High biomass yields of Chlorella protinosa with efficient nitrogen removal from secondary effluent in a membrane photobioreactor.

Further treatment of secondary effluents before their discharge into the receiving water bodies could alleviate water eutrophication. In this study, the Chlorella proteinosa was cultured in a membrane photobioreactor to further remove nitrogen from the secondary effluents. The effect of hydraulic retention time (HRT) on microalgae biomass yields and nutrient removal was studied. The results showed that soluble algal products concentration reduced in the suspension at low HRT, thereby alleviating microalgal growth inhibition. In addition, the lower HRT reduced the nitrogen limitation for Chlorella proteinosa's growth through the phase-out of nitrogen-related functional bacteria. As a result, the productivity for Chlorella proteinosa increased from 6.12 mg/L/day at an HRT of 24 hr to 20.18 mg/L/day at an HRT of 8 hr. The highest removal rates of 19.7 mg/L/day, 23.8 mg/L/day, and 105.4 mg/L/day were achieved at an HRT of 8 hr for total nitrogen (TN), ammonia, and chemical oxygen demand (COD), respectively. However, in terms of removal rate, TN and COD were the largest when HRT is 24 hr, which were 74.5% and 82.6% respectively. The maximum removal rate of ammonia nitrogen was 99.2% when HRT was 8 hr.

The Impact of Calcium Depletion on Proliferation of Chlorella sorokiniana Strain DSCG150.

This study analyzed the effects of Ca2+ metal ions among culture medium components on the Chlorella sorokiniana strain DSCG150 strain cell growth. The C. sorokiniana strain DSCG150 strain grew based on a multiple fission cell cycle and growth became stagnant in the absence of metal ions in the medium, particularly Ca2+. Flow cytometry and confocal microscopic image analysis results showed that in the absence of Ca2+, cell growth became stagnant as the cells accumulated into four autospores and could not transform into daughter cells. Genetic analysis showed that the absence of Ca2+ caused upregulation of calmodulin (calA) and cell division control protein 2 (CDC2_1) genes, and downregulation of origin of replication complex subunit 6 (ORC6) and dual specificity protein phosphatase CDC14A (CDC14A) genes. Analysis of gene expression patterns by qRT-PCR showed that the absence of Ca2+ did not affect cell cycle progression up to 4n autospore, but it inhibited Chlorella cell fission (liberation of autospores). The addition of Ca2+ to cells cultivated in the absence of Ca2+ resulted in an increase in n cell population, leading to the resumption of C. sorokiniana growth. These findings suggest that Ca2+ plays a crucial role in the fission process in Chlorella.

Feasibility study on heterotrophic utilization of galactose by Chlorella sorokiniana and promotion of galactose utilization through mixed carbon sources culture.

BACKGROUND: The development of alternative carbon sources is important for reducing the cost of heterotrophic microalgae cultivation. Among cheap feedstocks, galactose is one of the most abundant sugars and can be easily obtained from many natural biomasses. However, it is generally difficult to be utilized by microalgae. In addition, the mechanism of its low utilization efficiency in heterotrophic cultivation is still unknown. RESULTS: Among seven tested carbon sources, only glucose and acetate could be efficiently utilized by C. sorokiniana in heterotrophic cultivation while there were no apparent signs of utilization of other carbohydrates, including galactose, in regular heterotrophic cultivation. However, galactose could be utilized in cultures with high inoculation sizes. This confirmed that C. sorokiniana has a complete pathway for transporting and assimilating galactose under dark conditions, but the rate of galactose utilization is quite low. In addition, the galactose utilization was greatly enhanced in mixotrophic cultures, which indicated that galactose utilization could be enhanced by additional pathways that can enhance cell growth. Based on above results, a mixed carbon source culture strategy was proposed to improve the utilization rate of galactose, and a significant synergistic effect on cell growth was achieved in cultures using a mixture of galactose and acetate. CONCLUSIONS: This study indicated that the galactose metabolism pathway may not be inherently deficient in Chlorophyta. However, its utilization rate was too low to be detected in regular heterotrophic cultivation. Mixed carbon source culture strategy was confirmed effective to improve the utilization rate of galactose. This study contributes to a deeper understanding of the utilization ability of difficultly utilized substrates in the heterotrophic cultivation of microalgae, which is of great significance for reducing the cost of heterotrophic cultivation of microalgae.

Protective effect of Chlorella vulgaris on testicular damage, sperm parameters, androgen production, apoptosis and oxidative stress index in male rats following doxorubicin administration.

Doxorubicin (DOX) is a chemotherapy agent associated with adverse effects on male reproductive health. Chlorella vulgaris (ChV) is a potent natural antioxidant with promising applications in maintaining health and preventing oxidative stress-related diseases. The present study aimed to investigate the protective effect of ChV on DOX-induced testicular toxicity. Twenty-five Wistar rats (230 ± 20 g) were randomly assigned to five groups (n = 5), including the control group, sham group (received normal saline by oral gavage daily and intraperitoneally (IP) once a week), DOX group (3 mg/kg; once a week; IP), ChV group (300 mg/kg/day; by oral gavage), and DOX (3 mg/kg; once a week; IP) + ChV (300 mg/kg/day; by oral gavage) group. After 8 weeks of treatment, the rats were euthanized and serum testosterone level, testes histomorphometry, gonadosomatic index (GSI), apoptotic gene expression, oxidative stress index, and sperm parameters were assessed. The results showed that DOX led to a significant decrease in histological indexes, testosterone level, GSI, sperm parameters, and Bcl-2 gene expression and increased expression of P-53 and Bax genes, and oxidative stress markers (P<0.05). The administration of ChV in the DOX+ChV group significantly improved testosterone levels, sperm parameters, testicular tissue apoptosis, antioxidant enzymes, and structural integrity of the testes (P<0.05). The findings suggest that the co-administration of ChV can be a promising therapeutic agent to reduce the adverse effects of DOX on male reproductive performance.

Linking the removal of enrofloxacin to the extracellular polymers of microalgae in water bodies: A case study focusing on the shifts in microbial communities.

Microalgae can promote antibiotic removal, which has attracted growing attention. However, its synergistic removal performance with bacteria in antibiotic pollutants is still poorly understood. In this study, firstly, we selected two green algae (Dictyosphaerium sp. and Chlorella sp.) and exposed them to Enrofloxacin (ENR) to observe their extracellular polysaccharides (EPS) concentration dynamic and the removal of antibiotics. Secondly, EPS was extracted and added to in situ lake water (no algae) to investigate its combined effect with bacteria. The results indicate that both Dictyosphaerium sp. and Chlorella sp. exhibited high tolerance to ENR stress. When the biomass of microalgae was low, ENR could significantly stimulate algae to produce EPS. The removal rates of Dictyosphaerium sp. and Chlorella sp. were 15.8% and 10.5%, respectively. The addition of EPS can both alter the microbial community structure in the lake water and promote the removal of ENR. The LEfSe analysis showed that there were significant differences in the microbial marker taxa, which promoted the increase of special functional bacteria for decomposing ENR, between the EPS-added group and the control group. The EPS of Dictyosphaerium sp. increased the abundance of Moraxellaceae and Spirosomaceae, while the EPS of Chlorella sp. increased the abundance of Sphingomonadaceae and Microbacteriaceae. Under the synergistic effect, Chlorella sp. achieved a maximum removal rate of 24.2%, while Dictyosphaerium sp. achieved a maximum removal rate of 28.9%. Our study provides new insights into the removal performance and mechanism of antibiotics by freshwater microalgae in water bodies and contribute to the development of more effective water treatment strategies.

Specificity of Photochemical Energy Conversion in Photosystem I from the Green Microalga Chlorella ohadii.

Primary excitation energy transfer and charge separation in photosystem I (PSI) from the extremophile desert green alga Chlorella ohadii grown in low light were studied using broadband femtosecond pump-probe spectroscopy in the spectral range from 400 to 850 nm and in the time range from 50 fs to 500 ps. Photochemical reactions were induced by the excitation into the blue and red edges of the chlorophyll Qy absorption band and compared with similar processes in PSI from the cyanobacterium Synechocystis sp. PCC 6803. When PSI from C. ohadii was excited at 660 nm, the processes of energy redistribution in the light-harvesting antenna complex were observed within a time interval of up to 25 ps, while formation of the stable radical ion pair P700+A1- was kinetically heterogeneous with characteristic times of 25 and 120 ps. When PSI was excited into the red edge of the Qy band at 715 nm, primary charge separation reactions occurred within the time range of 7 ps in half of the complexes. In the remaining complexes, formation of the radical ion pair P700+A1- was limited by the energy transfer and occurred with a characteristic time of 70 ps. Similar photochemical reactions in PSI from Synechocystis 6803 were significantly faster: upon excitation at 680 nm, formation of the primary radical ion pairs occurred with a time of 3 ps in ~30% complexes. Excitation at 720 nm resulted in kinetically unresolvable ultrafast primary charge separation in 50% complexes, and subsequent formation of P700+A1- was observed within 25 ps. The photodynamics of PSI from C. ohadii was noticeably similar to the excitation energy transfer and charge separation in PSI from the microalga Chlamydomonas reinhardtii; however, the dynamics of energy transfer in C. ohadii PSI also included slower components.

Recent progress on the toxic effects of microplastics on Chlorella sp. in aquatic environments.

Microplastics (MPs) are emerging contaminants that have harmful effects on ecosystems. Microalgae are important primary producers in aquatic environments, providing nutrients for various organisms. These microorganisms may be affected by MPs. Therefore, it is important to investigate the toxicity aspects of different MPs on Chlorella species. It can be seen that the BG-11 culture medium was the most commonly used medium in 40 % of the studies for the growth of Chlorella sp. Chlorella sp. grows optimally at a temperature of 25 °C and a pH of 7. Most studies show that Chlorella sp. can grow in the range of 3000-6000 lux. Moreover, various techniques have been used to analyze the morphological properties of MPs in different studies. These techniques included scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and transmission electron microscopy (TEM), which were used in 65 %, 35 %, and 27 % of the studies, respectively. 53 % of the research has focused on the toxic effects of PS on Chlorella sp. Findings show that 41 % of the studies investigated MPs concentrations in the range of 10-100 mg/L, followed by 32 % of the studies in the range of 100-1000 mg/L. The studies found that MPs were used in a spherical shape in 45 % of the cases. The enzymes most affected by MPs were superoxide dismutase (SOD) and Malondialdehyde (MDA), accounting for 48 % of the studies each. Additionally, exposure to MPs increased the activity of enzymes such as SOD and MDA. In general, it can be concluded that MPs had a relatively high negative effect on the growth of Chlorella sp.

Comprehensive transcriptomic and metabolomic insights into simultaneous CO2 sequestration and nitrate removal by the Chlorella vulgaris and Pseudomonas sp. consortium.

Simultaneous CO2 sequestration and nitrate removal can be achieved by co-cultivation of Chlorella vulgaris with Pseudomonas sp. However, a comprehensive understanding of the synergistic mechanism between C. vulgaris and Pseudomonas sp. remains unknown. In this study, transcriptomics and metabolomics analysis were employed to elucidate the synergistic mechanism of C. vulgaris and Pseudomonas sp. Transcriptomic and metabolomic analyses identified 3664 differentially expressed genes and 314 metabolites. Transcriptome analysis revealed that co-culture with Pseudomonas sp. promoted the photosynthesis of C. vulgaris by promoting the synthesis of photosynthetic pigments and photosynthesis-antenna proteins. Furthermore, it stimulated pathways associated with energy metabolism from carbon sources, such as the Calvin cycle, glycolytic pathway, and TCA cycle. Additionally, Pseudomonas sp. reduced nitrate levels in the co-culture system by denitrification, and microalgae regulated nitrate uptake by down-regulating the transcript levels of nitrate transporter genes. Metabolomic analysis indicated that nutrient exchange was conducted between algae and bacteria, and amino acids, phytohormones, and organic heterocyclic compounds secreted by the bacteria promoted the growth metabolism of microalgae. After supplementation with differential metabolites, the carbon fixation rate and nitrate removal rate of the co-culture system reached 0.549 g L-1 d-1 and 135.4 mg L-1 d-1, which were increased by 20% and 8%, respectively. This study provides a theoretical insight into microalgae-bacteria interaction and its practical application, as well as a novel perspective on flue gas treatment management.

Improving protein extraction and peptide production from Chlorella vulgaris using combined mechanical/physical and enzymatic pre-treatments.

Chlorella vulgaris is a microalga rich in proteins with potential applications in food and feed industries. However, the presence of a cellulose-containing cell wall, which is a major barrier to protein extraction, together with fibroproteinaceous complexes, limits the bioaccessibility of nutritional and bioactive proteins and peptides from C. vulgaris biomass. Therefore, this study aimed to evaluate the effect of different mechanical/physical pre-treatments (bead milling, extrusion, freeze-drying, heating, microwave and sonication) combined or not with enzymatic treatments (commercial trypsin and pancreatin) on protein extraction and peptide formation from a C. vulgaris suspension. The amount of total protein and peptides released to the supernatant was quantified by Bradford and o-phthaldialdehyde assays, respectively. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis was used to analyse the extracted protein fractions. The results showed that extrusion caused a 3-fold increase in total peptides (p < 0.001) compared to no-pretreatment, and trypsin increased peptides formed in bead-milled (p = 0.020) and freeze-dried (p = 0.021) microalga relative to those pre-treatments alone. Some pre-treatments, such as bead milling and microwave, were effective in releasing specific protein fractions, particularly those from 32 to 40 kDa (up to 1.2-fold), compared to control. Pancreatin combined with bead milling decreased 32 to 40 kDa- and 26 kDa-protein fractions (p < 0.010) compared with the sole use of mechanical treatment, whereas the same enzyme mixture associated with microwave produced a similar result for 26 kDa-protein fraction (p = 0.023). Pancreatin also effectively reduced the total protein fraction released after pre-treatment with sonication (p = 0.013). These findings suggest that combining different pre-treatments and enzymatic treatments could improve protein extraction from C. vulgaris biomass, providing a useful approach for the development of sustainable protein sources. The present results highlight the need for further studies to assess the efficacy of extrusion in improving the bioaccessibility of C. vulgaris proteins in monogastric animals' diets.

Chlorella pyrenoidosa polysaccharides supplementation increases Drosophila melanogaster longevity at high temperature.

Chlorella pyrenoidos polysaccharides (CPPs) are the main active components of Chlorella pyrenoidos. They possess beneficial health properties, such as antioxidant, anti-inflammatory, and immune-enhancing. This study aims to investigate the protective function and mechanism of CPPs against high-temperature stress injury. Results showed that supplementation with 20 mg/mL CPPs significantly extended the lifespan of Drosophila melanogaster under high-temperature stress, improved its motility, and enhanced its resistance to starvation and oxidative stress. These effects were mainly attributed to the activation of Nrf2 signaling and enhanced antioxidant capacity. Additionally, it has been discovered that CPPs supplementation enhanced Drosophila resilience by preventing the disruption of the intestinal barrier and accumulation of reactive oxygen species caused by heat stress. Overall, these studies suggest that CPPs could be a useful natural therapy for preventing heat stress-induced injury.

Assessment of hydrocarbon degradation capacity and kinetic modeling of Chlorella vulgaris and Scenedesmus quadricauda for crude oil phycoremediation under mixotrophic conditions.

Crude oil spills imperil aquatic ecosystems globally, prompting innovative solutions such as microalgae-based bioremediation. This study explores the potential of Chlorella vulgaris and Scenedesmus quadricauda, for crude oil spill phycoremediation under mixotrophic conditions and varying crude oil concentrations (0.5-2%). C. vulgaris demonstrated notable resilience, thriving up to 1% crude oil exposure, while S. quadricauda adapted to lower concentrations. Optimal growth for both was observed at 0.5% exposure. Chlorophyll a content in C. vulgaris increases at 0.5% exposure but declines above 1%, while a decline was noticeable in chlorophyll b in treatment groups above 1%. Carotenoid levels varied, displaying the highest levels at higher concentrations above 1.5%. Similarly, S. quadricauda showed increased chlorophyll a content at 0.5% exposure, with stable carotenoid levels and a decline in chlorophyll b content at higher concentrations. GC/MS analyses indicated C. vulgaris efficiently degraded aliphatic compounds like decane and tridecane, surpassing S. quadricauda in degrading both aliphatic and aromatic hydrocarbons. Growth kinetics was best represented by the modified Gompertz and logistic models. These findings highlight the species-specific adaptability and optimal concentration for microalgae to degrade crude oil effectively, advancing phycoremediation processes and strategies critical for environmental restoration.

This study marks the first exploration of both Chlorella vulgaris and the previously unexplored Scenedesmus quadricauda for crude oil phycoremediation potential under mixotrophic conditions. Additionally, it pioneers the modeling and study of algae growth kinetics in response to crude oil exposure. Notably, this research demonstrated the adaptability and efficiency of C. vulgaris in degrading crude oil components under mixotrophic conditions up to a level of 1%, while S. quadricauda showed similar capabilities at a concentration of 0.5%.

Fabrication of porous adsorbents templated from Capillary foam stabilized with chlorella for highly efficient removal of cationic dyes.

The thermodynamic instability of traditional aqueous foams stabilized surfactants is the most critical bottleneck for construction of porous material. Herein, a novel strategy was proposed to prepare capillary foam based on chlorella and utilize it as a template for constructing porous materials with high-efficiency adsorption. The capillary foam, stabilized by chlorella particles enclosed within a gel network of oil bridges connecting the particles (capillary suspension). Chlorella particles, acting as stable particles, form oil bridges and were distributed at the phase interface of the Capillary foam. These particles exhibited resistance to shear force, allowing the formation of long-term stable Capillary foam. Utilizing this foam as a template, a porous material with outstanding adsorption performance for Methylene Blue (MB) and Brilliant Green (BG) dyes was successfully constructed. Additionally, the material exhibited sustained high adsorption performance even after undergoing 5 thermal regeneration-adsorption cycles. In conclusion, this study presented a green and straightforward method for constructing capillary foam with high stability, presenting a promising approach for developing porous materials with exceptional adsorption and regeneration properties for dyes.

Effect of Macro and Microalgae Addition on Nutritional, Physicochemical, Sensorial, and Functional Properties of a Vegetable Cream.

Algae are a booming resource in the food industry due to their several health benefits. This study assesses the impact of the combined use of selected macro- and microalgae to improve the nutritional profile and the labeling of a vegetable cream by the introduction of nutrition and health claims. As macroalgae, two Ascophyllum nodosum L., one natural (An) and one smoked (AnS), were selected for their high iodine concentration and flavor notes. A new strain of Chlorella vulgaris, golden (CvG), was selected as the microalgae, which is rich in proteins and has a neutral sensorial profile (golden color and mild flavor). In this study, two vegetable creams were compared. The control (CTRL) versus one enriched with a mixture of macroalgae and microalgae (CV-AN). Sensory, physicochemical, and functional properties of both vegetable creams were evaluated. The bioactivity assessed was the effect of iodine as a health claim and antioxidant and antihypertensive properties. CV-AN vegetable cream showed significantly higher values (p < 0.05) for protein content, iodine value, and antioxidant activity, with no significant differences (p > 0.05) in antihypertensive activity or sensory panel. The incorporation of these algae resulted in a vegetable cream with a better nutritional profile and sensory acceptability comparable to the control, offering protein and iodine source claims in the labeling.

The responses and tolerance of photosynthetic system in Chlorella vulgaris to the pharmaceutical pollutant carbamazepine.

Screening for sensitive toxicological indicators and understanding algal tolerance to pharmaceutical contaminants (PhCs) are essential for assessing PhCs risk and their removal by microalgae. Carbamazepine (CBZ) showed adverse effects on microalgae, but the specific toxicity mechanisms on the most sensitive algal photosynthetic system (PS) remain limited. This study delved into the impact of CBZ exposure on the growth, cell viability, pigment content, and PS of Chlorella vulgaris. The findings revealed a notable inhibition of C. vulgaris growth by CBZ, with an IC50 value of 27.2 mg/L at 96 hours. CBZ exposure induced algal membrane damage and cell viability. Intriguingly, CBZ drastically diminished intracellular pigment levels, notably showing "low promotion and high inhibition" of chlorophyll b (Chl b) by 72 hours. Moreover, the study identified a decreased number of active reaction centers (RCs) within algal PSII alongside inhibited electron transport from QA to QB on the PSII receptor side, leading to PSII disruption. As an adaptive response to CBZ stress, C. vulgaris stimulated its Chl b synthesis, increased non-photochemical quenching (NPQ), and adapted its tolerance to bright light. Additionally, the alga attempted to compensate for the CBZ-induced reduction in electron transfer efficiency at the PSII receptor side and light energy utilization by increasing its electron transfer from downstream. Principal component analysis (PCA) further verified that the parameters on non-photochemical dissipation, electron transport, and integrative performance were the most sensitive algal toxicological indicators for CBZ exposure, and algal PS has energy protection capability through negative feedback regulation. However, prolonged exposure to high doses of CBZ will eventually result in permanent damage to the algal PS. Hence, attention should be paid to the concentration of CBZ in the effluent and the exposure time, while methods to mitigate algal photodamage should be appropriately sought for algal treatment of dense effluents.

The anti-aging effects of Chlorella polysaccharide extract in Caenorhabditis elegans.

Chlorella has a variety of biological activities, and it is worth further exploring its pharmacological effects. In this study, we investigated the antioxidant and anti-ageing activities of Chlorella polysaccharide extract (CPE). Further studies revealed that CPE exhibited anti-ageing, and antioxidant activities in vivo, including an extended Caenorhabditis elegans stress resistance, decreased deposition of lipofuscin, and reduced effects of amyloid ß protein on mobility, decreased levels of reactive oxygen species and increased activity of antioxidant enzymes. Moreover, it dramatically increased the expression of anti-stress and longevity genes and reduced the expression of ageing-related genes; therefore, it was hypothesised that the mechanism of the age-delaying effect of CPE was related to the insulin signalling pathway. In summary, CPE could delay ageing and provide a new avenue for the application and development of CPE.

Characterization and potentiality of plant-derived silver nanoparticles for enhancement of biomass and hydrogen production in Chlorella sp. under nitrogen deprived condition.

Energy is a crucial entity for the development and it has various alternative forms of energy sources. Recently, the synthesis of nanoparticles using benign biocatalyst has attracted increased attention. In this study, silver nanoparticles were synthesized and characterized using Azadirachta indica plant-derived phytochemical as the reducing agent. Biomass of the microalga Chlorella sp. cultivated in BG11 medium increased after exposure to low concentrations of up to 0.48 mg L-1 AgNPs. In addition, algal cells treated with 0.24 mg L-1 AgNPs and cultivated in BG110 medium which contained no nitrogen source showed the highest hydrogen yield of 10.8 mmol L-1, whereas the untreated cells under the same conditions showed very low hydrogen yield of 0.003 mmol L-1. The enhanced hydrogen production observed in the treated cells was consistent with an increase in hydrogenase activity. Treatment of BG110 grown cells with low concentration of green synthesized AgNPs at 0.24 mg L-1 enhanced hydrogenase activity with a 5-fold increase of enzyme activity compared to untreated BG110 grown cells. In addition, to improve photolytic water splitting efficiency for hydrogen production, cells treated with AgNPs at 0.24 mg L-1 showed highest oxygen evolution signifying improvement in photosynthesis. The silver nanoparticles synthesized using phytochemicals derived from plant enhanced both microalgal biomass and hydrogen production with an added advantage of CO2 reduction which could be achieved due to an increase in biomass. Hence, treating microalgae with nanoparticles provided a promising strategy to reduce the atmospheric carbon dioxide as well as increasing production of hydrogen as clean energy.

Microalgae-mediated biofixation as an innovative technology for flue gases towards carbon neutrality: A comprehensive review.

Microalgae-mediated industrial flue gas biofixation has been widely discussed as a clean alternative for greenhouse gas mitigation. Through photosynthetic processes, microalgae can fix carbon dioxide (CO2) and other compounds and can also be exploited to obtain high value-added products in a circular economy. One of the major limitations of this bioprocess is the high concentrations of CO2, sulfur oxides (SOx), and nitrogen oxides (NOx) in flue gases, according to the origin of the fuel, that can inhibit photosynthesis and reduce the process efficiency. To overcome these limitations, researchers have recently developed new technologies and enhanced process configurations, thereby increased productivity and CO2 removal rates. Overall, CO2 biofixation rates from flue gases by microalgae ranged from 72 mg L-1 d -1 to over 435 mg L-1 d-1, which were directly influenced by different factors, mainly the microalgae species and photobioreactor. Additionally, mixotrophic culture have shown potential in improving microalgae productivity. Progress in developing new reactor configurations, with pilot-scale implementations was observed, resulting in an increase in patents related to the subject and in the implementation of companies using combustion gases in microalgae culture. Advancements in microalgae-based green technologies for environmental impact mitigation have led to more efficient biotechnological processes and opened large-scale possibilities.

Poly(ionic liquid)-Flocculated Chlorella Loading Bactericidal and Antioxidant Hydrogel as a Biological Hydrogen Therapy for Diabetic Wound Dressing.

Infection and oxidative stress seriously hinder the healing of diabetic wounds, resulting in various serious health and clinical problems. Herein, a sustainable biological hydrogen (H2)-producing hyaluronic acid-based hydrogel patch (HAP-Chl) was constructed by loading an imidazolium-based poly(ionic liquid) (PIL) flocculated live Chlorella as a diabetic wound dressing. The PIL can flocculate Chlorella through electrostatic interactions between PIL and Chlorella to form Chlorella agglomerates, endowing the Chlorella in the central agglomerates with the ability to continuously produce H2 for 24 h under mild conditions. Combining the membrane disruption-related bactericidal mechanism of PIL and the antioxidant properties of the produced H2, HAP-Chl was determined to be antibacterial and antioxidant. In addition to exhibiting biocompatible and nontoxic activities, subsequent Staphylococcus aureus-infected chronic wound studies revealed that HAP-Chl is capable of promoting the healing of chronic wounds by effectively killing bacteria, reducing extensive ROS, relieving inflammation, and promoting the deposition of mature collagen and angiogenesis. This study provides a new strategy for constructing an in situ sustainable H2-producing hydrogel, enabling the formation of novel antibacterial and antioxidant material platforms with potential for wound dressing applications.

The impact of artificial light pollution at night on the life history parameters of rotifer Brachionus plicatilis with different food experiences.

Artificial light at night (ALAN) may pose threat to rotifer Brachionus plicatilis. Additionally, the food of rotifer, i.e. algal community composition, often fluctuates. Thus, we selected five wavelengths of ALAN (purple, blue, green, red, white) and a three-colored light flashing mode (3-Flash) to test their impacts on life history traits of B. plicatilis with different food experiences, including those feeding Chlorella vulgaris (RC) or Phaeocystis globosa (RP). Results indicated purple ALAN promoted RC development, white ALAN inhibited RC development, while 3-Flash and white ALAN promoted RP development. Under red and white ALAN, RP increased fecundity but decreased lifespan. High-quality food enhanced rotifer's resistance to the impact of ALAN on lifespan. ALAN and food experience interacted on B. plicatilis. The effect of blue ALAN has less negative effects on B. plicatilis, based on hierarchical cluster analysis. Such findings are helpful to evaluate the potential impact of ALAN on marine zooplankton.

Microalgae cultivation trials in a membrane bioreactor operated in heterotrophic, mixotrophic, and phototrophic modes using ammonium-rich wastewater: The study of fouling.

In this work, microalgae cultivation trials were carried out in a membrane bioreactor to investigate fouling when the cultures of Chlorellavulgaris were grown under mixotrophic, heterotrophic, and phototrophic cultivation regimes. The Chlorella cultures were cultivated in wastewater as a source of nutrients that contained a high concentration of ammonium. In mixotrophic cultivation trials, the results showed that the elevated contents of carbohydrates in the soluble microbial product and proteins in extracellular polymeric substances probably initiated membrane fouling. In this case, the highest protein content was also found in extracellular polymeric substances due to the high nitrogen removal rate. Consequently, transmembrane pressure significantly increased compared to the phototrophic and heterotrophic regimes. The data indicated that cake resistance was the main cause of fouling in all cultivations. Higher protein content in the cake layer made the membrane surface more hydrophobic, while carbohydrates had the opposite effect. Compared to a mixotrophic culture, a phototrophic culture had a larger cell size and higher hydrophobicity, leading to less membrane fouling. Based on our previous data, the highest ammonia removal rate was reached in the mixotrophic cultures; nevertheless, membrane fouling appeared to be the fundamental problem.