from the rivers from 2018 to 2019. The relative distribution indicated the dominance of species from Chlorococcales (32%), Pennales (28%), Nostocales (15%), Chroococcales (15%), and Conjugales (7%). Diversity indices results revealed variability in Gadilam and Kollidam rivers. High fluctuation in occurrence especially during the monsoon season due to sporadic rainfall. During post-monsoon season, organic parameters like magnesium, calcium, chloride, and phosphate were found to impact the population. This study encompasses a pragmatic approach to evaluate the seasonal relationship between the environmental variables and microalgal population. Our findings include the first report of Klebsormidium nitens from India. River Kollidam (29.61%) and Vellar (24.32%) recorded high species diversity across all seasons and could be a source for more potent isolates. As evident from the results of multivariate statistics, variables like phosphate, calcium, and magnesium are the most important factors in influencing the seasonal pattern of the phytoplankton population. Overall, these results provide a comprehensive database on the algal diversity and its seasonal dynamics from the major rivers of India.

Selecting the optimal microalgal strain for carbon capture and biomass production is crucial for ensuring the commercial viability of microalgae-based biorefinery processes. This study aimed to evaluate the impact of varying bicarbonate concentrations on the growth rates, inorganic carbon (IC) utilization, and biochemical composition of three freshwater and two marine microalgal species. Parachlorella kessleri, Vischeria cf. stellata, and Porphyridium purpureum achieved the highest carbon removal efficiency (>85%) and biomass production at 6 g L -1 sodium bicarbonate (NaHCO 3 ), while Phaeodactylum tricornutum showed optimal performance at 1 g L -1 NaHCO 3 . The growth and carbon removal rate of Scenedesmus quadricauda increased with increasing NaHCO 3 concentrations, although its highest carbon removal efficiency (∼70%) was lower than the other species. Varying NaHCO 3 levels significantly impacted the biochemical composition of P. kessleri, S. quadricauda, and P. purpureum but did not affect the composition of the remaining species. The fatty acid profiles of the microalgae were dominated by C16 and C18 fatty acids, with P. purpureum and P. tricornutum yielding relatively high polyunsaturated fatty acid content ranging between 14% and 30%. Furthermore, bicarbonate concentration had a species-specific effect on the fatty acid and chlorophyll-a content. This study demonstrates the potential of bicarbonate as an effective IC source for microalgal cultivation, highlighting its ability to select microalgal species for various applications based on their carbon capture efficiency and biochemical composition., (© 2024 The Author(s). Biotechnology Journal published by Wiley‐VCH GmbH.)

Synthesized astaxanthin (ASX), stereoisomers of 3S,3′R, 3R,3′R, and 3S,3′S, have over 95% market share and have relatively poor antioxidant and bioactivity properties, with persistent issues in terms of biological functions, health benefits, and biosafety if compared to natural ASX. Bioprospecting of new microalgal strains could be vital for a new source of powerful antioxidant (ASX). In this study, a new algal strain was isolated from the Indian foothills of the Himalayas. Its identity was discerned by morphological and DNA barcode studies. It is a unicellular spheroidal cell-shaped alga with 100–200 μm diameter. The isolate has 93.4% similarity to Dysmorphococcus globosus species based on 18S-rDNA phylogenetic analysis and named as D. globosus-HI (HI stands for Himalayan India). Its growth and major cellular components (carotenoids, carbohydrates, protein, lipids, fatty acid profile, and ASX) were optimized using the seven different culture media. The highest biomass (1.14 g L−1) was observed in the MBBM medium, with a specific growth rate (0.087 day−1), division/day (0.125), and cellular yield (6.16 x 106 cells/mL). The highest carotenoids (1.56 mg g−1), lipids (32.5 mg L−1), and carbohydrates (135.62 mg L−1) were recorded in the 3N-BBM medium. The maximum ω3-FAs (17.78%), ω6-FAs (23.11%), and ω9-FAs (7.06%) were observed in MBBM, JW, and BG-11 medium respectively. The highest amount of antioxidant ASX was accumulated in the 3N-BBM medium (391 mg L−1). It is more than any other known algal species used in the production of natural ASX. The optimized biochemical studies on the D. globosus-HI strain should fulfill the increasing demand for natural ASX for commercial application.

Aquatic ecosystems represent one of the largest reservoirs of phytoplankton accounting for most of the primary production of the Earth. The Lake Massaciuccoli located in Tuscany (Italy) is one of the largest swamps that in ancient times entirely covered the Versilia coastal plain. Despite its peculiar features, especially the eutrophic characteristics, its native microalgal consortia have never been explored up to now. In this work, we isolated and described four autochthonous microalgal strains from different sites in the lake (FB, Idr, CL_Sc, and CL_Ch); the four microalgal strains were identified within the Chlorella sorokiniana clade. We exposed them to ten of the most common or emerging environmental contaminants in order to describe their preliminary response to the tested substances: five metals (As, Fe, Ni, Cu, and Zn), two herbicides (Metolachlor and Sethoxydim), two antibiotics (Ciprofloxacin and Benzylpenicillin) and a non-steroidal anti-inflammatory drug (Ibuprofen). Physiological response of the strains highlighted intraspecific differences; strain CL_Sc was the most tolerant in presence of metals while strain Idr was the most sensitive. All strains were sensitive to sethoxydim and tolerant to metolachlor at all the tested concentrations. Strains FB and Idr were the most sensitive in presence of Ibuprofen while strain CL_Ch was the most sensitive to the highest Benzylpenicillin concentration. Resistance pattern of strain Idr somehow reflects both the phylogenetic and the geographic “isolation” from all other three strains. Finally, optical microscope observation confirmed some differences also in the microalgae morphological aspect. Overall, all the strains showed interesting responses in presence of high concentrations of the tested substances, representing putative interesting candidates for water remediation in wastewater treatment plants.

Aquatic ecosystems represent one of the largest reservoirs of phytoplankton accounting for most of the primary production of the Earth. The Lake Massaciuccoli located in Tuscany (Italy) is one of the largest swamps that in ancient times entirely covered the Versilia coastal plain. Despite its peculiar features, especially the eutrophic characteristics, its native microalgal consortia have never been explored up to now. In this work, we isolated and described four autochthonous microalgal strains from different sites in the lake (FB, Idr, CL_Sc, and CL_Ch); the four microalgal strains were identified within the Chlorella sorokiniana clade. We exposed them to ten of the most common or emerging environmental contaminants in order to describe their preliminary response to the tested substances: five metals (As, Fe, Ni, Cu, and Zn), two herbicides (Metolachlor and Sethoxydim), two antibiotics (Ciprofloxacin and Benzylpenicillin) and a non-steroidal anti-inflammatory drug (Ibuprofen). Physiological response of the strains highlighted intraspecific differences; strain CL_Sc was the most tolerant in presence of metals while strain Idr was the most sensitive. All strains were sensitive to sethoxydim and tolerant to metolachlor at all the tested concentrations. Strains FB and Idr were the most sensitive in presence of Ibuprofen while strain CL_Ch was the most sensitive to the highest Benzylpenicillin concentration. Resistance pattern of strain Idr somehow reflects both the phylogenetic and the geographic "isolation" from all other three strains. Finally, optical microscope observation confirmed some differences also in the microalgae morphological aspect. Overall, all the strains showed interesting responses in presence of high concentrations of the tested substances, representing putative interesting candidates for water remediation in wastewater treatment plants. [ABSTRACT FROM AUTHOR]

Since nanomaterials (NMs) are particulate contaminants, their first contact with organisms is a physical encounter ruled by physic-chemical processes that can determinate the potential NMs accumulation, toxicity, and trophic transfer. Freshwater ecosystems often become a final depository for NMs, so they can get in contact with the biota, especially primary organisms as algae. There are almost none comparative studies of this interaction using various NMs in the same conditions. This work identifies, analyzes, and compares the algae–NMs interaction by flow cytometry after a short-term contact test in which three freshwater algae (Raphidocelis subcapitata, Desmodesmus subspicatus, and Chlorella vulgaris) interact individually with a set of twelve metallic oxide NMs. Dose–response profiles and differences in the algae–NMs interaction were found according to each algae species (C. vulgaris had the most affinity, starting the interaction from 0.5 mg/L and D. subspicatus had the less affinity starting at 5 mg/L). Flow cytometry results were confirmed by optical microscopy. Some NMs characteristics were identified as key-factors that govern the algae–NMs interaction: NMs composition (no interaction for SiO2 NMs), surface electric charge (higher interaction for the positively charged NMs and lower interaction for the negatively charged ones) and crystalline form (for TiO2 NMs). The presented method can be useful for a rapid determination of the interaction between free cells organisms as microalgae and (nano)particulate substances. [ABSTRACT FROM AUTHOR]

• Individual exposure to PS-NPs or PAHs showed no significant effect on C. reinhardtii. • High PS-NPs and PAHs concentrations inhibited growth and increased ROS levels on C. reinhardtii. • Algae were less oxidative damaged by combined PS-NPs + PAHs than by PS-NPs or PAHs individually. • The accumulation of PAHs in C. reinhardtii decreased in the presence of high PS-NPs concentration. While the toxicity of nano-microplastics and polycyclic aromatic hydrocarbons (PAHs) to aquatic organisms is well-studied, their joint impact on microalgae is less explored. This study focused on single and combined effects of PS-NPs (30 nm; concentrations: 2, 5, 10, and 25 mg/L) and two PAHs (chrysene and fluoranthene at 10, 100 µg/L) for 96 h on the accumulation, growth, photosynthetic parameters, and oxidative stress in the Chlamydomonas reinhardtii. The findings revealed that exposure to increasing concentrations of PS-NPs significantly reduced the growth inhibition ratio and chlorophyll- a content after 96 h. Both PAHs (100 µg/L) + PS-NPs (25 mg/L), significantly reduced the growth inhibition ratio and chlorophyll- a levels. Individual and combined exposures of PS-NPs and PAHs can prompt antioxidant responses like SOD, GPx, and GST, as well as an unaffected level of non-enzymatic antioxidant GSH and diminished CAT activity. Furthermore, both PAHs + PS-NPs triggered ROS levels, resulting in cell membrane damage. However, the reduced oxidative effect of LPO of combined exposures can be attributed to the activation of antioxidant defenses. In addition, the microscopic visualization data shows that PS-NPs adhered to the surface of microalgae. Also, PS-NPs reduced the adsorption of PAHs on the surface of C. reinhardtii. Altogether, this study implied that the influence of coexistent PS-NPs should be considered in the environmental risk assessment of PAHs in aquatic environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Heavy metals have adverse effects on microalgae metabolism and growth. Photosynthesis and lipid profile are quite sensitive to heavy metal toxicity. The impact of hexavalent chromium—Cr(VI) on photosynthesis and lipid accumulation in Mucidosphaerium pulchellum and Micractinium pusillum exposed to different concentrations (0–500 μg L−1) was investigated for 11 days. A significant (p < 0.05) increase in lipid content was observed with increasing Cr(VI) concentration. However, growth was suppressed at higher concentrations exceeding 100 μg L−1. Addition of Cr(VI) in the cell culture medium showed a negative effect on quantum yield (Fv/Fm), and a photosynthetic inhibition of >65% was noted in both species at 500 μg L−1. However, the lipid gravimetric analysis presented inner cell lipid content up to 36% and 30% of dry weight biomass for M. pulchellum and M. pusillum, respectively. The fatty acids profiles of both microalgae species showed higher levels of hexadecenoic acid as well as ω3, ω6, and ω7 fatty acids. The effect of Cr(VI) on photosynthesis and lipid accumulation in both microalgae species was concentration and exposure time dependent. This shows that an appropriate concentration of Cr(VI) in culture medium could be beneficial for higher lipid accumulation in freshwater eukaryotic microalgae species.

Highlights • Interaction of carboxylated polystyrene nanoparticles with copper and algae. • No adsorption of copper ions observed on PS-COOH NPs. • Alteration of PS-COOH NPs surface charge and hydrodynamic diameter support eco-corona formation. • PS-COOH food chain transfer plausible due to NPs ability to interact with algal exudates and adhere to algal cell wall. • Additional endpoints and longer exposure scenarios recommended for nanoplastics risk assessment. Abstract Nanoplastics are recognized as able to interact with other pollutants including heavy metals, and with natural organic matter, with implications for the potential risks to biota. We investigated the interaction of carboxylated polystyrene nanoparticles (PS–COOH NPs) with copper (Cu) and algal exudates (EPS) and how such interaction could affect Cu toxicity towards the freshwater microalga Raphidocelis subcapitata. PS–COOH NPs behavior in the presence of Cu and EPS was determined by dynamic light scattering (DLS), while PS–COOH NPs surface interaction with Cu ions and EPS was investigated by fluorimetric analysis. ICP-MS was used to test Cu ion adsorption to PS–COOH NPs in the presence and absence of algae. The interaction between PS–COOH NPs and the algal cell wall was assessed by fluorescence microscopy. Short- and long-term toxicity tests were carried out in parallel to assess the impact of PS–COOH NPs on algal growth. Results showed altered nanoparticle surface charge and hydrodynamic diameter following algal EPS exposure, supporting the hypothesis of a protein corona formation. In contrast, no absorption of Cu ions was observed on PS–COOH NPs, either in the presence or absence of algae. No differences on algal growth inhibition were observed between exposure to Cu only, and to Cu in combination with PS–COOH NPs, in short-term as well as long-term tests. However, after 72 h of exposure, the adsorption of PS-COOH NPs to algal cell walls appeared to correspond to morphological alterations, revealing potential disturbances in the mitotic cycle. Our findings confirm the ability of PS–COOH NPs to interact with EPS as shown for other nanomaterials. Environmentally realistic exposure scenarios are thus needed for evaluating nanoplastic toxicity, as nanoparticles will not maintain their pristine nature once released into natural media. Prolonged exposure and use of different end-points such as cell morphological changes and EPS production seem more reliable for the investigation of nanoplastic/algal cell interactions which can drive food chain transfer of nanoplastics and ultimately toxicity. [ABSTRACT FROM AUTHOR]

This study aimed to investigate fatty acid content and productivity of the insufficiently investigated group of freshwater microalgae—desmids (Zygnematophyceae, Streptophyta)—and to estimate their commercial potential. A total of 29 desmid strains of various environmental preferences were grown in standard cultivation conditions to assess fatty acid concentration and composition and biomass productivity during the growth phases. Six desmid strains belonging to Cosmarium crenatum var. boldtianum, C. meneghinii, C. regnellii var. pseudoregnellii, C. leave, Staurastrum boreale, and S. punctulatum had distinctly high total fatty acid contents (> 200 mg g−1 dry weight), among which C. crenatum had by far the highest average of total fatty acids (308.1 mg g−1 dry weight). Despite that desmids were grown in a medium which was not enriched with nutrients and CO2, these six strains achieved moderate biomass productivity (up to 0.14 g dry weight L−1 day−1), while the fatty acid productivity was in the range 8–11.1 mg L−1 day−1. The relatively high amounts of linoleic and palmitic acids in C. crenatum var. boldtianum and C. meneghinii were comparable to those found in several commercially grown plants, indicating that fatty acid extracts of these desmids could be utilized in cosmetics, pharmacy, medicine, or in additional industrial applications. On the other hand, the high proportion of oleic acid in a new isolate of Staurastrum boreale, along with its relatively high biomass productivity and cell size, pointed that this strain might be used for further investigations regarding biodiesel production. [ABSTRACT FROM AUTHOR]

Highlights • ZnO NPs induced growth inhibition toxicity and structural damage to freshwater algae. • ZnO NPs and TBBPA synergistically caused oxidative stress in the algal cells. • DOM alleviated oxidative damage causedby the binary mixtures of ZnO NPs and TBBPA. • Chloroplast was the main site of production of reactive oxygen species. Abstract The present study investigated the impacts of dissolved organic matters (DOM) on joint toxicity involved in zinc oxide nanoparticles (ZnO NPs) and tetrabromobisphenol A (TBBPA) at relevant low-exposure concentrations (<1 mg/L). It was found that ZnO NPs in single and combined systems exhibited severe inhibition effects on a freshwater microalgae Scenedesmus obliquus. However, the presence of DOM slightly alleviated the growth inhibition toxicity induced by the binary mixtures of ZnO NPs and TBBPA. Ultrastructure analysis revealed that ZnO NPs caused structural damage to cells, including plasmolysis, membrane destruction, and the disruption of thylakoid in the chloroplast, regardless of the presence of coexisting substances. Oxidative stress biomarker quantitative analysis and in situ observations indicated that the massive accumulation of reactive oxygen species in the binary mixtures of ZnO NPs and TBBPA caused severe oxidative damage, but the presence of DOM significantly mitigated the damage. [ABSTRACT FROM AUTHOR]

the research aim of this study was to characterize an isolated native strain of Chlorella sp. ACUF_802, well adapted to a high nitrate concentration environment and to investigate its potential to nitrate and phosphate removal from industrial wastewaters with the minimal addition of chemical reagents and energy. The isolated strain was identified and evaluated for its capability to support biomass growth and nutrient removal from synthetic wastewater in batch tests using different concentrations of carbon and nitrogen, different carbon sources and N:P ratios. The strain was isolated via the plating method from the settler of a pilot scale moving bed biofilm reactor performing a nitrification process. The strain was identified using molecular analysis with rDNA primers. Using sodium bicarbonate as carbon source, the batch productivity (71.43 mg L−1 day−1) of the strain Chlorella sp. ACUF_802 was calculated with a logistic model and compared to the values reported in the literature. Assays on the effect of the N:P ratio indicated that the productivity was increased 36% when the N:P ratio was close to 1 (111.96 mg L−1 day−1), but for a complete phosphorus removal a 5:1 N:P ratio with nitrate concentrations ≤125 mg∙L−1 is recommended. The isolated microalgae strain Chlorella sp. ACUF_802 showed versatility to grow in the synthetic industrial wastewaters tested and can be considered as an appropriate organism for nitrogen removal from industrial wastewaters in the presence of an organic or inorganic carbon source. [ABSTRACT FROM AUTHOR]

Lutein is the most abundant xanthophylls in the photosynthetic organisms and its dietary intake is thought to protect against the development of age-related macular degeneration. Microalgae are predicted to be the major contributors of lutein in the future and to date, various species of microalgae has been analyzed for its lutein content. This study examined the lutein content of six chlorophycean microalgae species grown in the laboratory culture under the comparable environmental condition in which the population doubling time (td) as well as the maximum growth rate (μmax) for each species was evaluated. Using batch culture operation grown under the heteroautotrophic condition, Scenedesmus dimorphus was observed to accumulate the highest lutein content (60.11 mg/g) with maximal biomass of 0.349 g/L culture. Based on the observations available, it appears that strains of unicellular microalgae of smaller size have appreciably higher intrinsic growth rates than algae of the larger size (Chlorella sp. B > Chlorella sp. TLL > Scenedesmus dimorphus > Scenedesmus obliquus TLL > Desmodesmus sp. TH > Ankistrodesmus sp. TH). [ABSTRACT FROM AUTHOR]

Copyright of News of Kazakhstan Science / Novosti nauki Kazahstana is the property of NCSTE (JSC National Center for State Scientific and Technical Evaluations) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pharmaceuticals are found in freshwater ecosystems where even low concentrations in the range of ng L −1 may affect aquatic organisms. In the current study, we investigated the effects of chronic exposure to three pharmaceuticals on two microalgae, a potential modulation of the effects by additional inorganic phosphorus (P i ) limitation, and a potential propagation of the pharmaceuticals’ effect across a trophic interaction. The latter considers that pharmaceuticals are bioaccumulated by algae, potentially metabolized into more (or less) toxic derivates and consequently consumed by zooplankton. We cultured Acutodesmus obliquus and Nannochloropsis limnetica in P i -replete and P i -limited medium contaminated with one of three commonly human used pharmaceuticals: fluoxetine, ibuprofen, and propranolol. Secondly, we tested to what extent first level consumers (Daphnia magna) were affected when fed with pharmaceutical-grown algae. Chronic exposure, covering 30 generations, led to (i) decreased cell numbers of A. obliquus in the presence of fluoxetine (under P i -replete conditions) (ii) increased carotenoid to chlorophyll ratios in N. limnetica (under P i -limited conditions), and (iii) increased photosynthetic yields in A. obliquus (in both P i -conditions). In addition, ibuprofen affected both algae and their consumer: Feeding ibuprofen-contaminated algae to P i -stressed D. magna improved their survival. We demonstrate, that even very low concentrations of pharmaceuticals present in freshwater ecosystems can significantly affect aquatic organisms when chronically exposed. Our study indicates that pharmaceutical effects can cross trophic levels and travel up the food chain. [ABSTRACT FROM AUTHOR]

Freshwater microalgae that contained high starch, carbohydrates and lipids contents are beneficial to human being in many industrial especially in food and food packing industries. There are a few freshwater microalgae that contained high starch and carbohydrates content such as Chlorella vulgaris, Chlorella emersonii, Chlorella sorokiniana, Nannochloropsis salina and Spirulina sp. Spirulina sp. is chosen in this research because of its strong adaptation to the environment changes, short life cycle and able to produce high intracellular starch. In this project, results have shown that microalgae at late exponential phase contained the highest starch and carbohydrate yield of 0.491±0.046 mg/L and 0.090±0.046 mg/L, respectively. Thus, the harvesting time for microalgae with high starch production and yield is phase dependent rather than time dependent. Under optimized cultivation conditions of aeration at 5 L/min, using white wavelength and 32°C, Spirulina sp. produced the highest starch and carbohydrate yield of 0.664±0.03 mg/L, and 1.019±0.025 mg/L, respectively. In conclusion, compared to before optimization, starch and carbohydrate yield after optimizations were increased. In conclusion, compared to before optimization, starch and carbohydrate yield after optimization were 435% and 221% increased, respectively. [ABSTRACT FROM AUTHOR]

Microalgae exhibit great potential for biomass production. Although microalgae display an enormous biodiversity, surprisingly only 15 species are used for large scale production processes worldwide. The implementation of new production strains with good process-oriented properties, especially fast growth rate and heat resistance, could improve production efficiency and reduce costs. In this study 130 environmental samples collected in Germany, Spain, Italy and Portugal were investigated for fast growing thermotolerant photosynthetic species. Isolates were characterized and identified on a molecular level. In total 21 of the isolated freshwater strains were able to grow at 40 °C. Additionally, 13 of those 21 strains are able to grow at 45 °C. The highest growth rate at room temperature was 1.16 per day (isolate T306A), compared to 0.053 per day at 45 °C (isolate Sp13). In three thermotolerant strains pigment production was induced. Molecular identification by 18S rDNA sequencing revealed that the isolates were all chlorophytes belonging to four different families.

This study for the first time reports on fresh water microalgae Chlorella minutissima aqueous extract (CmAe) which was utilized for the biogenic synthesis of silver nanoparticles and tested their antineoplastic potential against Liver Hepatocellular Carcinoma (HepG2) cell line. The characteristic colour change of the reaction mixture from greenish yellow to yellowish brown confirmed the synthesis of Chlorella minutissima silver nanoparticles (CmAgNPs). Microscopic analysis revealed CmAgNPs to be spherical‐shaped with particle size ranging from 10 to 30 nm. The carbohydrates and proteins distinctive peaks were observed in Fourier transform infrared spectroscopy (FTIR) spectra which suggested these biomolecules acted as reducing and capping agents. Further, the crystalline nature of CmAgNPs was confirmed by X‐ray diffraction (XRD) analysis. CmAgNPs showed maximum free radical scavenging proving it to be more potent antioxidant agent as compared to CmAe. The mortality rate of HepG2 cells treated with CmAgNPs was found to be 91.8 % at 120 μg/ml with IC50 value 12.42 ± 1.096 μg/ml after 48 h whereas no effect was observed on normal Human Embryonic Kidney (HEK 293) cells. Fluorescent images of the treated HepG2 cells revealed the formation of apoptotic bodies, condensed nuclei and cell shrinkage indicating their effectiveness against the cancer cells. [ABSTRACT FROM AUTHOR]

Promising biological objects containing the maximum amounts of lipids were selected for further study based on an analysis of published studies on the quantitative and qualitative composition of lipids accumulating in microalgae. The genera Navicula and Isochrysis were found to be most optimal for liquid biofuel production because they contained the maximum percentage of triacylglycerides in the total lipids. Freshwater species of these microalgae genera can be considered most suitable for cultivation in CFD bioreactors as a primary product of biofuel production. Innovative methods using vortex devices are proposed for removing the algal oil. [ABSTRACT FROM AUTHOR]

The Culture Collection of Freshwater Microalgae (CCMA-UFSCar, Coleção de Culturas de Microalgas de Água-Doce), based at the Universidade Federal de São Carlos, plays an important role in underpinning Brazilian microalgal research, providing biological materials, substrates and training personnel for a large proportion of the past and current projects in this area. However, recent efforts to expand the culture catalogue/holdings have reached a ceiling because of the logistical practicality of maintaining actively growing cultures. In order to reduce the costs associated with the maintenance regime of cultures, efforts were initiated on the establishment of a cryopreserved biobank for long term maintenance of cultures, thus minimizing the efforts associated with handling of material, as successfully frozen cultures, in theory, could be maintained effectively indefinitely, with the advantage of the stability of cells characteristics. Initial tests were performed on 93 strains including exemplar taxa across the different taxonomic groups in the collection catalogue. The highest levels of success were achieved for the smaller taxa, such as the small green algae; while for the larger and more complex organisms limited to no success was obtained. For the strains tested, over 70% had positive good levels of post-thaw viability and regenerated phenotypically normal cultures. [ABSTRACT FROM AUTHOR]

The objective of this study is to select and characterize the candidate for synchronous water purification and lipid production from eight freshwater microalgae strains ( Chlorella sp. HQ, C. emersonii, C. pyrenoidosa, C. vulgaris, Scenedesmus dimorphus, S. quadricauda, S. obiquus, Scenedesmus sp. LX1). The strains Chlorella sp. HQ, C. pyrenoidesa, and S. obliquus showed superiority in biomass accumulation, while the top biomass producers did not correspond to the top lipid producers. S. quadricauda achieved higher lipid content (66.1%), and Chlorella sp. HQ and S. dimorphus ranked down in sequence, with lipid content above 30%. Considering nutrient removal ability (total nitrogen (TN): 52.97%; total phosphorus (TP): 84.81%), the newly isolated microalga Chlorella sp. HQ was the possible candidate for water purification coupled with lipid production. To further investigate the lipid producing and nutrient removal mechanism of candidate microalga, the ultra structural changes especially the lipid droplets under different water qualities (different TN and TP concentrations) were characterized. The results elucidate the nutrient-deficiency (TN: 3.0 mg·L; TP: 0.3 mg·L) condition was in favor of forming lipid bodies in Chlorella sp. HQ at the subcellular level, while the biomass production was inhibited due to the decrease in chloroplast number which could further suppress the nutrient removal effect. Finally, a twophase cultivation process (a nutrient replete phase to produce biomass followed by a nutrient deplete phase to enhance lipid content) was conducted in a photo-bioreactor for Chlorella sp. HQ to serve for algae-based synchronous biodiesel production and wastewater purification. [ABSTRACT FROM AUTHOR]

Microalgal biomass is a potentially attractive source of several bioproducts, such as carbonic anhydrase, the enzyme responsible for catalyzing the reversible hydration of CO2. This biomolecule has been studied for its application in enzymatic systems of CO2capture and sequestration. Therefore, the aims of this study were to evaluate the production of carbonic anhydrase in the culture of marine and freshwater microalgae and to monitor the growth in terms of biomass and pH. The marine microalgaeDunaliella tertiolecta,Tetraselmis suecica,Phaeodactylum tricornutum,Isochrysis galbanaandNannochloropsis oculata, and the freshwater microalgaeChlorella vulgarisandScenedesmus obliquuswere cultured in Erlenmeyer flasks at 25 °C. The freshwater microalga that had the highest enzyme production wasC. vulgaris: its maximum activity was 44.0 U/L. Among the marine microalgae,P. tricornutumstood out as the best producer, with a maximum activity of 19.9 U/L. In terms of specific activity, the highest values were obtained fromD. tertiolecta(44.6 U/g) andP. tricornutum(24.5 U/g). These results show the potential of microalgae to produce the carbonic anhydrase enzyme. Microalgal biomass represents an attractive source of this biomolecule. [ABSTRACT FROM AUTHOR]

Microalgae offer the potential to sequestrate CO 2 and reduce the world's dependency on fossil fuels, thereby mitigating the greenhouse gas effect, which has resulted in climate change over time. Carbon is one of the critical nutrients for microalgae growth and product formation; the choice of carbon and pH control techniques has been identified as the key to improving the sustainability of microalgae cultivation. However, supplying CO 2 in the gas phase is not cost-effective and could be counterproductive as a high percentage could be lost back to the atmosphere due to low solubility in the medium. Additionally, using conventional pH control techniques such as acid, base, and buffers is expensive at scale. This study assessed freshwater Chlorella sorokiniana cultivation using NaHCO 3 solely as the inorganic carbon and for pH modulation. The investigation focuses on the effect of bicarbonate feed rates and culture starting pH in the acidic, neutral, and basic regimes on the pH modulation, biomass accumulation, and product yield in a fed-batch system. The final pH increased beyond the upper limit threshold for each pH regime, with the highest level of control achieved in the basic regime (7.50–8.48 ± 0.11). The maximum biomass accumulation reached 2.49 g/L and a doubling time of 49 h. Evaluation of the pigment showed a higher chlorophyll a content, 25.85 mg/L, similar to a CO 2 -fed culture and higher than the bicarbonate culture reported. The lipid contents showed a fatty acid composition suitable for biodiesel production with a higher percentage of saturated fatty acids (SFAs) (62.93 %–90.86 %) across all conditions. The sole use of bicarbonate for simultaneous inorganic carbon supply and pH control can be a cost-effective measure without compromising biomass and lipid productivities. • Freshwater C. sorokiniana was phototrophically cultured solely with NaHCO 3 without conventional pH control. • The highest level of pH control was obtained at the basic culture pH region. • The maximum chlorophyll a concentration of 25.85 mg/L was relatively higher than those reported in other bicarbonate culture. • The fatty acid composition showed a higher percentage of saturated fatty acids. [ABSTRACT FROM AUTHOR]

Microalgae exhibit great potential for biomass production. Although microalgae display an enormous biodiversity, surprisingly only 15 species are used for large scale production processes worldwide. The implementation of new production strains with good process-oriented properties, especially fast growth rate and heat resistance, could improve production efficiency and reduce costs. In this study 130 environmental samples collected in Germany, Spain, Italy and Portugal were investigated for fast growing thermotolerant photosynthetic species. Isolates were characterized and identified on a molecular level. In total 21 of the isolated freshwater strains were able to grow at 40 °C. Additionally, 13 of those 21 strains are able to grow at 45 °C. The highest growth rate at room temperature was 1.16 per day (isolate T306A), compared to 0.053 per day at 45 °C (isolate Sp13). In three thermotolerant strains pigment production was induced. Molecular identification by 18S rDNA sequencing revealed that the isolates were all chlorophytes belonging to four different families. [ABSTRACT FROM AUTHOR]

Astaxanthin, a carotenoid pigment found in several aquatic organisms, is responsible for the red colour of salmon, trout and crustaceans. In this study, astaxanthin production from freshwater microalga Chlorella sorokiniana and marine microalga Tetraselmis sp. was investigated. Cell growth and astaxanthin production were determined spectrophotometrically at 620 and 480 nm, respectively. Astaxanthin was extracted using acetone and measured subsequent to biomass removal. Aerated conditions favoured astaxanthin production in C. sorokiniana, whereas Tetraselmis sp. was best cultured under unaerated conditions. C. sorokiniana produced more astaxanthin with the highest yield reached at 7.83 mg/l in 6.0 mM in nitrate containing medium compared to Tetraselmis sp. which recorded the highest yield of only 1.96 mg/l in 1.5 mM nitrate containing medium. Production in C. sorokiniana started at the early exponential phase, indicating that astaxanthin may be a growth-associated product in this microalga. Further optimization of astaxanthin production was performed using C. sorokiniana through a 2 full factorial experimental design, and a yield of 8.39 mg/l was achieved. Overall, the study has shown that both microalgae are capable of producing astaxanthin. Additionally, this research has highlighted C. sorokiniana as a potential astaxanthin producer that could serve as a natural astaxanthin source in the current market. [ABSTRACT FROM AUTHOR]

The algal culture collection of the University of the Philippines Los Baños-Museum of Natural History (ACC-UPLB-MNH) is one of the oldest (47 years old) and one of the largest freshwater resources of microalgal cultures in the Philippines. It is supporting researchers, students, and teachers in the academe, as well as those involved in biotechnological applications of microalgae and those engaged in commercial/economic productions. At present it holds 86 strains distributed in three algal divisions, i.e., the Cyanophyta (15 genera and 32 species and varieties), Chlorophyta (six genera and six species), and Bacillariophyta (two genera and two species). [ABSTRACT FROM AUTHOR]

Microalgae are considered as a promising feedstock for biomass production. The selection of the most suitable species is based on several key parameters such as lipid and fatty acid productivity. In the present study, the growth of different microalgae strains was examined in freshwater media for photoautotrophs suited for large-scale applications to identify the most suitable medium for each species. In the optimal medium, Scenedesmus obliquus showed the highest biomass productivity measured as increase of cell dry weight (0.25 g cellu dry weight (CDW) L day), while Botryococcus braunii showed the highest lipid and total fatty acid content (430 and 270 mg g CDW, respectively) among the tested species. Regarding lipid and total fatty acid productivity, S. obliquus was the most lipid and total fatty acid productive strain with 41 and 18 mg L day during the exponential phase, respectively. Additionally, the proportion of saturated and monounsaturated fatty acids increased with duration of the incubation in S. obliquus, while polyunsaturated fatty acids decreased. These results nominate S. obliquus as a promising microalga in order to serve as a feedstock for renewable energy production. [ABSTRACT FROM AUTHOR]

Two freshwater microalgae including Chlamydomonas mexicana and Scenedesmus obliquus were grown on Bold Basal Medium (BBM) with different levels of salinity up to 100 mM NaCl. The dry biomass and lipid content of microalgae were improved as the concentration of NaCl increased from 0 to 25 mM. Highest dry weight (0.8 and 0.65 g/L) and lipid content (37 and 34 %) of C. mexicana and S. obliquus, respectively, were obtained in BBM amended with 25 mM NaCl. The fatty acid composition of the investigated species was also improved by the increased NaCl concentration. At 50 mM, NaCl palmitic acid (35 %) and linoleic acid (41 %) were the dominant fatty acids in C. mexicana, while oleic acid (41 %) and α-linolenic acid (20 %) were the major fractions found in S. obliquus. [ABSTRACT FROM AUTHOR]

The widespread increase of pesticides application in crops frequently leads to the contamination of freshwater ecosystems. Betanal Expert® is a post-emergent herbicide which retards the emergence of shoots, inhibits the growth of meristems and cell division, and limits the waxy cuticle formation. Phytoplankton (micro-algae) and zooplankton (micro-invertebrates) have long been used as suitable groups to assess the impact of environmental change, in part due to their position in the trophic food web. This study aims to determine the Betanal Expert® thresholds which inhibit the growth of three freshwater green microalgae - Pseudo- kirchneriella subcapitata (Korshikov) Hindak, Chlorella vulgaris Beijerinck and Chlamydomonas pseudocostata Pascher & Jahoda - as well as the acute toxicity effects on two freshwater cladoceran species - Daphnia magna Straus and Daphnia longispina O. F. Müller. P. subcapitata showed to be the most sensitive alga and C. pseudo-costata the most tolerant to this agrochemical (EC50 3.22 and 266 μg.L-1, correspondingly). The EC50 value determined for C. vulgaris was 22.5 μg.L-1. Acute tests demonstrated that D. magna is more tolerant than D. longispina (EC50 4.45 and 2.73 mg.L-1, respectively) to the toxicant. The results of this work suggest that the application of this herbicide for weed control in agricultural practices must be done carefully, since any disturbance affects planktonic species with similar or higher sensitivity which may have severe repercussions on higher trophic levels. [ABSTRACT FROM AUTHOR]