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Cyanobacterial phycobiliproteins, such as phycoerythrin (PE) and phycocyanin (PC), are colored potential bioactive proteins that have antioxidant and antimicrobial properties. In this study, we formulated a new food prototype based on PE and PC-fortified low-fat yogurt and cream cheese. Four distinct low-fat yogurt and cream cheese products were manufactured, including a control group (No PE and PC), samples produced with phycoerythrin (+ PE), samples produced with phycocyanin (+ PC), and samples produced with both phycoerythrin and phycocyanin (PC + PE). Afterwards statistically compared the physicochemical composition, colorimetric properties, antioxidant and antimicrobial activities, and sensory profile of the fortified foods at 4 °C and 8 °C for 28 and 42 days. Additionally, we confirmed that PE and PC are not toxic to Caenorhabditis elegans at concentrations up to 1 mg/mL. The results showed that the MIC of PE and PC against E. coli was significantly higher than against S. aureus (3.12 ± 0.05 µg/mL vs. 1.56 ± 0.01 µg/mL, respectively; p ≤ 0.05). Additionally, the maximum diameter of the inhibition zone of PE and PC against S. aureus was significantly higher than against E. coli (6.6 ± 0.011 mm vs. 11.66 ± 0.02 mm, respectively; p ≤ 0.05). Results of color parameters showed that the control group had significantly higher L* values than the samples enriched with PE and PC. Moreover PE and PC significantly increased the a* and b* values respectively. The amount of ΔE in the control yogurts and cream cheese was higher than in the samples with PE and PC. Overall, the results showed that adding PE and PC had a significant effect on all measured factors (p < 0.01). Cream cheeses and low-fat yogurts enriched with either PE or PE + PC had the greatest antioxidant activity and the lowest number of psychrophilic bacteria and mold, and yeast counts at the end of the test period. Therefore, low-fat yogurt and cream cheese containing cyanobacterial PE and PC can be considered an innovative dairy product for the food industry. This study marks the initial effort to employ PE and PC derived from Nostoc sp. and Spirulina sp. as antioxidant and antimicrobial agents in the food industry. [ABSTRACT FROM AUTHOR]

Abstract Cyanobacterial phycobiliproteins, such as phycoerythrin (PE) and phycocyanin (PC), are colored potential bioactive proteins that have antioxidant and antimicrobial properties. In this study, we formulated a new food prototype based on PE and PC-fortified low-fat yogurt and cream cheese. Four distinct low-fat yogurt and cream cheese products were manufactured, including a control group (No PE and PC), samples produced with phycoerythrin (+ PE), samples produced with phycocyanin (+ PC), and samples produced with both phycoerythrin and phycocyanin (PC + PE). Afterwards statistically compared the physicochemical composition, colorimetric properties, antioxidant and antimicrobial activities, and sensory profile of the fortified foods at 4 °C and 8 °C for 28 and 42 days. Additionally, we confirmed that PE and PC are not toxic to Caenorhabditis elegans at concentrations up to 1 mg/mL. The results showed that the MIC of PE and PC against E. coli was significantly higher than against S. aureus (3.12 ± 0.05 µg/mL vs. 1.56 ± 0.01 µg/mL, respectively; p ≤ 0.05). Additionally, the maximum diameter of the inhibition zone of PE and PC against S. aureus was significantly higher than against E. coli (6.6 ± 0.011 mm vs. 11.66 ± 0.02 mm, respectively; p ≤ 0.05). Results of color parameters showed that the control group had significantly higher L* values than the samples enriched with PE and PC. Moreover PE and PC significantly increased the a* and b* values respectively. The amount of ΔE in the control yogurts and cream cheese was higher than in the samples with PE and PC. Overall, the results showed that adding PE and PC had a significant effect on all measured factors (p

Abstract This study examines the effect of phycoerythrin (PE) from a cyanobacterial Nostoc strain encapsulated with alginate as a potential prebiotic to produce synbiotic ice cream products with Lactobacillus casei. It was found that the addition of the encapsulated PE affected, mostly favourably, the physicochemical properties, antioxidant activity, probiotic survival, volatile compound contents, and sensory acceptability of the synbiotic ice cream samples before and after aging at the freezing periods of one day to eight weeks. Thus, it confirms the prebiotic potential of PE for synbiotic ice creams with L. casei.

Background: The use of natural ingredients in skincare products has become a topic of interest in contemporary society. The adverse effects and environmental risks of synthetic compounds have prompted studies on the use of photosynthetic organisms as sustainable and ecofriendly sources of effective ingredients. Natural extracts have gained attention in the cosmetic industry, especially those derived from plants, algae, and cyanobacteria. Cyanobacteria have gained prominence in the cosmetic industry because of their low culture requirements, rapid growth rates, and capacity to produce different bioactive metabolites. As a result, cyanobacteria are economically viable and sustainable resources. Objective: We aimed to determine the effect of coating with natural phycocyanin and phycoerythrin pigments from two cyanobacterial species, Spirulina platensis and Nostoc sp., on the properties of three cosmetic products: soap, anti-acne face wash, and hand sanitizer gel. Methods: After cyanobacterial culture, the pigments were extracted, purified, and coated with the stabilizer, chitosan. Thereafter, cosmetic products were formulated with phycocyanin and phycoerythrin, and their viscosity, pH, stability, and antioxidant and antibacterial properties against bacteria were evaluated using the appropriate assays. Results: The anti-acne wash gel and soap had better properties when coated with both pigments and phycocyanin alone, whereas the hand sanitizer gel had better properties when coated with phycoerythrin alone and both pigments. Conclusion: Overall, three coated and stable cosmetic products can be produced using cyanobacterial pigments owing to their high fortifying capacity.

This study examines the effect of phycoerythrin (PE) from a cyanobacterial Nostoc strain encapsulated with alginate as a potential prebiotic to produce synbiotic ice cream products with Lactobacillus casei. It was found that the addition of the encapsulated PE affected, mostly favourably, the physicochemical properties, antioxidant activity, probiotic survival, volatile compound contents, and sensory acceptability of the synbiotic ice cream samples before and after aging at the freezing periods of one day to eight weeks. Thus, it confirms the prebiotic potential of PE for synbiotic ice creams with L. casei. [ABSTRACT FROM AUTHOR]

The focus on utilization of marine macroalgae for green synthesis of bimetallic nanoparticles with potential applications in cancer treatment has gained a lot of attention in recent years. In this present study, we synthesized a nanobiocomposite using the red pigment R-phycoerythrin from the marine red algae Porphyridium purpureum and explored its anticancer potential. This vibrant red fluorescent pigment plays a crucial role as a reducing and stabilizing agent. Ag-ZnO nanobiocomposite was synthesized by green approach using phycoerythrin as a capping agent. The synthesized nanobiocomposite was characterized using UV-Vis spectroscopy, XRD, FT-IR and SEM-EDX techniques. The obtained UV-Vis graph has confirmed the presence of Ag, Zn and phycoerythrin in the synthesized nanobiocomposite. The FT-IR showed the occurrence of Zn--O vibration peak along with hydroxyl and carboxyl groups. The XRD results confirmed the crystalline nature and hexagonal shape of the nanobiocomposite. The overall effect of the synthesized phycoerythrin-Ag-ZnO nanobiocomposite was studied by MTT assay to check its anticancer applications. From the obtained results, the IC50 value was found to be 100 µg against MCF-7 cell line. This confirms that the synthesized phycoerythrin-Ag-ZnO nanobiocomposite inhibited the growth of MCF-7 cell line and thus can be efficiently used as a photosensitive drug for chemotherapy in future. [ABSTRACT FROM AUTHOR]

Red phycoerythrin (R-PE) is a highly valuable protein found in an edible seaweed, Pyropia yezoensis. It is used extensively in biotechnological applications due to its strong fluorescence and stability in diverse environments. However, the current methods for extracting and purifying R-PE are costly and unsustainable. The aim of the present study was to enhance the financial viability of the process by improving the extraction and purification of R-PE from dried P. yezoensis and to further enhance R-PE value by incorporating it into a tandem dye for molecular biology applications. A combination of ultrafiltration, ion exchange chromatography, and gel filtration yielded concentrated (1 mg·mL–1) R-PE at 99% purity. Using purified PE and Cyanine5 (Cy5), an organic tandem dye, phycoerythrin-Cy5 (PE-Cy5), was subsequently established. In comparison to a commercially available tandem dye, PE-Cy5 exhibited 202.3% stronger fluorescence, rendering it suitable for imaging and analyzes that require high sensitivity, enhanced signal-to-noise ratio, broad dynamic range, or shorter exposure times to minimize potential damage to samples. The techno-economic analysis confirmed the financial feasibility of the innovative technique for the extraction and purification of R-PE and PE-Cy5 production. [ABSTRACT FROM AUTHOR]

Solieria tenuis has the tendency to become a potential bloom in some regions of the sea in China. It has massive biomass. Therefore, making the best use of the bioresource of S. tenuis has gained attention. This study proposed a process for the comprehensive extraction of carrageenan and phycoerythrin from new resource S. tenuis and measured their bioactivities. The results showed that the purity of phycoerythrin could be up to 4.19 and the yield of phycoerythrin could be 0.06 mg/g (dry weight). The yield of carrageenan was 19.60% at 4% alkali concentration, 2 h alkali treatment time, and 62 °C alkali treatment temperature using the S. tenuis residue. The phycoerythrin had applications as an antioxidant and antibacterial agent, and carrageenan had applications in the culture medium. Thus, this emerging method fully used S. tenuis as new bioresources, which realized high value use and reduced the nitrogen content in production, having potential applications in the future. [ABSTRACT FROM AUTHOR]

Mesodinium rubrum is a kleptoplastidic ciliate that sequesters the chloroplasts and nuclei of cryptophyte algae to perform photosynthesis. Blooms of M. rubrum can cause red tides in coastal oceans worldwide. Such red tides are detectable by remote sensing, and studying M. rubrum pigments and optical properties is a crucial step toward characterizing its blooms using satellite observation. Previous studies have shown that M. rubrum photoacclimates, modifying its pigment content depending on irradiance. Using cultures at different irradiance levels, we observed that photoacclimation in M. rubrum closely resembles that of its cryptophyte prey Teleaulax amphioxeia , leading to substantial phenotypic variability. In both species, phycoerythrin 545 cellular concentrations increased 3-fold between the highest and lowest irradiance, suggesting a major role in photoacclimation. Absorption cross-section decreased, and pigment-specific absorption coefficients increased with irradiance at the peak absorption wavelengths of chlorophyll a and phycoerythrin 545. After assessing the variability of absorption properties in M. rubrum , we combined field measurements and high-resolution Sentinel-2 satellite images to estimate chlorophyll a concentration of a coastal red tide and document small-scale spatio-temporal features. This work provides an overview of pigment photoacclimation in a peculiar phytoplankter and suggests guidelines for future studies of M. rubrum blooms. [ABSTRACT FROM AUTHOR]

Phycoerythrin and polysaccharides have significant commercial value in medicine, cosmetics, and food industries due to their excellent bioactive functions. To maximize the production of biomass, phycoerythrin, and polysaccharides in Porphyridium purpureum, culture media were supplemented with calcium gluconate (CG), magnesium gluconate (MG) and polypeptides (BT), and their optimal amounts were determined using the response surface methodology (RSM) based on three single-factor experiments. The optimal concentrations of CG, MG, and BT were determined to be 4, 12, and 2 g L−1, respectively. The RSM-based models indicated that biomass and phycoerythrin production were significantly affected only by MG and BT, respectively. However, polysaccharide production was significantly affected by the interactions between CG and BT and those between MG and BT, with no significant effect from BT alone. Using the optimized culture conditions, the maximum biomass (5.97 g L−1), phycoerythrin (102.95 mg L−1), and polysaccharide (1.42 g L−1) concentrations met and even surpassed the model-predicted maximums. After optimization, biomass, phycoerythrin, and polysaccharides concentrations increased by 132.3%, 27.97%, and 136.67%, respectively, compared to the control. Overall, this study establishes a strong foundation for the highly efficient production of phycoerythrin and polysaccharides using P. purpureum. [ABSTRACT FROM AUTHOR]

Abstract Cyanobacterial phycocyanin and phycoerythrin are gaining commercial interest due to their nutrition and healthcare values. This research analyzed the biomass accumulation and pigment production of two strains of Leptolyngbya under different combinations of light colors and intensities. The results showed that while Leptolyngbya sp.4 B1 (B1) produced all phycobiliproteins, Leptolyngbya sp.5 F2 (F2) only had phycocyanin and allophycocyanin. Both the color of the light and its light intensity affect the biomass accumulation and phycoerythrin concentration in strain B1. Although white light at medium intensity (50 μmol m-2 s-1) causes greater biomass accumulation (1.66 ± 0.13 gDW L-1), low-intensity (25 μmol m-2 s-1) green light induces lower biomass accumulation with twice the pigment content (87.70 ± 2.46 mg gDW -1), culminating in 71% greater productivity. In contrast, for the F2 strain, light intensity positively influenced biomass and pigment accumulation, being observed 2.25 ± 0.10 gDW L-1 under white light at 100 μmol m-2 s-1 and higher phycocyanin concentration (138.38 ± 3.46 mg gDW -1) under red light at 100 μmol m-2 s-1. These findings provide insights into optimizing the growth conditions by altering the intensity and wavelength of light for future production of phycocyanin and phycoerythrin from local cyanobacteria.

Phycoerythrin (PE) extraction from Porphyridium sp. was studied employing ultrasound-assisted extraction combined with aqueous mixtures of two imidazolium-based ionic liquids (ILs) simultaneously, marking a significant novelty. A face-centred central composite design and response surface optimised PE yield (EPE), considering the effects of ionic liquid concentration (IL), [Emim][EtSO4]/[Bmim][EtSO4] mass ratio (E/B), biomass concentration (BM), and time (t). Improvements in EPE by 300 % and 115 % were achieved compared to a phosphate buffer solution and the freeze-thaw method, respectively. Temperature and pH effects were examined independently, leading to the determination of optimal operating conditions: BM = 10 mg mL−1, IL = 18.6 wt%, E/B = 0.78/0.22, t = 10 min, T = 35 °C, and pH = 7.5. Results indicated the potential for reusing the ILs for at least five consecutive extraction cycles, maintaining an EPE of 94.2 % compared to fresh ones. This underscores the success and innovation of the developed technology in enhancing PE extraction from Porphyridium sp.

Phycoerythrin, a phycobiliprotein recognized for its brilliant crimson hue and essential role in light harvesting during photosynthesis, was extracted from the red alga Porphyridium purpureum. A final concentration of 0.3 mg mL−1, accompanied by an exceptional purity index of 6.05 was achieved. Then, its stability in response to pH fluctuations was evaluated, elucidating its robust resilience to varying pH conditions. To gauge its antioxidant prowess, two established techniques, the Ferric Reducing Antioxidant Power (FRAP) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, were employed, revealing both the inherent antioxidant capacity and a dose-dependent response. The obtained IC50 values were 22.61 mM for FRAP and 0.159 mg mL−1 for ABTS. After assessing its stability and antioxidant capacity, phycoerythrin encapsulated by an electrospray-assisted technique, employing diverse encapsulating materials. Impressively, each treatment surpassed an encapsulation efficiency threshold of 80%, opening promising avenues for controlled-release systems and targeted applications. The study culminated in an exploration of the protein's antiproliferative potential against colon cancer cells (CaCo2), both in its free and encapsulated states. At the highest tested concentration (0.3 mg mL−1) at 48 h, the non-encapsulated pigment exhibited a cellular viability of 41.0 ± 2.93%, whereas the encapsulated pigment reached a lower level of 27.27 ± 8.29%. These results show that encapsulation significantly enhances the in vitro anticancer activity of this pigment over time, underscoring its potential in biomedical applications. [ABSTRACT FROM AUTHOR]

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Phycoerythrin (PE) is a photosensitive red pigment from phycobiliprotein family predominantly present in the red algae. The concentration of PE depends on photon flux density (PFD) and the quality of light absorbed by the algae tissue. This necessitates robust techniques to extract PE from the embedded cell-wall matrix of the algal frond. Similarly, PE is sensitive to various factors which influence its stability and purity of PE. The PE is extracted from Red algae through different extraction techniques. This review explores an integrative approach of fractionating PE for the scaling-up process and commercialization. The mechanism for stabilizing PE pigment in food was critically evaluated for further retaining this pigment within the food system. The challenges and possibilities of employing efficient extraction for industrial adoption are meticulously estimated. The techniques involved in the sustainable way of extracting PE pigments improved at a laboratory scale in the past decade. Although, the complexity of industrial-scale biorefining was found to be a bottleneck. The extraction of PE using benign chemicals would be safe for food applications to promote health benefits. The precise selection of encapsulation technique with enhanced sensitivity and selectivity of the membrane would bring better stability of PE in the food matrix. [ABSTRACT FROM AUTHOR]

Mycosporine-like amino acids (MAAs) are natural UV-absorbing compounds found in microalgae and macroalgae. The content of MAAs in algae varies with the seasons and environmental factors. Red alga dulse in Usujiri (Hokkaido, Japan) is an underutilized resource. Therefore, we investigated the amount of MAAs in Usujiri dulse in 2022 to clarify the suitable months for MAA extraction. In addition, we also evaluated the extraction method focusing on the extraction volume. MAAs were prepared via the 20 volumes of 25% ethanol extraction method and detected via HPLC. The results showed that the amount of MAAs on 25 March 2022 showed the highest value (40.4 μmol/g DW) among the samples from 24 January to 13 May. The tendency of suitable samples for MAA preparation corresponded to the term from mid-February to early April, which was the same as the previous three years. Although the surveys from 2019–2021 were performed by using the successive water–methanol method, it was found that the improved method also reflected the monthly variation in MAAs. The extraction of MAAs was performed via 20 or 40 volumes of 25% ethanol at 4 °C for 24 h. The amount of MAAs with 40 volumes of 25% ethanol extraction increased 1.3-fold compared to that with 20 volumes of 25% ethanol extraction. These data are useful information for valuable compound extraction from Usujiri dulse.

The present study was performed to evaluate the effect of phycoerythrin (PE) treatment extracted from Nostoc sp. on the shelf-life extension of the Nile Tilapia (Oreochromis niloticus) fillet at 4°C and 8°C. After extraction and purification of pigment in BG-110 medium, the pigment PE was extracted and purified with 56% ammonium sulfate followed by dialysis. After that, the effect of pigment on Escherichia coli and Staphylococcus aureus were investigated. The fillet samples were immersed in pigment solution, and their physicochemical, microbiological and sensory properties were examined. The results showed that the concentration and purity of the pigments increased after the dialysis. The results from performed chemical tests and total number of living mesophilic bacteria, psychrotrophic bacteria, Staphylococcus aureus coagulase positive, and coliform bacteria of the samples compared to the blank sample showed that sample treated with algae extracts were able to control the increase in these parameters. In these tests, the highest levels belonged to Nile Tilapia fillet sample Nile Tilapia fillet coated with PE solution at a temperature 8°C and the lowest amount was observed with fillet coated with PE solution at a temperature of 4°C (P≤0.05). The results of sensory evaluation showed that the highest score of taste, texture, color, and total acceptance were observed for Nile Tilapia fillet coated with PE solution at temperature 8°C. In conclusion, the extract pigments from Nostoc sp. has strong antimicrobial activity and can maintain the quality parameters for controlling of spoilage bacteria and extend the shelf-life of Oreochromis niloticus. [ABSTRACT FROM AUTHOR]

Gloeobacter violaceus is an ancient cyanobacterium as it branches out from the basal position in the phylogenic tree of cyanobacteria. It lacks thylakoid membranes and its unique bundle-shaped type of phycobilisomes (PBS) for light harvesting in photosynthesis are located on the interior side of cytoplasmic membranes. The PBS from G. violaceus have two large linker proteins that are not present in any other PBS, Glr2806, and Glr1262, which are encoded by the genes glr2806 and glr1262, respectively. The location and functions of the linkers Glr2806 and Glr1262 are currently unclear. Here, we report the studies of mutagenetic analysis of glr2806 and the genes of cpeBA, encoding the β and α subunits of phycoerythrin (PE), respectively. In the mutant lacking glr2806, the length of the PBS rods remains unchanged, but the bundles are less tightly packed as examined by electron microscopy with negative staining. It is also shown that two hexamers are missing in the peripheral area of the PBS core, strongly suggesting that the linker Glr2806 is located in the core area instead of the rods. In the mutant lacking the cpeBA genes, PE is no longer present and the PBS rods have only three layers of phycocyanin hexamers. The construction of deletional mutants in G. violaceus, achieved for the first time, provides critical information for our understanding of its unique PBS and should be useful in studies of other aspects of this interesting organism as well. [ABSTRACT FROM AUTHOR]

Mycosporine-like amino acids (MAAs) are natural UV-absorbing compounds found in microalgae and macroalgae. The content of MAAs in algae varies with the seasons and environmental factors. Red alga dulse in Usujiri (Hokkaido, Japan) is an underutilized resource. Therefore, we investigated the amount of MAAs in Usujiri dulse in 2022 to clarify the suitable months for MAA extraction. In addition, we also evaluated the extraction method focusing on the extraction volume. MAAs were prepared via the 20 volumes of 25% ethanol extraction method and detected via HPLC. The results showed that the amount of MAAs on 25 March 2022 showed the highest value (40.4 μmol/g DW) among the samples from 24 January to 13 May. The tendency of suitable samples for MAA preparation corresponded to the term from mid-February to early April, which was the same as the previous three years. Although the surveys from 2019–2021 were performed by using the successive water–methanol method, it was found that the improved method also reflected the monthly variation in MAAs. The extraction of MAAs was performed via 20 or 40 volumes of 25% ethanol at 4 °C for 24 h. The amount of MAAs with 40 volumes of 25% ethanol extraction increased 1.3-fold compared to that with 20 volumes of 25% ethanol extraction. These data are useful information for valuable compound extraction from Usujiri dulse. [ABSTRACT FROM AUTHOR]

Multiple immunolabeling introduces high risks of interferences between fluorescences. As an example, in analyzing T cell clonality, we recently reported a fluorescence resonance energy transfer (FRET) effect providing an unexpected signal on B770 (PE‐Cy7) detector, on the Vβ‐PE positive CD3 APC‐Alexa750+ T cell subsets. Here, we report another FRET effect produced by the violet laser in Vβ‐FITC positive CD3‐Pacific Blue (PB) T cells providing signal on V550 (Krome Orange; KrO) detector. The study was performed on fresh whole blood, labeled with anti‐CD3‐PB, CD8‐KrO, Vbeta FITC, Vbeta PE, CD4 AA750 then fixed, treated for erythrolysis, and washed before analysis on DxFlex cytometer from Beckman Coulter. Data were analyzed using Kaluza software. Using this panel, we repeatedly observed an added CD8dim‐KrO (V550) cell population on all Vβ FITC positive T cells. The unexpected green signal excited by the violet laser was still observed after removing anti‐CD8‐KrO (FMO) but disappeared where either anti‐CD3‐PB or anti‐Vβ‐FITC was removed. The effect was also observed with an anti‐TCR gamma delta‐FITC labeling, but not with another FITC labeled antibody targeting a protein out of the CD3‐TCR complex. The analysis of fluorochrome spectra confirms that PB emission and FITC excitation spectra partly overlap. This observation clearly reminds users that FRET can give misleading results in case of labeling of very close markers with complementary fluorochromes. This risk has to be considered in panel design. These observations clearly highlight the potential for FRET to give misleading results in cases where very close markers are labeled with complementary fluorochromes. This risk must be considered when designing panels. To our knowledge, this is the first description of a FRET between PB and FITC as acceptor thus excited by the violet laser. [ABSTRACT FROM AUTHOR]

Reducing non-specific adsorption of proteins on the surface of magnetic nanoparticles (MNPs) is becoming increasingly important. In this paper, we proposed a novel surface modification procedure by grafting hyperbranched polyglycerol (HPG) onto the surface of MNPs (Fe3O4@SiO2@MAA), in which lots of hydroxyl groups from HPG not only provide the hydrates sheath to prevent non-specific adsorption of proteins, but also react with succinic anhydride to generate carboxyl groups that serve as active sites to specifically bind proteins. The protein adsorption experiments showed that the non-specific adsorption (0.07 μg mg-1) was reduced to 4.58% of that before modification. It also showed that the antigen binding capacity was 9.7 times higher than the original when detecting cardiac troponin I (cTnI) in human plasma samples, which indicated that the final synthesized MNPs had great application prospects in bio-separation and bioanalysis.

Red phycoerythrin (R-PE) is a highly valuable protein found in an edible seaweed, Pyropia yezoensis. It is used extensively in biotechnological applications due to its strong fluorescence and stability in diverse environments. However, the current methods for extracting and purifying R-PE are costly and unsustainable. The aim of the present study was to enhance the financial viability of the process by improving the extraction and purification of R-PE from dried P. yezoensis and to further enhance R-PE value by incorporating it into a tandem dye for molecular biology applications. A combination of ultrafiltration, ion exchange chromatography, and gel filtration yielded concentrated (1 mg·mL–1) R-PE at 99% purity. Using purified PE and Cyanine5 (Cy5), an organic tandem dye, phycoerythrin-Cy5 (PE-Cy5), was subsequently established. In comparison to a commercially available tandem dye, PE-Cy5 exhibited 202.3% stronger fluorescence, rendering it suitable for imaging and analyzes that require high sensitivity, enhanced signal-to-noise ratio, broad dynamic range, or shorter exposure times to minimize potential damage to samples. The techno-economic analysis confirmed the financial feasibility of the innovative technique for the extraction and purification of R-PE and PE-Cy5 production.

Phycoerythrin and polysaccharides have significant commercial value in medicine, cosmetics, and food industries due to their excellent bioactive functions. To maximize the production of biomass, phycoerythrin, and polysaccharides in Porphyridium purpureum, culture media were supplemented with calcium gluconate (CG), magnesium gluconate (MG) and polypeptides (BT), and their optimal amounts were determined using the response surface methodology (RSM) based on three single-factor experiments. The optimal concentrations of CG, MG, and BT were determined to be 4, 12, and 2 g L−1, respectively. The RSM-based models indicated that biomass and phycoerythrin production were significantly affected only by MG and BT, respectively. However, polysaccharide production was significantly affected by the interactions between CG and BT and those between MG and BT, with no significant effect from BT alone. Using the optimized culture conditions, the maximum biomass (5.97 g L−1), phycoerythrin (102.95 mg L−1), and polysaccharide (1.42 g L−1) concentrations met and even surpassed the model-predicted maximums. After optimization, biomass, phycoerythrin, and polysaccharides concentrations increased by 132.3%, 27.97%, and 136.67%, respectively, compared to the control. Overall, this study establishes a strong foundation for the highly efficient production of phycoerythrin and polysaccharides using P. purpureum.

Suitability of microalgae valorization mainly depends on its biochemical composition. Overall, among all microalgal derivatives, pigments currently stand out as the major added-value component. While it is well recognized that microalgal growth conditions strongly affect biomass composition, final tuning of already grown microalgae has been scarcely studied. Herein, pigment crude extract and debris biomass composition of an already grown microalgal consortium was evaluated after a short-term exposure (90 min) to different levels of irradiance (15, 50, 120 μmol m−2 s−1) and sulfide concentrations (0, 3.2, 16 mg L−1). Although lipid, protein, and carbohydrate contents of debris biomass were not decisively modified by the short-term exposures, pigments content of the crude extracts were strongly modified after 90-min exposure at given sulfide and irradiance conditions. Particularly, a higher content of chlorophyll a, chlorophyll b, and total carotenoids was estimated at an optimal sulfide concentration of 5 mg L−1, and the higher irradiance of 120 μmol m−2 s−1. Contrarily, the average irradiation level of 50 μmol m−2 s−1 and the absence of sulfide stimulated the production of phycoerythrin and phycocyanin which could be increased by 65 and 50%, respectively. Thus, a final qualitative and quantitative tuning of pigment content is plainly achievable on grown microalgal biomass, in a reduced exposure time, at given irradiance or sulfide conditions. [ABSTRACT FROM AUTHOR]

This study aims to identify a local red microalga in Taiwan through morphology and molecular phylogeny. Then, to determine the optimal culture conditions, as in temperature, light intensity and light quality, for the mass production of B-phycoerythrin using the microalga, growth and pigment content of the microalga under different cultivation conditions were studied with two-factor experiments. The microalga was cultivated at four temperatures (16, 20, 24 and 28 ℃) and under three light intensities (20, 60 and 100 μmol photons m−2 s−1) to study the interaction effect of temperature and light intensity. The microalga was also cultivated at the mentioned temperatures under white, red, green and blue lights to study the interaction effect of temperature and light quality. The cell number, relative index of chlorophyll, and relative index of phycoerythrin (RIPE) were analysed by flow cytometry. After morphological and molecular phylogenetic analyses, the species was identified as Rhodosorus marinus. When studying the effect of temperature and light intensity, the R. marinus cultivated at 20–24 ℃ under a light intensity of 100 μmol photons m−2 s−1 produced high cell number and RIPEs. Using the optimal light intensity for cell number accumulation, R. marinus cultivated under white light at 20–28 ℃ produced high cell number and RIPEs. In conclusion, this study showed that a temperature of 20–24 ℃ with 100 μmol photons m−2 s−1 of white light can promote growth in R. marinus and produce cell number containing the highest phycoerythrin contents. [ABSTRACT FROM AUTHOR]

Phycoerythrin (PE) is a naturally produced colorant with great fluorescent and antioxidant properties, which has an important potential in food pharmaceutical industries. This study was conducted by randomly experimental design in order to optimize the phycoerythrin extraction under different independent variable (biomass: buffer ratio, buffer ionic strength and cellular disruption method) from Caspian Sea red macroalgae (Osmundea caspica). Purity and concentrations of PE changed significantly under different treatments (P<0.05). The highest PE purity and concentrations was obtained in 100Mm sodium phosphate buffer and 1:20 biomass: buffer ratio. Therefore, the positive correlation has been observed between increasing levels of buffer ionic strength with PE purity and concentrations while lowest PE purity and highest PE concentrations (mg/gr fresh algae) were obtained with increasing level of biomass: buffer ratio. Antioxidant activity of extracted PE was evaluated by measuring the free radical scavenging ability using DPPH. PE was found to have better free radical scavenging activity at highest concentration with dose-dependent manner. Therefore, the obtained phycoerythrin in 100mM buffer in the extraction process approximatlly with a purity of one can be introduced with the aim of application in the food industry. [ABSTRACT FROM AUTHOR]

Some cyanobacteria species have a high capacity for accumulating phycobiliprotein contents in their cells. However, there is a lack of information on screening tropical freshwater cyanobacteria, particularly phycobiliproteins. In addition, it is unclear which characteristics of cyanobacteria (morphological and/or growth) could affect phycobiliprotein contents. This study aimed to screen and characterise Malaysian indigenous freshwater cyanobacteria for the growth, biomass, and pigment contents and determine the major characteristic that contributed to the variation of phycobiliproteins. The surface/volume (S/V) ratio, specific growth rate, biomass productivity, and pigment contents of the isolated cyanobacteria were analysed. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to distinguish the factor responsible for phycobiliprotein variations in cyanobacteria. For the phycobiliprotein contents, Arthrospira sp., Pseudanabaena sp., and Synechococcus elongatus showed significantly higher (p < 0.05) amounts of cyanobacterial phycocyanin (C-PC), phycoerythrin (C-PE), and allophycocyanin (C-APC), respectively, than other studied cyanobacteria. This study showed no apparent trend of similarity and difference between the unicellular and filamentous cyanobacteria. In addition, carotenoid contents demonstrated a positive correlation with total phycobiliproteins, C-PC and C-APC. Based on the current findings, Arthrospira sp., Pseudanabaena sp. and Synechococcus elongatus might be the promising candidate to be the C-PC, C-PE and C-APC sources, respectively, for commercial production purposes. The selection of optimal cyanobacterial strain is crucial for efficient phycobiliprotein production. This study underlined the potential of freshwater cyanobacteria in producing respective and total phycobiliproteins. Future studies such as the optimization process should be adopted to improve the phycobiliprotein production of these cyanobacteria significantly. [ABSTRACT FROM AUTHOR]

Summary: Food colours from natural resources have rapidly increased in popularity in recent years, with increased demand from the industry and health‐conscious consumers. Natural pigments may be of plant, animal or microbial origin. The pigments derived from microorganisms, including bacteria, fungi and microalgae are in higher demand as reliable sources of natural food colours. Similarly, the commercial use of algae has received a lot of attention, due to its potential applications in a variety of fields, including food, cosmetics, agriculture, horticulture and in human health. Chlorophylls, carotenoids (carotenes and xanthophylls) and phycobilins are the three main families of photosynthetic pigments found in algae. In spite of its great demand, the application of phycoerythrin (PE), a red‐coloured pigment under the phycobilin family, is however very challenging in terms of its extraction and stability under normal conditions. It is found in cyanobacteria (prokaryotic green‐blue microalgae) and microalgae (eukaryotic microalgae). The present review intends to provide an insight into the less explored phycoerythrin pigment, its sources, properties, extraction techniques and applications in the food industry. [ABSTRACT FROM AUTHOR]

Phycoerythrin (R-PE) is a naturally occurring colorant with excellent fluorescent and antioxidant properties with a wide range of applications. This study aimed to compare the use of different purification methods, which are activated charcoal (AC), ammonium sulfate precipitation (ASP), or anion-exchange chromatography (IE) alone and a combination of AC, ASP, and IE, for R-PE extraction from the Caspian Sea red macroalga (Osmundea caspica). Response surface methodology (RSM) was employed for preliminary purification, with the independent variables being activated charcoal content (0.1–1% w/v) and stirring time (2–10 min). With an AC content of 0.4% and a stirring time of 2 min, R-PE purity and concentration were optimized. The predicted values from the equations agreed well with the experimental values, demonstrating the model's robustness. A three-step increase in the ionic strength of IE was also evaluated at three different treatments (PECE, PECE + AC + IE, and ASP + IE). The highest R-PE purity and lowest Fluorescence intensity and antioxidant activity were obtained in the fraction of AE-200 (second fraction) with an index of 2.8 and a recovery yield of 48% in ASP + IE, whereas an index purity of 2 and the highest recovery yield of 67% were obtained using PECE + AC + IE. [ABSTRACT FROM AUTHOR]

Microalgae can represent a reliable source of natural compounds with different activities. Here, we evaluated the antioxidant and anti-inflammatory activity of sulfated exopolysaccharides (s-EPSs) and phycoerythrin (PE), two molecules naturally produced by the red marine microalga Porphyridium cruentum (CCALA415). In vitro and cell-based assays were performed to assess the biological activities of these compounds. The s-EPSs, owing to the presence of sulfate groups, showed biocompatibility on immortalized eukaryotic cell lines and a high antioxidant activity on cell-based systems. PE showed powerful antioxidant activity both in vitro and on cell-based systems, but purification is mandatory for its safe use. Finally, both molecules showed anti-inflammatory activity comparable to that of ibuprofen and helped tissue regeneration. Thus, the isolated molecules from microalgae represent an excellent source of antioxidants to be used in different fields. [ABSTRACT FROM AUTHOR]

The research in the field of food storage and preservation intensified in recent years to develop alternative preservatives and colorants to chemical ones. The algal preservatives and colorants have emerged as a viable green alternative in this context. The primary food preservatives from the algae are phycobiliproteins (PBPs) and their primary constituents: allophycocyanin (APC), phycocyanin (PC), and phycoerythrin (PE). As the foods have been subjected to the adverse environmental conditions during the production, storage, and utilization stages, it is important to research the determinants of the thermal, acidic, light, and color stability of the PBPs in these adverse environmental conditions such as light and acid exposure as well as elevated and sub-zero temperatures relevant to the food storage. Although there have been around 60 papers published in this research field, there has been no review of the research on the stability of the PBPs in these adverse environmental conditions relevant to the food storage. Hence, this paper reviews the research in this field as a first-ever population study. These studies reveal that these PBPs are stable at a wide range of acid and light exposure, and temperatures, making them perfect for the foods and beverages as a green alternative to chemical preservatives. Furthermore, a wide range of preservatives improve the stability of these PBPs through their close interaction with the PBPs and encapsulation of the PBPs is an efficient way to improve their stability, potentially using the nanotechnology. A couple of recommendations were made for the further research. [ABSTRACT FROM AUTHOR]

In the present study, phycoerythrin pigment protein was extracted and purified from Gracilaria corticata (marine macroalga). The concentration of phycoerythrin (PE) obtained from G. corticata was 0.15 ​mg/ml (fresh weight). In this study, phycoerythrin expressed less antimicrobial activity against pathogens but found effective in total antioxidant activity (264.90 ​± ​10.20 ​μg/ml), DPPH scavenging effect (22.91 ​± ​1.90%) and ferrous ion chelating ability (26.06 ​± ​1.60%). Further, the cytotoxicity assay of PE using colon cancer cells such as SW620 and HCT-116 was tested. Different concentrations (2, 4, 8, 16, 32 ​μl) of phycoerythrin was tested in MTT assay after 24 ​h and 48 ​h incubation. The MTT assay concludes that increasing concentration of phycoerythrin (4.8 ​μg) decreases the cell viability to 42% after 48 ​h in SW 620 ​cell line. Whereas in the HCT 116 ​cell line the increasing concentration of phycoerythrin induces the cell growth on 24 ​h but later drastically reduced growth of cell line (39%) was observed after 48 ​h time in 4.8 ​μg of PE. From this preliminary study, the phycoerythrin pigment extracted from Gracilaria corticata proved to be a potential molecule of interest for cancer studies and diagnosis.

Pigments-producing microorganisms are quite common in Nature. However, there is a long journey from the Petri dish to the market place. Twenty-five years ago, scientists wondered if such productions would remain a scientific oddity or become an industrial reality. The answer is not straightforward as processes using fungi, bacteria or yeasts can now indeed provide carotenoids or phycocyanin at an industrial level. Another production factor to consider is peculiar as Monascus red colored food is consumed by more than one billion Asian people; however, still banned in many other countries. European and American consumers will follow as soon as "100%-guaranteed" toxin-free strains (molecular engineered strains, citrinin gene deleted strains) will be developed and commercialized at a world level. For other pigmented biomolecules, some laboratories and companies invested and continue to invest a lot of money as any combination of new source and/or new pigment requires a lot of experimental work, process optimization, toxicological studies, and regulatory approval. Time will tell whether investments in pigments such as azaphilones or anthraquinones were justified. Future trends involve combinatorial engineering, gene knock-out, and the production of niche pigments not found in plants such as C50 carotenoids or aryl carotenoids. [ABSTRACT FROM AUTHOR]

In the present study swine wastewater diluted at the different percentages (10%, 20%, 60%, and 100%) was used to cultivate the red alga Porphyridium purpureum to evaluate microalgal growth, nutrient removal and the production of polysaccharide and phycoerythrin. The results showed the dilution level significantly affected algal growth and nutrient removal. The best growth was in the swine wastewater diluted at 60% resulting in the highest biomass concentration of 9.44 ± 0.44 g L−1, and the corresponding removal efficiency of COD, total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH4+-N) reached up to 94.85 ± 0.08%, 92.69 ± 0.09%, 96.08 ± 0.02%, and 100 ± 0.00%, respectively. Moreover, the algal cells cultured in the wastewater produced high concentration of polysaccharide and phycoerythrin. Microalgae cultured in 10% swine wastewater produced the highest polysaccharide concentration of 2.16 ± 0.02 g L−1. The highest phycoerythrin concentration of 54.45 ± 4.76 mg L−1 was observed in the 60% swine wastewater group. The results showed that P. purpureum has great potential in treating wastewater and producing high-value byproducts, which is conducive to the development of the bio-circular economy. [ABSTRACT FROM AUTHOR]

ACE inhibitors generated from food proteins have recently become the most well-known subclass of bioactive peptides, and their bio-functionality can be a potential alternative to natural bioactive food components and synthetic drugs. The bioactivities of Acrochaetium sp., the red alga used in this investigation, have never been reported before. Screening of bioactive peptides from Acrochaetium sp. as ACE inhibitors were hydrolyzed with various proteolytic enzymes. Protein hydrolysates were fractionated separately using reversed phased (RP) and strong cation exchange (SCX) chromatography and identified as VGGSDLQAL (VL-9) using α-chymotrypsin. It comes from Phycoerythrin (PE), an abundant protein in a primarily red alga. The peptide VL-9 shows the ACE inhibitory activity with IC50 value 433.1 ± 1.08 µM. The inhibition pattern showed VL-9 as a non-competitive inhibitor. Molecular docking simulation proved that VL-9 was non-competitive inhibition due to the interaction peptide and ACE was not in the catalytic site. Moreover, VL-9 derived from Acrochaetium sp. is a natural bioactive peptide that is safer and available for food protein; also, the ACE inhibitory peptide derived from Acrochaetium sp. could be the one alternative resource to develop functional food for combating hypertension. [ABSTRACT FROM AUTHOR]

The food industry is increasingly turning to microalgae pigments as natural functional colourants to replace potentially harmful synthetic dyes. Among those, phycobiliproteins offer deep and vibrant colours with bioactivities, showing to be a promising alternative. However, incorporating them into a food matrix can be challenging due to their inherent instability, low bioavailability, and off-flavours. Accordingly, the present work aimed to prepare microparticles of phycocyanin (PC MP ) and of an ultrasound-assisted phycoerythrin-rich extract from Porphyridium purpureum (PE MP ) to improve these natural colourants' stability and functional properties. The microparticles were prepared by Nano spray-drying using inulin and gum Arabic as coating materials, resulting in particles with high yield, encapsulation efficiency (from 69 % to 80 %), solubility, and colour retention. Combining inulin and gum Arabic allowed the formation of smaller and more homogeneous particles with increased antioxidant potential when compared to using inulin alone. Moreover, gum Arabic improved the bioaccessibility of PE MP from 35 % to 51 %, demonstrating the potential of this microparticle formulation to enhance the stability and functionality of phycobiliproteins., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Microalgae not only fix carbon dioxide, but also represent a promising alternative resource for the production of proteins, lipids, and polysaccharides. This study employed two Porphyridium strains to compare their responses under different light qualities. P. purpureum up-regulated the content (up to 69.37 ± 0.92 mg/g DW) and proportion of phycoerythrin to enhance light absorption, which led to the accumulation of total soluble proteins, neutral lipids and exopolysaccharides under blue light. In contrast, P. aerugineum primarily improved the light energy utilization by increasing phycocyanin levels (up to 81.10 ± 0.60 mg/g DW), resulting in the degradation of neutral lipids and the accumulation of exopolysaccharides. Given the biomass, the highest yields of phycoerythrin (169.61 ± 2.90 mg/L) and phycocyanin (216.92 ± 1.90 mg/L) were achieved by P. purpureum and P. aerugineum cultured under white light, respectively. These findings indicate that Porphyridium can serve as a valuable resource for phycobiliprotein production, with biomolecules synthesis being tightly regulated by light quality., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Microalgae can produce secondary metabolites like phycoerythrin (Phy). The effects of some microplastics (MPs), wastewater (WW), and light intensity (LI) parameters, including complex data sets, on Phy concentration from Porphyridium cruentum were investigated using machine learning methods in this study. Also, the deep learning (DL) model was developed to get the maximum phy concentration from the dataset. The dataset (232 data groups), including a feature set, polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), WW, LI, and an output variable, Phy, were randomly divided into training and test sets to create and evaluate the models. The highest experimental and predicted Phy concentrations were 52.3 mg/g and 58.32 mg/g in a scenario with 15% WW, 80 mg/L PE, PP, PS, and PVC, and a LI of 175 μmolm -2 s -1 , respectively. The Pearson correlation coefficient (r) indicates a positive correlation between Phy and the variables PE (r = 0.35), PVC (r = 0.69), PP (r = 0.27), PS (r = 0.29), and LI (r = 0.22). However, variables such as WW (r = -0.05) have a weak correlation, and while PVC and PE showed the most significant effect on Phy concentration, WW had the lowest effect. Furthermore, LIME (local interpretable model-agnostic explanations) and SHAP (shapley additive explanations) provided us with important results for interpreting the random forest regression (RF) and DL models' predictions, respectively. The LIME and SHAP analyses suggest that the system with more PVC has a higher predicted Phy value. For WW, the reverse is true; higher WW values result in lower Phy predictions. Researchers were given the model explainability decision tree (DT) structure to study reactants' effects on output (Phy). In conclusion, the dye industry can use microalgae to treat WW contaminated with MPs while also producing high amounts of Phy using a DL model., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Marine Synechococcus efficiently harvest available light for photosynthesis using complex antenna systems, called phycobilisomes, composed of an allophycocyanin core surrounded by rods, which in the open ocean are always constituted of phycocyanin and two phycoerythrin (PE) types: PEI and PEII. These cyanobacteria display a wide pigment diversity primarily resulting from differences in the ratio of the two chromophores bound to PEs, the green-light absorbing phycoerythrobilin and the blue-light absorbing phycourobilin. Prior to phycobiliprotein assembly, bilin lyases post-translationally catalyze the ligation of phycoerythrobilin to conserved cysteine residues on α- or β-subunits, whereas the closely related lyase-isomerases isomerize phycoerythrobilin to phycourobilin during the attachment reaction. MpeV was recently shown in Synechococcus sp. RS9916 to be a lyase-isomerase which doubly links phycourobilin to two cysteine residues (C50 and C61; hereafter C50, 61) on the β-subunit of both PEI and PEII. Here we show that Synechococcus sp. WH8020, which belongs to the same pigment type as RS9916, contains MpeV that demonstrates lyase-isomerase activity on the PEII β-subunit but only lyase activity on the PEI β-subunit. We also demonstrate that occurrence of a histidine at position 141 of the PEI β-subunit from WH8020, instead of a leucine in its counterpart from RS9916, prevents the isomerization activity by WH8020 MpeV, showing for the first time that both the substrate and the enzyme play a role in the isomerization reaction. We propose a structural-based mechanism for the role of H141 in blocking isomerization. More generally, the knowledge of the amino acid present at position 141 of the β-subunits may be used to predict which phycobilin is bound at C50, 61 of both PEI and PEII from marine Synechococcus strains.

Simple Summary: In recent decades, the demand for natural and sustainable bioproducts has risen markedly. Accordingly, microalgae have received much attention as a promising biological resource with great industrial potential, since the microalgal production of biologically active compounds can be boosted by changing their cultivation conditions. Light is one of the key factors in the photosynthetic process, which directly affects cell division and the production of biochemical compounds. This study investigated the effect of light color and the species-specific capability of cryptophyte algae to produce phycoerythrin, phenolic compounds, and exopolysaccharides. The produced biomolecules were further studied for their antioxidant activity. The results showed that changes in light quality significantly affect the biochemical compositions of cryptophyte algae. Moreover, species-specific responses to changes in light quality were identified. The quantity and quality of derived biomolecules from the studied cryptophytes are remarkable and indicate that cryptophytes could be considered promising candidates for producing natural biochemical products for practical applications in various industry sectors, such as food, pharmacy, and cosmetics. The accumulation and production of biochemical compounds in microalgae are influenced by available light quality and algal species-specific features. In this study, four freshwater cryptophyte strains (Cryptomonas ozolinii, C. pyrenoidifera, C. curvata, and C. sp. (CPCC 336)) and one marine strain (Rhodomonas salina) were cultivated under white (control), blue, and green (experimental conditions) lights. Species-specific responses to light quality were detected, i.e., the color of light significantly affected cryptophyte biomass productivity and biochemical compositions, but the optimal light for the highest chemical composition with high antioxidant capacity was different for each algal strain. Overall, the highest phycoerythrin (PE) content (345 mg g−1 dry weight; DW) was reached by C. pyrenoidifera under green light. The highest phenolic (PC) contents (74, 69, and 66 mg g−1 DW) were detected in C. curvata under control conditions, in C. pyrenoidifera under green light, and in C. ozolinii under blue light, respectively. The highest exopolysaccharide (EPS) content (452 mg g−1 DW) was found in C. curvata under the control light. In terms of antioxidant activity, the biochemical compounds from the studied cryptophytes were highly active, with IC50 -values < 50 µg mL−1. Thus, in comparison to well-known commercial microalgal species, cryptophytes could be considered a possible candidate for producing beneficial biochemical compounds. [ABSTRACT FROM AUTHOR]

Phycoerythrin, a special photosynthetic pigment, is widely used as fluorescent dye and has lots of underlying beneficial effects on health. A marine red microalga Porphyridium is considered as the potential feedstock for phycoerythrin production. However, the phycoerythrin-related properties of Porphyridium have not been systematically evaluated, especially between the species of P. cruentum and P. purpureum. The present study aimed to evaluate the production and fluorescence characteristics of phycoerythrin of three strains of Porphyridium. The results showed that P. purpureum SCS-02 presented the highest biomass, phycoerythrin content and yield were 6.43 g L−1, 9.18% DW and 0.288 g L−1, respectively. There was no significant difference between P. purpureum and P. cruentum in α and β subunits amino acid sequences of phycoerythrin and in fluorescence characteristics. The high gene expression level of the key enzymes in phycoerythrobilin synthesis (porphobilinogen synthase and oxygen-dependent coproporphyrinogen-III oxidase) could be related to the high phycoerythrin content of Porphyridium. Based on systematic evaluation, P. purpureum SCS-02 was selected due to its high biomass and phycoerythrin yield. P. purpureum and P. cruentum were highly similar in the phylogenetic tree, as well as in fluorescence characteristics; therefore, it was speculated that they might be the same Porphyridium species. [ABSTRACT FROM AUTHOR]

Microalgae are photoautotrophic microorganisms known as producers of a large variety of metabolites. The taxonomic diversity of these microorganisms has been poorly explored. In this study, a newly isolated strain was identified based on the 18S rRNA encoding gene. The phylogenetic analysis showed that the isolated strain was affiliated with the Rhodomonas genus. This genus has greatly attracted scientific attention according to its capacity to produce a large variety of metabolites, including phycoerythrin. Growth and phycoerythrin production conditions were optimized using a Plackett–Burman design and response surface methodology. An expression profile analysis of the cpeB gene, encoding the beta subunit of phycoerythrin, was performed by qRT-PCR under standard and optimized culture conditions. The optimization process showed that maximum cell abundance was achieved under the following conditions: CaCl2 = 2.1328 g/L, metal solution = 1 mL/L, pH = 7 and light intensity = 145 μmol photons/m2/s, whereas maximum phycoerythrin production level occurred when CaCl2 = 1.8467 g/L, metal solution = 1 mL/L, pH = 7 and light intensity = 157 μmol/m2/s. In agreement, positive transcriptional regulation of the cpeB gene was demonstrated using qRT-PCR. This study showed the successful optimization of abiotic conditions for highest growth and phycoerythrin production, making Rhodomonas sp. suitable for several biotechnological applications. [ABSTRACT FROM AUTHOR]

The cryptophyte alga Proteomonas sulcata is rich in unsaturated fatty acids, phycoerythrin, and other biologically active substances and is suitable for aquatic feed, biomedical applications, and other related industries. To stimulate and increase the production of P. sulcata, we investigated the optimal culture conditions and two-stage culture of this alga under various factors (temperature, light intensity, and quality) using flow cytometry analysis. When cultivated at 24 °C with a light intensity of 100 μmol photons m-2 s-1 and white light, the highest yield of biomass production was achieved (5.87 ± 0.30 × 106 cells mL-1), while the highest relative index of phycoerythrin (i. e., phycoerythrin content) was obtained under green or red light. Although white light will result in the highest growth, red light could stimulate higher phycoerythrin content in cells. Finally, we suggested that flow cytometry could provide a dependable relative value of phycoerythrin content. This study is the first to confirm that flow cytometry can be used to collect physiological information on P. sulcata and sheds light on the optimal culture conditions for the growth of this alga. [ABSTRACT FROM AUTHOR]

Complement‐mediated interference is a well described phenomenon in single antigen bead (SAB) Luminex assay that leads to falsely low or negative results for anti‐HLA antibody (Ab). In a context of high amount of Ab, the enrichment of the Ab around the bead can lead to complement cascade activation and deposition, thereafter impairing Ab detection. EDTA is now routinely used to circumvent this interference. In this report, we attempted to decipher the role of the phycoerythrin (PE) label conjugated to the secondary Ab in this interference. Indeed, PE is a huge molecule (240 kDa) that could participate to limiting access of the conjugate to its Ab target on the bead. To this purpose, 22 sera displaying complement interference without pre‐treatment with EDTA were compared on SAB assay with three detection strategies: the recommended PE‐conjugated secondary Ab (IgGPE), an Alexa Fluor 532‐conjugated Ab (IgGAF) bearing a tiny 724 Da fluorochrome, and a biotinylated Ab followed by PE‐conjugated streptavidin (IgGBiot). Complement interference occurred with the three detection methods, but its depth, defined by the percentage of MFI loss with neat serum, was the highest for IgGPE. Our study highlighted the partial role of the PE fluorochrome in complement interference in SAB assays. [ABSTRACT FROM AUTHOR]