Marine Microalgae Research Articles

Using δFIP as a potential biomarker for risk assessment of environmental pollutants in aquatic ecosystem: A case study of marine cyanobacterium Synechococcus sp. PCC7002

Increased hazardous substances application causes more environmental pollution and risks for human health. Microalgae are the important biological groups in marine ecosystem, and considered to be sensitive to environmental pollutants. Therefore, toxicity test on marine microalgae could provide the most efficient method for aquatic toxicity assessment, and could also be used as the early warning signals in aquatic ecosystem. In view of this, our study aimed at investigating the toxicity potential of two typical organic compounds, and screening out novel photosynthetic indicators for the risk assessment of environmental pollutants. In this study, benzyl alcohol and 2-phenylethanol were chosen as the target organic compounds, and preliminary toxicity mechanism of these organic compounds on marine cyanobacterium Synechococcus sp. PCC7002 was investigated with chlorophyll fluorescence technology. Results showed that PCC7002 could be affected by benzyl alcohol or 2-phenylethanol stress, and the toxicity effect was concentration-dependent. And external benzyl alcohol and 2-phenylethanol stress damaged the oxygen evolving complex, and suppressed electron transport at the donor and receptor sides of photosystem II (PSII), influencing the absorption, transfer, and application of light energy. Furthermore, potential biomarkers were screened by half maximal inhibitory concentration (IC50) on the basis of pearson correlation coefficient analysis, and fluorescence intensity difference between the I-step and P-step of OJIP curve (δFIP) seems to be the most sensitive indicator for external stress. This study would be of significant interest to the biomarker community, and pave the way for the practical resource for marine pollution monitoring and assessment.

Simultaneous photoautotrophic production of DHA and EPA by Tisochrysis lutea and Microchloropsis salina in co-culture

Marine microalgae have received much attention as a sustainable source of the two health beneficial omega-3-fatty acids docosahexaenoic acid (DHA, C22:6) and eicosapentaenoic acid (EPA, C20:5). However, photoautotrophic monocultures of microalgae can only produce either DHA or EPA enriched biomass. An alternative may be the photoautotrophic co-cultivation of Tisochrysis lutea as DHA-producer with Microchloropsis salina for simultaneous EPA production to obtain EPA- and DHA-rich microalgae biomass in a nutritionally balanced ratio. Photoautotrophic co-cultivation processes of T. lutea and M. salina were studied, applying scalable and fully controlled lab-scale gas-lift flat-plate photobioreactors with LED illumination for dynamic climate simulation of a repeated sunny summer day in Australia [day–night cycles of incident light (PAR) and temperature]. Monocultures of both marine microalgae were used as reference batch processes. Differences in the autofluorescence of both microalgae enabled the individual measurement, of cell distributions in co-culture, by flow cytometry. The co-cultivation of T. lutea and M. salina in artificial sea water with an inoculation ratio of 1:3 resulted in a balanced biomass production of both microalgae simultaneously with a DHA:EPA ratio of almost 1:1 (26 mgDHA gCDW−1, and 23 mgEPA gCDW−1, respectively) at harvest after depletion of the initially added fertilizer. Surprisingly, more microalgae biomass was produced within 8 days in co-cultivation with an increase in the cell dry weight (CDW) concentration by 31%, compared to the monocultures with the same amount of light and fertilizer. What is more, DHA-content of the microalgae biomass was enhanced by 33% in the co-culture, whereas EPA-content remained unchanged compared to the monocultures.Graphical

Polystyrene nanoplastics alleviate the toxicity of CuO nanoparticles to the marine algae Platymonas helgolandica var. tsingtaoensis

The increasing presence of pollutants such as engineered nanoparticles (ENPs) and nanoplastics (NPLs) poses potential risks to the marine environment. However, there is a scarcity of information on their joint toxic effects. In this study, we investigated the toxicity of copper oxide nanoparticles (nCuO) combined with polystyrene nanoplastics (PS-NPLs) on the marine microalgae Platymonas helgolandica var. tsingtaoensis. The inhibitory effect of nCuO increased with increasing concentrations, and nCuO ≥ 100 mg/L significantly restrained the growth and chlorophyll content of microalgae. nCuO could be adsorbed by algal cells, which was responsible for membrane lipid oxidation and the disruption of membrane permeability. Simultaneous exposure to nCuO and PS-NPLs had a.n antagonistic effect on the growth inhibition of the microalgae, and nCuO played a leading role in the joint toxicity of nCuO and PS-NPLs. In comparison to nCuO exposure alone, combined exposure decreased the oxidative stress and alleviated the increase in the cell membrane permeability of microalgae. PS-NPLs could heteroaggregate with nCuO, which reduced the interaction between nCuO and microalgae, inducing decreased joint toxicity. Findings of this study will clarify our understanding of the joint toxicity of ENPs and NPLs.

Identification and characterization of <italic>Dunaliella salina</italic> OH214 strain newly isolated from a saltpan in Korea

Carotenoids are effective antioxidants that are found in various photosynthetic organisms. Marine microalgae are an advantageous bioresource for carotenoid production because they do not compete with other crops for freshwater and arable land. This study reports a newly isolated Dunaliella strain from the Geumhong Saltpan on Yeongjong Island, West Sea, Korea. The new strain was isolated and classified as Dunaliella salina through phylogenetic analysis and was named the OH214 strain (Deposit ID: KCTC14434BP). The newly isolated strain can survive in a wide range of NaCl concentrations (0.3−5.0 M NaCl), but grows well in 0.6 to 1.5 M NaCl culture medium. Under high-light conditions (500 ± 10 μmol photons m<sup>-2</sup> s<sup>-1</sup>), the cells accumulated three times more β-carotene than under low-light conditions (50 ± 5 μmol photons m<sup>-2</sup> s<sup>-1</sup>). The cells accumulated 2.5-fold more β-carotene under nitrogen-deficient (1 mM KNO<sub>3</sub>) conditions (3.24 ± 0.36 μg 106 cells<sup>-1</sup>) than in nitrogen-sufficient conditions (>5 mM KNO<sub>3</sub>). The lutein content under nitrogen-deficient conditions (1.73 ± 0.09 μg 106 cells<sup>-1</sup>) was more than 24% higher than that under nitrogen-sufficient conditions. Under the optimized culture condition for carotenoid induction using natural seawater, D. salina OH214 strain produced 7.97 ± 0.09 mg g DCW<sup>-1</sup> of β-carotene and 4.65 ± 0.18 mg g DCW<sup>-1</sup> of lutein, respectively. We propose that this new microalga is a promising strain for the simultaneous production of β-carotene and lutein.

Characterization and Optimization of Culture Conditions for Aurantiochytrium sp. SC145 Isolated from Sand Cay (Son Ca) Island, Vietnam, and Antioxidative and Neuroprotective Activities of Its Polyunsaturated Fatty Acid Mixture.

Aurantiochytrium is a heterotrophic marine microalga that has potential industrial applications. The main objectives of this study were to isolate an Aurantiochytrium strain from Sand Cay (Son Ca) Island, Vietnam, optimize its culture conditions, determine its nutritional composition, extract polyunsaturated fatty acids (PUFAs) in the free (FFA) and the alkyl ester (FAAE) forms, and evaluate the antioxidation and neuroprotection properties of the PUFAs. Aurantiochytrium sp. SC145 can be grown stably under laboratory conditions. Its culture conditions were optimized for a dry cell weight (DCW) of 31.18 g/L, with total lipids comprising 25.29%, proteins 7.93%, carbohydrates 15.21%, and carotenoid at 143.67 µg/L of DCW. The FAAEs and FFAs extracted from Aurantiochytrium sp. SC145 were rich in omega 3-6-9 fatty acids (40.73% and 44.00% of total fatty acids, respectively). No acute or subchronic oral toxicity was determined in mice fed with the PUFAs in FFA or FAAE forms at different doses over 90 days. Furthermore, the PUFAs in the FFA or FAAE forms and their main constituents of EPA, DHA, and ALA showed antioxidant and AChE inhibitory properties and neuroprotective activities against damage caused by H2O2- and amyloid-ß protein fragment 25-35 (Aβ25-35)-induced C6 cells. These data suggest that PUFAs extracted from Aurantiochytrium sp. SC145 may be a potential therapeutic target for the treatment of neurodegenerative disorders.

Evaluation of The Biochemical Contents in Guillard f/2 and Walne Growth Medium to Fulfill the Animal-Free Aspects of Microalgal Bioprocessing

Marine microalgae with their diverse biomolecule contents could be used as potential sources of food, cosmetics, and pharmaceutical ingredients. In accordance with regulations in some countries and to competitively engage huge numbers of consumers, microalgae-based products should be properly manufactured using non-animal-derived materials. As a cultivable microorganism using a scalable bioreactor technique, consideration of the origin of the material used in the upstream process of marine microalgae was inevitable. Currently, the material origin of chemical contents within common artificial microalgal seawater medium had not been evaluated. This article evaluated Guillard f/2 and Walne medium as common artificial microalgal nutrients used in marine microalgal bioprocess-related activities. The risk assessment results showed that the largest portion of Guillard f/2 and Walne media were inorganic salts considered as low, while the remaining biochemical contents of vitamins were categorized as high risk due to their relatively complex chemical synthesis and enzymatic stages during the manufacturing process. As a suggestion, several plant-based bioproducts were proposed as alternative sources to substitute related biochemical actions to fulfill non-animal-origin aspects in the initial stages of the bioprocessing of marine microalgal-based products.

Isochrysis sp. cultivation in pilot-scale to concurrently produce sustainable triacylglycerols for human milk fat substitutes and fucoxanthin

Isochcrysis strains as versatile cell factories can produce varieties of high-valued bioproducts for food, nutraceuticals and pharmaceuticals. This work aimed to evaluate the ability of Isochrysis sp. to produce high-valued triacylglycerols (TAGs) for human milk fat substitutes (HMFs) and fucoxanthin by batch, fed-batch and semi-continuous cultivation modes in 50-L column photobioreactors. It was found that, Isochrysis cells by three cultivation modes had individual growth characteristics, nutrients consumption, and biochemical composition. In all cultivation modes, microalga cultivated by the semi-continuous cultivation at 10 % renewable rate achieves the highest TAGs and fucoxanthin productivities with 8.2 and 0.5 mg/(L·d), respectively. Additionally, the obtained results showed that the microalgal growth phase and the levels of nitrogen and phosphorus had distinct impacts on the deducting G value for microalgal TAGs produced by three cultivation modes. Based on the fatty acid composition and positional distribution, Isochrysis TAGs by the semi-continuous process at 10 % renewable rate had 73.0 deducting G value that were close to the ones by the batch cultivation (13th day) and fed-batch cultivation. Taken together, Isochrysis sp. was the promising marine microalga to concurrently produce sustainable high-valued TAGs for HMFs and fucoxanthin by semi-continuous cultivation in pilot-scale photobioreactors. This work provides a new marine microalgal platform to exploit Isochrysis-derived TAGs as human milk fat subsitutes for infant formulas and fucoxanthin for nutraceuticals and pharmaceuticals.

Effect of marine microalgae Synechococcus sp., Chlorella sp., Thalassiosira sp. on corrosion behavior of Q235 carbon steel in f/2 medium

The effect of marine microalgae on the corrosion behavior of carbon steel (CS) still needs further investigation due to their dual roles. In this study, the corrosion behavior of Q235 CS specimens in f/2 medium with absence and presence of three classes of marine microalgae Synechococcus sp., Chlorella sp., and Thalassiosira sp. was investigated during a 16-day immersion period by the weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization curve, and surface analysis techniques. The biomass of the three microalgae was monitored at the same time. The results showed that the values of weight loss and corrosion current density decreased, and the values of charge transfer resistance increased in the CS specimens treated with these microalgae. On day 16, the inhibition efficiency of Thalassiosira sp. group was the highest (80.78%), followed by Chlorella sp. group (70.80%), and finally Synechococcus sp. group (69.38%). But the inhibition efficiency diminished with time. Furthermore, in these microalgal treatment groups, the passivation films were found to consist of a biofilm and a corrosion product film. This study revealed that the three microalgae can effectively strengthen the barrier of the CS specimens in the f/2 medium, leading to slow down their corrosion rates.

Effects of coating layers chitosan/pectin on lipid stability and in vitro digestion of astaxanthin-loaded multilayer emulsions

Astaxanthin (Ax), a hydrophobic carotenoid from marine animals and microalgae, is claimed to exhibit various beneficial biological activities. In this study, quillaja saponin, chitosan and pectin were employed to formulate Ax-loaded primary, secondary, and tertiary multilayer emulsions using a layer-by-layer electrostatic deposition technique. The effects of the coating layers on the antioxidation of lipid, in vitro digestion properties, and Ax bioaccessibility were investigated. The results showed that the coating layers improved the lipid stability during the storage process and gastrointestinal digestion of lipid droplets effectively. In particular, the release of free fatty acids was reduced by nearly 20% in tertiary multilayer emulsions coated by chitosan and pectin. Meanwhile, the coating layers postponed the release of Ax effectively. The multilayer emulsions developed in this study could be used to load, protect, and deliver astaxanthin, which may contribute to the development of more effective functional foods, supplements, and pharmaceutical products.

Algal Biomass Accumulation in Waste Digestate after Anaerobic Digestion of Wheat Straw

Cultivation of microalgae in waste digestate is a promising cost-effective and environmentally friendly strategy for algal biomass accumulation and valuable product production. Two different digestates obtained as by-products of the anaerobic fermentation at 35 °C and 55 °C of wheat straw as a renewable source for biogas production in laboratory-scale bioreactors were tested as cultivation media for microalgae after pretreatment with active carbon for clarification. The strains of microalgae involved were the red marine microalga Porphyridium cruentum, which reached 4.7 mg/mL dry matter when grown in thermophilic digestate and green freshwater microalga-Scenedesmus acutus, whose growth was the highest—7.3 mg/mL in the mesophilic digestate. During cultivation, algae reduced the available nutrient components in the liquid digestate at the expense of increasing their biomass. This biomass can find further applications in cosmetics, pharmacy, and feed. The nitrogen and phosphorus uptake from both digestates during algae cultivation was monitored and modeled. The results led to the idea of nonlinear dynamic approximations with an exponential character. The purpose was to develop relatively simple nonlinear dynamic models based on available experimental data, as knowing the mechanisms of the considered processes can permit creating protocols for industrial-scale algal production toward obtaining economically valuable products from microalgae grown in organic waste digestate.

Sulfated polysaccharides derived from marine microalgae, Synechococcus sp. VDW, inhibit the human colon cancer cell line Caco-2 by promoting cell apoptosis via the JNK and p38 MAPK signaling pathway

This study offers an examination of the physicochemical qualities of marine microalgae-derived sulfated polysaccharides (MMPS) from Synechococcus sp. VDW along with an investigation of their antioxidant and antitumor activities. On average, MMPS offered a molecular weight of 190.94 kDa with sulfate content of 16.83 %. There were shown to be four different monosaccharides contained within MMPS. The anticancer characteristics of human colon cancer cell lines (Caco-2) were also investigated. Flow cytometry revealed that MMPS triggered apoptosis at doses of 1 mg mL−1. Meanwhile, analysis of gene and apoptosis protein expression demonstrated that MMPS increased apoptosis in Caco-2 cells via the p38 MAPK and JNK signaling pathways. These findings contribute to our current understanding of how MMPS helps promote tumor suppression. In conclusion, the possibility that MMPS may possess anticancer qualities in the treatment of human colon cancer makes it an appealing candidate for anticancer polysaccharide combinations with chemotherapeutic agents and functional foods.

Bait microalga harboring antimicrobial peptide for controlling Vibrio infection in Argopecten irradians aquaculture

Vibrio infection is a longstanding and serious bacterial disease of various shellfish species that has caused high mortality rates for many decades. Antibiotics can effectively prevent and control bacterial diseases. However, the long-term abuse of antibiotics exacerbates the risk of environmental pollution, which also poses a threat to food safety. In this study, transgenic lines of the marine microalga Tetraselmis subcordiformis harboring antimicrobial peptide NZ2114 were attempted to be created as an oral drug-delivery system in shellfish aquaculture. Toward this, codon-optimized nz2114 was respectively assembled into nuclear and chloroplast expression vectors of T. subcordiformis. After particle bombardment, two stable transgenic lines Y1 (with nuclear transformation) and Y2 (with chloroplast transformation) were selected, each expressing a stable transgene inheritance for at least 12 months. In vitro experiments demonstrated the significant inhibition of total protein containing NZ2114 from transgenic lines on two marine Vibrio species and Staphylococcus aureus. To test the efficacy of transgenic baits, pathogen-infected scallops (Argopecten irradians) were fed with transgenic T. subcordiformis via oral delivery. The results showed that the survival rate (after 20 days of infection) of the scallops fed transgenic T. subcordiformis was much higher than that of scallop fed with wild-type algae (95.92% versus 80.41%). In summary, this strategy offers a new, efficient, and low-cost method for controlling Vibrio in scallop aquaculture through oral drug-delivery system, which is a promising step toward the development of safe and environment-friendly antimicrobial baits.

Nghiên cứu đặc điểm sinh học của chủng vi tảo biển Dunaliella tertiolecta NY phân lập từ nước biển của đảo Nam Yết thuộc Quần đảo Trường Sa, Việt Nam

Marine microalgae are an important source of raw materials for the extraction of highly bioactive substances for humans and domestic animals. In this study, the biological characteristics and the ability to grow biomass of green marine microalga of Dunaliella tertiolecta NY isolated from seawater of Namyit Island belonging to Spratly Islands, Vietnam (in May-June, 2021) was presented. Scientific name of the strain Dunaliella tertiolecta NY based on morphological characteristics and analysis of the sequence of rDNA ITS1-5.8S-ITS2 region was identified (with accession number of this gene region of this strain was supplied on the GenBank is OM 101011). At the best conditions for the growth (i.e. Walne medium, initial cell density of 2.0 x 106 cells/mL, growth temperature of 30oC, light intensity of 60 - 100 µmol/m2s, pH 7, salinity of 30-40‰), highest NY strain cell density of 8.63 x 106 cells/mL was obtained after 15 days of culture. The microalga D. tertiolecta NY was also successfully cultured on a pilot scale in the plastic bottles 10 L and closed photobioreactors 20 - 100 L resulting in a high biomass productivity of 285 mg/L/day and a biomass rich in polyunsaturated fatty acids such as gamma - linolenic acid (C18:3 ω-6; 5.07±0.59 % of total fatty acid - TFA), alpha - linolenic acid (ALA, C18:3 ω-3, 61.79±1.98 % of TFA) and stearidonic acid (SDA; C18: 4 ω-3, 1.59±0.65 % of TFA) qualified for the extraction of value bioactive compounds.

Đa dạng vi tảo biển vùng quần đảo Trường Sa, Việt Nam

In this study, marine microalgal communities in 12 islands belonging to the sea water region of Truong Sa Islands (Spratly Islands), Vietnam in May-June and October-November 2021 was studied. There were 305 species of marine microalgae belonging to 7 phyla were identified in 12 islands in this sea water region of Truong Sa Islands (Spratly Islands) in 2021 in which with 39 dominant species, highest species number of 147 in Central (London) Reef (D1) and the lowest species number of 15 in Ambonya Cay (D4) were detected. Up to 2021, in the sea water region of the Truong Sa Islands (Spratly Islands), 14 genera of toxic harmful algae have appeared. The average value of biodiversity index (H') and the diversity value index (Dv) in all 12 studied islands in the Truong Sa Islands (Spratly Islands) in 2021 is 3.61±0.40 and 3.43±0.39, respectively, showing that the diversity of marine microalgae of this sea water region is rich and the quality of its sea water is generally good. It has been determined that two main factors NO3- and oil content, followed by DO, salinity, temperature and Hg content in seawater were affected the density of marine microalgal cells in the sea water of Truong Sa Islands (Spratly Islands) in 2021. In which, the marine microalgal cell density has a negative correlation with temperature, salinity, NO3- and Hg content of seawater and has a positive correlation with DO parameter was discovered.

Extending Omega 3/6 Fatty Acid Pathway in Arabidopsis thaliana using Microalgal Gene Δ6Des for Stearidonic acid and Dihomo-γ-linolenic acid Production

• Microalgal gene Δ6Des was cloned in a binary vector pCAMBIA1303. • F 1 transgenic plants having Δ6Des were viable at a concentration of 25 mg/L of hygromycin medium • Transgenic Arabidopsis thaliana showed novel ω3/6 fatty acids SDA (0.58%) and DGLA (25. 34%) To enhance the quality and quantity of oils in plant systems, specific candidate genes such as desaturase and elongase that can extend the biosynthetic pathways of very long chain poly unsaturated fatty acids (VLCPUFAs) are essential. In general, plant systems are capable of synthesizing essential fatty acids (EFAs). However, incorporation of a preliminary gene, Δ6Desaturase ( Δ6Des ), in the fatty acid biosynthetic pathway will elongate the pathway further to produce successive fatty acids. In this study, Δ6Des gene extracted from the marine microalga Isochrysis sp. was used to extend the omega (ω) 3/6 fatty acid biosynthetic pathway in a model plant Arabidopsis thaliana using Agrobacterium -mediated genetic transformation. Hygromycin-resistant plants were (25 mg/L) used for GUS and GFP assays and for molecular confirmation. GUS assay showed an intense blue color in F 1 transgenic A. thaliana plant tissues grown in the selection medium, which confirmed the presence of GUS gene in the T-DNA region, whereas non-transformed plant tissues such as leaf or stem did not show any blue color. GFP analysis also showed a green fluorescent color in tissues such as leaf, stem, and floral parts of F1 transgenic A. thaliana plants, which confirmed the presence of T-DNA. PCR and Southern blotting analyses also clearly showed the presence of Δ6Des in the T-DNA region of the F 1 transgenic plants. The fatty acid profile of F 1 transgenic plants showed the production of new fatty acids such as stearidonic acid (SDA-0.58%) and dihomo-γ-linolenic acid (DGLA-25.34%) that were not observed in non-transformed control plants. All these results showed the synthesis of new fatty acids in the transgenic plant, which proved that PUFA biosynthetic pathway can be extended in oilseed plants if specific genes are introduced through genetic transformation. This is the first study to report the productions of new fatty acids like SDA and DGLA in A. thaliana using Δ6Des gene from marine microalga Isochrysis sp.

The Effect of Culture Media Types on the Growth of Marine Microalgae Chlorella vulgaris

Chlorella vulgaris is one of the marine microalgae that has potential to be developed, one of which is the renewable energy sector, biodiesel. The growth media used in the biomass production of microalgae are very various, such as Walne, Guillard, and Agriculture Fertilizer (Urea). This study aims to determine the effect of types of growth media on population density, absolute growth, relative growth rate, and specific growth rate of C. vulgaris. Study on 3 media types of microalgae growth shows the density of C. vulgaris cultured on a laboratory scale experienced the highest peak density in the Guillard media on the 3rd day around 7430 x 104 cells/mL. However, the lowest density peak was in the Urea culture about 2520 x 104 cells/mL, followed by Walne media around 3335 x 104 cells/mL. The highest absolute growth average was found in the Guillard media about 6311 x 104 cells/mL and the lowest was in the Urea and Walne media about 1401 x 104 cells/mL and 2216 x 104 cells/mL, respectively. Meanwhile, in C. vulgaris culture, it was found that Guillard and Walne media produced the highest relative growth of 564% and 198% and the lowest was at 125% for Agriculture Fertilizer (Urea). In the process of culturing C. vulgaris for 6 days, it was found that Guillard media showed the highest average specific growth rate of 58% per day and the lowest was on Urea culture as much as 27% per day, followed by Walne media about 36%.

Humic acid-mediated reduction in toxicity of Co3O4 NPs towards freshwater and marine microalgae in surfactant mixed medium.

The ever-increasing applications of Co3O4 nanoparticles (NPs) have posed a serious concern about their discharge in the aquatic environment and ecotoxic implications. Being toxic towards aquatic species, the impact of other aquatic components such as dissolved organic matter (DOM), salinity, and surfactants are not studied sufficiently for their effect on the stability and ecotoxicity of Co3O4 NPs. The present study aims at the influence of humic acid (HA) on the toxicity of Co3O4 NPs in freshwater (C. minutissima) and marine (T. suecica) microalgae under surfactants mixed medium. The measure of % reduction in biomass and photosynthetic pigment were used as toxicity endpoints. Among various tested concentrations of HA, 25mg/L HA was found suitable to minimize the NP's toxicity with or without the presence of surfactants. Co3O4 NPs mediated reduction in biomass of C. minutissima was significantly minimized by the cumulative effect of HA with T80 (51.68 ± 4.55%) followed by CTAB (46.23 ± 5.62%) and SDS (42.60 ± 2.46%). Similarly, HA with T80 (26.93 ± 6.38%) followed by SDS (17.02 ± 6.64%) and CTAB (13.01 ± 3.81%) were found to minimize the growth inhibitory effect of Co3O4 NPs in T. suecica. The estimation of chlorophyll - a content also indicated that microalgae treated with HA could maintain their photosynthetic ability more than control even in the co-presence of surfactants. Also, the reduced toxicity of Co3O4 NPs were attributed to an increase in hydrodynamic sizes of HA-treated Co3O4 NPs in both marine media (f/2) and freshwater media (BG11) due to increased aggregation and faster sedimentation of Co3O4 NPs.

The Microalga Skeletonema marinoi Induces Apoptosis and DNA Damage in K562 Cell Line by Modulating NADPH Oxidase.

Chronic myeloid leukemia (CML) is a myeloproliferative disease that activates multiple signaling pathways, causing cells to produce higher levels of reactive oxygen species (ROS). Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are a major generator of ROS in leukemia, and marine natural products have shown promising activities for the treatment of hematopoietic malignancies. In the present study, we investigated the effect of the marine microalga Skeletonema marinoi (S.M.), a ubiquitous diatom that forms massive blooms in the oceans, on the human leukemia cell line K562. The effects of S.M. extract on cell viability, production of ROS, nitric oxide (NO), and apoptosis were examined. In this preliminary work, S.M. was able to decrease cell viability (p < 0.05) and increase apoptosis levels (p < 0.05) in K562 cells after 48 h of treatment. In addition, the levels of NOX, NO, and malondialdehyde (MDA) were reduced in K562-treated cells (p < 0.05), whereas the levels of SOD, CAT, and GPx increased during treatment (p < 0.05). Finally, analyzing Bax and Bcl-2 expression, we found a significant increase in the proapoptotic protein Bax and a sustained decrease in the antiapoptotic protein Bcl-2 (p < 0.05) in the K562-treated cells.

Sustained power output from an algal biophotovoltaic (BPV) platform using selected marine and freshwater microalgae

Sustained power output from an algal biophotovoltaic (BPV) platform using selected marine and freshwater microalgae

Evaluation of bioactive compounds from robust consortium microalgae species under actual flue gas exposure

The application of phototrophic microalgae for biological CO2 fixation has been regarded as a sustainable means to curb emissions, treat wastewater, and provide essential and valuable bioactive compounds that can serve multitudes industries, e.g., aquaculture, nutraceutical, and biofuel. This article highlights the utilization of microalgae consortium to enhance carbon fixation ability. Marine microalgae species were isolated and identified from their native condition of seawater discharge canals at the TNB Janamanjung Sdn. Bhd.’s coal-fired power station. The experimental runs were performed with exposure of actual flue gas as a CO2 source from a live operating coal-fired power plant. The bioassays of protein and amino acids were conducted to the consortium to explore potential bio-products. The proximate analysis illustrated that the consortium content of protein (45%), lipid (21%), and carbohydrate (17%) is comparable and more balanced from other types of mono species. Also, the essential amino acid content of 42% is encouragingly good and exceeds some other species and other sources. Premises and observations from various microalgae research works are collated and presented in a manner sufficient to highlight the essential roles of this tiny creature to become our mentor in providing some solutions to our worldly problems.