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Fish farmers’ dependence on costly formulated fish feed has affected their income. The cost of formulated feed is also constantly rising. Efforts to mass-produce the locally available natural resource, namely water flea (Moina sp.), were initiated as an alternative to the commercially formulated fish feed. This study evaluates the most suitable growth medium for commercially culturing Moina sp. and Chlorella sp. and studies the effect of their growth activity on water quality. In this study, the growth behaviour of Moina sp. and Chlorella sp. was monitored individually before Moina sp. was cultured together with Chlorella sp. in a growth medium. Chlorella sp. was cultured in different mediums (BG-11, Bristol, and organic fertiliser). The first generation of Moina sp. took 96 h to mature and begin to reproduce, while the next generation took a shorter time (from 24 h to 48 h). The brood size was between five and 15 neonates, while the maximum brood count recorded was eight. The Chlorella sp. culture had grown well on Day 5 (555.33 ug/L); thus, it was introduced with Moina sp. on Day 6. Although an organic fertiliser medium provided the optimum conditions for Chlorella sp. growth, it slightly inhibited the Moina sp. growth due to higher ammonia (NH3) concentration. However, the organic fertiliser medium could sustain Chlorella sp. growth while being ingested by Moina sp. The growth activity of both species slightly affected the water quality. Meanwhile, the increase in ammonia (NH3), carbon dioxide (CO2), and calcium carbonate (CaCO3) was recorded. In conclusion, organic fertiliser is the best medium for Chlorella sp. growth, which is the main food source for Moina sp. culture. [ABSTRACT FROM AUTHOR]

Chronic diabetic wound remains a critical challenge suffering from the complicated negative microenvironments, such as high-glucose, excessive reactive oxygen species (ROS), hypoxia and malnutrition. Unfortunately, few strategies have been developed to ameliorate the multiple microenvironments simultaneously. In this study, Chlorella sp. (Chlorella) hydrogels were prepared against diabetic wounds. In vitro experiments demonstrated that living Chlorella could produce dissolved oxygen by photosynthesis, actively consume glucose and deplete ROS with the inherent antioxidants, during the daytime. At night, Chlorella was inactivated in situ by chlorine dioxide with human-body harmless concentration to utilize its abundant contents. It was verified in vitro that the inactivated-Chlorella could supply nutrition, relieve inflammation and terminate the oxygen-consumption of Chlorella-respiration. The advantages of living Chlorella and its contents were integrated ingeniously. The abovementioned functions were proven to accelerate cell proliferation, migration and angiogenesis in vitro. Then, streptozotocin-induced diabetic mice were employed for further validation. The in vivo outcomes confirmed that Chlorella could ameliorate the undesirable microenvironments, including hypoxia, high-glucose, excessive-ROS and chronic inflammation, thereby synergistically promoting tissue regeneration. Given the results above, Chlorella is considered as a tailor-made therapeutic strategy for diabetic wound healing. Living Chlorella sp. (Chlorella) could treat wound healing by producing dissolved oxygen and depleting glucose andreactive oxygen species (ROS) during the daytime and was inactivated at night to terminate oxygen-consumption of Chlorella-respiration. [Display omitted] [ABSTRACT FROM AUTHOR]

Chemical industry wastewater containing metals must be treated so as not to threaten the environment or human life. One of the wastewater treatments is the biosorption process using living microalgae. Although living microalgae can provide better results as a biosorbent, the mechanism of this biosorption process is complex because it involves two steps of the process, active and passive uptake, which run simultaneously. In addition, several process parameters need to be adjusted for the biosorption process to operate optimally. This study aims to investigate the effect of several parameters such as microalgae concentration, salinity, and light color. Synthetic CuSO4 solution at a concentration of 40 mg/L and pH 5 is used as artificial waste, while microalgae Chlorella sp. is used as biosorbent. The biosorption process was operated in a batch system at room temperature for 6 days. The experimental results show that 96.83% of the Cu(II) ions could be removed when the microalgae concentration, salinity, and light color were conditioned at 1.5 x 106 cells/mL, 3,000 mg/L, and red light, respectively. [ABSTRACT FROM AUTHOR]

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Conventional biological wastewater treatment systems have a low pathogen removal capacity. Microalgae-based systems are sustainable and low-cost alternatives for wastewater treatment and are capable of removing pathogens from domestic effluents. Other microorganisms have been identified as alternative indicators of disinfection since they have greater resistance than Escherichia coli, either because of the formation of spores or because of other mechanisms of protection, and because they spread in wastewater treatment plants; the most important are Clostridium perfringens and Staphylococcus spp. This study assessed the influence of microalgal strains (e.g., Chlorella vulgaris and Scenedesmus acutus Meyen) and the addition of CO2 and O2 on the removal of C. perfringens and Staphylococcus spp. from domestic wastewater in microalgal–bacterial systems. The removal of C. perfringens (2.5 to 3.2 log units) and Staphylococcus sp. (1.8 to 2.0 log units) was higher when using Chlorella sp. inoculum. The addition of CO2 and O2 did not have a significant effect on the removal of pathogenic bacteria. The main mechanism of C. perfringens removal was by means of toxins and bactericidal substances produced by the microalgae, while Staphylococcus spp. removal also occurred through photooxidative processes. [ABSTRACT FROM AUTHOR]

Chlorella sp., a common type of algae found in global surface waters, is prone to causing "blooms" and can accumulate significant amounts of nutrients such as nitrogen, phosphorus, and carbon. While carbon materials derived from Chlorella sp. are widely used in the field of adsorption, there are relatively few reports focused on electrocatalysis. This study utilized Chlorella sp. as a raw material to synthesize functional carbon materials, and prepared nitrogen-doped (CN), nickel-doped (CNi), and nitrogen-nickel co-doped (CNNi) carbon-based catalysts with both metal and non-metal elements. The results showed that the CN, CNi and CNNi catalysts possessed certain electrocatalytic properties, among which the CNNi material had the best electrocatalytic activity towards CO 2 reduction (CO 2 RR). In 1.0 M KHCO 3, the CNNi catalyst exhibited an instantaneous current density of 15.4 mA/cm2 under the potential of -0.82 V (vs. RHE). In terms of product selectivity, the Faraday efficiency of CO on the CNNi electrode was up to 90 % when the electrode potential was -0.62 V (vs. RHE), while the selectivity of the CN and CNi catalysts for CO was only 59 % under the optimal conditions. The co-doping of nitrogen and nickel significantly enhanced the electrocatalytic activity and the selectivity towards CO of Chlorella -based carbon materials. [Display omitted] [ABSTRACT FROM AUTHOR]

This study emphasises the significant role of various microalgal species in promoting environmental sustainability through their ability to treat Palm Oil Mill Effluent (POME) while enhancing biomass and biodiesel production. The microalgae strains, Nannochloropsis oculata, Chlorella vulgaris, Chlamydomonas biconvexa, Scenedesmus dimorphus, Spirulina platensis, and Tetraselmis suecica , were assessed for their POME treatment efficiency under diverse growth conditions. In flask cultures, N. oculata effectively reduced oil, grease, COD, BOD, TOC, and TN; while immobilized C. vulgaris showed significant reduction in COD, BOD, Fe(II), TN, TP, and Mn(II). S. dimorphus and S. platensis showed excellent pollutant removal in outdoor raceway ponds, whereas C. biconvexa effectively eliminated PO 4 and NH 4 +-N in photobioreactors. S. platensis and C. sorokiniana showed impressive growth rates and biomass production. Furthermore, cytochrome P450 monooxygenases in N. oculata and C. vulgaris provided a 70–90 % reduction in polyaromatic hydrocarbons (PAHs). Biodiesel potential was confirmed with Nannochloropsis sp. achieving lipid productivity of 362–600 mg/L−1d and a lipid content of 61.60 %, while Chlorella pyrenoidosa yielded 230 mg/L−1d and 68 % lipid content. FAME analysis highlighted Chaetoceros affinis with 74.6 % monounsaturated fatty acids (MUFA) and 72.3 % oleic acid (C18:1), while C. vulgaris exhibited a diverse FAME profile. These results demonstrate the dual capacity of microalgae in renewable energy production and wastewater treatment, showcasing their potential as a sustainable feedstock for biodiesel production from palm oil mills effluents. • Effective removal of contaminants from Palm Oil Mill Effluents (POME) using microalgae Nannochloropsis sp. and Chlorella sp. • Nannochloropsis sp., absorbs and enzymatically degrades PAHs from POME. • Microalgae produce cytochrome P450 monooxygenases to degrade PAHs into simpler hydroxylated molecules in treated POME. • Phycoremediation enhances Chlorella sp. biomass from POME treatment, promoting lipid accumulation for biofuel production. [ABSTRACT FROM AUTHOR]

Microalgae cultures have emerged as a promising strategy in diverse areas, ranging from wastewater treatment to biofuel production, thus contributing to the search for carbon neutrality. These photosynthetic organisms can utilize the resources present in wastewater and fix atmospheric CO 2 to produce biomass with high energy potential. In this study, the removal efficiency of Polycyclic Aromatic Hydrocarbons (PAHs), CO 2 fixation and lipid content in the biomass produced from microalgae grown in airlift photobioreactor were evaluated. Four mesoscale cultures were carried out: Control (Seawater + Conway medium), Treatment A (Oil Produced Water + Poultry Effluent Water), Treatment B (Poultry Effluent Water + Seawater) and Treatment C (Oil Produced Water, Seawater and nutrients). The impact of biostimulation, through the addition of nutrients, on PAHs removal efficiency (up to 90%), CO 2 fixation rate (up to 0.20 g L−1 d−1) and the composition of the generated biomass was observed. Primarily, the addition of nitrates to the culture medium impacted CO 2 fixation rate of the microalgae. In addition, a direct correlation was observed between PAHs removal and lipid accumulation in the biomass, up to 36% in dry weight, demonstrating microalgae's ability to take advantage of the organic carbon (PAHs) present in the culture medium to generate lipid-rich biomass. The concentration of polysaccharides in the biomass obtained did not exceed 12% on a dry weight basis, and the Higher Heating Value (HHV) ranged between 17 and 21 MJ kg−1. Finally, the potential of generating hydrogen through pyrolysis was highlighted, taking advantage of the characteristics of biomass as a conversion route to produce biofuels. These results show that microalgae are effective in wastewater treatment and have great potential in producing biofuels, thus contributing to the transition towards more sustainable energy sources and climate change mitigation. • Chlorella sp. is efficient in removing toxic pollutants in industrial effluents. • Airlift photobioreactor is efficient for the treatment of wastewater and CO 2 fixation. • The biostimulation and salinity increase the efficiency of PAH removal. • Microalgae take PAHs to accumulate lipids and proteins and not polysaccharides. [ABSTRACT FROM AUTHOR]

• Elevated temperatures and nutrients boost growth of Microcystis aeruginosa. • Chlorella sp. boots microcystin production under competitive conditions. • Nutrient levels outshine temperature for toxin production during competitions. • Interspecific competition intensity correlates strongly with heightened microcystin. • Interspecific competition should be included in the future toxin risk assessment. Global warming and eutrophication contribute to frequent occurrences of toxic algal blooms in freshwater systems globally, while there is a limited understanding of their combined impacts on toxin-producing algal species under interspecific competitions. This study investigated the influences of elevated temperatures, lights, nutrient enrichments and interspecific interactions on growth and microcystin (MC) productions of Microcystis aeruginosa in laboratory condition. Our results indicated that elevated temperatures and higher nutrient levels significantly boosted biomass and specific growth rates of Microcystis aeruginosa , which maintained a competitive edge over Chlorella sp. Specifically, with phosphorus levels between 0.10 and 0.70 mg P L−1, the growth rate of Microcystis aeruginosa in mixed cultures increased by 23 %–52 % compared to mono-cultures, while the growth rate of Chlorella sp. shifted from positive in mono-cultures to negative in mixed cultures. Redundancy and variance partition analyses suggested that Chlorella sp. stimulate MC production in Microcystis aeruginosa and nutrient levels outshine temperature for toxin productions during competition. Lotka‒Volterra model revealed a positive correlation between the intensities of competitions and MC concentration. Our findings indicate that future algal bloom mitigation strategies should consider combined influence of temperature, nutrients, and interspecific competition due to their synergistic effects on MC productions. [Display omitted] [ABSTRACT FROM AUTHOR]

• NAB Catalyst served as an efficient ORR catalyst for MCC. • Increase in algal-biosorption on increasing initial Ni concentration. • 3.5 times higher power density as compared to the MCC without any catalyst loading. • Easily synthesizable NAB catalyst supported uninterrupted algal cultivation. Lately, the bio electrochemical systems are emerging as an efficient wastewater treatment and energy conversion technology. However, their scaling-up is considerably restrained by slow-rate of cathodic oxygen reduction reaction (ORR) or otherwise by the high cost associated with the available efficient ORR catalysts. In this investigation, a cost-effective and eco-friendly approach for synthesizing Ni based ORR catalyst utilizing biosorption property of microalgae is accomplished. The synthesised Ni adsorbed algal biochar (NAB) served as an efficient cathode catalyst for enhancing ORR in a microbial carbon-capture cell (MCC). On increasing the initial concentration of Ni2+ in the aqueous medium from 100 mgL−1 to 500 mgL−1, the biosorption capacity was found to increase from 3 mgg−1 to 32 mgg−1 of algae cell. The MCC operated with NAB based cathode catalyst loading of 2 mgcm-2 exhibited 3.5 times higher power density (4.69 Wm−3) as compared to the one with commercial activated carbon. A significant organic matter removal (82 %) in the anodic chamber with simultaneous algal biomass productivity in the cathodic chamber was attained by MCC with cathode loaded with 2 mgcm−2 of NAB. Hence, this easily synthesised low-cost catalyst, out of waste stream, proved its ability to improve the performance of MCC. [ABSTRACT FROM AUTHOR]

Microalgae are highly studied microorganisms for the production of high-value products due to their high content of proteins, lipids, carbohydrates, and chlorophyll. These compounds are refined to obtain profitable industrial products. This article analyzes the lipid production of Chlorella sp. biomass, considering 18 scenarios for its production, with 9 of these being partially supplemented with swine wastewater. A 1 ha area was considered for biomass cultivation, primary and secondary biomass harvesting, and lipid extraction. Using simulation in the software SuperPro Designer v10, parameters such as CO2 capture (from a thermoelectric power plant), freshwater consumption, wastewater consumption, energy consumption, and unit production cost were evaluated. The results show that the production cost is high, ranging from 836.9 US $/kg to 1131.5 US $/kg of produced lipids, with a maximum CO2 capture of 454 kg of CO2/kg of lipids. The use of wastewater reduces the production cost by approximately 10%. The evaluation of technical and economic parameters allows us to identify bottlenecks and implement strategies to reduce production costs.

Algal Organic Matter (AOM) is derived from the dissolved organic matter composition of the algal species being observed. In this study, excitation–emission fluorescence spectroscopy was used to determine Chlorella sp.’s AOM and pigment characteristics in varying algal biomass concentrations. The AOM and pigment characteristics were observed at 400–600 nm and 600–800 nm fluorescence emission, respectively, with an excitation spectrum of 300–450 nm. F450/680 was computed based on the ratio between the dissolved organic matter contribution at 450 nm and chlorophyll-a at 680 nm. F450/680 positively correlated with algal biomass (r = 0.96) at an excitation wavelength of 405 nm. This study is a good reference for those interested in algal biomass estimation and production in natural waters.

Research background. Microalgae represent an emergent sustainable source of bioactive compounds such as antioxidants, vitamins, minerals and polyunsaturated fatty acids that can ameliorate the nutritional characteristics of foods. The biochemical composition of microalgae could be modulated by varying the culture conditions to enhance the accumulation of biomolecules of interest. The aim of this work is to optimise the nutri-functional properties of two microalgae that can be used in food production. Experimental approach. Nannochloropsis gaditana L2 and Chlorella sp. SM1 were screened for growth, biochemical composition and radical scavenging activity employing four different growth media (algal, BG-11, f/2 and Conway) with different nutrient composition. The feasibility of using Chlorella sp. SM1 cultivated in BG-11 medium, in an under-investigated Mediterranean dairy product ricotta cheese and its effect on the sensory attributes was investigated. Additionally, Arthrospira platensis was used as reference in sensory analysis. Results and conclusions. Nitrate- and phosphate-rich media (BG-11 and algal) enhanced the biomass productivity. However, the highest lipid production (23.10 and 11.86 mg/(L·day) by strains SM1 and L2 respectively) and carbohydrate content (34.79 and 44.84% by SM1 and L2 respectively) were obtained with the nitrate-deficient f/2 medium. Regardless of the used medium, the lipid profile of Chlorella sp. SM1 and N. gaditana L2 remained adequate for different applications with >50% C16-18 as the main fatty acids. Significant increase in oleic acid (C18:1) content was recorded in response to nitrogen deficiency, being the highest in SM1 in f/2 medium (34%). Nitrogen deficiency was also found to enhance phenolic compound (expressed as gallic acid equivalents, 48.8 and 35.1 mg/g in SM1 and L2 respectively) and carotenoid contents (2.2 and 2.0 mg/g in SM1 and L2 respectively). Due to its interesting antioxidant potential, Chlorella sp. SM1 was used at different mass fractions (0.2, 1 and 1.5%) to enrich the ricotta cheese. The sample with 0.2% Chlorella sp. SM1 was found to give the most appreciated product. Novelty and scientific contribution. This study presents the production of an innovative ricotta cheese using Chlorella sp. as a functional ingredient, without altering the manufacturing procedure, while maintaining acceptable sensorial characteristics. The biochemical composition of the used strains varied depending on the culture medium composition, which enabled the accumulation of phytonutrients of interest.

RESUMEN | La camaronicultura es una actividad en constante crecimiento, lo que ha llevado al deterioro de los ecosistemas por la deposición de efluentes que impactan al medio ambiente, generando no solo daños a los ecosistemas sino también a la misma calidad del agua que ingresa al cultivo. Esta investigación busca evaluar la eficiencia de consorcios microbianos autóctonos (in vitro) en la biorremediación del efluente de una finca camaronera ubicada en el sector Cabello Manabí, Ecuador. Para ello, se analizaron los parámetros: fosfatos, amonio, nitritos, nitratos, sólidos en suspensión, oxígeno disuelto, temperatura, pH, DBO5 y coliformes totales. Se utilizó un diseño completamente aleatorio con un factor y 4 niveles y se realizaron 4 tratamientos: consorcio bacteriano (T1) incluyendo la levadura Saccharomyces cerevisiae, consorcio de microalgas (T2), consorcio de hongos (T3) conformado por Trichoderma harzianum, S. cerevisiae, Lactobacillus acidophilus, Bacillus subtilis, Lactobacillus plantarum, y como (T4) un consorcio combinado de los tres tratamientos anteriores. Se observó una diferencia estadísticamente significativa en T2 con respecto a los demás tratamientos, pues debido a sus actividades metabólicas se logró la biorremediación de elementos como fosfatos, compuestos nitrogenados y coliformes totales, mientras que en los demás parámetros no se logró una mejora significativa. El proceso llevado a cabo por las microalgas permitió ajustar los parámetros analizados a criterios de calidad del agua para ser reutilizados en actividades agrícolas y ganaderas e incluso vertidos en cuerpos de agua dulce, concluyendo que la aplicación de microalgas autóctonas de la zona es útil para la biorremediación de los efluentes camaroneros de la localidad. ABSTRACT | Shrimp farming is a constantly growing activity, which has led to the deterioration of ecosystems due to the deposition of effluents that impact the environment, which generates not only damage to ecosystems but also to the same quality of the water that enters the cultivation area. That is why this research seeks to evaluate the efficiency of autochthonous microbial consortia (in vitro) in the bioremediation of the effluent of a shrimp farm located in the Cabello Manabí sector - Ecuador. For this, the following parameters were analyzed: phosphates, ammonium, nitrites, nitrates, suspended solids, dissolved oxygen, temperature, pH, BOD5 and total coliforms. A Completely Randomized Design with one factor and 4 levels was used, using 4 treatments: bacterial consortium (T1) including the yeast Saccharomyces cerevisiae., microalgae consortium (T2)., fungal consortium (T3) made up of Trichoderma harzianum, S. cerevisiae, Lactobacillus acidophilus, Bacillus subtilis, Lactobacillus plantarum., and as (T4) a combined consortium of the three previous treatments. A statistically significant difference was observed in T2 with respect to the other treatments, since thanks to its metabolic activities, the bioremediation of elements such as phosphates, nitrogen compounds and total coliforms was observed, while in the other parameters a significant improvement was not achieved. The process carried out by the microalgae made it possible to adjust the parameters analyzed to water quality criteria to be reused in agricultural and livestock activities and even discharged into freshwater bodies, concluding that the application of microalgae native to the area was useful for the bioremediation of shrimp effluents from the locality.

This study investigates the effects of catalyst preparation techniques on the yield and quality of liquid biofuel produced from slow catalytic pyrolysis of microalgae Chlorella sp. using various catalysts, including acid catalysts (HZSM-5) and base catalysts (activated carbon). The effects of different temperatures, catalyst loading, and reaction time on the yield and quality of liquid biofuels, including chemical composition, density, and the resulting viscosity at the optimal variable, were investigated. The results showed that slow catalytic pyrolysis using 1 wt.% activated carbon catalyst, a temperature of 550°C, and a reaction time of three hours produced a maximum yield of liquid biofuel at 50.38 wt.% with high aromatic hydrocarbons, less oxygen and acid, a density of 0.88 kg/L, and a viscosity of 5.79 cSt that satisfied specifications of biodiesel No. 2. Slow catalytic pyrolysis with a variety of catalyst types and catalyst preparation techniques affects the increase in yield and quality adjustment of liquid biofuel. The proposed technology can be further developed for commercial applications, replacing conventional diesel fuel.

The removal of microalgae represents a problematic part of the water decontamination process, in which most techniques are expensive and non-ecological. In the paper, we focus on the synergistic relationship between microscopic filamentous fungi and algal culture. In the process of decontamination of a model sample containing ammonium ions, efficient biocoagulation, resp. co-pelletization of dried algae Chlorella sp. and Aspergillus niger sensu stricto are shown. The microscopic filamentous fungus species A. niger was added to a culture of an algal suspension of Chlorella sp., where the adhesion of the algal cells to the fungi subsequently occurred due to the electrostatic effect of the interaction, while the flocculation activity was approximately 70 to 80%. The algal cells adhered to the surface of the A. niger pellets, making them easily removable from the solution. The ability of filamentous fungi to capture organisms represents a great potential for the biological isolation of microalgae (biocoagulation) from production solutions because microalgae are considered to be a promising renewable source of oil and fermentables for bioenergy. This form of algae removal, or its harvesting, also represents a great low-cost method for collecting algae not only as a way of removing unnecessary material but also for the purpose of producing biofuels. Algae are a robust bioabsorbent for absorbing lipids from the environment, which after treatment can be used as a component of biodiesel. Chemical analyses also presented potential ecological innovation in the area of biofuel production. Energy-efficient and eco-friendly harvesting techniques are crucial to improving the economic viability of algal biofuel production. [ABSTRACT FROM AUTHOR]

The present study aimed to optimize synthetic wastewater composition as a mixotrophic medium for enhanced growth and lipid accumulation coupled with high nitrogen removal by the green microalga Chlorella sp. Individual effects of the three main independent variables (nitrate concentration, seawater ratio, and glycerol supplementation) were tested initially, then response surface methodology (RSM) was subsequently performed to explore the optimum combined conditions. The highest lipid productivity of 37.60 mg/L day was recorded at 25% seawater. Glycerol supplementation enhanced both lipid content and biomass production, which resulted in the highest recorded lipid productivity of 42.61 mg/L day at 4 g/L glycerol. Central composite design followed by numerical optimization was further applied which suggested NaNO3 concentration at 101.5 mg/L, seawater ration of 23.8%, and glycerol supplementation of 0.25 g/L as the optimum conditions for dual maximum lipid productivity and nitrogen removal of 46.9 mg/L day and 98.0%, respectively. Under the optimized conditions, dry weight and lipid content increased by 31.9% and 20.3%, respectively, over the control, which resulted in increase in lipid productivity by 71.5%. In addition, optimization process resulted in pronounced changes in fatty acid proportions where saturated fatty acids increased by 7.4% in the optimized culture with simultaneous reduction of polyunsaturated fatty acids. The estimated biodiesel characteristics calculated from the fatty acid methyl ester (FAMEs) profile showed agreement with the international standards, while optimized cultures showed an 8.5% lower degree of unsaturation, which resulted in higher cetane numbers and lower iodine values. This study provides economical approach for optimization and efficient nutrient recycling through cultivation of Chlorella sp. for further enhanced biodiesel production. [ABSTRACT FROM AUTHOR]

With the accelerated urbanization and rapid development of the industrial and agricultural sectors, concern about the pollution of water environments is becoming more widespread. Algal blooms of varying sizes are becoming increasingly frequent in lakes and reservoirs; temperatures, nutrients, heavy metals, and dissolved oxygen are the factors that influence algal bloom occurrence. However, knowledge of the combined effect of heavy metals and temperature on algal growth remains limited. Thus, this study investigated how specific concentrations of heavy metals affect algal growth at different temperatures; to this end, two heavy metals were used (0.01 mg/L Pb2+ and 0.05 mg/L Cr6+) at three incubation temperatures (15, 25, and 30 °C) with the alga Chlorella sp. A higher incubation temperature contributed to a rise in soluble proteins, which promoted algal growth. The density of algal cells increased with temperature, and catalase (CAT) decreased with increasing temperature. Chlorella sp. growth and catalase activity were optimal at 30 °C (algal cell density: 1.46 × 107 cell/L; CAT activity: 29.98 gprot/L). Pb2+ and Cr6+ significantly promoted Chlorella sp. growth during incubation at 25 and 30 °C, respectively. At specific temperatures, 0.01 mg/L Pb2+ and 0.05 mg/L Cr6+ promoted the production of soluble proteins and, hence, the growth of Chlorella sp. The results provide a useful background for the mitigation and prevention of algal blooms. [ABSTRACT FROM AUTHOR]

As the human population grows and the demand for food grows with it, the recycling, or containment of materials is important for resource consumption. Nitrogen is one of the main plant nutrients, most commonly used as the chemical substance urea. Because urea is very soluble and at a relatively low temperature (50–60 °C) it hydrolyses easily (releases N2 and CO2) in soil solutions; this is why very large amounts of nitrogen are lost and greenhouse gases are released and this causes serious environmental problems. Therefore, the aim of this study was to create microalgae-enriched nitrogen fertilizers with different binders that inhibit nitrogen leaching from the soil. Binders such as water (W), polyvinyl acetate dispersion (PVAD), molasses (M), potato starch (S), and carboxymethyl cellulose (CMC) were used in this study and their influence on leaching was analysed. Granular fertilizers were produced in a drum granulator and dryer under equal conditions: granulation time was 7 min, granulation took place at a temperature of 50–60 °C, at a drum rotation speed of 26 rpm, with a 5° inclination angle of the drum. The results show that the highest quantity of the marketable fraction was 43.01 (±3.068%) and it was obtained using urea, with 10% (w/w) microalgae additive, and 11.4% (w/w) of 5% concentration molasses solution. The granules of the fertilizer marketable fraction are similar in size because the size guide number (SGN) of the granules vary in a narrow range and fall within the interval of 287 to 304; this means that the average particle size is ~3 mm. When different binders were used, the average static crushing strength of the granulated fertilizers was lower (approximately 6–12 MPa) than using water alone (approximately 12–16 MPa), but the lower values still fell into the required range. Additives of PVAD solutions and molasses solutions have been found to retain nitrogen in sand. The method of one-way analysis of variance (ANOVA) was used to evaluate the results. [ABSTRACT FROM AUTHOR]

This study assessed the impact of dietary Chlorella sp. and Schizochytrium sp. extracts on growth performance, feed utilization, body composition, and gene expression related to growth, digestion, antioxidant defense, and immune response in rainbow trout (Oncorhynchus mykiss). A total of 180 fish (average weight 8.92 ± 0.04 g) were randomly distributed into 12 fiberglass tanks (400 L, 15 fish per tank, three replicates per treatment). Fish were divided into four dietary groups for 60 days: 0 % (Control), 0.5 % Chlorella sp. extract (CH), 0.5 % Schizochytrium sp. extract (SC), and a combined 0.25 % Chlorella sp. and 0.25 % Schizochytrium sp. (CH + SC). At trial end, fish in the CH + SC group had a final weight (FW) of 27.06 ± 0.28 g, significantly higher than other groups (P < 0.05), with improved growth parameters (P < 0.05). While body composition showed no differences in moisture, lipid, or ash content, crude protein was significantly higher in CH + SC (P < 0.05). Gene expression analysis showed upregulation of the growth hormone GH-I gene in the CH + SC group (P < 0.05). Genes related to digestive enzymes (trypsin, lipase, amylase) were also upregulated in all microalgae groups, with the highest levels in CH + SC (P < 0.05). Additionally, antioxidant genes (SOD, CAT, GPx) and immune-related genes (LYZII, TNF-α, IL-1β) showed elevated expression in CH + SC (P < 0.05). This study demonstrated that a diet containing Chlorella sp. and Schizochytrium sp. extracts supports growth, enhances nutrient utilization, and upregulates genes related to antioxidant and immune function in rainbow trout. Further research is recommended to assess functional immune responses and enzyme activities to confirm these physiological effects., Competing Interests: Declaration of competing interest The author declares that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2024. Published by Elsevier Inc.)

Remediation of hexavalent chromium with conventional chemical and physical methods is a costly process, while replacing some critical steps in physiochemical remediation with self-sustaining bioremediation agents are expected to be cost-effective and environmentally friendly implementation. In this study, a microalga isolated from a freshwater stream receiving treated textile wastewater was identified up to its molecular level and investigated its ability to tolerate and remove hexavalent chromium from extremely acidic conditions under different temperatures. The ability of microalgae to tolerate and remove Cr(VI) was investigated by growing it in BG11 media with different pH (1, 2, 3 & 7), amended with several concentrations of Cr(VI) and incubated under different temperatures for 96 hrs. Microalga was identified as Chlorella vulgaris and found that the isolated strain has a higher hexavalent chromium removal potential in extremely acidic conditions than in neutral pH conditions at 25 °C. In contrast, its Cr(VI) removal potential is significantly influenced by the pH and temperature of the growth medium. Furthermore, it exhibited a permanent viability loss at extreme acidic conditions (pH 1 − 3) and prolonged exposure to the higher chromium content. The microalga investigated will be a highly useful bioagent in hexavalent chromium remediation in high acidic conditions. [ABSTRACT FROM AUTHOR]

In recent years, in order to deal with the excessive CO2 emission caused by fossil fuel combustion and the resulting global warming and energy depletion, CO2 mitigation strategy via carbon fixation and conversion to high-value products by microalgae cultivation system has attracted a great deal of attentions. In particular, the addition of CO2 absorbents has been reported effective to promote microalgal growth and carbon fixation rates. In this study, Chlorella sp. with excellent CO2 tolerance was used as the experimental strain to explore the effects of chemical adsorbent monoethanolamine (MEA) on algal physiological and biochemical characteristics and carbon sequestration efficiency under 20% CO2 concentration with ventilation rate of 0.33. The results showed that adding MEA could alleviate the growth inhibition of microalgae by culture medium acidification caused by high concentration CO2. In addition, MEA with appropriate concentration could also effectively improve the growth, metabolism, CO2 fixation efficiency and photosynthetic activity of Chlorella sp. The biomass concentration, CO2 fixation rate and lipid content of Chlorella sp. all reached maximum value of 3.07 g/L, 0.55 g CO2/(L·d) and 23.5% respectively under 50 mg/L MEA, which were 43.7%, 45.6% and 21.7% respectively higher than those without MEA in control. In summary, 50 mg/ L CO2 absorbent monoethanolamine could significantly improve the biomass, lipid accumulation and carbon sequestration efficiency of Chlorella sp. under high CO2 concentration. The above results would provide theoretical basis for CO2 emission reduction and clean energy development by microalgae. [ABSTRACT FROM AUTHOR]

Converting microalgal lipids into biodiesel is considered a promising route in the field of biofuel production. However, the cost of microalgae-based biodiesel is still too high to be economically feasible, especially economical and effective methods for microalgae cell wall breaking are still lacking. In this study, five algicidal bacteria and their cell-free supernatant were evaluated by the percentage of cell disruption and lipid extraction of Chlorella sp.. Results showed that both bacteria and supernatant could induce cell disruption of Chlorella sp. to release lipids. Among them, the supernatant of Aeromonas hydrophila showed the best effects both in terms of the percentage of cell disruption and lipid extraction, and the cell disruption percentage increased with the extension of co-culture time with A. hydrophila supernatant. The inoculation volume of co-culture (A. hydrophila cell-free supernatant and Chlorella sp.) was explored, indicating that 10% volume ratio of A. hydrophila supernatant was identified as optimal proportion to improve lipid extraction. In addition, A. hydrophila supernatant showed obvious effects on the composition distribution of lipids extracted from Chlorella sp. that the fraction of unsaturated fatty acids decreased apparently, which would be beneficial to biodiesel production. The mechanism of microalgal cell disruption by A. hydrophila supernatant was further studied by scanning electron microscopy, ROS levels and antioxidant responses. This indicated that the cell morphology of Chlorella sp. changed dramatically with the time of co-culture with A. hydrophila supernatant.. These findings implied that algicidal properties of bacteria components are a promising tool for microalga cell disruption and lipid recovery, providing a new insight into the method for biofuel production. [ABSTRACT FROM AUTHOR]

Laponite nanoparticles have been proposed for soil densification to reduce the negative impacts of seismic hazards. However, the effects of laponite on the aquatic ecosystem are lacking. In this study, different concentrations (0.1, 0.2, 0.3, 0.4, and 0.5%) of laponite were used to investigate the growth and total chlorophyll content of microalgae: Chlorella sp. This study examined the potential toxic effects of laponite on the growth characteristics of freshwater green algae Chlorella sp. isolated from northern Ontario. The experiments were carried out in a 500-ml glass flask with 300 ml working volume and placed under white fluorescent lights for 16 h: 8 h day-night cultivation cycle in a constant orbital shaker. The results revealed that the lower concentration of laponite can enhance microalgae growth, while the higher laponite concentration had a growth inhibitory effect. The total chlorophyll content increased by 33% at 0.1% treatment group than that of the control group. Based on the SEM images, aggregation of microalgae was significantly noticeable at the lower concentration of laponite (0.1% treatment) whereas, in the higher laponite concentration (0.4 and 0.5% treatment), algal cells were embedded in laponite gel and also noticed some physical impairment. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles (MNPs) are gaining popularity because of their small size allowing for research into the fundamentals of magnetism. In wastewater treatment, adsorption methods commonly remove heavy metals, but copper (Cu+2) ion removal using magnetic nanoparticles (NPs) has not been investigated. In this study two different modes were used to determine maximum adsorption capacity to remove copper(II). The nanoparticles containing the Fe3O4 with Chlorella, core-shell Fe3O4/SiO2 with Chlorella sp. synthesized and characterized by Fourier transform infrared (FT-IR) analysis, the morphology observed by scanning electron microscope (SEM), crystalline structure, and grain size provided by energy dispersive X-ray (EDX) and X-ray diffraction (XRD). Copper(II) ion removal showed in both modes. The maximum copper(II) ion reduction percent was obtained by nanoparticles containing core-shell Fe3O4/Chlorella 80.3%, Fe3O4/SiO2 with Chlorella sp. (86.9%) the result showed maximum removal using Fe3O4/SiO2 with Chlorella sp. due to increase of surface area. The results indicate that the adsorption using magnetic nanoparticles with Chlorella sp. enhances the cell surface and provides easy access to the separation for both preparation and recapture. [ABSTRACT FROM AUTHOR]

Biofouling represents one of the major issues in Photobioreactors (PBRs) for microalgae cultivation. At this aim, a series of zwitterionic-containing polymethylmethacrylate (PMMA) co -ter-polymers, differing in the molar percentage of sulfobetaine (SBMA)- and 2-hydroxyethylmethacrylate (HEMA) components were designed as antifouling (AF) potential coatings for inner PMMA surface of photobioreactors (PBRs). Among these, the sample named PSBM, P(HEMA-co-MMA-co-SBMA), showing the best film capabilities on PMMA slides, was selected, characterized and its AF activity investigated. High transparent and thin PSBM films, as confirmed by AFM and optical transparency investigations, were obtained by a simple drop-casting procedure using a basic isopropylalcohol/water mixture. AFM images of raw PSBM and PSBM films clearly indicate that a conformational change occurred upon treatment with electrolytes. PSBM was further characterized by ATR-FTIR Spectroscopy, Dynamic Light Scattering, X-Ray Photoelectron Spectroscopy, Thermogravimetric analysis, Differential Scanning Calorimetry and Static Water Contact Angle (WCA) investigations. Consistent with hydrophilic behavior, the PSBM surface provided a WCA of 60.9 ± 0.8° which, interestingly, decreased to 27.7 ± 1.2° after immersion in electrolyte culture media. PSBM films displayed a high satisfactory AF behavior in that a rare or no cell adhesion was observed when placed for 7 days in a suspension of the green microalga Chlorella sp. For comparison, the experiments were carried out with untreated and rough PMMA surfaces. [Display omitted] • Sulfobetaine Containing-Polymethylmethacrylate (PSBM) coating produced high transparent coupons when applied on PMMA surfaces • Untreated and artificially worn PMMA surfaces showed a higher algal cells adhesion than PSBM coated surfaces • No toxicity was observed during biomass production • Chlorella sp. confirmed to be a good model microorganism due to its fast growth and reproducible results [ABSTRACT FROM AUTHOR]

Dhiba port has a strategic location near the Neom project. Various anthropogenic activities contributed to the discharge of metals, metalloids and oil spills in the aquatic system and caused environmental pollution. Microalgae are the best microorganisms in aquatic conditions known to be capable of eliminating contaminants. In this work the Chlorella sp. was isolated from seawater, the metals, metalloids were determine using ICP- OES (Inductively Coupled Plasma-Optical Emission Spectrometer) and hydrocarbons were determine using GC-MS in different five sites in Dhiba port, after and before treated with Chlorella sp, and immobilized Chlorella sp. The growth parameters (optical density and pigment contents) of Chlorella sp and immobilized Chlorella sp. were investigated during 14 days of grown. The results showed that the most contaminated site by metals and metalloids was site no 3, by Sb, As, Be, Se, and Zn with concentrations 0.07546, 0.05709, 0.09326, 0.4618, and 0.00979 mg/L respectively, and site no 1 was the most contamination by organic compounds, so the site no 1 and site no 3 were chosen to test the efficiency of Chlorella sp. and immobilized Chlorella sp. to remove hydrocarbons and both metals and metalloids. Chlorella sp. and immobilized Chlorella sp. had completely removed metals and metalloids that were present in site 3. There were only 6 compounds remained, after treatments with immobilized alga in site 1. Immobilized Chlorella sp. is the most effective than suspended Chlorella sp in reduces the number of organic compounds in contaminated area. It is an economic tool due to simplifying harvesting and then retaining for further processing.

Microalgae extracts have a wide range of uses in the field of healthcare and nutrition. However, the use of microalgae extracts in anti-inflammatory properties and their mechanism of action have not yet been fully studied. Here, we show that extracts from Chlorella sp. WZ13 (CSE-WZ13) dose-dependently reduced nitrite production, inhibited the expression of inducible nitric oxide synthase (iNOS) protein, and decreased the production of the gene and inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Using high-content imaging analysis, it was found that CSE-WZ13 inhibited the translocation of nuclear factor kappa B (NF-κB) from the cytoplasm to the nucleus. CSE-WZ13 also exerted anti-inflammatory effects in an ear edema mouse model induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). CSE-WZ13 inhibited edema by 36.17% and 25.66% at a dose of 0.3 and 0.1 mg/ear, respectively. Histological analysis showed that topical application of CSE-WZ13 decreased TPA-induced inflammatory cell infiltration. Our results indicate that CSE-WZ13 may be a useful candidate for the purpose of decreasing inflammation.

Abstract Recently, mass production of lipid along with heavy metal reduction is gaining momentum due to their cost-effective and greener approach towards waste water treatment. The purpose of this study is to investigate the small scale photo bioreactor treatment of tannery effluent using Chlorella sp. isolated form Yercaud lake, Tamil Nadu, India. The results showed a significant decrease in the heavy metals content in the tannery effluent after the treatment. Maximum reduction of the heavy metal Chromium (Cr) of 10.92 mg L−1 was recorded, followed by Cobalt (Co)-7.37 mg L−1, Nickel (Ni)-9.15 mg L−1, Cadmium (Cd)-8.48 mg L−1, Lead (Pb)-12.54 mg L−1, Zinc (Zn)-11.56 mg L−1 and Copper (Cu)-10.71 mg L−1 at the end of the 20th day of treatment. The microalgae, Chlorella sp. was analyzed for their biosorption ability and the maximum biosorption capacity (qmax) rate against heavy metals was 81.36, 70.53, 82.15, 63.29, 58.92, 83.43, 64.83 µg L−1 for Cr, Pb, Ni, Cd, Co, Zn, and Cu respectively. It matched with the Langmuir and Freundlich kinetics models. The maximum CO2 utilization was found to be 60.50% and maximum concentration of lipid, carbohydrate and protein was found to be 0.95 g L−1, 250 µg mL−1 and 160 µg mL−1, respectively. The presence of various groups such as hydroxyl, alkyl, carbonyl and carboxylic acids was confirmed using Fourier transform infrared analysis. Thus, the isolated microalgae showed good biosorption ability towards the various heavy metal pollutants from tannery waste water.

Biofertilizers and biostimulators have become alternative sources of plant nutrients. Biofertilizers derived from microalgae represent a new approach in plant production. The aim of the study was to examine the capacity of the microalgal cell suspension to improve germination and initial growth (root and shoot length) of white Icicle Radish (Raphanus sativus) and Kohlrabi (Brassica oleracea var. gongylodes). By applying soil microalgal biofertilizer, initial growth was improved. Compared to the control, the root length of white radish was increased by 64.24% and 41.32%, using Chlorella sp. and Dictyosphaerium sp. cell suspension, respectively. Kohlrabi root growth was stimulated by application of Chlorella sp. and Dictyosphaerium sp. suspension by 60.97% and 55.02%, respectively. A significant difference in the shoot length was recorded, as well.

Energy diversification using microalgae biomass offers a solution to the fossil fuel crisis, which has become a global issue. Chlorella sp. is a microalga that can produce lipids and reduce chemical oxygen demand (COD) in liquid waste. In this research, we used Chlorella sp. to produce lipids and reduce COD in tofu liquid waste. This research aimed to identify the interaction between a complex microorganism, as a decomposer agent, with the addition of the photosynthetic microalgae Chlorella sp. as an oxygen producer to reduce COD in tofu liquid waste. Moreover, we aimed to determine the interaction between Chlorella sp. and a bacterial consortium for microalgae growth and lipid production. This study was conducted in batches with the addition of bacteria at five different concentrations (% v/v): 0 (no addition), up to 0.25, 0.50, 0.75, and 1. Cultivation was conducted for 13 days with solar irradiation in a photobioreactor. As a result, the highest density and the highest growth rate were obtained from the treatment with 1% bacteria, achieving as many as 5.65´106 cell/mL and 0.21/day. The 1% treatment was able to produce lipids and COD removal efficiencies of 20.93% and 96.30% at the best-removing detention times, which both occurred on the 13th day of cultivation.

• Sulfuric acid proves to be the most efficient for the acid hydrolysis of molasses. • An optimal hydrolysis was observed at a concentration of 0.15 M sulfuric acid. • Heterotrophic cultivation of C. sorokiniana MB-1-M12 was achieved using molasses. • Using 10 g/L reducing sugars yield 2.57 g/L biomass and 2.1 mg/g lutein content. • The process fulfills the objective of waste recycling and reutilization. Lutein is a xanthophyll carotenoid commonly found in photosynthetic organisms, such as microalgae and plants. It serves as a photosynthetic accessory pigment and possesses antioxidant properties. Lutein is recognized for its prophylactic use in preventing Age-Related Macular Degeneration (AMD) and is widely employed in health supplements. The demand for lutein is steadily increasing. This study utilized Chlorella sorokiniana MB-1-M12 for heterotrophic growth and lutein production, employing molasses as a model of food industrial waste as an alternative carbon source. Molasses was hydrolyzed using acids, and the optimal hydrolysis conditions were determined by varying the types and concentrations of the acids. The resulting hydrolysate, which contains reducing sugars, was then recovered and used to support the heterotrophic growth of C. sorokiniana MB-1-M12 for lutein production. The best efficiency in molasses hydrolysis was achieved using 0.15 M sulfuric acid, resulting in a maximum sugar recovery of 0.721 gs of reducing sugar per gram of molasses. When the molasses hydrolysate reached a sugar concentration of 10 g/L, it yielded a biomass of 2.57 g/L and a lutein content of 2.1 mg/g. These findings indicate that molasses can effectively serve as a substitute for glucose as a carbon source, although it cannot provide all the essential micronutrients required for biomass growth. Consequently, the addition of nutrients in BG-11 medium became necessary. This study successfully demonstrates the upcycling of waste resources, such as molasses, into a high-value product like lutein, all achieved in a cost-effective and resource-efficient manner. [ABSTRACT FROM AUTHOR]

Objective: The increased production of titanium dioxide (TiO2) incorporated consumer products have expressed concerns about their potential threat to the environment. It is warranted to investigate the importance of the release of TiO2 from consumer products and the resulting environmental repercussions. Thus, the present study evaluated the toxicity of TiO2 extracted from toothpaste along with the commercially available TiO2 (nano and bulk). Methods: The extracted and commercially available TiO2 were characterized for their shape, size, crystallinity, and functional groups. Chlorella sp. (0.1 optical density) was interacted with extracted, nano, and bulk TiO2 particles (0.01, 0.1, and 1 mg/L) for 72 h in a 100 mL sterile beaker. After 72 h, the cellular viability (%) was evaluated by cell count method. Oxidative stress in Chlorella sp. was computed by determining the reactive oxygen species generated. Intracellular concentration of Ti in Chlorella sp. was determined by inductively coupled plasma mass spectrophotometer. Principal component analysis was used to establish the relation between the different TiO2 particles and assays performed in Chlorella sp. Results: The extracted TiO2 was in the rutile phase and had a particle size in the sub-micron range. Toxicity of TiO2 was dose- and size-dependent and nano-form of TiO2 were found to be more toxic to Chlorella sp. followed by extracted and bulk TiO2. In addition to toxicity, oxidative stress and intracellular Ti concentration were measured. Our findings emphasize that extracted TiO2 at environmentally relevant concentrations of TiO2 were less toxic compared to commercially procured nano TiO2. Conclusion: This study highlights the need of assessing the environmental risks of nanoparticles used in consumer products by studying their interactions with aquatic organisms. [ABSTRACT FROM AUTHOR]

The Mediterranean diet has, among its cornerstones, the use of olive oil for its nutraceutical and organoleptic properties. Despite the numerous merits, olive-oil mill wastewater (OMWW), which is generated by the olive-oil extraction process, is one of the most serious environmental pollutants in the Mediterranean countries. The polluting potential of OMWW is due to its high content of tannins, polyphenols, polyalcohols, pectins and lipids. In order to close the recovery cycle of a fortified citrus olive oils previously developed, we tested the ability of five microalgae of the Chlorella group (SEC_LI_ChL_1, CL_Sc, CL_Ch, FB and Idr) in lowering the percentage of total phenolic compounds in vegetation water. This was obtained with three different extraction processes (conventional, and lemon and orange peels) at three concentrations each (10%, 25% and 50%). The results showed that strains Idr, FB and CL_Sc from the Lake Massaciuccoli can tolerate vegetation water from conventional and lemon peel extractions up to 25%; these strains can also reduce the phenolic compounds within the tests. The application of microalgae for OMWW treatment represents an interesting opportunity as well as an eco-friendly low-cost solution to be developed within companies as a full-scale approach, which could be applied to obtain a fortified microalgal biomass to be employed in nutraceutical fields. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV-C) irradiation is the most important part of water filtration, which has no side effects on the environment and has been used in water purification systems in the aquaculture and transistor industries. In this research, the effect of UV-C on Chlorella sp. was investigated. Chlorella sp. was irradiated 0, 1, 2 or 3 times at a fixed flow rate of 6.5 L min−1 and the effects of UV-C LED on the apoptosis rate and death rate of Chlorella sp. were analyzed by flow cytometry after staining cells with the nucleic acid dye SYTOX Green and the membrane-associated protein stain Annexin V-PE Reagent. As a result of UV-C irradiation, the Chlorella sp. cells underwent phosphatidylserine (PS) ectropion and plasma membrane damage, which resulted in death. The effect of UV-C was proportional to the number of times of irradiation. Three doses of UV-C LED irradiation resulted in a 91.76 ± 3.33% death rate, as observed through SYTOX Green staining, with no rebound within 72 h. This research is the first report to observe that delayed cellular apoptosis occurred in Chlorella sp., and we expect that our study can be used as a standard reference for future industrial applications. [ABSTRACT FROM AUTHOR]

Microalgae, as a potential raw material for biofuel, has several advantages compared to other biomass. One effective way to convert microalgae into biofuel is by thermal cracking or pyrolysis, and using a catalyst or not. So far, studies on the use of microalgae, that are converted into biofuels, is still use highly concentrated catalysts in packed bed reactors, which is not economical. Therefore, the aim of this study is to convert Chlorella sp. into biofuels with conventional pyrolysis without and using an activated carbon catalyst using packed bed reactor with bubble column. The reaction temperature is 400–600 °C, pyrolysis time is 1–4 hours, and the active carbon catalyst concentration is 0–2%. The 200 grams of Chlorella sp. and the catalyst was mixed in a fixed bed reactor under vacuum (−3 mm H20) condition. Next, we set the reaction temperature. When the temperature was reached, the pyrolysis was begun. After certain time was reached, the pyrolysis produced a liquid oil product. Oil products are measured for density and viscosity. The results showed that the conventional pyrolysis succeeded in converting microalgae Chlorella sp. into liquid biofuels. The highest yield of total liquid oil is obtained 50.2 % (heavy fraction yield, 43.75% and light fraction yield, 6.44%) at the highest conditions which was obtained with 1% activated carbon at a temperature and pyrolysis time of 3 hours. Physical properties of liquid biofuel are density of 0.88 kg/m3 and viscosity of 5.79 cSt. This physical properties are within the range of the national biodiesel standard SNI 7182-2012. The packed bed reactor completed with bubble column is the best choice for converting biofuel from microalgae, because it gives different fractions, so that it is easier to process further to the commercial biofuel stage. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Lampenflora communities of bacteria, cyanobacteria, algae, mosses and lichens colonize illuminated show-caves as a consequence of disturbances to the caves’ ecological equilibrium. These communities have unesthetic impacts and can cause the biodeterioration of limestone. A 15% hydrogen peroxide solution was proposed for use as an ecological agent for the safe removal of these microorganisms. This study tested the effects of three different biocides (hydrogen peroxide, a commercial solution containing salicylic acid and a product containing chlorine dioxide as the active component), on the growth of green algae (Chlorella sp.), which are frequently encountered in lampenflora communities. Chlorella sp. was treated with the biocides under laboratory condition, and chlorophyll a (Chl a) concentrations were measured 1 h, 3 days, 7 days and 10 days after treatment. The change in Chl a concentration was compared to the untreated control group at each time point. All three biocides prevented the growth of green algae and the product containing chlorine dioxide appeared to be the most effective growth inhibitor. Hydrogen peroxide is known to suppress lampenflora growth in caves, and further studies on other biocides remain necessary to identify a solution that is both ecologically safe and economically feasible.

In recent years, many researchers have focused on microalgae as a potential source of lipids for various purposes. To improve the lipid yield, different biomass pretreatments have been investigated. The aim of this work was to determine the effect of an ultrasound and deep eutectic solvent (DES) pretreatment on lipid yield from green microalgae Chlorella sp. The chosen DESs were choline chloride:urea (ChCl:U), choline chloride:glycerol (ChCl:G) and choline chloride:acetic acid (ChCl:Aa), all in the mole ratio of 1:2. Lipids were extracted from the pretreated and untreated biomasses by Bligh and Dyer’s method. The results showed that the lipid yields for the untreated and ultrasound-pretreated biomass were 39 and 48%, respectively. The pretreatments with ChCl:U, ChCl:G and ChCl:Aa resulted in lipid yields of 51, 46 and 40%, respectively. Therefore, the use of efficient and environmentally friendly DESs for the microalgae biomass pretreatment resulted in a higher lipid yield.

The present work evaluates the bioremediation potential of the microalgae Chlorella sp. cultivated in industrial wastewaters of a metallurgy facility for CO2 fixation. Its growth in wastewaters was investigated experimentally and growth rate was determined based on different dilutions. Taguchi's experimental design was carried out and values found in laboratory were compared to those of a mathematical model adjusted based on growth rate. Process efficiency was evaluated to reduce organic load, nutrient consumption, and cell count during the initial and final stages via microscopy. After the biological treatment, reduction percentages of 99% for COD (Chemical Oxygen Demand) and 95% for SS (Sedimentable Solids) were achieved, in addition to 86% and 93% of nutrient and cyanide removal, respectively, and average CO2 biofixation of 0.1854 gL-1d-1.These values are close to those found in literature for other cultivation media. It was also observed that biomass productivity and CO2 fixation data are in agreement with those obtained in other studies, thus evidencing the efficiency of Chlorella sp. microalgae and its high photosynthetic capacity.

产油微生物具有生长迅速、对环境适应能力强等诸多优点，是油脂生产领域的研究热点。与单一微生物培养相比，微生物混合培养对底物的选择性更广泛、利用效率更高，近几年越来越多地应用于工农业废弃物、城市废水和食物垃圾等的处理以及微生物油脂的生产。简要介绍了微生物油脂，综述了微生物混合培养生产油脂的现状以及发酵底物的研究情况，并提出了今后的研究方向。藻-菌、藻-藻和菌-菌混合培养是微生物混合培养生产油脂的主要研究对象，尤其是微藻与酵母混合培养利用废弃物生产油脂，对于降低生产成本和保护环境具有重要意义。今后应扩大混合培养微生物的种类，并筛选高产高附加值代谢产物的微生物作为混合培养的研究对象。Oleaginous microorganism which have many advantages, such as rapid growth and strong adaptability to the environment, has attracted intensive attention. Besides, compared with the monoculture, mixed culture exhibite wider selection for substrates as well as higher utilization efficiency. Recently, it has been increasingly used in the treatment of industrial and agricultural wastes, municipal wastewater and food wastes, as well as the microbial oil production. The microbial oil was simply introduced, the present situation of oil production by microbial mixed culture and the research status of substrates were reviewed, and the future research directions were proposed. The main object of microbial oil production by mixed culture was the combination of algae-yeast, algae-algae and yeast-yeast. Especially, oil production using wastes by mixed culture of microalgae and yeasts was of great significance in cost reduction and environment protection. Besides, it was necessary to enlarge the microorganism species as well as screening high-yield and high-value-added ones in the mixed culture in the future.

Antibiotic resistance is one of the most important environmental challenges. Microalgae has been considered as a promising green media for environmental purification. In this work, sulfadimethoxine (SDM) biodegradation potential of Chlorella sp. L38 and Phaeodactylum tricornutum MASCC-0025 is investigated. Experimental results indicated that the tested freshwater and marine microalgae strains presented stress response to SDM addition. For Chlorella sp. L38, it has a good adaptability to SDM condition via antioxidant enzyme secretion (SOD, MDA, and CAT up to 23.27 U/mg, 21.99 μmol/g, and 0.31 nmol/min/mg) with removal rate around 88%. P. tricornutum MASCC-0025 exhibited 100% removal of 0.5 mg/L SDM. With increasing salinity (adding a certain amount of NaCl) of cultivation media, the removal rate of SDM by microalgae increased. Although its adaptive process was slower than Chlorella sp. L38, the salinity advantage would facilitate enzyme accumulation. It indicated that microalgae could be used to remove SDM from freshwater and marine environment via suitable microalgae strain screening. [ABSTRACT FROM AUTHOR]

The reaction kinetics and the effect of power on microwave-assisted pyrolysis (MAP) in converting microalgae to biofuel were investigated to determine the decomposition mechanism and then characterize the best product. The resulting product consisted of three phases, namely liquid phase (bio-oil), solid residue (char), and uncondensable gas products. The results showed that the optimal increase in microwave power obtained was 20.57% with a 600-watt microwave power condition, a reaction time of 20 minutes, a microwave absorber to microalgae ratio of 1:6, and a heating rate of 25.96 K/min (600 watts). The reaction kinetics evaluated in the best condition showed a second-order reaction with activition energy (Ea) and pre-exponential factor (A) at 35.5971 kJ/moles and 2,606.75/minute, respectively. The characteristics of the biofuel product obtained were 1.01 gr/mL density, viscosity 10.97 cP, and pH 9.30. In addition, based on GC-MS analysis, the bio-oil contained aliphatic, aromatic, phenol, FAME, and polycyclic aromatic hydrocarbon (PAH) organic compounds. These results indicate that MAP has the potential to be developed as an alternative production process for biofuels. [ABSTRACT FROM AUTHOR]

This paper explores the ability of Chlorella sp. and Scenedesmus sp. to convert landfill leachates into usable metabolites. Different concentrations (0.5, 1, 5, and 10% v/v) of leachate coupled with an inorganic carbon source (Na2CO3, and NaHCO3) were tested to improve biomass production, metabolites synthesis, and removal of NO3 and PO4. The result shows that both strains can effectively grow in media with up to 5% (v/v) leachate, while significantly reducing the concentrations of NO3, and PO4 (80 and 50%, respectively). The addition of NaHCO3 as a carbon source improved the final concentration of biomass, lipids, carbohydrates, and the removal of NO3 and PO4 in both strains. [ABSTRACT FROM AUTHOR]

Open sewage contaminated channel wastewater (OSCCW) has high pollutant loads, responsible for eutrophication, when mixed with various channels of urban communities. But, these pollutants can be converted and recovered into useful end products with the help of algal species. In this study, two species of Chlorella (C. vulgaris and C. pyrenoidosa) were selected and investigated for the production of algal biomass and nutrient removal efficiencies with 50% concentration of OSCCW, in a comparative way at lab-scale. Chlorella sp. cultivated in OSCCW have removed nitrate (76.9–78.8%) and phosphate (67.6–79.7%) whereas COD (72.4–76.2%) and BOD (62.3–72.4%) respectively. Correlation analysis was investigated between physico-chemical parameters and biochemical profile of both species to analyze the positive and negative correlation between two variables. The bio-chemical profile and biomass productivity of both species of Chlorella were observed well on the basis of productivity of biomass (60.1, 56.5 mg/l/d), carbohydrate (15.71, 8.82 mg/l/d), protein (11.21, 15.82 mg/l/d), lipid (20.8, 17.5 mg/l/d) and chlorophyll (0.78, 0.67 mg/l/d) in OSCCW. The maximum lipid content (34.6%) was obtained with C. pyrenoidosa as compared to C. vulgaris. Findings also support that OSCCW is well-off with nutrient resources, which can be suitable alternative for algal biomass production and remediated wastewater can be used for animal and fish farming type activities. [Display omitted] • Chlorella sp. are used to treat open sewage contaminated channel wastewater (OSCCW). • Nutrients and pollutants in OSCCW have been investigated for dual benefits. • Maximum resource recovery is observed from OSCCW. • C. pyrenoidosa produced the highest 34.6% lipid in 50% of OSCCW. • Correlation analyzed between biochemical profile of algae and parameter of OSCCW. [ABSTRACT FROM AUTHOR]

The most common method of treating palm oil mill effluent (POME) is by using various types of bacteria communities. However, the utilization of microalgae in consuming the high nutrient content in wastewater offer additional benefit, particularly for CO2 sequestration. In this study, we proposed to evaluate the performance of multicultural bacteria obtained from municipal wastewater and Chlorella sp. for batch treatment of POME at different COD concentrations (ranges between 600 to 1,300 mg/L), microalgae species (C. vulgaris and C. pyrenoidosa) and speed of agitation (0 and 150 rpm). The results showed that between the bacteria and microalgae that are involved in POME treatment, microalgae give high removal of colour (93%) and ammoniacal nitrogen (95%). As for the COD and phosphate removal, both microorganisms show comparable performances. It was observed that C. pyrenoidosa was able to remove more colour compared to C. vulgaris where higher lipid yield production was obtained (47.6%). However, there is no significant impact of agitation on pollutant removal. This study also reveals that co-cultivation of different microalgae species does not affect the efficiency of the system. This study provides an important insight into developing an efficient and environmentally friendly method to treat wastewater by incorporating green technology in the treatment system. [ABSTRACT FROM AUTHOR]

The ciliate Paramecium bursaria harbors several hundred symbiotic Chlorella spp. cells in the cytoplasm. Algal re-endosymbiosis can be artificially induced using alga-removed P. bursaria. During algal re-endosymbiosis, algae ingested into the host digestive vacuoles (DVs) avoid digestion by the host lysosomal enzymes and then escape into the cytoplasm by budding off of the DV membrane. The budded alga-enclosing DV membrane then differentiates into the symbiosome or perialgal vacuole (PV) membrane and is localized beneath the host cell cortex. In this study, we determined whether the PV membrane has the ability to recognize the symbiotic alga singly by eliminating other small microspheres in the same DV. To clarify the accuracy of the budding process, we mixed fluorescent-labeled microspheres of diameter 0.20 µm with isolated symbiotic algae during algal re-endosymbiosis. No fluorescence was observed from the PV membrane, as expected, and the budding DVs that enclosed both undigested and digested algae. Additionally, the algal re-endosymbiosis rate was significantly reduced in the presence of microspheres. These observations showed that the host P. bursaria allowed budding of the algae singly from the membranes of DVs without microspheres and this process required close contact between the DV membrane and the algal cell wall. [ABSTRACT FROM AUTHOR]

Research background. Microalgae represent an emergent sustainable source of bioactive compounds such as antioxidants, vitamins, minerals and polyunsaturated fatty acids that can ameliorate the nutritional characteristics of foods. The biochemical composition of microalgae could be modulated by varying the culture conditions to enhance the accumulation of biomolecules of interest. The aim of this work is to optimise the nutri-functional properties of two microalgae that can be used in food production. Experimental approach. Nannochloropsis gaditana L2 and Chlorella sp. SM1 were screened for growth, biochemical composition and radical scavenging activity employing four different growth media (algal, BG-11, f/2 and Conway) with different nutrient composition. The feasibility of using Chlorella sp. SM1 cultivated in BG-11 medium, in an under-investigated Mediterranean dairy product ricotta cheese and its effect on the sensory attributes was investigated. Additionally, Arthrospira platensis was used as reference in sensory analysis. Results and conclusions. Nitrate- and phosphate-rich media (BG-11 and algal) enhanced the biomass productivity. However, the highest lipid production (23.10 and 11.86 mg/(L· day) by strains SM1 and L2 respectively) and carbohydrate content (34.79 and 44.84 % by SM1 and L2 respectively) were obtained with the nitrate-deficient f/2 medium. Regardless of the used medium, the lipid profile of Chlorella sp. SM1 and N. gaditana L2 remained adequate for different applications with >50 % C16-18 as the main fatty acids. Significant increase in oleic acid (C18:1) content was recorded in response to nitrogen deficiency, being the highest in SM1 in f/2 medium (34 %). Nitrogen deficiency was also found to enhance phenolic compound (expressed as gallic acid equivalents, 48.8 and 35.1 mg/g in SM1 and L2 respectively) and carotenoid contents (2.2 and 2.0 mg/g in SM1 and L2 respectively). Due to its interesting antioxidant potential, Chlorella sp. SM1 was used at different mass fractions (0.2, 1 and 1.5 %) to enrich the ricotta cheese. The sample with 0.2 % Chlorella sp. SM1 was found to give the most appreciated product. Novelty and scientific contribution. This study presents the production of an innovative ricotta cheese using Chlorella sp. as a functional ingredient, without altering the manufacturing procedure, while maintaining acceptable sensorial characteristics. The biochemical composition of the used strains varied depending on the culture medium composition, which enabled the accumulation of phytonutrients of interest. [ABSTRACT FROM AUTHOR]