Microalgae Cultivation Research Articles

Effect of different microalgae-bacterium-fungus symbiont technologies on nutrient removal from aquaculture wastewater and biogas upgrading under a variety of mixed light wavelengths

To develop and characterize novel microalgae-based technology under different mixed light-emitting diode (LED) light wavelengths for simultaneous treatment of actual aquaculture tailwater and biogas upgrading, the performance of four microalgal cultivations in bamboo shrimp aquaculture tailwater treatment and biogas upgrading were systematically examined and analyzed. The results demonstrated that Chlorella vulgaris (C. vulgaris)-endophytic bacterium (S395-2)-Clonostachys rosea (C. rosea) symbiont had the highest growth rate, daily production rate and carbonic anhydrase activity at the 7th d treatment time-point under Red(5): Blue(5) LED mixed light source. After 10d treatment, the nutrient removal efficiency of C. vulgaris-S395-2-C. rosea symbiont under Red(5): Blue(5) LED mixed wavelengths reached up to 93.7% for total inorganic nitrogen, 97.4% for ammonium nitrogen, 96.9% for nitrate nitrogen and 98.8% for phosphate; carbon dioxide (CO2) removal rate maintained at 53.1% without significantly affecting methane (CH4) level. In summary, the present study demonstrates that Red (5): Blue(5) LED mixed wavelengths optimally increase the performance of C. vulgaris-S395-2-C. rosea symbiont in nutrient and CO2 removal without loss of CH4, providing a framework for future simultaneous performing actual aquaculture tailwater treatment and biogas upgrading using microalgae-endophytic bacteria-fungus symbiont.

Sequential co-processing of olive mill wastewater and organic residues by anaerobic co-digestion and pyrolysis for the generation of bioadsorbent and low-cost media for microalgae cultivation

This investigation aims to evaluate the co-valorization of olive mill wastewater with other organic residues involving acid pretreatment, co-digestion, pyrolysis, and microalgae cultivation. Phosphoric acid pretreatment (5%, 60°C for 1 h) was used to solubilize the organic matter in a mixture of coffee grounds, orange peel, olive mill wastewater, and cardboard. The acidic treatment led to the production of 328 Nml of biogas/gVS, while the untreated mixture provided 257 Nml of biogas/gVS. The solid digestates were subjected to pyrolysis (500°C for 1 h), providing a biochar yield of approximately 44% for both digestates. Adsorption tests using methylene blue revealed an adsorption capacity of the biochar generated from the digestate of the acid pre-treated mixture of 4 mg/g, which was higher than that of the biochar from the untreated mixture (3.5 mg/g). The liquid digestates were also used as growth media for microalgae. Compared to the reference media (BG11), the use of the digestates-based media resulted in a lower growth rate (0.04 d-1) and biomass (247 mg/L) but significantly higher lipid content (49%). The study shows, therefore, that the use of acid pretreatment had a positive effect on biogas production (solubilization of sugars), on the adsorption efficiency of the biochar (improvement of the porosity of the material), and on the production of lipids from the microalgae which can be destined to biodiesel.

Life cycle assessment and technoeconomic analysis of biofuels produced from polyculture microalgae cultivated in greywater

This study evaluated the environmental and economic impacts of substituting synthetic media with greywater for cultivating microalgae in the biofuel production process. Life cycle assessment (LCA) and technoeconomic assessment (TEA) were employed to compare the impacts of two scenarios – one containing bold's basal (BB) media and another containing greywater as growth mediums for microalgae cultivation. Scenarios 1 and 2 mitigated 1.74 and 2.14 kg CO2 per kg of biofuel production, respectively. Substituting BB media with greywater resulted in a 16.3% reduction in energy requirements, leading to a 79.3% increase in net energy recovered. LCA findings demonstrate a reduction in all seven environmental categories. TEA reveals that, despite a 21.7% higher capital investment, scenario 2 proves more economically viable due to a 39.8% lower operating cost and additional revenue from wastewater treatment and carbon credits. The minimum selling price of biofuel dropped from Rs 73.5/kg to Rs 36.5/kg, highlighting the economic and environmental advantages of substituting BB media with greywater in microalgal biofuel production.

Enhancing Diatom, Cyclotella meneghiniana Growth Using Growth-Promoting Bacteria Isolated From the Phycosphere of Chlorophytes and Chrysophytes

The relationship between microalgae and bacteria in a microenvironment, the phycosphere, has a significant role in enhancing the quality and quantity of microalgal production, which would in turn affect consumers' growth and nutritional quality, such as the zooplankton, which are important live feeds in aquaculture. Thus, selecting and characterising suitable microalgal growth-promoting bacteria (MGPB) for enhancing microalgal production is an important process since not all bacteria promote high growth. In this study, physcosphere bacteria associated with chlorophytes and chrysophytes were isolated, screened for their microalgae-promoting attributes (phosphorus solubilisation, indole-3-acetic acid (IAA) production, and nitrogen fixation) and re-inoculated into microalgal cultures. A total of seven bacterial isolates were recorded to have multiple growth promoting traits, with three strains (CY-2, CY-4, CY-5) showing the greatest (P < 0.05) link for those traits. These seven potential MGPB were molecularly characterised using 16S rRNA approach. The phylogenetic tree of the isolated bacteria demonstrated the dominant bacteria associated with the chlorophytes were in the class bacteroidetes, while the chrysophytes appeared to be associated with Firmicutes bacteria suggesting that the compositions were strictly species-specific to the microalgae host. Enhanced Cyclotella meneghiniana growth by the seven isolated bacterial strains was highly dependent on the growth-promoting traits; especially those demonstrated by Pseudomonas hibiscicola and Ochrobactrum haematophilum. These two bacteria showed the potential to enhance the quality of microalgae, and they could be bioencapsulated and used to improve the quality of zooplankton as one of the main live feeds in the aquaculture industry.

Culture of photosynthetic microalgae consortium in artificial produced water supplemented with liquid digestate in closed column photobioreactors and open-pond raceway

Large amounts of produced water are extracted by the Oil and Gas energy sector since the industrial revolution. This available water, often salty, can be used to dilute liquid digestate from the anaerobic digestion process, a promising source of nutrients for microalgae cultivation. The study investigates the growth of halotolerant microalgae and their associated bacteria in column photobioreactors (PBRs) and open raceway pond (RWP), to treat industrial wastewaters while producing biomass for energy valorisation. Microalgae were cultured in mixtures of saline artificial produced water (7–44 %v/v), liquid digestate (5 %v/v using PBRs, 29–63 %v/v using RWP) and seawater. Nannochloropsis oceanica and Tetraselmis suecica strains were firstly cultivated in 70 L PBRs in indoor conditions for 3 months and later in 1.1 m3 RWP operated in outdoor conditions for 5 months in spring-summer period. In PBRs, average productivity was 9.0 ± 4.2 gVSS·m−2·d−1 (102–153 mgVSS·L−1·d−1), with daily removal efficiencies for chemical oxygen demand, nitrogen and phosphorous up to 61.8, 31.6 and 97.2 %, respectively. In RWP, strong changes in the microalgae populations were observed. Productivity was 6.7 ± 5.2 gVSS·m−2·d−1 (30 ± 23 mgVSS·L−1·d−1), with daily removal efficiencies for chemical oxygen demand, nitrogen and phosphorous up to 48.4, 44.4 and 88.1 %, respectively. In parallel with the production of microalgae, a nitrifying microbial population grew in the RWP despite the high salinity (70 g L−1). Over these periods of several months, microalgae production was maintained using a culture medium containing high salt concentration, metals and harmful aromatic compounds.

Integrated nutrient recycling: Ammonia recovery from thermophilic composting of shrimp aquaculture sludge via self-heated bench-scale reactor and mango plant growth enhancement by the compost

Due to the rapid growth of the aquaculture industry, large amounts of organic waste are released into nature and polluted the environment. Traditional organic waste treatment such as composting is a time-consuming process that retains the ammonia (NH3) in the compost, and the compost produced has little economic value as organic fertilizer. Illegal direct discharge into the environment is therefore widespread. This study investigates the recovery of NH3 through thermophilic composting of shrimp aquaculture sludge (SAS) and its application as a soil conditioner for the growth of mango plants. A maximum composting temperature of 57.10 °C was achieved through self-heating in a 200 L bench-scale reactor, resulting in NH3 recovery of 224.04 mol/ton-ds after 14 days. The addition of calcium hydroxide and increased aeration have been shown to increase NH3 volatilization. The recovered NH3 up to 3 kg-N can be used as a source of clean nitrogen for high-value microalgae cultivation, with a theoretical yield of up to 34.85 kg-algae of microalgae biomass from 1 ton-ds of SAS composting. Despite the high salinity, SAS compost improved mango plant growth and disease resistance. These results highlight the potential of SAS compost as a sustainable source of clean nitrogen for microalgae cultivation and soil conditioner, contributing to a waste-free circular economy through nutrient recycling and sustainable agriculture.

Effect of light intensity and photoperiod on high-value production and nutrient removal performance with bacterial-algal coupling system

Direct discharge of mariculture wastewater can lead to eutrophication, posing a threat to aquatic ecosystems. A novel Bacteria-Algae Coupled Reactor (BACR) offers advantages in treating mariculture wastewater, which can effectively remove pollutants while simultaneously obtaining microalgal products. However, there is limited information available on how illumination affects the cultivation of mixotrophic microalgae in this bacteria-algae coupling system. Therefore, a combined strategy of photoperiod and light intensity regulation was employed to improve the biological mariculture wastewater remediation, promote microalgae biomass accumulation, and increase the high-value product yield in this study. Optimal light conditions could effectively enhance microalgal carbohydrate, protein, lipid accumulation and photosynthetic activity, with the carbohydrate, protein and lipid contents reached 44.11, 428.57 and 399.68 mg/L, respectively. Moreover, excellent removal rates were achieved for SCOD, NH4+-N and TP, reaching 86.68%, 87.35% and 95.13% respectively. This study proposes a comprehension of BACR processes in mariculture wastewater under different light conditions.

Biogas Purification through the use of a Microalgae-Bacterial System in Semi-Industrial High Rate Algal Ponds.

In recent years, a number of technologies have emerged to purify biogas into biomethane. This purification entails a reduction in the concentration of polluting gases such as carbon dioxide and hydrogen sulfide to increase the content of methane. In this study, we used a microalgal cultivation technology to treat and purify biogas produced from organic waste from the swine industry to obtain ready-to-use biomethane. For cultivation and purification, two 22.2 m3 open-pond photobioreactors coupled with an absorption-desorption column system were set up in San Juan de los Lagos, Mexico. Several recirculation liquid/biogas ratios (L/G) were tested to obtain the highest removal efficiencies; other parameters, such as pH, dissolved oxygen (DO), temperature, and biomass growth, were measured. The most efficient L/Gs were 1.6 and 2.5, resulting in a treated biogas effluent with a composition of 6.8%vol and 6.6%vol in CO2, respectively, and removal efficiencies for H2S up to 98.9%, as well as maintaining O2 contamination values of less than 2%vol. We found that pH greatly determines CO2 removal, more so than L/G, during cultivation because of its participation in the photosynthetic process of microalgae and its ability to vary pH when solubilized due to its acidic nature. DO, and temperature oscillated as expected from the light-dark natural cycles of photosynthesis and the time of day, respectively. Biomass growth varied with CO2 and nutrient feeding as well as reactor harvesting; however, the trend remained primed for growth.

Cultivation of microalgae in food processing effluent for pollution attenuation and astaxanthin production: a review of technological innovation and downstream application.

Valorization of food processing effluent (FPE) by microalgae cultivation for astaxanthin production is regarded as a potential strategy to solve the environmental pollution of food processing industry and promote the development of eco-friendly agriculture. In this review paper, microalgal species which have the potential to be employed for astaxanthin in FPE were identified. Additionally, in terms of CO2 emission, the performances of microalgae cultivation and traditional methods for FPE remediation were compared. Thirdly, an in-depth discussion of some innovative technologies, which may be employed to lower the total cost, improve the nutrient profile of FPE, and enhance the astaxanthin synthesis, was provided. Finally, specific effects of dietary supplementation of algal astaxanthin on the growth rate, immune response, and pigmentation of animals were discussed. Based on the discussion of this work, the cultivation of microalgae in FPE for astaxanthin production is a value-adding process which can bring environmental benefits and ecological benefits to the food processing industry and agriculture. Particularly, technological innovations in recent years are promoting the shift of this new idea from academic research to practical application. In the coming future, with the reduction of the total cost of algal astaxanthin, policy support from the governments, and further improvement of the innovative technologies, the concept of growing microalgae in FPE for astaxanthin will be more applicable in the industry.

Sub-pilot scale sequential microalgal consortium-based cultivation for treatment of municipal wastewater and biomass production

Municipal wastewater (MWW) was treated by a sequential pilot microalgal cultivation process. The cultivation was performed inside a specifically designed low-cost photobioreactor (PBR) system. A microalgal consortium 2:1 was developed using Tetraselmis indica (TS) and Picochlorum sp. (PC) in the first stage and PC:TS (2:1) in the second stage and the nutrient removal efficiency and biomass production and biomolecules production was evaluated and also compared with monoculture in a two-stage sequential cultivation system. This study also investigated the effect of seasonal variations on microalgae growth and MWW treatment. The results showed that mixed microalgal consortium (TS:PC) had higher nutrient removal efficiency, with chemical oxygen demand (COD), total phosphate (TP), and total nitrate (TN) removal efficiencies of 78.50, 84.49, and 84.20%, respectively, and produced a biomass of 2.50 g/L with lipid content of 37.36% in the first stage of cultivation under indoor conditions. In the second stage of indoor cultivation, the PC:TS consortium demonstrated maximum COD, TP, and TN removal efficiencies of 92.49, 94.24, and 94.16%, respectively. It also produced a biomass of 2.65 g/L with a lipid content of 40.67%. Among all the seasonal variations, mass flow analysis indicated that the combination of mixed consortium-based two-stage sequential process during the winter season favored maximum nutrient removal efficiency of TN i.e. 88.54% (84.12 mg/L) and TP i.e., 90.18% (43.29 mg/L), respectively. It also enhanced total biomass production of 49.10 g in 20-L medium, which includes lipid yield ∼15.68 g compared to monoculture i.e., 82.06% (78.70 mg/L) and 82.87% (40.26 mg/L) removal of TN and TP, respectively, and produced biomass 43.60 g with 11.90 g of lipids.

Effect of urban wastewater ratio in the influent of a membrane photobioreactor for microalgae cultivation and nutrient removal

Microalgae are increasingly attracting attention for the wastewater regeneration, removing nutrients, and obtaining a high-value product. These nutrients are essential for the growth of algae and aquatic plants, but an overabundance of them in aquatic ecosystems can cause eutrophication, so it is very important to control the concentration of these nutrients in wastewater discharges to the environment. In this study, we have carried out the adaptation of microalgae by gradually changing the influent from a culture medium to treated urban wastewater in membrane photobioreactors, analysing the consortium of microalgae and bacteria present and evaluating the removal of nutrients such us nitrogen and phosphorus. A satisfactory adaptation was observed, reaching concentrations of 0.164 g/L at the end of the study. In the case of the chlorophyte communities studied, it was found that the predominant species was the same in all adaptation phases (unclassified environmental Eukaryota), as well as in the photobioreactors that worked in parallel under extreme conditions. Regarding nitrogen and phosphorus removal during the adaptation phases, the values increased in both cases, reaching 96.99% and 48.10%, respectively. Following the microbiological study, bacterial families have been detected that show symbiotic activity during the growth of microalgae. Multidimensional scaling revealed positive correlations between the detected microalgae and nitrogen removal in the membrane photobioreactor. Our data suggest that MPBRs are a potential tertiary treatment that can produce microalgae biomass from real treated wastewater by utilising its nitrogen and phosphorus content, resulting in a higher quality effluent that is less harmful to the environment.

Strategies to enhance biohydrogen production from microalgae: A comprehensive review

Microalgae represent a promising renewable feedstock for the sustainable production of biohydrogen. Their high growth rates and ability to fix carbon utilizing just sunlight, water, and nutrients make them well-suited for this application. Recent advancements have focused on improving microalgal hydrogen yields and cultivation methods. This review aims to summarize recent developments in microalgal cultivation techniques and genetic engineering strategies for enhanced biohydrogen production. Specific areas of focus include novel microalgal species selection, immobilization methods, integrated hybrid systems, and metabolic engineering. Studies related to microalgal strain selection, cultivation methods, metabolic engineering, and genetic manipulations were compiled and analyzed. Promising microalgal species with high hydrogen production capabilities such as Synechocystis sp., Anabaena variabilis, and Chlamydomonas reinhardtii have been identified. Immobilization techniques like encapsulation in alginate and integration with dark fermentation have led to improved hydrogen yields. Metabolic engineering through modulation of hydrogenase activity and photosynthetic pathways shows potential for enhanced biohydrogen productivity. Considerable progress has been made in developing microalgal systems for biohydrogen. However, challenges around process optimization and scale-up remain. Future work involving metabolic modeling, photobioreactor design, and genetic engineering of electron transfer pathways could help realize the full potential of this renewable technology.

Lipidomic analysis of microalgae and its application in microalgae cultivation and alternative liquid biofuel production

Lipidomic analysis of microalgae and its application in microalgae cultivation and alternative liquid biofuel production

Enhancing urban wastewater treatment: Chlorella vulgaris performance in tertiary treatment and the impact of anaerobic digestate addition

The rising urban wastewater discharge into waterways resulted in harmful environmental effects. Microalgae can bioremediate wastewaters by removing contaminants such as nitrogen and phosphorus and can be rather tolerant to toxic compounds. Managing the anaerobic digestate resulting from sludge treatment in wastewater treatment plants faces some obstacles related to its high contaminant content. This work aims to study the ability of the microalga Chlorella vulgaris to perform the tertiary treatment of urban wastewater, assessing its growth, nutrient removal and the effect of the addition of digestate at different concentrations in this treatment phase. A secondary effluent was supplied with 1% (M1), 5% (M5) and 10% (M10) (v/v) of anaerobic digestate and used to culture microalgae. An assay using only secondary effluent was also performed (S). C. vulgaris grew successfully in all effluents except for the M10, and the highest specific growth rate was obtained in the M1 assay, 0.35 ± 0.01 d−1. Ammonium-nitrogen was completely removed in the S, M1 and M5 assays (>99.9%). Microalgae successfully removed phosphate-phosphorus from the tested effluents, achieving a negligible concentration in the M1 assay and a removal efficiency of 96.2 ± 0.2%, 51 ± 2%, and 43 ± 3% in S, M5 and M10, respectively. These results showed that microalgal cultures could efficiently remediate the secondary effluent and its mixture with 1% (v/v) of anaerobic digestate, achieving nutrient concentrations below the current legislation limits and the more restrictive limits predicted for future legislation.

Optimizing cultivation strategies and scaling up for fucoxanthin production using Pavlova sp.

The microalgal-based production of fucoxanthin has emerged as an imperative research endeavor due to its antioxidant, and anticancer properties. In this study, three brown marine microalgae, namely Skeletonema costatum, Chaetoceros gracilis, and Pavlova sp., were screened for fucoxanthin production. All strains displayed promising results, with Pavlova sp. exhibiting the highest fucoxanthin content (27.91 mg/g) and productivity (1.16 mg/L·day). Moreover, the influence of various cultivation parameters, such as culture media, salinity, sodium nitrate concentration, inoculum size, light intensity, and iron concentration, were investigated and optimized, resulting in a maximum fucoxanthin productivity of 7.89 mg/L·day. The investigation was further expanded to large-scale outdoor cultivation using 50 L tubular photobioreactors, illustrating the potential of Pavlova sp. and the cultivation process for future commercialization. The biomass and fucoxanthin productivity for the large-scale cultivation were 70.7 mg/L·day and 4.78 mg/L·day, respectively. Overall, the findings demonstrated considerable opportunities for fucoxanthin synthesis via microalgae cultivation and processing.

Chemotactic Interactions of Scenedesmus sp. and Azospirillum brasilense Investigated by Microfluidic Methods

The use of algae for industrial, biotechnological, and agricultural purposes is spreading globally. Scenedesmus species can play an essential role in the food industry and agriculture due to their favorable nutrient content and plant-stimulating properties. Previous research and the development of Scenedesmus-based foliar fertilizers raised several questions about the effectiveness of large-scale algal cultivation and the potential effects of algae on associative rhizobacteria. In the microbiological practice applied in agriculture, bacteria from the genus Azospirillum are one of the most studied plant growth-promoting, associative, nitrogen-fixing bacteria. Co-cultivation with Azospirillum species may be a new way of optimizing Scenedesmus culturing, but the functioning of the co-culture system still needs to be fully understood. It is known that Azospirillum brasilense can produce indole-3-acetic acid, which could stimulate algae growth as a plant hormone. However, the effect of microalgae on Azospirillum bacteria is unclear. In this study, we investigated the behavior of Azospirillum brasilense bacteria in the vicinity of Scenedesmus sp. or its supernatant using a microfluidic device consisting of physically separated but chemically coupled microchambers. Following the spatial distribution of bacteria within the device, we detected a positive chemotactic response toward the microalgae culture. To identify the metabolites responsible for this behavior, we tested the chemoeffector potential of citric acid and oxaloacetic acid, which, according to our HPLC analysis, were present in the algae supernatant in 0.074 mg/ml and 0.116 mg/ml concentrations, respectively. We found that oxaloacetic acid acts as a chemoattractant for Azospirillum brasilense.

Electrochemical decolorization of liquid digestate from coffee waste biomass using a boron-doped diamond anode

AbstractLiquid digestate can be used to provide nutrients for microalgae cultivation but the medium needs to be clear and colorless. The aim of this work was to use liquid digestate from coffee waste biomass to produce a light-permeable medium for microalgae cultivation. A boron-doped diamond anode was applied for electrochemical decolorization of the digestate. The electrochemical oxidation process reduced the platinum-cobalt color value by up to 97% and the chemical oxygen demand by 84.1%. After electrochemical oxidation, 87.4% of the ammonium nitrogen (NH4-N) was retained. Decolorization of the spent coffee grounds liquid digestate was compared with that of dairy cow manure liquid digestate. It took 90 min longer to fully decolorize the spent coffee grounds liquid digestate compared with the dairy cow manure liquid digestate. The boron-doped diamond anode performed better in the decolorization than Ti/IrO2 and Ti/Pt anodes. The effects of the initial Fe2+ concentration and current on the electrochemical oxidation process were also evaluated. Increasing the initial Fe2+ concentration enhanced the Fenton reaction and chemical oxygen demand removal. A higher current enhanced the electrochemical decolorization process and side reactions. Electrochemical oxidation using a boron-doped diamond anode is a promising method for producing an appropriate medium for microalgae cultivation because it promotes decolorization of liquid digestate and retains most of the NH4-N.

Environmental impact assessment via life cycle analysis on ultrafiltration membrane fabricated from polyethylene terephthalate waste to treat microalgal cultivation wastewater for reusability

The current study had conducted the life cycle analysis (LCA) to assess the environmental impact of microalgal wastewater treatment via an integrated membrane bioreactor. The functional unit selected for this analysis was 1 kg of treated microalgal wastewater with contaminants eliminated by ultrafiltration membrane fabricated from recycled polyethylene terephthalate waste. Meanwhile, the applied system boundary in this study was distinguished based on two scenarios, namely, cradle-to-gate encompassed wastewater treatment only and cradle-to-cradle which included the reutilization of treated wastewater to cultivate microalgae again. The environmental impacts and hotspots associated with the different stages of the wastewater treatment process had clearly elucidated that membrane treatment had ensued the highest impact, followed by microalgal harvesting, and finally cultivation. Among the environmental impact categories, water-related impact was found to be prominent in the following series: freshwater ecotoxicity, freshwater eutrophication and marine ecotoxicity. Notably, the key performance indicator of all environmental impact, i.e., the global warming potential was found to be very much lower at 2.94 × 10−4 kg CO2 eq as opposed to other literatures reported on the LCA of wastewater treatments using membranes. Overall, this study had proffered insights into the environmental impact of microalgal wastewater treatment and its stimulus for sustainable wastewater management. The findings of this study can be instrumental in making informed decision for optimizing microalgal wastewater treatment and reutilization assisted by membrane technology with an ultimate goal of enhancing sustainability.

Valorization of Nannochloropsis oceanica for integrated co-production of violaxanthin cycle carotenoids

The development of integrated co-production of multiple high-purity carotenoids from microalgal cells holds considerable significance for the valorization of microalgae. In this study, the economical microalga Nannochloropsis oceanica was identified as an accumulator of violaxanthin cycle carotenoids, including violaxanthin, antheraxanthin, and zeaxanthin. Notably, a novel and competent approach for the integrated co-production of violaxanthin cycle carotenoids was explored, encompassing four steps: microalgal cultivation, solvent extraction, octadecylsilyl open-column chromatography, and ethanol precipitation. Under optimal co-production conditions, the purities of the obtained violaxanthin, antheraxanthin, and zeaxanthin all exceeded 92%, with total recovery rates of approximately 51%, 40%, and 60%, respectively. Utilizing nuclear magnetic resonance techniques, the purified violaxanthin, antheraxanthin, and zeaxanthin were identified as all-trans-violaxanthin, all-trans-antheraxanthin, and all-trans-zeaxanthin, respectively. This method held significance for the multiproduct biorefinery of the microalga N. oceanica and carried potential future implications for the violaxanthin cycle carotenoids.

An Evidence of Carbonic Anhydrase Activity in Native Microalgae for CO2 Capture Application.

A promising alternative for effective carbon capture has been found in microalgae because of their high photosynthetic capacity and quick growth. The carbon concentration mechanism of many microalgae is heavily reliant on the enzyme carbonic anhydrase (CA), which catalyze the production of bicarbonate from carbon dioxide. In this study, microalgal samples were collected, characterized, and cultured under controlled conditions for their optimal growth of cultures I-IX. The CA activity was investigated using a standard method; the Wilbur-Anderson assay was used to calculate CA activity in microalgal cultures. The comparative study was then used to measure the activity rate of the collected microalgae. Among the tested, culture I, VI, and IX showed a high enzyme activity rate of 4.15, 4.0, and 4.2µg·mL-1, respectively. To determine the rate of carbon dioxide hydration, the method involved tracking the pH change in a reaction mixture. In addition, genetic analysis facilitates the identification of key genes involved in CA activity and other metabolic processes, which enhance the knowledge of microalgal physiology, and enables genetic engineering efforts in the future studies. Overall, this investigation emphasizes the significance of studying unknown microalgal culture and their potential CA activity for industrial and bio-energy applications.