Phycoerythrin Content Research Articles

Annual hydrographic variability in Antarctic coastal waters infused with glacial inflow

Abstract. During the 38 months between December 2018 and January 2022, multiparameter hydrographic measurements were taken at 31 sites within Admiralty Bay, King George Island, Antarctica. These records consisted of water column measurements (down to 100 m) of temperature, conductivity, turbidity, and pH as well as the dissolved oxygen, dissolved organic matter, chlorophyll-a and phycoerythrin contents. The sites were chosen due to their variable distances from glacial fronts and open ocean waters. Fifteen sites were localized within smaller glacial coves, with waters highly impacted by glacial infusions; seven sites were located in the open waters of the main body of Admiralty Bay; and nine sites were located in the intermediate conditions of the Ezcurra Inlet. The final dataset consists of measurements carried out over 142 separate days, with an average of 3.74 measurements per month. However, data were not collected regularly throughout the year and were collected less frequently during winter, although data were gathered for all but 2 winter months. On average, each site was investigated 98.2 times. Due to calibration issues, absolute values of optically measured properties occasionally show unrealistic negative values, but the relative distributions of these values remain valid. Variabilities in the measured properties each season and throughout the whole duration of the project reveal regular oscillations as well as possible long-term trends. The described dataset is freely available at PANGAEA: https://doi.org/10.1594/PANGAEA.947909 (Osińska et al., 2022).

Effects of Lead and Zinc Exposure on Uptake and Exudation Levels, Chlorophyll-a, and Phycobiliproteins in Sarcodia suiae

The present study aimed to determine the changes in the biosorption, bioaccumulation, chlorophyll-a (chl-a), phycobiliproteins, and exudation in the red seaweed Sarcodia suiae exposed to lead and zinc. The seaweed was exposed to ambient lead and zinc environments for 5 days before being transferred to fresh seawater, and the changes in biodesorption, biodecumulation, chl-a, and phycobiliprotein levels in S. suiae were investigated. Lead and zinc biosorption and bioaccumulation in the seaweed increased with the increase in the lead and zinc concentrations and exposure times. Meanwhile, the biosorption and bioaccumulation of zinc in the seaweed following exposure to zinc were significantly higher (p < 0.05) than the biosorption and bioaccumulation of lead in the seaweed following exposure to lead with the same concentration at each exposure time. The chl-a, phycoerythrin (PE), phycocyanin (PC), and allophycocyanin (APC) contents in the seaweed significantly decreased with the increase in the lead and zinc concentrations and exposure times. The chl-a, PE, PC, and APC contents in S. suiae, which was exposed to 5 Pb2+ mg/L for 5 days, were significantly higher (p < 0.05) than those in the seaweed exposed to zinc at the same concentration and for the same exposure times. In the lead and zinc exudation tests, the highest biodesorption and biodecumulation were observed on the 1st day of exudation after the seaweed was transferred to fresh seawater. The residual percentages of the lead and zinc in the seaweed cells were 15.86% and 73.08% after 5 days of exudation, respectively. The biodesorption rate and biodecumulation rate of the seaweed exposed to lead were higher than those of the seaweed exposed to zinc. However, the effect of lead on chl-a and phycobiliproteins was greater than that of zinc. This might be the result of lead not being a necessary metal for these algae, whereas zinc is.

Extraction of phycobiliprotein pigments from Oscillatoria princeps by using different methods

In the current study, one isolation was obtained from the Cyanophyta Oscillatoria princeps which was collected from pond water located in Khor Al-Zubair/Basrah during August 2018. The current study aims at extracting and purifying of some effective pigments from the above isolate, test them chemically. Allophycocyanin (APC) pigments were highest among other pigments in sample removal-oil compared to the quantities of concentrations of phycoerythrin (PE) and phycocyanin (PC) pigments. The stationary phase in the industrial media have produced the largest amount of pigments. Phycobiliproteins were observed through the UV-Visible peaks. Freeze-dried samples or removal-oil showed that phycobiliproteins aren't affected by increasing or decreasing the sonication period. The study showed that it’s possible to use different media for pigments extraction as buffers and acetate buffer has been mastered. The freezing-thawing method is the best compared with other methods, the concentration of phycoerythrin (PE) pigments began to increase gradually from 6-12 days at PC and PE pigments extract, respectively. According to the statistical analysis, there are significance differences in Phycoerythrin. pigments concentration from 9th day to the 12th day.

A Review on a Hidden Gem: Phycoerythrin from Blue-Green Algae

Phycoerythrin (PE) is a pink/red-colored pigment found in rhodophytes, cryptophytes, and blue-green algae (cyanobacteria). The interest in PE is emerging from its role in delivering health benefits. Unfortunately, the current cyanobacterial-PE (C-PE) knowledge is still in the infant stage. It is essential to acquire a more comprehensive understanding of C-PE. This study aimed to review the C-PE structure, up and downstream processes of C-PE, application of C-PE, and strategies to enhance its stability and market value. In addition, this study also presented a strengths, weaknesses, opportunities, and threats (SWOT) analysis on C-PE. Cyanobacteria appeared to be the more promising PE producers compared to rhodophytes, cryptophytes, and macroalgae. Green/blue light is preferred to accumulate higher PE content in cyanobacteria. Currently, the prominent C-PE extraction method is repeated freezing-thawing. A combination of precipitation and chromatography approaches is proposed to obtain greater purity of C-PE. C-PE has been widely exploited in various fields, such as nutraceuticals, pharmaceuticals, therapeutics, cosmetics, biotechnology, food, and feed, owing to its bioactivities and fluorescent properties. This review provides insight into the state-of-art nature of C-PE and advances a step further in commercializing this prospective pigment.

Evaluation of antimicrobial, antioxidant and cytotoxicity potential of R-phycoerythrin extracted from Gracilaria corticata seaweed

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.

Gloeotrichia pisum in Lake Kinneret: A successful epiphytic cyanobacterium.

With climate change and re-oligotrophication of lakes due to restoration efforts, the relative importance of benthic cyanobacteria is increasing, but they are much less studied than their planktonic counterparts. Following a major water level rise event that inundated massive reed stands in Lake Kinneret, Israel, we discovered the appearance of a vast abundance of Gloeotrichia pisum (cyanobacteria). This provided an opportunity to investigate the biology and ecology of a benthic epiphytic colonial cyanobacterium, proliferating under altered environmental conditions, with possible toxin production potential and as a model for an invasive epiphyte. The species was identified by its typical morphology, and by sequencing its 16S rRNA gene and the intragenic space. We report on the abundance and spatial distribution of the detected colonies, their morphological characteristics, and pigment composition. High phycoerythrin content provides a brownish color and supports growth at low light levels. Genomic community composition analysis revealed that G. pisum colonies host a diverse microbial community of microalgae, cyanobacteria, bacteria, and archaea with a conserved and characteristic taxonomic composition. The Synechococcales order showed high relative abundance in the colony, as well as other prokaryotes producing secondary metabolites, such as the rhodopsin producer Pseudorhodobacter. The microbial consortium in the colonies performed nitrogen fixation. The diazotroph's phylogenetic relations were demonstrated. Tests for the presence of cyanotoxins (microcystin and cylindrospermopsin) proved negative. This study is the first documentation of this genus in Israel, providing insights into the invasive nature of G. pisum and the ecological implications of its appearance in a lake ecosystem.

Primary Composition and Pigments of 11 Red Seaweed Species from the Center of Portugal

Macroalgae have been regarded as a natural food source since ancient times, their nutritional value being not only proven by recent studies, but also triggering further in-depth research efforts on the matter. The present study aims to provide an insight into the nutritional potential of selected red seaweed species collected in central Portugal by specifically comparing the moist yield and ash content, crude protein, total lipids, carbohydrates and pigment content between species and, ultimately, finding out if there are differences between taxa. The results obtained highlighted the most nutritionally appealing species, namely, Plocamium cartilagineum with respect to protein content (23.18% dw) and Sphaerocococcus coronopifolius with respect to carbohydrate content (40.23% dw), while none of the species studied showed a lipid content higher than 1.80% dw. Regarding pigment content, the highest concentrations of phycoerythrin, carotenoid and chlorophyll a were obtained, respectively, from P. cartilagineum (0.09 mg.mL−1), Porphyra umbilicalis (1.88 µg.g−1 fw) and Jania rubens (38.41 µg.mL−1). We concluded that there are significant differences between the species studied regarding their nutritional profile, with a marked difference between Corallinales and all other species not belonging to this order; regarding pigment content, this variation between orders was not observed. Nevertheless, all the studied species may act as promising complements in a human healthy diet.

Promising Biomolecules with High Antioxidant Capacity Derived from Cryptophyte Algae Grown under Different Light Conditions.

Simple SummaryIn 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.

Comparison of Production and Fluorescence Characteristics of Phycoerythrin from Three Strains of Porphyridium.

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.

Amplified cyanobacterial bloom is derived by polyphosphate accumulation triggered by ultraviolet light

Cyanobacterial blooms appear more strongly, constantly and globally, yet the positive effect of surface solar ultraviolet radiation (UV) on cyanobacterial bloom in natural freshwater habitats is largely ignored. Here in-situ and laboratory studies were jointly designed to probe the mechanism of cyanobacterial bloom promoted by solar UV light. The results showed that solar UV light is a key trigger factor for the accumulation of total phosphorus, dissolved inorganic phosphorus and polyphosphate (polyP) in blooming cyanobacterial cells. The increase of UV dose induces polyP accumulation to result in the excessive phosphorus uptake of blooming cyanobacteria, which provides sufficient phosphorus for cyanobacterial growth in suitable environment. Solar UV light also can promote the contents of phycocyanin, allophycocyanin, and phycoerythrin, producing sufficient ATP by photosynthesis for polyP synthesis in cyanobacterial cells in lake enviroment. The frequent variations of UV irradiance exposure prompts cyanobacteria to absorb excessive phosphorus from suspended solid or sediment. Cyanobacterial intracellular phosphorus is accumulated for their growth. UV light promotes polyP accumulation in blooming cyanobacterial cells to avoid damage. The adsorption amount of phosphorus increases for exuberant growth and then more surface blooming cyanobacteria are exposed to UV light to absorb ample phosphorus. Thus, the positive feedback occurs in lake water bodies with abundant phosphorus. This amplified cycle of cyanobacterial density and phosphorus due to solar UV light in eutrophic water bodies is analogous to a triode to amplify visible photosynthesis by UV light as a base electric current in the energy flow process in lake environment, therefore, “Cyanobacterial Phosphorus Assimilation Ultraviolet Effect” is used to describe this phenomenon. A new explanation is provided for the continuing proliferating mechanism of cyanobacterial bloom. Besides, a new perspective appears on the outbreak of cyanobacterial blooms in natural eutrophic lake water bodies worldwide.

Environmental nitrogen and phosphorus nutrient variability triggers intracellular resource reallocation in Gracilariopsis lemaneiformis (Rhodophyta)

The variability in anthropogenic input of nutrients to coastal water has profound impacts on the ecology of Gracilariopsis lemaneiformis, a rhodophyte that is protein-rich and economically valuable for food and industry. However, little is known about how this alga responds to the dynamics of nitrogen and phosphorus (NP) nutrients. In this study, G. lemaneiformis was grown in batch cultures under three nutrient regimes (low-, medium- and high-NP abundances, with a constant N:P ratio of 10) to investigate the physiological, biochemical and transcriptional responses to the variation in N and P nutrient abundances. Under high-NP treatment conditions, G. lemaneiformis exhibited a high growth rate and contents of phycoerythrin, Chl a and soluble protein, but lower contents of soluble sugar and activities of nitrate reductase and glutamine synthetase. Besides, we found a negative correlation between the soluble sugar and soluble protein (R2 = 0.86), suggesting reallocation of intracellular resources modulated by extracellular NP nutrients. Furthermore, the carbon content decreased under high-NP conditions, indicating G. lemaneiformis biomass accumulation at the expense of per unit weight carbon content. In addition, we found that arginine was the main storage form of N in G. lemaneiformis, and its content increased 1017 times in a two-week period under N- and P- enriched conditions. Moreover, the phycoerythrin was the main biologically active N-compound used by G. lemaneiformis for growth, compared to soluble protein and Chl a, under N- and P-deficient conditions. These findings demonstrate that even under constant stoichiometry, the environmental variability of nutrient abundance shapes biochemical landscapes in the algal cell and provides baseline information to help design G. lemaneiformis cultivation to obtain higher protein or higher soluble sugar with respect to NP nutrition.

Effect of pH on Rhodomonas salina growth, biochemical composition, and taste, produced in semi-large scale under sunlight conditions

Rhodomonas salina is a microalgal species, belonging to the cryptophytes, and is widely used as aquaculture feed because of its high nutritional profile and phycoerythrin content. This study investigated the effect of pH on the growth, biochemical composition, and taste of R. salina when cultivated on a semi-large scale under natural light conditions. Two tubular photobioreactors (200 L) were used for the cultivation of R. salina with sunlight as the only illumination source. Two different pH setpoints were applied, 7 and 8.5. Optimal temperature and nutrient conditions were applied, according to previous research findings. The results demonstrated that the productivity of R. salina was higher at pH 7, 0.06–0.14 gdry weight L−1 day−1, compared to pH 8.5, 0.03–0.12 gdry weight L−1 day−1. It was found that protein and total fatty acid concentrations were higher in the biomass that was produced at pH 8.5, 33.7% and 12.3% of dry weight, respectively, while at pH 7, the protein content was 31.9% and the total fatty acids 8.8% of dry weight. The phycoerythrin concentration, like protein, was higher at pH 8.5, 2.7% of dry weight, compared to pH 7, 1% of dry weight. The free amino acid and nucleotide profile of R. salina was affected by the pH, resulting in increased equivalent umami concentration at pH 7. For the sensory evaluation, an expert panel on algae flavors evaluated the effect of pH on the taste of R. salina, reporting that the biomass that was produced at pH 7 had more umami flavor than the biomass that was produced at pH 8.5, which was evaluated as more bitter.

Vitamin supplements enhance Spirulina platensis biomass and phytochemical contents

Abstract Spirulina platensis (SP) has a high impact on multidiscipline usage worldwide. Vitamins are considered as growth promoters due to their metabolic bio-regulating roles. This study was conducted to investigate the effect of vitamins: riboflavin (B2), thiamine (B1), and ascorbic acid (C) on SP growth and contents of pigments, phenols, and phytochemicals besides its antioxidant activities. Vitamins were added in different concentrations to Zarrouk’s medium and tested for their effects weekly for three weeks of spirulina cultivation. The results revealed that 25 mg·L−1 thiamine or riboflavin promoted the most significant contents of chlorophyll and carotenoids, respectively, after 14 days of cultivation. However, adding 10 mg·L−1 thiamine achieved the most significant increase in algal biomass yield and contents of chlorophyll, carotenoids phycocyanin, allophycocyanin, phycoerythrin, and phycobiliprotein after 21 days of cultivation. Qualitative analysis showed that both SP and SP supplemented with 10 mg·L−1 thiamine (SPt) for 21 days contain tannins and flavonoids but quantitative analysis approved that SPt recorded significant increase in phenolic and tannin contents. Moreover, SPt induced a significant increase of total antioxidant activity in vitro 1,1-diphenyl-1,2-picrylhydrazyl assay in comparison with SP. Vitamins especially thiamine added during SP culture could improve SP biomasses, pigments, and phytochemical contents and hence increased antioxidant capacity.

Effects of indoor culture conditions on growth and phycoerythrin content of Proteomonas sulcata (Cryptophyta) assessed by flow cytometry

Effects of indoor culture conditions on growth and phycoerythrin content of Proteomonas sulcata (Cryptophyta) assessed by flow cytometry

Comparative analysis of phycoerythrin production in cryptophytes

Phycobiliproteins are pigments with uses in pharmacology, cosmetics, foods, and as fluorescent probes in biochemistry. Cryptophyte microalgae are one possible source of phycobiliproteins as well as other molecules such as omega-3 fatty acids. The use of cryptophytes in biotechnology is currently very limited and especially the potential of freshwater species is poorly documented. For commercial microalgae production, it is important to find the best performing strains in terms of growth and yields of the products of interest. Phycoerythrin is a phycobiliprotein with red colour and strong yellow fluorescence. In this study, we evaluate the growth and phycoerythrin production of eight strains of freshwater cryptophytes belonging to the genus Cryptomonas, comparing them to two marine strains. The strains are grown in batch cultures under standardised conditions. Most of the studied freshwater strains have lower growth rates and all of them have lower biomass yields than the marine strains. However, most of them have much higher cellular phycoerythrin concentrations, which in the case of two strains leads them to a significantly higher overall phycoerythrin yield. There is large variation among cryptophytes in growth rates and phycoerythrin content. Our results suggest that freshwater cryptophytes of the genus Cryptomonas may be better sources of phycoerythrin than the more extensively studied marine strains.

Enhancing Phycoerythrin and Phycocyanin Production from Porphyridium cruentum CCALA 415 in Synthetic Wastewater: The Application of Theoretical Methods on Microalgae

Phycoerythrin (PE) and phycocyanin (PC) are florescent pigments. They have the colorant role in the industry. In this study, production of PE and PC from Porphyridium cruentum were investigated at the various conditions such as different concentrations of municipal wastewater, wavelengths and salicylic acid using Response Surface Methodology-Central Composite Design (RSM-CCD), regression analysis and rstool models. The maximum RSM predicted PE concentration was 29.5 mg/g biomass at 50 % of wastewater, 510 nm of wavelength and 10 µM of salicylic acid. On the other hand, maximum RSM predicted PC concentration was 6.9 mg/g biomass at 50% of wastewater, 680 nm and 40 µM of salicylic acid. According to the ANOVA results, the square effects of the three variables (X1, X2 and X3) were found to be significant for the phycocyanin concentration, while the wastewater and salicylic acid variables (X1 and X3) were found to be important in the Phycoerythrin concentration. In addition to this, the highest PE and PC concentrations were 27.648 and 5.7104 mg/g biomass, respectively, for 50 % of wastewater, 512.5 nm and 47.0833 µM of salicylic acid according to rstool model. In conclusion, the variables such as wastewater, wavelength and salicylic acid can be used for the highest PE and PC concentration by means of RSM-CCD and rstool models and these variables may contribute to the industrial production of the two pigments.

Mechanical Disintegration and Particle Size Sieving of Chondrus crispus (Irish Moss) Gametophytes and Their Effect on Carrageenan and Phycoerythrin Extraction.

To better understand the migration properties of hybrid carrageenan from the seaweed tissue during carrageenan extraction, the effect of increasing the seaweed surface area by the mechanical disintegration of gametophyte Chondrus crispus chips was studied under various temperature and time extraction conditions. Dried Chondrus crispus seaweed chips were milled by a rotor beater mill and classified into eight different size fractions by sieving with varying mesh sizes from 50 to 2000 μm. During extraction at 22 °C, the red color of the filtrate increased significantly with the decreasing particle size of the fraction, correlating with the increasing phycoerythrin concentration (from 0.26 mg PE/g dry seaweed in the >2000 μm size fraction to 2.30 mg PE/g dry seaweed in the <50 μm size fraction). On the other hand, under the same extraction conditions, only a small increase in carrageenan precipitate was obtained with the decreasing size fractions (from no recovery in the >2000 μm size fraction to 2.1 ± 0.1 g/kg filtrate in the <50 μm size fraction). This yield was significantly lower than the ones from extractions at 45 °C (5.4 ± 0.1 g/kg) or at 90 °C (9.9 ± 2.1 g/kg) for the same particle size and time conditions. It could be concluded that hybrid carrageenan extraction is not surface area dependent, while phycoerythrin is. Therefore, it seems that phycoerythrin and carrageenan extraction follow different mechanisms. This creates potential for the selective extraction of each of those two compounds.

Potential of Neoporphyra kitoi (Bangiales, Rhodophyta) as a candidate species for marine crops with high temperature tolerance

We isolated the conchocelis strain OHN-1 from a long linear blade growing in a natural population of bladed Bangiales in Ohara, Chiba Prefecture, the Boso Peninsula in Japan, which is affected by the warm Kuroshio Current. The strain was identified as Neoporphyra kitoi based on the RUBISCO spacer sequences and phylogenetic analysis of the rbcL gene. Under identical laboratory cultures, the growth and pigment contents of the strain were compared with those of Neopyropia yezoensis f. narawaensis, which is the main cultivar currently cultivated in Japan. The conchocelis maturity of OHN-1 was remarkably higher than that of strain HG-4 of Neopy. yezoensis f. narawaensis at higher temperatures of 25 and 30 °C among the 5 temperature conditions (10, 15, 20, 25, 30 °C). The growth of the gametophytic blade was significantly higher in OHN-1 than in HG-4 at each examined temperature (15, 20, 25 °C). In particular, the OHN-1 blades at the highest temperature of 25 °C grew the largest until 3 weeks of culture, although the blades grew larger over 3 weeks with decreasing temperature. Moreover, the photosynthetic pigment contents, especially the phycoerythrin content, were significantly higher in OHN-1 than in HG-4. These results demonstrate that Neoporphyra kitoi has potential as a candidate species for marine crops with high temperature tolerance despite faster blade maturity.

Epiphytic effects of Licmophora paradoxa on pigments of Pyropia yezoensis

Epiphytic diatoms usually cause adverse effects on photosynthesis of the host plants due to shading light or by interfering with the biochemical pathways. The present study investigated the epiphytic effects of the diatom Licmophora paradoxa on the pigments of red alga Pyropia yezoensis, such as the chlorophyll-a (Chl-a), Phycoerythrin (PE), Phycocyanin (PC), Allophycocyanin (APC) and carotenoid contents. The results showed that Chl-a was significantly decreased while other pigments such as PE, PC, APC and carotenoid contents were significantly increased in P. yezoensis due to the attachment of epiphytic diatom L. paradoxa. The present results indicated that epiphytic diatoms produced negative effects on the host PSII reaction center by reducing its main pigment Chl-a. Whereas, antenna pigments of Phycobiliprotein, of P. yezoensis such as PE, PC and APC were increased to capture more light energy supplying photosynthesis. The increase in carotenoid content under this epiphytic situation implied an enhancement of its assisted function in light-harvesting, photoprotection and stress-tolerance mechanism. The present findings contribute to well understanding the response mechanism of host macroalgae to epiphytic microalgae.

Effect of urea on growth and biochemical composition of Porphyridium purpureum (Rhodophyta) and scaling-up under non-optimal outdoor conditions

ABSTRACT The goal of this study was to determine the effect of urea on the growth and accumulation of commercially important metabolites (lipids, proteins, fatty acids and phycoerythrin) and antioxidant activity in the red microalga of commercial interest Porphyridium purpureum. One-litre cultures were established containing 140 mg N l–1 or 400 mg N l–1, using nitrate (potassium nitrate) or urea as nitrogen source. Urea was as suitable as nitrate as the nitrogen source for P. purpureum. The nitrogen source significantly affected lipid but not protein content in P. purpureum, whereas nitrogen concentration significantly affected protein and lipid content, with the highest values obtained under 30 mM potassium nitrate and 14.8 mM urea (= 400 mg N l–1). Phycoerythrin content was not affected by nitrogen source or concentration in the culture. Considering the economic convenience of urea as a nitrogen source, the strain was scaled-up outdoors in Concepción, Chile (Mediterranean climate), in a closed tubular photobioreactor and an open raceway pond (350 and 700 litres, respectively) with 14.8 mM urea. Biomass production was about four times lower in outdoor systems than in 1-litre cultures; however, results were comparable to other large-scale trials. These results demonstrate the feasibility of using urea as a low-cost nitrogen source for P. purpureum culture and the viability of growing this species outdoors in Central-Southern Chile, where climate conditions are not traditionally considered suitable for setting up commercial microalgal cultures.