Effect of Phycoerythrin on Antimicrobial Activity and Shelf-life Extension of the Nile Tilapia (Oreochromis niloticus) at Refrigerator Temperature.

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.

Implementation of kLa-Based Strategy for Scaling Up Porphyridium purpureum (Red Marine Microalga) to Produce High-Value Phycoerythrin, Fatty Acids, and Proteins.

Porphyridium purpureum is a well-known Rhodophyta that recently has attracted enormous attention because of its capacity to produce many high-value metabolites such as the pigment phycoerythrin and several high-value fatty acids. Phycoerythrin is a fluorescent red protein-pigment commercially relevant with antioxidant, antimicrobial activity, and fluorescent properties. The volumetric mass transfer coefficient (kLa) was kept constant within the different scaling-up stages in the present study. This scaling-up strategy was sought to maintain phycoerythrin production and other high-value metabolites by Porphyridium purpureum, using hanging-bag photobioreactors. The kLa was monitored to ensure the appropriate mixing and CO2 diffusion in the entire culture during the scaling process (16, 80, and 400 L). Then, biomass concentration, proteins, fatty acids, carbohydrates, and phycoerythrin were determined in each step of the scaling-up process. The kLa at 16 L reached a level of 0.0052 s-1, while at 80 L, a value of 0.0024 s-1 was achieved. This work result indicated that at 400 L, 1.22 g L-1 of biomass was obtained, and total carbohydrates (117.24 mg L-1), proteins (240.63 mg L-1), and lipids (17.75% DW) were accumulated. Regarding fatty acids production, 46.03% palmitic, 8.03% linoleic, 22.67% arachidonic, and 2.55% eicosapentaenoic acid were identified, principally. The phycoerythrin production was 20.88 mg L-1 with a purity of 2.75, making it viable for food-related applications. The results of these experiments provide insight into the high-scale production of phycoerythrin via the cultivation of P. purpureum in an inexpensive and straightforward culture system.

Enriching Rotifers with "Premium" Microalgae: Rhodomonas lens.

The nutritional value of the marine cryptophyte Rhodomonas lens for the filter feeder Brachionus plicatilis as well as its biotechnological potential as a source of phycoerythrin (PE) and polyunsaturated fatty acids (PUFA) were evaluated in semi-continuous cultures maintained with different daily renewal rates (RR), from 10% (R10) to 50% (R50) of the total volume. Steady-state cell density decreased from 22 to 7 × 106 cells mL-1 with increasing RR, with the maximum cell productivity, nearly 0.4 g L-1 day-1, observed with R40. PE cell content attained the highest values with the highest RR (circa 9 pg cell-1). All treatments of R. lens maintained under nitrate-saturated conditions (R20-R50) showed a similar high content of PUFAs, > 60% of total fatty acids (FA), with linolenic acid (18:3n-3) and 18:4n-3, representing 12 and 29% of total FA respectively. The PUFA level in the nitrogen-limited R10 cultures was significantly lower (37%). R. lens promoted higher weight gain in the rotifer B. plicatilis than Tisochrysis lutea (T-ISO), a species commonly used for rotifer culture and enrichment. Significant differences were found in the protein content and in the ratio n-3/n-6 fatty acids among rotifers fed with R. lens from different RRs, with higher values being found in those fed with R. lens from higher RRs. The enrichment of the rotifers for short periods of 3 h was sufficient to modify the biochemical composition of the rotifers, but it was evidenced as too short for the accumulation of PUFAs, when compared to long-term (24 h) enrichment. The rotifers reflected the higher protein and PUFA content of R. lens cultivated with nutrient sufficient microalgae (R40) after only 3 h of enrichment. These results demonstrate that semi-continuous culture of R. lens under appropriate conditions can strongly enhance the nutritional value of this species, being reflected in the growth and biochemical composition of the filter feeder, even in short exposure periods.

Effect of Oven-Drying on the Recovery of Valuable Compounds from Ulva rigida, Gracilaria sp. and Fucus vesiculosus.

The effect of oven-drying at 25, 40 and 60 °C was evaluated on three macroalgae of relevance in Europe, namely Ulva rigida, Gracilaria sp. and Fucus vesiculosus, with respect to quality aspects, including their potential to be exploited as a source of valuable compounds. Notably, as compared to freeze-drying, oven-drying at 25 °C promoted the extraction of chlorophylls and carotenoids from U. rigida, as well as those of phycoerythrin and chlorophyll a from Gracilaria sp., while 40 °C favored the recovery of fucoxanthin and pheophytin a from F. vesiculosus. On the other hand, the use of oven-drying had a negative impact on the extraction of phenolic compounds from this alga, also diminishing the antioxidant activity of the resulting extracts. Instead, the impact of oven-drying of raw material on the recovery of specific polysaccharides differed among the macroalgae. While the amounts of ulvans and fucoidans obtained from macroalgae dried at higher temperatures tended to be superior, the recovery of agar was not affected with the drying temperatures applied to Gracilaria sp. The overall results showed that oven-drying might serve as a good alternative to stabilize Ulva rigida, Gracilaria sp. and Fucus vesiculosus, especially if extraction of pigments and polysaccharides is aimed, thought the appropriate temperature applied must be adapted for each macroalgae.

Expanding the Dynamic Range of Fluorescence Assays through Single-Molecule Counting and Intensity Calibration.

Surface capture assays can measure fluorescently labeled analytes across a 1000-fold concentration range and at the sub-nanomolar level, but many biological molecules exhibit 1,000,000-fold variations in abundance down to the femtomolar level. The goal of this work is to expand the dynamic range of fluorescence assays by using imaging to combine molecular counting with single-molecule calibration of ensemble intensities. We evaluate optical limits imposed by surface-captured fluorescent labels, compare performances of different fluorophore classes, and use detector acquisition parameters to span wide ranges of fluorescence irradiance. We find that the fluorescent protein phycoerythrin provides uniquely suitable properties with exceptionally intense and homogeneous single-fluorophore brightness that can overcome arbitrary spot detection threshold biases. Major limitations imposed by nonspecifically bound fluorophores were then overcome using rolling circle amplification to densely label cancer-associated miRNA biomarkers, allowing accurate single-molecule detection and calibration across nearly 5 orders of magnitude of concentration with a detection limit of 29 fM. These imaging and molecular counting strategies can be widely applied to expand the limit of detection and dynamic range of a variety of surface fluorescence assays.

Purification of R-phycoerythrin from Gracilaria lemaneiformis by centrifugal precipitation chromatography.

Centrifugal precipitation chromatography (CpC) is a powerful chromatographic technique invented in the year 2000 but so far very little applied. The method combines dialysis, counter-current and salting out processes. The separation rotor consists of two identical spiral channels separated by a dialysis membrane (6-8 K MW cut-off) in which the upper channel is eluted with an ammonium sulfate gradient and the lower channel with water, and the mixtures are separated according to their solubility in ammonium sulfate as a chromatographic technique. In the present study, the method was successfully applied for separation and purification of R-phycoerythrin (R-PE), a protein widely used as a fluorescent probe, from the red alga Gracilaria lemaneiformis. The separation was performed with the elution of ammonium sulfate from 50% to 0% in 21.5 h at a flow rate of 0.5 ml/min, while the lower channel was eluted with water at a flow rate of 0.05 ml/min after sample charge, and the column was rotated at 200 rpm. After a single run, the absorbance ratio A565/A280 (a criterion for the purity of R-PE) was increased from 0.5 of the crude to 6.5. The purified R-PE exhibited a typical "three peaks" spectrum with absorbance maximum at 497, 538 and 565 nm. The Native-PAGE showed one single protein band and 20 kDa (subunits α and ß) and 30 kDa (subunit γ) can be observed in SDS-PAGE analysis which were consistent with the (αß)6γ subunit composition of R-PE. The results indicated that CpC is an efficient method to obtain protein with the high purity from a complex source.

[Caracterization of HLA allo-immunization and clinical impact in transfusion and organ transplantation]. / Caractérisation de l'allo-immunisation anti-HLA et impact clinique en transfusion et en transplantation d'organe.

Allo-immunizations against HLA antigens are known to be deleterious in transfusion and organ transplantation. The development of new tests based on solid phase assays for screening and identification of HLA antibodies in particular those using Luminex® bead based technology has completely changed the way of allo-immunization monitoring because of their extreme sensitivity. They allow a better characterization of these antibodies, identification of acceptable antigens and the use of virtual cross-matches. All these new possibilities improve the managing of patients before and after platelets transfusion or organ transplantation. However, this technology displays some limits that should be known in order to interpret correctly the results. Beside these bead based assays, cellular cross-matches based on Complement Dependent Cytotoxicity (CDC) and flow cytometry are still used and useful in organ transplantation since beads are produced in vitro and do not reflected exactly what happens physiologically. Moreover, differences of sensitivity between these methods make results interpretation and decision making difficult in some cases.

Phylogeography and pigment type diversity of Synechococcus cyanobacteria in surface waters of the northwestern pacific ocean.

The widespread unicellular cyanobacteria Synechococcus are major contributors to global marine primary production. Here, we report their abundance, phylogenetic diversity (as assessed using the RNA polymerase gamma subunit gene rpoC1) and pigment diversity (as indirectly assessed using the laterally transferred cpeBA genes, encoding phycoerythrin-I) in surface waters of the northwestern Pacific Ocean, sampled over nine distinct cruises (2008-2015). Abundance of Synechococcus was low in the subarctic ocean and South China Sea, intermediate in the western subtropical Pacific Ocean, and the highest in the Japan and East China seas. Clades I and II were by far the most abundant Synechococcus lineages, the former dominating in temperate cold waters and the latter in (sub)tropical waters. Clades III and VI were also fairly abundant in warm waters, but with a narrower distribution than clade II. One type of chromatic acclimater (3dA) largely dominated the Synechococcus communities in the subarctic ocean, while another (3dB) and/or cells with a fixed high phycourobilin to phycoerythrobilin ratio (pigment type 3c) predominated at mid and low latitudes. Altogether, our results suggest that the variety of pigment content found in most Synechococcus clades considerably extends the niches that they can colonize and therefore the whole genus habitat.

FlowCam: Quantification and Classification of Phytoplankton by Imaging Flow Cytometry.

The ability to enumerate, classify, and determine biomass of phytoplankton from environmental samples is essential for determining ecosystem function and their role in the aquatic community and microbial food web. Traditional micro-phytoplankton quantification methods using microscopic techniques require preservation and are slow, tedious and very laborious. The availability of more automated imaging microscopy platforms has revolutionized the way particles and cells are detected within their natural environment. The ability to examine cells unaltered and without preservation is key to providing more accurate cell concentration estimates and overall phytoplankton biomass. The FlowCam(®) is an imaging cytometry tool that was originally developed for use in aquatic sciences and provides a more rapid and unbiased method for enumerating and classifying phytoplankton within diverse aquatic environments.

Qualitative and quantitative determination of R-phycoerythrin from Halymenia floresia (Clemente) C. Agardh by polyacrylamide gel using electrophoretic elution technique.

R-Phycoerythrin is one of the phycobiliproteins widely found in seaweeds. In this study, we have shown to extract and purify R-Phycoerythrin from the south east cost Indian red seaweed Halymenia floresia. R-Phycoerythrin was extracted in 50mM phosphate buffer (pH 7.0). The preparative native PAGE purification was employed alternative to the chromatography and therefore can be scaled up efficiently. Both the yield and the purity of R-Phycoerythrin are very effective. The purified R-Phycoerythrin showed a single band on the examination by native PAGE electrophrosis. SDS-PAGE analysis showed five bands at 16kDa, 21kDa, 30kDa, 39kDa and 47kDa which corresponds to the α, ß and γ', γ and αß subunits. This preparative method for R-Phycoerythrin purification can offer a reference for R-Phycoerythrin purification from other marine red macro algae.

Sulphide Resistance in the Cyanobacterium Microcystis aeruginosa: a Comparative Study of Morphology and Photosynthetic Performance Between the Sulphide-Resistant Mutant and the Wild-Type Strain.

The cyanobacterium Microcystis aeruginosa is a mesophilic freshwater organism, which cannot tolerate sulphide. However, it was possible to isolate a sulphide-resistant (S(r)) mutant strain that was able to survive in a normally lethal medium sulphide. In order to evaluate the cost of the mutation conferring sulphide resistance in the S(r) strain of M. aeruginosa, the morphology and the photosynthetic performance were compared to that found in the wild-type, sulphide-sensitive (S(s)) strain. An increase in size and a disrupted morphology was observed in S(r) cells in comparison to the S(s) counterpart. Phycoerythrin and phycocyanin levels were higher in the S(r) than in the S(s) cells, whereas a higher carotenoid content, per unit volume, was found in the S(s) strain. The irradiance-saturated photosynthetic oxygen-production rate (GPR max) and the photosynthetic efficiency (measured both by oxygen production and fluorescence, α(GPR) and α(ETR)) were lower in the S(r) strain than in the wild-type. These results appear to be the result of package effect. On the other hand, the S(r) strain showed higher quantum yield of non-photochemical quenching, especially those regulated mechanisms (estimated throughout qN and Y(NPQ)) and a significantly lower slope in the maximum quantum yield of light-adapted samples (Fv'/Fm') compared to the S(s) strain. These findings point to a change in the regulation of the quenching of the transition states (qT) in the S(r) strain which may be generated by a change in the distribution of thylakoidal membranes, which somehow could protect metalloenzymes of the electron transport chain from the lethal effect of sulphide.

Geochemical Evidence of the Seasonality, Affinity and Pigmenation of Solenopora jurassica.

Solenopora jurassica is a fossil calcareous alga that functioned as an important reef-building organism during the Palaeozoic. It is of significant palaeobiological interest due to its distinctive but poorly understood pink and white banding. Though widely accepted as an alga there is still debate over its taxonomic affinity, with recent work arguing that it should be reclassified as a chaetetid sponge. The banding is thought to be seasonal, but there is no conclusive evidence for this. Other recent work has, however demonstrated the presence of a unique organic boron-containing pink/red pigment in the pink bands of S. jurassica. We present new geochemical evidence concerning the seasonality and pigmentation of S. jurassica. Seasonal growth cycles are demonstrated by X-ray radiography, which shows differences in calcite density, and by varying δ13C composition of the bands. Temperature variation in the bands is difficult to constrain accurately due to conflicting patterns arising from Mg/Ca molar ratios and δ18O data. Fluctuating chlorine levels indicate increased salinity in the white bands, when combined with the isotope data this suggests more suggestive of marine conditions during formation of the white band and a greater freshwater component (lower chlorinity) during pink band precipitation (δ18O). Increased photosynthesis is inferred within the pink bands in comparison to the white, based on δ13C. Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS) and Fourier Transform Infrared Spectroscopy (FTIR) show the presence of tetramethyl pyrrole, protein moieties and carboxylic acid groups, suggestive of the presence of the red algal pigment phycoerythrin. This is consistent with the pink colour of S. jurassica. As phycoerythrin is only known to occur in algae and cyanobacteria, and no biomarker evidence of bacteria or sponges was detected we conclude S. jurassica is most likely an alga. Pigment analysis may be a reliable classification method for fossil algae.

A rapid assay for Hendra virus IgG antibody detection and its titre estimation using magnetic nanoparticles and phycoerythrin.

Detection of Hendra viral IgG antibody in animal sera is useful for surveillance following a virus outbreak. The commonly used enzyme-linked immunosorbent assay and fluorescence-based Luminex assay typically consist of three steps and take at least several hours to complete. We have simplified the procedure to two steps in an effort to develop a rapid procedure for IgG antibody, but not IgM antibody, detection. This is achieved by conjugating the fluorescence label R-phycoerythrin directly onto the IgG binding protein Protein G. The use of magnetic nanoparticles, due to their large specific surface area, has helped reduce each of the binding steps to 20 min. As a result, the whole assay can be completed in 60 min. We also demonstrate a method to quickly estimate IgG antibody titres by assaying the sera at only two dilutions (i.e. 1:20 and 1:1000) and using the fluorescence ratio at these dilutions as an indicator of antibody titre. The results of this approach correlated well with the well-regarded serum neutralization test in virus antibody assays. This protocol reported here can be adopted in Luminex assays, fluorescence-linked immunosorbent assays and assays on microfluidics platforms for rapid antibody surveillance of Hendra and other viruses.

One-step purification of R-phycoerythrin from the red edible seaweed Grateloupia turuturu.

A one-step chromatographic method for the purification of R-phycoerythrin (R-PE) of Grateloupia turuturu Yamada is described. Native R-PE was obtained with a purity index of 2.89 and a recovery yield of 27% using DEAE-Sepharose Fast Flow chromatography with a three-step increase in ionic strength. The analysis by SDS electrophoresis showed a broad band between 18 and 21kDa in size corresponding to subunits α and ß and a low intensity band of 29kDa corresponding to the γ subunit. Two forms of R-PE were identified by gel filtration chromatography: a native form with a molecular weight of 260±5kDa and a dissociated form with a molecular weight of 60±2kDa. The native form presented the characteristic absorption spectrum of R-PE with three absorbance maxima at 498, 540 and 565nm, whereas the dissociated form presented only the 498 and 540nm peaks. Moreover, the two forms displayed two different fluorescence maxima.

Chalicogloea cavernicola gen. nov., sp. nov. (Chroococcales, Cyanobacteria), from low-light aerophytic environments: combined molecular, phenotypic and ecological criteria.

This work characterizes a unicellular cyanobacterium with nearly spherical cells and thin-outlined sheaths that divide irregularly, forming small packets immersed in a diffluent mucilaginous layer. It was isolated growing on calcite speleothems and walls in a show cave in Collbató (Barcelona, Spain). Spectral confocal laser and transmission electron microscopy were used to describe the morphology, fine structure and thylakoid arrangement. The pigments identified were phycoerythrin, phycocyanin, allophycocyanin and chlorophyll a. Three-dimensional reconstructions, generated from natural fluorescence z-stacks, revealed a large surface area of nearly flat, arm-like thylakoidal membranes connected to each other and forming a unified structure in a way that, to our knowledge, has never been described before. Phylogenetic analyses using the 16S rRNA gene sequence showed 95% similarity to strain Chroococcus sp. JJCM (GenBank accession no. AM710384). The diacritical phenotypic features do not correspond to any species currently described, and the genetic traits support the strain being classified as the first member of an independent genus in the order Chroococcales and the family Chroococcaceae. Hence, we propose the name Chalicogloea cavernicola gen. nov., sp. nov. under the provisions of the International Code of Nomenclature for Algae, Fungi and Plants. The type strain of Chalicogloea cavernicola is COLL 3(T) (=CCALA 975(T) =CCAP 1424/1(T)).

Phycoerythrin evolution and diversification of spectral phenotype in marine Synechococcus and related picocyanobacteria.

In marine Synechococcus there is evidence for the adaptive evolution of spectrally distinct forms of the major light harvesting pigment phycoerythrin (PE). Recent research has suggested that these spectral forms of PE have a different evolutionary history than the core genome. However, a lack of explicit statistical testing of alternative hypotheses or for selection on these genes has made it difficult to evaluate the evolutionary relationships between spectral forms of PE or the role horizontal gene transfer (HGT) may have had in the adaptive phenotypic evolution of the pigment system in marine Synechococcus. In this work, PE phylogenies of picocyanobacteria with known spectral phenotypes, including newly co-isolated strains of marine Synechococcus from the Gulf of Mexico, were constructed to explore the diversification of spectral phenotype and PE evolution in this group more completely. For the first time, statistical evaluation of competing evolutionary hypotheses and tests for positive selection on the PE locus in picocyanobacteria were performed. Genes for PEs associated with specific PE spectral phenotypes formed strongly supported monophyletic clades within the PE tree with positive directional selection driving evolution towards higher phycourobilin (PUB) content. The presence of the PUB-lacking phenotype in PE-containing marine picocyanobacteria from cyanobacterial lineages identified as Cyanobium is best explained by HGT into this group from marine Synechococcus. Taken together, these data provide strong examples of adaptive evolution of a single phenotypic trait in bacteria via mutation, positive directional selection and horizontal gene transfer.

Brilliant violet fluorophores: a new class of ultrabright fluorescent compounds for immunofluorescence experiments.

The Nobel Prize in Chemistry was awarded in 2000 for the discovery of conductive organic polymers, which have subsequently been adapted for applications in ultrasensitive biological detection. Here, we report the first use of this new class of fluorescent probes in a diverse range of cytometric and imaging applications. We demonstrate that these "Brilliant Violet" reporters are dramatically brighter than other UV-violet excitable dyes, and are of similar utility to phycoerythrin (PE) and allophycocyanin (APC). They are thus ideally suited for cytometric assays requiring high sensitivity, such as MHC-multimer staining or detection of intracellular antigens. Furthermore, these reporters are sensitive and spectrally distinct options for fluorescence imaging, two-photon microscopy and imaging cytometry. These ultra-bright materials provide the first new high-sensitivity fluorescence probes in over 25 years and will have a dramatic impact on the design and implementation of multicolor panels for high-sensitivity immunofluorescence assays.

A preliminary investigation of the relationship between circulating tumor cells and cancer stem cells in patients with breast cancer.

In this study, we explored the relationship between the circulating tumor cells (CTC) and the CTC-cancer stem cells (CSC) in the patients with breast cancer. The magnetic-activated cell separation (MACS) method and flow cytometry (FCM) for selection of epithelial cells from the peripheral blood mononuclear cells (PBMC) were used to analyze the enriched epithelial cells that were labeled with anti-cytokeratin(CK)-fluorescein isothiocyanate, anti-CD44-phycoerythrin (PE) and anti-CD24-PE, respectively. The CK+ cells were attributed to CTC and the CK+CD44+ CD24-/low cells were thought as to CTC-CSC in 26 breast cancer patients, respectively. Our results showed the CK+ tumor cells were detected in 19 of 26 patients, with the CK+ tumor cells varying from 0.11% to 5.42 %. The CTC-CSC were identified in 18 of the 19 patients with CTC and the percentage of CTC-CSC in CTC was 19.01%. The results yet suggested the breast cancer patients with high-rate CK+ tumor cells were at the advanced tumor node metastases (TNM) stage III, and the patients with low-rate CK+ cells were at the modest TNM stage I. The difference between the two groups was statistically significant (p<0.001). We concluded that there is a significant relationship between CTC and CTC-CSC, but not among TNM stages, in breast cancer metastasis.

Synthesis of NaYF(4):Yb/Er/Gd up-conversion luminescent nanoparticles and luminescence resonance energy transfer-based protein detection.

High-quality NaYF4:Yb/Er/Gd up-conversion nanoparticles (UCNPs) were first synthesized by a solvothermal method using rare earth stearate, sodium fluoride, ethanol, water, and oleic acid as precursors. Doped Gd³âº ions can promote the transition of NaYF4 from cubic to hexagonal phase, shorten the reaction time, and reduce the reaction temperature without reducing the luminescence intensity of NaYF4:Yb/Er UCNPs. X-ray diffraction, infrared spectroscopy, transmission electron microscopy, and luminescence spectroscopy were applied to characterize the UCNPs. The nanoparticles exhibited small size and excellent green up-conversion photoluminescence, making them suitable for biological applications. After the surfaces of NaYF4:Yb/Er/Gd UCNPs were modified with amino groups through the Stöber method, they could be brought close enough to the analytically important protein called R-phycoerythrin (R-PE) bearing multiple carboxyl groups so that energy transfer could occur. A luminescence resonance energy transfer (LRET) system was developed using NaYF4:Yb/Er/Gd UCNPs as an energy donor and R-PE as an energy acceptor. As a result, a detection limit of R-PE of 0.5 µg/ml was achieved by the LRET system with a relative standard deviation of 2.0%. Although this approach was first used successfully to detect R-PE, it can also be extended to the detection of other biological molecules.

Effect of light quality on the C-phycoerythrin production in marine cyanobacteria Pseudanabaena sp. isolated from Gujarat coast, India.

The isolated cyanobacterium containing biopigments like chlorophyll-a, phycoerythrin, phycocyanin, and carotenoid was cultured under different quality of light modes to ascertain biomass and pigment productivity. On the basis of 16S rRNA gene sequence, the isolate was identified as Pseudanabaena sp. Maximum biomass concentration obtained in white-, blue-, and green-light was 0.82, 0.94, and 0.89 g/L, respectively. It was observed that maximum phycoerythrin production was in green light (39.2 mg/L), ensued by blue light (32.2 mg/L), while phycocyanin production was maximum in red light (10.9 mg/L). In yellow light, pigment production as well as the growth rate gradually declined after 12 days. Carotenoid production decreased in blue-, white-, and red-light after 15 days, while in green light it had increased gradually. The present communication suggests that Pseudanabaena sp. can be used for commercial production of phycoerythrin when grown under green light.