Phycoerythrin Content Research Articles

Evaluation of protic ionic liquids as potential solvents for the heating extraction of phycobiliproteins from Spirulina (Arthrospira) platensis

An alternative methodology using different protic ionic liquids (PILs), mechanical agitation and thermal heating was proposed to obtain phycobiliproteins from the Spirulina (Arthrospira) platensis microalgae. The PILs N-methyl-2-hydroxyethylammonium acetate (2-HEAA) protic ionic liquid; N-methyl-2-hydroxyethylammonium formate (2-HEAF) protic ionic liquid; the mixture of these protic ionic liquids (2-HEAA + 2-HEAF) (1:1, v/v) were synthesized and their performance as solvent was compared to a control (sodium phosphate buffer). The results showed that all PILs were efficient in the extraction of phycobiliproteins. The most suitable conditions were: temperature of 35 °C; pH 6.50 and ratio solvent:biomass 6.59 mL·g−1, using 2-HEAA + 2-HEAF as solvent after 150 min of extraction. The maximum concentrations of phycocyanin, allophycocyanin and phycoerythrin were 1.65 g·L−1, 1.70 g·L−1 and 0.64 g·L−1, respectively. The obtained phycobiliproteins presented a purification index around 0.50 and can be applied in cosmetics and foods. The phycobiliproteins obtained by extraction using 2-HEAA + 2-HEAF exhibited appreciable antioxidant activity, 61.1% of DPPH scavenging activity and 77.4% of H2O2 scavenging activity, at a concentration of 20 mg/mL.

Physiological responses of the red algae Gracilaria caudata (Gracilariales) and Laurencia catarinensis (Ceramiales) following treatment with a commercial extract of the brown alga Ascophyllum nodosum (AMPEP)

Extracts of brown algae are used commercially for agricultural crops due to their plant growth-promoting effects and they can also be applied to help improve seaweed cultivation. Gracilaria caudata is commercially exploited as a raw material for agar production in Brazil, and Laurencia catarinensis is a source of halogenated terpenoids with several biological activities. Investigations to understand the development of seaweeds of biotechnological interest are required in order to improve their cultivation and the sustainability for biomass production on an industrial scale. The aim of the present study was to evaluate the effects of Ascophyllum/Acadian marine plant extract powder (AMPEP), a commercial, water-soluble extract of the brown alga Ascophyllum nodosum, on the growth, branching development, and pigment content of G. caudata and L. catarinensis. Four concentrations of AMPEP (0, 0.1, 1.0, and 5.0 mg L−1) were added to sterilized seawater (seawater+AMPEP), and to a medium comprised of half-strength von Stosch solution (VSES/2+AMPEP). Experiments were performed under conditions of 23 ± 2 °C, a light:dark cycle of 14:10 h, salinity at 32 psu, and photon flux densities of 60 ± 10 μmol photons m−2 s−1. Data were analyzed by one-way ANOVA, followed by a posteriori multiple comparison, Student-Newman-Keuls’ test. Treatments of seawater+AMPEP at concentrations of 0.1 and 1.0 mg L−1 stimulated the growth rates of G. caudata when compared to the control. However, the effects of seawater+AMPEP and VSES/2+AMPEP on the branching architecture of the thalli were not significant for either species. Concentrations of phycoerythrin, phycocyanin, allophycocyanin, and chlorophyll-a in L. catarinensis were stimulated by the highest concentration of VSES/2+AMPEP (i.e., 5.0 mg L−1). This is the first study to report the stimulatory effect of AMPEP on the phycobiliprotein contents of selected red algae. Furthermore, seawater+AMPEP in concentrations of 0.1 and 1.0 mg L−1 stimulated growth rates of G. caudata, which could be applied in its large-scale cultivation. The results obtained for G. caudata and L. catarinensis, an agar-producing and a terpenoid-producing species, respectively, contributed to extending the knowledge of the beneficial uses of a brown seaweed-derived extract with biostimulatory properties for use with cultivated, economically important red algae.

A singular nitric oxide synthase with a globin domain found in Synechococcus PCC 7335 mobilizes N from arginine to nitrate

The enzyme nitric oxide synthase (NOS) oxidizes L-arginine to NO and citrulline. In this work, we characterise the NOS from the cyanobacteria Synechococcus PCC 7335 (SyNOS). SyNOS possesses a canonical mammalian NOS architecture consisting of oxygenase and reductase domains. In addition, SyNOS possesses an unusual globin domain at the N-terminus. Recombinant SyNOS expressed in bacteria is active, and its activity is suppressed by the NOS inhibitor L-NAME. SyNOS allows E. coli to grow in minimum media containing L-arginine as the sole N source, and has a higher growth rate during N deficiency. SyNOS is expressed in Synechococcus PCC 7335 where NO generation is dependent on L-arginine concentration. The growth of Synechococcus is dramatically inhibited by L-NAME, suggesting that SyNOS is essential for this cyanobacterium. Addition of arginine in Synechococcus increases the phycoerythrin content, an N reservoir. The role of the novel globin domain in SyNOS is discussed as an evolutionary advantage, conferring new functional capabilities for N metabolism.

Study on the Effect of Sodium Nitroprusside on Growth and Nitrogen Fixation in Blue-Green Algae Nostoc linckia

In this research, we investigated the effect of sodium nitroprusside (SNP) on growth, nitrogen fixation and some metabolites on Nostoc linckia. Culture medium with different concentrations of SNP (0, 0.01, 0.1 and 1 μM) was prepared. After 7, 14 and 21 days, samples were harvested and analyzed. Adding 1 μM SNP to culture medium decreased fresh weight significantly after 14 and 21 days. The alga treated with 0.01 μM SNP had lower heterocyst percent after 14 days. The amount of carotenoids increased with adding 1 μM SNP in 14-day-old cultures. The highest phycocyanin content was observed after 14 days in culture treated with 0.1 μM SNP. Increase in allophycocyanin content was observed by adding 0.1 and 1 μM SNP after 14 days and with 0.01, 0.1 and 1 μM SNP after 21 days. Treatment with SNP induced phycoerythrin content at 0.01 μM concentration after 21 days. The alga treated with 0.1 and 1 μM SNP had higher reducing sugar content after 14 days. However, in 21-day-old cultures all SNP concentrations showed decreased reducing sugar content in treated alga. The amount of soluble sugars was reduced by the highest SNP concentration after 7 days. SNP treatment could induce protein accumulation after 7 and 21 days by some concentrations, but in 14-day-old cultures SNP treatment had reduction effect on protein content. Nitrogenase activity considerably increased in culture exposed to SNP after 7 days. According to our results, positive effects of SNP on phycobiliproteins, protein content and nitrogenase activity and its inhibitory effect on heterocyst differentiation were important findings of this study.

Content of phycoerythrin, phycocyanin, alophycocyanin and phycoerythrocyanin in some cyanobacterial strains: Applications.

Cyanobacteria are unique prokaryotes, which are capable to perform oxygenic photosynthesis. Within these organisms, phycobilisomes (PBS) act as an antenna of the photosynthetic pigment apparatus. Phycobilisomes contain several phycobiliproteins (PBP): phycoerythrin (PE), phycocyanin (PC), allophycocyanin (APC) and phycoerythrocyanin (PEC). The application of phycobiliproteins in the biotechnology, food industry and medicine during the last years is rapidly increasing. The aim of our study was to assess the qualitative and quantitative content of phycoerythrin, phycocyanin, allophycocyanin and phycoerythrocyanin in 14 cyanobacterial strains kept in Plovdiv Algal Culture Collection (PACC) and 4 strains purchased from the Culture Collection of Autotrophic Organisms (CCALA). Our data demonstrated that three strains of Microcoleus autumnalis (PACC 5505, PACC 5522 and PACC 5527) have high potential to produce phycoerythrins (0.132, 0.201 and 0.136 mg/mL, respectively). Similarly, one Microcoleus autumnalis strain (PACC 5522) and one strain of Leptolyngbya boryana (CCALA 084) are suitable for biotechnological production of phycocyanins (0.051 and 0.264 mg/mL, respectively) as well as allophycocyanins (0.102 and 0.171 mg/mL, respectively). In addition, the data about the pigment content could be used as a biochemical marker for taxonomic purposes within the group.

Phycobiliprotein-mediated synthesis of biogenic silver nanoparticles, characterization, in vitro and in vivo assessment of anticancer activities

Phycoerythrin is the main phycobiliprotein that responsible for harvesting light for photosynthesis in cyanobacteria. In this research, phycoerythrin extracted from the cyanobacterium Nostoc carneum has been used to reduce silver nitrate for silver nanoparticles (AgNPs) biosynthesis. UV–visible spectrophotometry for measuring surface plasmon resonance showed a single absorption peak at 430 nm, which confirmed the presence of AgNPs. The face-centered central composite design was chosen to evaluate the interaction effects between four process variables and also to determine their optimal levels which influence the AgNPs biosynthesis using phycoerythrin. The maximum silver nanoparticles biosynthesis (1733.260 ± 21 µg/mL) was achieved in the central runs under the conditions of initial pH 10, incubation period of the 24 h, phycoerythrin concentration of the 0.8 mg/mL and 20 mM of AgNO3. The biosynthesized AgNPs were characterized using TEM which revealed the formation of spherical shape nanoparticles with size ranged between 7.1‒26.68 nm. EDX analysis confirmed silver as the major constituent element. FTIR spectrum indicates the presence of proteinaceous capping agent that prevents silver nanoparticles agglomeration. The IC50 of cell inhibition by AgNPs was observed at 13.07 ± 1.1 µg/mL. Treatment of mice bearing Ehrlich ascites carcinoma with 5 mg AgNPs/kg of mice body weight significantly decreased tumor volume, tumor cells count, white blood cells count and body weight. It was concluded that the phycoerythrin protein has the ability to synthesize AgNPs, which have antibacterial, antihemolytic, in vitro and in vivo cytotoxic activities.

Growth and biochemical responses of tropical and subtropical strains of Gracilaria domingensis (Gracilariales, Rhodophyta) to temperature and irradiance variations

Gracilaria domingensis (Kutzing) Sonder ex Dickie is widely distributed in the Brazilian coast and is one of a few Gracilaria species with occurrence in the southern region of the country. Its commercial importance is in the use in human food (in natura) and knowledge of the physiology is fundamental to make its cultivation successful. The objectives of the present work were to determine the limits of tolerance to temperature and irradiance variations and to evaluate comparatively their effects on growth rates and contents of total soluble proteins and pigments in female gametophytes of G. domingensis from Brazilian tropical region (ES strain) and from subtropical region (SC strain). Variations in temperature (from 15 to 35 °C) and irradiance (from 20 to 250 μmol photons m−2 s−1) were tested. Both strains tolerated temperature variation from 15 to 30 °C, but died at 35 °C. The ES strain had higher growth rates (from 3.1 to 6.1% day−1) in relation to the SC strain (from 1.3 to 4.1% day−1), but the two strains had the highest growth rate at 25 °C. The ES strain had higher concentrations of total soluble proteins at low temperature (15 °C), while the SC strain showed higher protein concentrations at high temperatures (25 and 30 °C). In addition, the chlorophyll a concentration of the ES strain was higher at 20 °C and lower at 30 °C. The irradiance variation influenced the growth rates of the two strains (from 2.7 to 6.0% day−1) and the lowest growth rates were observed at irradiance of 20 μmol photons m−2 s−1 and the highest growth rates were observed at a wide range of irradiance variation (from 40 to 250, and from 60 to 250 μmol photons m−2 s−1 for SC and ES strains, respectively). The studied strains of G. domingensis showed higher concentrations of total soluble protein at low irradiances (20, 40, and 80 μmol photons m−2 s−1). The highest concentrations of phycoerythrin (423.0 μg g−1 FW) and phycocyanin (215.3 μg g−1 FW) were observed in the ES strain grown at low irradiance (40 μmol photons m−2 s−1). The chlorophyll a concentration of the two strains decreased with increased irradiance, indicating a photoacclimation. Our results showed that the tropical strain of G. domingensis has higher growth rates over a broader temperature range than the subtropical strain, which could be an advantageous feature for maricultural purposes.

Isolation and characterization of a high-growth-rate strain in Pyropia yezoensis induced by ethyl methane sulfonate

Chemical treatment is a powerful way to induce mutagenesis and has been applied in various studies. Here we describe the isolation of a high-growth-rate mutant Pyropia yezoensis induced by ethyl methane sulfonate (EMS) exposure. The mutation was induced using EMS on the thallus. When the gametophytic blades were treated with 2 mM EMS, a high-growth mutant strain PyE2 was obtained. Physiological and proteomic analysis were conducted to compare this strain with the wild-type (WT). The results demonstrated that the growth rate of mutant strain PyE2 was significantly higher than that of the WT in the laboratory. By measuring the biomass of three generations, it was confirmed that the high growth rate of the mutant strain was maintained. The photochemical efficiency and phycoerythrin content of the mutant strain PyE2 were found to be higher than those of the WT. Analysis of random amplified polymorphic DNA also revealed genetic modifications in the mutant. Extracted proteins from PyE2 grown under culture conditions were separated using two-dimensional gel electrophoresis, and changes in the proteome of the blades were analyzed. Approximately 302 protein species were detected, of which 19 were differentially expressed in the mutant and the WT. These results indicate that the growth rate of PyE2 was increased due to the upregulation of proteins potentially involved in photosynthesis and protein synthesis. The use of mutagenesis methods may help to develop new cultivars useful in the nori industry.

Pyropia acanthophora var. brasiliensis E. C. Oliveira and Coll (Rhodophyta: Bangiales) cultivated in seawater under laboratory conditions favors the production of economically important secondary metabolites

Pyropia represents most domesticated seaweed in the world. Therefore, we aimed to determine if cultivation of the red macroalga Pyropia acanthophora E. C. Oliveira and Coll (Rhodophyta: Bangiales) under laboratory conditions would affect the presence and concentration of secondary metabolites. To accomplish this, experiments were performed with ambient sample and acclimated sample (laboratory conditions). The conditions of the culture room were as follows: 24 oC, salinity of 35%o, constant aeration, irradiance of 80 umol.photons.m-2.s-1 and photoperiod of 12 h, for 7 days. Ambient sample showed lower concentrations of allophycocyanin and phycoerythrin when compared to the acclimated sample, but phycocyanin concentration was higher in the ambient sample. Carotenoids showed higher concentrations in the acclimated sample when compared to the ambient sample. Total phenolics were insignificant, while total flavonoids were higher in the ambient sample. No pattern in the production of these secondary metabolites could be identified. On the other hand, the acclimated samples showed a greater inhibition of the free radical DPPH, indicating a higher antioxidant activity. Acclimatization under laboratory conditions, in which P. acanthophora is submerged in seawater, favors the production of economically important secondary metabolites as a result of submersion stress and changes in cultivation patterns, such as irradiance and photoperiod.

Effects of nitrogen source and irradiance on Porphyridium cruentum

We determined the effects of two nitrogen sources (ammonium and nitrate) and two irradiance levels (50 and 200 μmol photons m−2 s−1) on the growth rate, cell size, proximate composition, pigment content, and photosynthesis of the unicellular red alga, Porphyridium cruentum. Irradiance significantly affects growth rate, as well as carbohydrate, protein, and phycoerythrin content. Nitrogen form significantly affects cell size, total dry weight, organic dry weight, ash content, carotene content, phycocyanin content, allophycocyanin content, maximum relative electron transport rate (rETRm), and photosynthetic efficiency (α). However, the irradiance and nitrogen source had significantly interaction with the content of lipids and chlorophyll a content, relative electron transport rate (rETR), and irradiance of saturation (Ik). These findings demonstrate that irradiance and nitrogen source influence the metabolism of P. cruentum and that the combination of these two variables induces the production of chemical products for biotechnological, aquaculture, and nutraceutical industry.

The photosynthetic responses to stocking depth and algal mat density in the farmed seaweed Gracilaria lemaneiformis (Gracilariales, Rhodophyta).

The branches and mass of Gracilaria lemaneiformis increase with growth season, and the thalli sink to deeper depths with increasing biomass density during maricultivation. The changing depth and algal mat density may affect the physiology of the algae. In the present study, the photosynthetic behaviors regarding different biomass densities in G. lemaneiformis thalli collected from different stocking depths were determined, to examine how photosynthesis of this farmed alga was affected by the growth depths and algal mat densities. Our results showed that the chlorophyll a (Chl a), carotenoids (Car), phycoerythrin (PE) contents, and irradiance-saturated maximum photosynthetic rates (P max) of the deeper layer-grown algae were significantly increased relative to the surface layer-grown algae. The P max, apparent photosynthetic efficiency (α) and dark respiration rate (R d) of G. lemaneiformis thalli, were reduced, whereas the irradiance saturation points (I k) were increased, with the increasing algal mat density. We proposed that appropriate measures are needed to trade off the stocking depth and biomass density, in an effort to maintain a relative high photosynthetic productivity during G. lemaneiformis maricultivation.

Growth and Photosynthetic Characteristics of Toxic and Non-Toxic Strains of the Cyanobacteria Microcystis aeruginosa and Anabaena circinalis in Relation to Light.

Cyanobacteria are major bloom-forming organisms in freshwater ecosystems and many strains are known to produce toxins. Toxin production requires an investment in energy and resources. As light is one of the most important factors for cyanobacterial growth, any changes in light climate might affect cyanobacterial toxin production as well as their growth and physiology. To evaluate the effects of light on the growth and physiological parameters of both toxic and non-toxic strains of Microcystis aeruginosa and Anabaena circinalis, cultures were grown at a range of light intensities (10, 25, 50, 100, 150 and 200 µmol m−2 s−1). The study revealed that the toxic strains of both species (CS558 for M. aeruginosa and CS537 and CS541 for A. circinalis) showed growth (µ) saturation at a higher light intensity compared to the non-toxic strains (CS338 for M. aeruginosa and CS534 for A. circinalis). Both species showed differences in chlorophyll a, carotenoid, allophycocyanin (APC) and phycoerythrin (PE) content between strains. There were also differences in dark respiration (Rd), light saturated oxygen evolution rates (Pmax) and efficiency of light harvesting (α) between strains. All other physiological parameters showed no statistically significant differences between strains. This study suggest that the different strains respond differently to different light habitats. Thus, changes in light availability may affect bloom intensity of toxic and nontoxic strains of cyanobacteria by changing the dominance and succession patterns.

Adaptation of the Cyanobacterium fischerella sp. ISC 107 to the combined effects of pH and carbon dioxide concentration.

The aim of this study was to investigate the adaptation of the cyanobacterium Fischerella sp. ISC 107to combined effects of carbon dioxide concentration, acidic and alkalinity. Axenic strain was incubated in BG0-11 medium. Carbon dioxide treatments were limited and relatively non-limited. Acidic (pH 5), neutral (pH7), and alkaline (pH 9) conditions were employed in each treatment. Survival, growth, chlorophyll, phycocyanin, allophycocyanin, and phycoerythrin contents were evaluated in each treatment along with ammonium liberation, frequency, and biometry of heterocyst. Results showed that like other explored stigonematalean and nostocalean cyanobacteria, this strain cannot grow in acidic condition. Under limited carbon dioxide condition, difference in growth rates were not significant between acidic and alkaline conditions; however, carbon dioxide enrichment caused significant increase in growth rates. Phycobilisome system of this strain lacked phycoerythrin and may complete its structure both at the core and the rod under alkaline condition. Heterocyst frequency and biometry were maximum at alkaline condition showing significant correlation with nitrogenase activity. Heterocyst showed cylindrical and sub-cylindrical morphology on days 4and 5 after inoculation. Overall, the results showed that this strain may be qualified to be used as a biofertilizer similar to the other cyanobacteria.

Effect of salinity on some physiological and biochemical responses in the cyanobacterium Synechococcus elongatus

In this study, some physiological and biochemical responses of Synechococcus elongatus to salt stress were investigated. The cyanobactrium was grown in BG-11 medium under different concentrations of NaCl (0, 0.5, 1 M). The results indicated that the growth of S. elongatus was significantly inhibited under salt stress on days 5, 9 and 12. Protein content increased in S. elongatus on day 12 in presence of salt. Salinity induced proline accumulation at 1 M NaCl on day 12 and caused a significant enhance in hydrogen peroxide content on day 5. Catalase (CAT) activity continuously increased on day 5. An increasing trend in polyphenol oxidase (PPO) activity was indicated on days 5 and 9. Superoxide dismutase (SOD) activity gradually induced with increasing NaCl concentrations on day 5. Salt stress decreased chlorophyll content compared to that of control in three stages of growth, and carotenoid content declined on days 9 and 12. The contents of phycobiliprotein (PBP), phycoerythrin (PE) and phycocyanin (PC) enhanced significantly under different NaCl concentrations on days 5 and 9. These results show that S. elongatus has limited adaptative potential to salinity, and the optimum medium for its culture should not bear NaCl even at a moderate level, if production of carotenoids is aimed.

Characterization of the genuine type 2 chromatic acclimation in the two Geminocystis cyanobacteria.

Certain cyanobacteria can adjust the wavelengths of light they absorb by remodeling their photosynthetic antenna complex phycobilisome via a process called chromatic acclimation (CA). Although several types of CA have been reported, the diversity of the molecular mechanisms of CA among the cyanobacteria phylum is not fully understood. Here, we characterized the molecular process of CA of Geminocystis sp. strains National Institute of Environmental Studies (NIES)-3708 and NIES-3709. Absorption and fluorescence spectroscopy revealed that both strains dramatically alter their phycoerythrin content in response to green and red light. Whole-genome comparison revealed that the two strains share the typical phycobilisome structure consisting of a central core and peripheral rods, but they differ in the number of rod linkers of phycoerythrin and thus have differing capacity for phycoerythrin accumulation. RNA sequencing analysis suggested that the length of phycoerythrin rods in each phycobilisome is strictly regulated by the green light and red light-sensing CcaS/R system, whereas the total number of phycobilisomes is governed by the excitation-balancing system between phycobilisomes and photosystems. We reclassify the conventional CA types based on the genome information and designate CA of the two strains as genuine type 2, where components of phycoerythrin, but not rod-membrane linker of phycocyanin, are regulated by the CcaS/R system.

Physiological responses of Porphyra haitanensis (Rhodophyta) to copper and cadmium exposure

Abstract The aim of the present work was to evaluate the effects of copper (Cu) and cadmium (Cd) on the physiology of the red macroalga Porphyra haitanensis Chang and Zheng. The alga was cultured in media with different Cu or Cd concentrations for 7 days. The relative growth rate was significantly reduced at Cu concentrations of 0.10 mg l−1 and above or at Cd concentrations of 4 mg l−1 and above. Chlorophyll a (Chl a), carotenoids (Car), phycoerythrin (PE) and phycocyanin (PC) contents decreased at high Cu or Cd concentrations, and PE content increased at 0.10 mg l−1 Cu or 4–8 mg l−1 Cd. Moreover, the optimal quantum yield, maximum net photosynthetic rate (Pm) and apparent photosynthetic efficiency (α) were significantly reduced at high Cu or Cd concentrations. In contrast, malondialdehyde (MDA) content and superoxide dismutase (SOD) activity increased in response to Cu or Cd treatment. Catalase activity increased at 2–8 mg l−1 Cd and significantly declined at 0.50 mg l−1 Cu or 10 mg l−1 Cd. Nitrate reductase (NR) activity declined at high Cu or Cd concentrations. Consequently, both Cu and Cd were physiological stressors for P. haitanensis, with Cu being more toxic than Cd. This work has generated valuable knowledge about the toxic effects of Cu and Cd on macroalgae.

Isolation and Characterization of Two Cyanobacterial Strains Calothrix Sp. and Microchaete Sp. from Rice Fields of Karimganj District, Assam, North East India

Studies on various nitrogen fixing microalgal strains found in the rice paddy field soils are carried out in different parts of the world. In the present study two cyanobacterial strains belonging to the order nostocales, Calothrix sp. and Microchaete sp. were isolated from the rice fields of Karimganj district, South Assam, India and characterized based on their morphological, biochemical and molecular analysis. For the phenotypic characterization - growth, pigments (chlorophyll a, total carotenoid content, phycobiliproteins) and biochemical properties (total carbohydrate and soluble proteins) were studied. The study showed that both strains contain lower phycoerythrin content as compared to the other pigments. The Microchaete strain contain a higher total carotenoid content while chlorophyll a accumulation was higher in the Calothrix strain. Phylogenetic compairision was made using 16S rRNA gene sequences including other sequences of Calothrix, Microchaete and Tolypothrix species from GenBank. The results showed that polyphasic approach provides necessary information for the identification of cyanobacterial species using morphological analysis in combination with molecular techniques.

Growth and biochemical characterization of green and red strains of the tropical agarophytes Gracilaria debilis and Gracilaria edulis (Gracilariaceae, Rhodophyta)

Cultivation of the wild-type red strain and green natural mutant strains of Gracilaria debilis (Forsskal) Borgesen (RD and GD) and Gracilaria edulis (Gmelin) Silva (RE and GE) was attempted by raft method from August, 2014 to May, 2015 at Thonithurai, southeastern coast of India, for 180 days in order to evaluate color stability, growth rates, pigment composition, sap components, and the agar yield and quality. Coloration pattern of green and red strains of G. debilis and G. edulis was fixed, and no interchange in color occurred during the cultivation. Red strains of both G. edulis (RE) and G. debilis (RD) showed higher performance in biomass yield and phycoerythrin content over their green counterparts. Maximum biomass yields of 12.458 ± 1.24 kg fresh wt m−2 and 5.49 ± 0.26 kg fresh wt m−2 were observed in G. debilis and G. edulis, respectively. Higher DGR of 5.82 ± 0.57 % day−1 and 5.42 ± 1.73 % day−1 were observed in G. edulis and G. debilis, respectively. Highest gel strength recorded in G. debilis was 800 ± 15 g cm−2 and followed by G. edulis 695 ± 15 g cm−2. Green and red strain of G. debilis (GD and RD) and G. edulis (GE and RE) showed similar pattern in DGR, phycocyanin and allophycocyanin content, agar yield, gel strength, gelling temperature, melting temperature, sulfate content, and mineral composition of sap (p > 0.05). The growth rates observed in green and red strains of both species were considered adequate for commercial farming, and the present agar-related data fulfilled the industrial and pharmaceutical requirements.

Physiological assessment of the mariculture potential of a Gracilaria caudata (Gracilariales, Rhodophyta) variant

On the Brazilian coast, the red alga Gracilaria caudata is exploited for agar production. Recently, among the common red wild type (RD), a greenish-brown variant (GB) was collected from a natural population. The aim of this work was to compare the growth (GR), photosynthesis, and pigment content of GB and RD tetrasporophytes cultivated under two irradiances, 70 and 150 μmol photons m−2 s−1, for a period of 28 days. The GB variant is deficient in phycoerythrin, but it produced higher levels of allophycocyanin (APC) and phycocyanin (PC) at 150 μmol photons m−2 s−1. At this irradiance, no difference of phycoerythrin content was observed between strains, suggesting that RD could be using this pigment as a nitrogen source. RD growth rates, irrespective of irradiance, were higher when compared to GB up to 14 days, although no differences were observed in photosynthesis. During the 14-day period, both color strains showed higher GR, maximum electron transport rate, and effective quantum yield at 150 μmol photons m−2 s−1 when compared to 70 μmol photons m−2 s−1. After that, although no differences were observed in the photosynthetic properties, a decrease in GR was seen at both irradiances when RD and GB simultaneously differentiated tetrasporangia. The GB, although fertile, was better able to maintain its growth and even exceed the growth rates of RD in the last week (150 μmol photons m−2 s−1). This characteristic could be advantageous to the species, favoring GB in natural populations, since G. caudata is normally found in the fertile state along the Brazilian coast, and most individuals are tetrasporophytes. This feature could also be important to the selection of this GB strain for future mariculture in Brazil. In addition, their higher concentration of PC and APC could open prospects for a possible use as source of material for pharmaceuticals and fluorescent applications.

Effect of gibberellic acid on the cyanobacterium Nostoc linckia

We investigated the influence of gibberellic acid (GA3; 0, 1, 10, and 100 μM) on Nostoc linckia culture at 7, 14, and 21 days. The fresh and dry weight of N. linckia was increased considerably by the 10 and 100 μM GA3 treatments. A reduction in heterocyst frequency was observed in cultures treated with 1 and 10 μM GA3. Adding GA3 to N. linckia culture had a little effect on cell size. The amount of chlorophyll a and carotenoids decreased at all concentrations of GA3. The amount of phycocyanin increased up to twofold in 7-day-old culture treated with 1 μM GA3, and similar changes were observed for allophycocyanin and phycoerythrin content after 7 days. The effect of GA3 on reducing sugar content was different and was dependent on the growth period. A reduction in soluble sugar content was detected after GA3 application in 7- and 14-day-old cyanobacteria. Cultures treated with GA3 had a higher protein content after 14 days and a lower protein content after 7 and 21 days, and reduced nitrogenase activity after 7, 14, and 21 days. Our data show that GA3 application can be a suitable and inexpensive way to increase N. linckia biomass and phycobiliprotein production.