Microalgae Chlorella Sp Research Articles

Algal EPS modifies the toxicity potential of the mixture of polystyrene nanoplastics (PSNPs) and triphenyl phosphate in freshwater microalgae Chlorella sp.

Triphenyl phosphate (TPP) and polystyrene nanoplastics (PSNPs) are prevalent freshwater contaminants obtained mainly from food packaging, textiles and electronics. Algal extracellular polymeric substances (EPS), a part of natural organic matter, may influence these pollutants' behaviour and toxicity. The presence of EPS can enhance the aggregation of TPP-PSNP mixtures, and reduce the bioavailability, and thus the toxicity potential. Understanding the mutual interactions between TPP, PSNPs, and EPS in the aquatic environment is a prerequisite for the environmental risk assessment of these chemicals. The study examines the toxicity effects of various surface-modified PSNPs (1 mg/L of plain, animated, and carboxylated) and TPP (0.05, 0.5, and 5 mg/L) in pristine and combined forms on freshwater microalgae, Chlorella sp., as a model organism. The physical-chemical interactions of algal EPS (10 mg/L) with PSNPs and TPP and their mixtures were studied. The toxicity potential of the PSNPs was estimated by quantifying growth inhibition, oxidative stress, antioxidant activity, and photosynthesis in the cells. TPP toxicity increased in the presence of the PSNPs, however the addition of algal EPS reduced the combined toxic effects. EPS plays a protective role by reducing oxidative stress and enhancing photosynthetic efficiency in the algal cells. The Pearson modeling analysis indicated a positive correlation between growth inhibition, and reactive oxygen species, malondialdehyde production. The cluster heatmap and correlation mapping revealed a strong correlation among the oxidative stress, growth inhibition, and photosynthetic parameters. The study clearly highlights the potential of EPS in mitigating the risk of mixed emerging pollutants in the aquatic environment.

Harnessing synergistic metabolism: Bioelectricity and color removal from palm oil mill effluent in bacteria consortium – microalgae microbial fuel cell

This study investigated the application of a microbial fuel cell (MFC) system integrated with freshwater microalgae Chlorella sp. TSU-FF67for wastewater treatment, electricity generation, and bio-oil production. The MFC with Chlorella sp. TSU-FF67achieved a significantly higher open-circuit voltage (OCV) of 413.67 ± 15.67 mV compared to the control (13.33 ± 6.38 mV), indicating enhanced bioelectrocatalytic activity. The system also demonstrated efficient organic matter removal from palm oil mill effluent (POME) with a maximum color removal of 95.12 ± 3.50%. Furthermore, Chlorella sp. TSU-FF67 recovered from the PMFC exhibited a remarkable docosahexaenoic acid (DHA) yield of 1,932.28 ± 88.69 µg/mL (1.93 ± 0.08 mg/mL), highlighting its potential as a feedstock for bio-oil production. This work presents a promising approach for sustainable wastewater treatment while simultaneously generating bioelectricity and bio-oil using microalgae-MFC integration.

Study on Lipid and Pigment Contents of Microalgae Cultivated in Water from Litopenaeus vannamei Shrimp Farm

This study aimed to cultivate microalgae in water from Litopenaeus vannamei shrimp farm to be used as supplement for shrimp. The study focused on its growth, lipid and pigment contents and effects of urea addition as nitrogen source and scale-up of microalgae cultivation. Microalga Chlorella sp. SHP isolated from shrimp farm showed higher pigment content and antioxidant activity than other two isolated strains. Chlorella sp. SHP grew best in effluent from treatment pond compared to water from reservoir pond and shrimp pond. The addition of urea at 2 g/L and the scale up in 50 L microalgae cultivation pond gave the maximum biomass of 0.19±0.03 g/L, the lipid content of 44.96±2.79%, and the contents of chlorophyll ab and carotenoids of 11.65 mg/g and 5.45 mg/g, respectively. The antioxidant activity based on radical scavenging activity of 1 g microalgal biomass was 66.71±0.02%. The findings from this study could be an alternative for producing microalgae with high lipid and pigment contents, and further utilization as low-cost supplements for shrimp cultivation.

Adaptability and nutritional analysis of a newly isolated Chlorella sp. NeZha in brackish and marine environments with potential bioeconomic impacts.

The microalga Chlorella sp. NeZha, recently isolated from a balcony environment, shows significant adaptability across various salinity conditions, including seawater (SeaW), freshwater (FreshW), and high salinity levels (45‰). This study investigates its potential for sustainable aquaculture and biotechnological applications. Morphological and genetic identification were conducted using optical microscopy and DNA sequencing. The microalga was cultivated in a 400 L outdoor photobioreactor, and its biochemical composition, including chlorophyll a, carbohydrate, protein, and lipid content, was analyzed. Its compatibility with zooplankton and growth in aquaculture wastewater were also evaluated. Chlorella sp. NeZha produced chlorophyll a at concentrations exceeding seaweed and Spirulina by 10- and 5-fold, respectively, with a dry weight chlorophyll a content of 34.25 mg/g and 25 pg./cell. The microalga also contained carbohydrate (~33%), protein (~20%), and lipids (~14%). It was compatible with zooplankton species, such as rotifers and brine shrimp, and showed promising growth in aquaculture wastewater. The findings suggest that Chlorella sp. NeZha is a viable candidate for sustainable aquaculture and biotechnological applications, offering high nutritional value and environmental resilience. Its adaptability to diverse salinity conditions and ability to thrive in wastewater highlight its potential for bioremediation and use as feedstock for zooplankton. Further research is recommended to optimize its cultivation and explore broader applications.

Insights into the physiology, biochemistry, and metabolic pathways of ethanol-resistant marine microalgae in phytoplankton

Over two decades have passed since genetically modified prokaryotic cyanobacteria became capable of photosynthetically producing bioethanol. However, the limitation of low ethanol tolerance has impeded bioethanol production. In this study, the findings revealed that eukaryotic marine microalgae exhibited higher tolerance to ethanol compared to freshwater microalgae through a comparison of the growth performance of algal species under ethanol-induced stress. Specifically, the marine microalga Chlorella sp. MEM17 (MEM17) demonstrated tolerance to ethanol concentrations up to 6.0 % (v/v). Additionally, the polysaccharide and unsaturated fatty acid contents of MEM17 were considerably higher compared to ethanol-untreated control groups under ethanol stress. In conjunction with the comparative metabolomics approach, the remodeling of glycerophospholipid metabolic pathways was observed, specifically the conversion of a fraction of the reduced glycerophospholipids into specific glycerophospholipids, thereby enhancing the hindrance of ethanol entry into cells. The up-regulation of amino acid-related metabolic pathways aimed to augment the relative content of specific metabolites, such as gamma-aminobutyric acid (GABA), with the objective of scavenging intracellular reactive oxygen species (ROS). Furthermore, bolstered properties of the cell wall potentially facilitated by the increased polysaccharide content of MEM17 further impeded the potential entry of ethanol into the cell, while excess polysaccharide assisted in scavenging intracellular ROS. This study represents the first discovery of a high-concentration ethanol-tolerant eukaryotic marine microalga and its key metabolic pathways, with potential as “marine photosynthetic cell factories” for bioethanol production.

Assessing the role of the graphene family nanomaterials (GFNs: Graphene, GO, rGO) in modifying the toxicity potential and environmental risk of flame retardant, tetrabromobisphenol-A (TBBPA) in the marine microalgae Chlorella sp.

In recent years, a growing concern has emerged regarding the environmental implications of flame retardants (FRs) like tetrabromobisphenol-A (TBBPA) and graphene family nanomaterials (GFNs), such as graphene, graphene oxide (GO), and reduced graphene oxide (rGO), on marine biota. Despite these substances' well-established individual toxicity profiles, there is a notable gap in understanding the physicochemical interactions within the binary mixtures and consequent changes in the toxicity potential. Therefore, our research focuses on elucidating the individual and combined toxicological impacts of TBBPA and GFNs on the marine alga Chlorella sp. Employing a suite of experimental methodologies, including Raman spectroscopy, contact angle measurements, electron microscopy, and chromatography, we examined the physicochemical interplay between the GFNs and TBBPA. The toxicity potentials of individual constituents and their binary combinations were assessed through growth inhibition assays, quantifying reactive oxygen species (ROS) generation and malondialdehyde (MDA) production, photosynthetic activity analyses, and various biochemical assays. The toxicity of TBBPA and graphene-based nanomaterials (GFNs) was examined individually and in combinations. Both pristine TBBPA and GFNs showed dose-dependent toxicity. While lower TBBPA concentrations exacerbated toxicity in binary mixtures, higher TBBPA levels reduced the toxic effects compared to pristine TBBPA treatments. The principal mechanism underlying toxicity was ROS generation, resulting in membrane damage and perturbation of photosynthetic parameters. Cluster heatmap and Pearson correlation were employed to assess correlations between the biological parameters. Finally, ecological risk assessment was undertaken to evaluate environmental impacts of the individual components and the mixture in the algae.

Exploring the influence of sulfadiazine-induced stress on antibiotic removal and transformation pathway using microalgae Chlorella sp.

Sulfadiazine (SDZ) is a kind of anti-degradable antibiotics that is commonly found in wastewater, but its removal mechanism and transformation pathway remain unclear in microalgal systems. This study investigated the effects of initial algae concentration and SDZ-induced stress on microalgal growth metabolism, SDZ removal efficiency, and transformation pathways during Chlorella sp. cultivation. Results showed that SDZ had an inhibitory effect on the growth of microalgae, and increasing the initial algal biomass could alleviate the inhibitory effect of SDZ. When the initial algal biomass of Chlorella sp. was increased to 0.25 g L−1, the SDZ removal rate could reach 53.27%–89.07%. The higher the initial algal biomass, the higher the SOD activity of microalgae, and the better the protective effect on microalgae, which was one of the reasons for the increase in SDZ removal efficiency. Meanwhile, SDZ stress causes changes in photosynthetic pigments, lipids, total sugars and protein content of Chlorella sp. in response to environmental changes. The main degradation mechanisms of SDZ by Chlorella sp. were biodegradation (37.82%) and photodegradation (23%). Most of the degradation products of SDZ were less toxic than the parent compound, and the green algae were highly susceptible to SDZ and its degradation products. The findings from this study offered valuable insights into the tradeoffs between accumulating microalgal biomass and antibiotic toxic risks during wastewater treatment, providing essential direction for the advancement in future research and full-scale application.

Utilizing melanoidin consuming microalgae for electricity generation and wastewater treatment via photosynthetic microbial fuel cell

Aim of the studyIn our investigation, the freshwater microalgae Chlorella sp. BF01 to degrade the melanoidin in the palm oil mill effluent and generate electricity in the photosynthetic microbial fuel cell (PMFC).Material and methodsThe freshwater microalgae Chlorella sp. were used in a PMFC consortium for the degradation of melanoidin and electricity generation. The removal (%), electrochemical properties, and biomass recovery were monitored without adding exogenous medium.Results and conclusionsIn this study, lipid-producing microalgae were employed as whole-cell biocatalysts in a PMFC using palm oil mill effluent as a substrate. The maximal melanoidin removal of 79.54±0.45% was gained. The maximum power density reached was 3.98±0.10 W/m3. The research presents findings that pave the way for the practical implementation of this innovative approach on an industrial scale.

Influence of different pyrolysis temperatures on chemical composition and graphite-like structure of biochar produced from biomass of green microalgae Chlorella sp

There is a great demand for environmentally friendly carbon materials as an alternative to fossil raw materials in industrial production. Microalgae biomass can be a valuable renewable source for the production of biochar. The study examined the effect of the pyrolysis temperature on the chemical composition, morphological features and the degree of order of the carbon structure of biochar based on green microalgae – Chlorella sp. Thermochemical conversion was carried out at 400÷900 °C in a CO2 atmosphere. The obtained biochar material had a porous structure. It was found that as the temperature increased, the biochar yield decreased from 38.4 to 21.9 wt%, while its aromaticity and stability, determined by the H/C molar ratio, increased. Based on the results of FTIR and Raman spectroscopy, it was evidenced that the biochar produced at 400÷500 °C was distinguished by the presence of functional groups and double bonds (i.e. –NH2, C–O, CC, CN, NO) as well as a high degree of order in the carbon structure (ID/IG=0.2). As the temperature increases, the amorphous nature of biochar began to develop. This study could provide data for the proper selection of temperature for pyrolysis of green algae to obtain biochar with the desired graphite-like structure and properties.

Synthesis of Methyl Ester from Microalgae Chlorella sp. TAD Using the In-Situ Transesterification Method

Synthesis of methyl ester from Chlorella sp. TAD microalgae was carried out using the in-situ transesterification method. This study aims to determine the methyl ester composition of Chlorella sp. TAD microalgae using the in-situ transesterification method. The in-situ transesterification method is a modified method that allows extraction and transesterification into methyl ester products in one process simultaneously. The in-situ transesterification process lasted 8 hours, followed by a distillation process to remove the n-hexane content and an oven for 2 hours to evaporate the remaining water. The results of the analysis using GC-MS to determine the chemical content of the methyl ester compound from Chlorella sp. TAD, showed the methyl ester composition of 7,10-hexadecanoic methyl ester, 8,11,14-docosatrienoic methyl ester, 9-hexadecanoic methyl ester, hexadecanoic methyl ester, heptadecanoic methyl ester, 10-octadecenoic methyl ester, octadecenoic methyl ester, 9,12-octadecadienoic methyl ester, 10-octadecenoic methyl ester, 2-hexyl cyclopropaneoctanoic methyl ester, eicosanoic methyl ester, 10-heptadecen-8-ynoic acid methyl ester, nonahexacontanoic methyl ester, and tetracosanoic methyl ester.

Urea-N influences biomass yield, neutral lipids accumulation, and unsaturated fatty acid production in photoautotrophically grown microalga Chlorella sp

Microalgal cultivation using cost-effective nutrients is found to decrease the biodiesel production cost significantly. Therefore, in this study, various nitrogen sources namely sodium nitrate, ammonium nitrate, potassium nitrate, and fertilizer-grade urea, were tested to evaluate their impact on the biomass, lipids, and fatty acid content of microalga Chlorella sp. For biodiesel production. Onset of the study, the highest biomass yield, about 1.35g/L, was obtained in urea-N, potassium nitrate, and sodium nitrate. For lipid extraction, different methods such as sonication, stirring, Soxhlet, homogenization, and sonication + Soxhlet were compared, and the highest efficiency (19.86% lipid content) was noticed in the combined sonication + Soxhlet method with chloroform: methanol (2:1). Regarding the lipid content, 19.86, 19.91, 18.44, and 19.13% were extracted from sodium nitrate, ammonium nitrate, potassium nitrate, and fertilizer grade urea-grown cultures, respectively. Further optimization of urea-N revealed that, of the 0.0, 0.75, 1.5, 2.25, and 3.0 g/L urea-N concentrations, total lipid content and neutral lipid was decreased when increasing the urea-N level in the medium and maximum content of 23.6%, and 14.7 %, were observed, respectively in 0.0 g/L urea-N. Biodiesel yield with respect to urea-N concentration showed a maximum of 64.7% biodiesel from 0 g/L grown microalgal cells. The fatty acid fingerprinting of the biodiesel by gas chromatography showed higher levels of UFAs (57.18% w/w lipids) in nil urea-N concentration (0 g/L) and higher levels of SFAs (39.84% w/w lipids) in higher urea-N (3.0 g/L) grown culture.

Macular pigments produced from microalga Chlorella sp. and applied to alleviate the pathogenic process in diabetic mice

Macular pigments (MP), which consist of lutein and zeaxanthin, have antioxidant capabilities and are widely used in eye healthcare. However, few studies have focused on the protective mechanisms of MP against diabetes mellitus. In addition, the advantages of MP produced by microalgae include non-competition with grains for land, year-round harvesting, and rapid growth. Therefore, this study aims to investigate the MP produced and extracted from the microalga Chlorella sp. AT1 and assess its impact on mitigating retinopathy and atherosclerotic damage in diabetic apolipoprotein E-deficient mice (ApoE−/−) subjected to high-fat diet and streptozotocin treatment. The results showed that the major components of MP were lutein and zeaxanthin in a 5:1 ratio. MP supplementation significantly reduced glucose tolerance and insulin resistance by 25 and 41 %, respectively, in comparison to the diabetic group. MP supplementation resulted in the moderation of various inflammatory cytokines and lowered the serum levels of disease markers in comparison to the control group. In addition, the expression levels of cellular antioxidant enzymes were significantly elevated, aligning with a reduction in lipid peroxidation after MP supplementation, in comparison to the diabetic group. Pathological changes in the outer nuclear layer and aortic plaques in diabetic ApoE−/− mice were significantly alleviated by MP supplementation. In summary, microalgal MP alleviated the symptoms of type 2 diabetes mellitus in the diabetic ApoE−/− mice. Consequently, MP holds the potential to serve as a beneficial ingredient in healthy food, contributing to biological efficacy by scavenging free radicals and stabilizing blood glucose levels.

Utilization of microalgae for agricultural runoff remediation and sustainable biofuel production through an integrated biorefinery approach

Generally wastewater such agricultural runoff is considered a nuisance; however, it could be harnessed as a potential source of nutrients like nitrates and phosphates in integrated biorefinery context. In the current study, microalgae Chlorella sp. S5 was used for bioremediation of agricultural runoff and the leftover algal biomass was used as a potential source for production of biofuels in an integrated biorefinery context. The microalgae Chlorella sp. S5 was cultivated on Blue Green (BG 11) medium and a comprehensive optimization of different parameters including phosphates, nitrates, and pH was carried out to acquire maximum algal biomass enriched with high lipids content. Dry biomass was quantified using the solvent extraction technique, while the identification of nitrates and phosphates in agricultural runoff was carried out using commercial kits. The algal extracted lipids (oils) were employed in enzymatic trans-esterification for biodiesel production using whole-cell biomass of Bacillus subtilis Q4 MZ841642. The resultant fatty acid methyl esters (FAMEs) were analyzed using Fourier transform infrared (FTIR) spectroscopy and gas chromatography coupled with mass spectrometry (GC–MS). Subsequently, both the intact algal biomass and its lipid-depleted algal biomass were used for biogas production within a batch anaerobic digestion setup. Interestingly, Chlorella sp. S5 demonstrated a substantial reduction of 95% in nitrate and 91% in phosphate from agricultural runoff. The biodiesel derived from algal biomass exhibited a noteworthy total FAME content of 98.2%, meeting the quality standards set by American Society for Testing and Materials (ASTM) and European union (EU) standards. Furthermore, the biomethane yields obtained from whole biomass and lipid-depleted biomass were 330.34 NmL/g VSadded and 364.34 NmL/g VSadded, respectively. In conclusion, the findings underscore the potent utility of Chlorella sp. S5 as a multi-faceted resource, proficiently employed in a sequential cascade for treating agricultural runoff, producing biodiesel, and generating biogas within the integrated biorefinery concept.Graphical

An Innovative Co-Cultivation of Microalgae and Actinomycete-Inoculated Lettuce in a Hydroponic Deep-Water Culture System for the Sustainable Development of a Food–Agriculture–Energy Nexus

In recent years, researchers have turned their attention to the co-cultivation of microalgae and plants as a means to enhance the growth of hydroponically cultivated plants while concurrently producing microalgal biomass. However, the techniques used require precise calibration based on plant growth responses and their interactions with the environment and cultivation conditions. This study initially focused on examining the impact of hydroponic nutrient concentrations on the growth of the microalga Chlorella sp. AARL G049. The findings revealed that hydroponic nutrient solutions with electrical conductivities (EC) of 450 µS/cm and 900 µS/cm elicited a positive response in microalgae growth, resulting in high-quality biomass characterized by an elevated lipid content and favorable properties for renewable biodiesel. The biomass also exhibited high levels of polyunsaturated fatty acids (PUFAs), indicating excellent nutritional indices. The microalgae culture and microalgae-free culture, along with inoculation-free lettuce (Lactuca sativa L. var. longifolia) and lettuce that was inoculated with plant growth actinobacteria, specifically the actinomycete Streptomyces thermocarboxydus S3, were subsequently integrated into a hydroponic deep-water culture system. The results indicated that several growth parameters of lettuce cultivated in treatments incorporating microalgae experienced a reduction of approximately 50% compared to treatments without microalgae, and lowering EC levels in the nutrient solution from 900 µS/cm to 450 µS/cm resulted in a similar approximately 50% reduction in lettuce growth. Nevertheless, the adverse impacts of microalgae and nutrient stress were alleviated through the inoculation with actinomycetes. Even though the co-cultivation system leads to reduced lettuce growth, the system enables the production of high-value microalgal biomass with exceptional biodiesel fuel properties, including superior oxidative stability (>13 h), a commendable cetane number (>62), and a high heating value (>40 MJ/kg). This biomass, with its potential as a renewable biodiesel feedstock, has the capacity to augment the overall profitability of the process. Hence, the co-cultivation of microalgae and actinomycete-inoculated lettuce appears to be a viable approach not only for hydroponic lettuce cultivation but also for the generation of microalgal biomass with potential applications in renewable energy.

Bioflocculation harvesting of oleaginous microalga Chlorella sp. using novel lipid-rich cellulolytic fungus Aspergillus terreus (MD1) for biodiesel production

AbstractThe isolation of lipid-rich cellulolytic fungi was targeted to be investigated as bioflocculant agents for microalgae harvesting. The fungal isolate coded MD1 was selected based on its lipid content, cellulolytic activity, and its harvesting efficiency for the freshwater oleaginous microalga Chlorella sp. The selected fungus which was molecularly identified as Aspergillus terreus has been applied as bioflocculant after solid state cultivation on pre-treated rice straw (as abundant agro-cellulosic waste). Optimization of harvesting efficiency of Chlorella microalga using A. terreus/rice straw biomass as the “bioflocculant” was investigated. The optimization conditions included microalga/bioflocculant ratio, microalgal age, contact time between the bioflocculant and the microalga, pH of microalgal culture at harvesting time, and cell density of microalgal culture. The obtained results revealed that the harvesting efficiency could reach 97.6% due to 24 h as contact time at 30% flocculant/microalga ratio and pH 7. While after 2 h contact time, 93.3% harvesting efficiency could be obtained using the same bioflocculant:microalga ratio at pH 6. The lipid extracted from harvested Chlorella/A. terreus mixture was applied to produce biodiesel (fatty acid methyl ester) after methylation. The resulted biodiesel contains high percentage (67.2%) of C18:1,2 unsaturated fatty acids which is considered a suitable fraction for biodiesel production. Obtained results revealed the suitability of the novel A. terreus strain as sustainable bioflocculation agent to harvest microalga(e) for biofuel production.

Fabrication of Magnetic Silica Nanomaterials and Their Effects on Algal Harvesting

Harmful algal blooms are a global problem in water environments, and their explosive growth endangers the health of aquatic ecosystems. Magnetic nanomaterials for the harvesting of microalgae have received a lot of attention because of their high efficiency, low cost, and ease of operation. In this study, magnetic mesoporous silica nanomaterials were prepared using Fe3O4 as a carrier and harvesting on Chlorella sp. HQ. It was found that silica coated with magnetic Fe3O4 microspheres has good dispersion. The harvesting of Chlorella sp. HQ via magnetic mesoporous silica could be maintained over a wide pH range (4 to 12). After the removal of organic components from the surface of the material, the magnetic mesoporous silica obtained a better porous structure. The ethanol reflux method was more beneficial than the calcination method in maintaining the stable structure of the material, thus improving the harvesting efficiency of the material for the microalgae Chlorella sp. HQ by a maximum of 17.8% (65.9% to 83.7%). When the molar ratio of active agent cetyltrimethylammonium bromide (CTAB) and stabilizer polyvinylpyrrolidone (PVP) was 1: 0.092 at pH 4 and algal concentration of 0.5 g/L, the materials showed the maximum harvesting efficiency of Chlorella sp. HQ was 84.2%.

Two-phase microalgae cultivation for RAS water remediation and high-value biomass production.

The overall goal of this study was to provide solutions to innovative microalgae-based technology for wastewater remediation in a cold-water recirculating marine aquaculture system (RAS). This is based on the novel concept of integrated aquaculture systems in which fish nutrient-rich rearing water will be used for microalgae cultivation. The produced biomass can be used as fish feed, while the cleaned water can be reused, to create a highly eco-sustainable circular economy. Here, we tested three microalgae species Nannochloropis granulata (Ng), Phaeodactylum tricornutum (Pt), and Chlorella sp (Csp) for their ability to remove nitrogen and phosphate from the RAS wastewater and simultaneously produce high-value biomass, i.e., containing amino acids (AA), carotenoids, and polyunsaturated fatty acids (PUFAs). A high yield and value of biomass were achieved for all species in a two-phase cultivation strategy: i) a first phase using a medium optimized for best growth (f/2 14x, control); ii) a second "stress" phase using the RAS wastewater to enhance the production of high-value metabolites. Ng and Pt performed best in terms of biomass yield (i.e., 5-6 g of dry weight, DW.L-1) and efficient cleaning of the RAS wastewater from nitrite, nitrate, and phosphate (i.e., 100% removal). Csp produced about 3 g L-1 of DW and reduced efficiently only nitrate, and phosphate (i.e., about 76% and 100% removal, respectively). The biomass of all strains was rich in protein (30-40 % of DW) containing all the essential AA except Methionine. The biomass of all three species was also rich in PUFAs. Finally, all tested species are excellent sources of antioxidant carotenoids, including fucoxanthin (Pt), lutein (Ng and Csp) and β-carotene (Csp). All tested species in our novel two-phase cultivation strategy thus showed great potential to treat marine RAS wastewater and provide sustainable alternatives to animal and plant proteins with extra added values.

Proteomics Reveals Damaging Effect of Alpha-Cypermethrin Exposure in a Non-Target Freshwater Microalga Chlorella sp. NC-MKM

Alpha-cypermethrin, a pyrethroid pesticide, is frequently used on crops to prevent insect attacks. However, occasionally, due to drift, leaching, or with rainwater, it enters the aquatic environment and poses a serious threat to the growth of non-target aquatic organisms. In the current study, we were interested in investigating the damaging effect of alpha-cypermethrin on a local freshwater non-target green alga Chlorella sp. NC-MKM in terms of its protein levels. This was achieved by exposing Chlorella sp. NC-MKM to an EC50 concentration of alpha-cypermethrin for 1day, followed by the two-dimensional (2-D) gel electrophoresis and MALDI-TOF MS. Fifty-three proteins, which had showed significant differential accumulation (> 1.5 fold, P < 0.05) after exposure to alpha-cypermethrin, were considered as differentially accumulated proteins (DAPs). These DAPs were further divided into several functional categories, and the expressions of each in control and treatment samples were compared. Comparison revealed that alpha-cypermethrin exposure affects the accumulation of proteins related with photosynthesis, stress response, carbohydrate metabolism, signal transduction and transporters, translation, transcription, cell division, lipid metabolism, amino acid and nucleotide biosynthesis, secondary metabolites production, and post-translational modification, and thus rendered the tested algal isolate sensitive toward this pesticide. The overall findings of this research thus offer a fundamental understanding of the possible mechanism of action of the insecticide alpha-cypermethrin on the microalga Chlorella sp. NC-MKM and also suggest potential biomarkers for the investigation of pesticide exposed microalgae.

Unmasking effects of masks: Microplastics released from disposable surgical face masks induce toxic effects in microalgae Scenedesmus obliquus and Chlorella sp.

During the COVID-19 pandemic billions of face masks were used since they became a necessity in everyone's lives. But these were not disposed properly and serve as one of the most significant sources of micro and nano plastics in the environment. The effects of mask leached plastics in aquatic biota remains largely unexplored. In this work, we quantified and characterized the released microplastics from the three layers of the mask. The outer layer of the face mask released more microplastics i.e., polypropylene than middle and inner layers. We investigated and compared the acute toxic effects of the released microplastics between Scenedesmus obliquus and Chlorella sp. The results showed a decrease in cell viability, photosynthetic yield, and electron transport rate in both the algal species. This was accompanied by an increase in oxidative stress markers such reactive oxygen species (ROS) and malondialdehyde (MDA) content. There was also a significant rise of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) in both the algal cells. Furthermore, morphological changes like cell aggregation and surface chemical changes in the algae were ascertained by optical microscopy and FTIR spectroscopy techniques, respectively. The tests confirmed that Scenedesmus obliquus was more sensitive than Chlorella sp. to the mask leachates. Our study clearly revealed serious environmental risk posed by the released microplastics from surgical face masks. Further work with other freshwater species is required to assess the environmental impacts of the mask leachates.

Toxic Effect of Anionic Surfactants on Freshwater Sponge Lubomirskia baikalensis and Its Endosymbiotic Microalgae Chlorella sp.

A number of reports on sponge diseases, including from Lake Baikal, have increased dramatically all over the world in recent years. Herewith, there are various hypotheses for sponge mortality. Lubomirskia baikalensis (phylum Porifera, order Spongillida) is a unique endemic freshwater sponge of Lake Baikal that contains a complex community of eukaryotic and prokaryotic endosymbiotic microorganisms. In this work, we present the first results for the effect of anionic surfactants viz. linear alkylbenzene sulphonates (LAS) at low 10 and 20 µg L−1 concentrations on Baikal sponge species and their symbiotic community as an experimental model. A new toxicity test protocol under conditions close to natural is proposed. It uses the sponge amoebocytes called as SA1-cells, which contain eukaryotic green microalgae Chlorella sp. These SA1-cells are shown to be representative indicator in assessing the impact of anionic surfactants. The acute toxic effect resulted in 97–100% sponge cell death in less than 48 h, as well as 100% symbiotic microalgae Chlorella sp. death over 72 h was noted under LAS solution (20 μg L−1) exposure during in vivo experiments. This includes the cell membrane fatty acid changes, change in the cell sizes, cell swelling, and lysis. Long term exposure to LAS solution (10 μg L−1) reflected in cellular stress (oxidative stress) and accompanied by malondialdehyde formation (0.16–2.0 μg g−1 of dry weight) during 14-day exposure was noted. Oxidative stress and mortality of L. baikalensis are associated with their low antioxidant activity. Trolox-equivalent antioxidant capacity (TEAC) found in the range from 0.00031 to 0.00077 Trolox equivalents for these freshwater sponges.