China
Africa
Explore chapters and articles related to this topic
Potentials and Challenges in the Production of Microalgal Pigments with Reference to Carotenoids, Chlorophylls, and Phycobiliproteins
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
Delia B. Rodriguez-Amaya, Iriani R. Maldonade
Phycobiliproteins (phycobilins bonded to protein) are deep-colored, fluorescent proteins that can be found in microalgae, especially cyanobacteria (e.g., Spirulina (Arthrospira) platensis) and rhodophytes (e.g., Galdieria sulphuraria). Generally, they are classified into phycoerythrin (red), phycocyanin (blue), allophycocyanin (bluish green), and phycoerythrocyanin (orange).
Nutritional Composition of the Main Edible Algae
Published in Leonel Pereira, Therapeutic and Nutritional Uses of Algae, 2018
Red algae are rich in phycobiliproteins, i.e., water soluble pigments found in the cytoplasm or in the stroma of the chloroplasts, which are formed by complexes of phycobilins with co-valently bound proteins. Chemically, phycobilins are open-chain tetrapyrrole chromophores bearing A, B, C, and D rings. These chromophores link to the polypeptide chain at conserved positions, either by one cysteinyl thioester linkage through the vinyl substituent on the pyrrole ring A, or occasionally, by two cysteinyl thioester linkages through the vinyl substituent on both A and D pyrrole rings (Cai et al. 2012). The phycobilins are the main component determining the color of the phycobiliproteins. Based on their absorption properties, they can be blue (phycocyanobilin), red (phycoerythrobilin), yellow (phycourobilin), or purple (phycobiliviolin). Molecular pigments are organized in supra-molecular complexes (i.e., phycobilisomes) and they exert a fundamental role in the photosynthetic process of the red algae (Pereira 2009). Phycoerythrin (Fig. 2.5) is the most common phycobiliprotein in many red algae, with levels, on a dry weight basis, of approximately 0.2% for Polysiphonia stricta and Pyropia (as Porphyra) yezoensis, 0.5% for Palmaria palmata and Gracilaria gracilis, and 12% for G. tikvahiae (Romay et al. 2003, Wang 2002, Jespersen et al. 2005, Sekar and Chandramohan 2008, Kim et al. 2013). R-phycoerythrin, together with other phycobiliproteins, have been used for decades as natural colorants in foods (e.g., chewing gum, ice creams, soft drinks, fermented milk products, milk shakes, desserts, jellies, and coated sweet cakes, cosmetic, and pharmaceutical products) (Jespersen et al. 2005, Sekar and Chandramohan 2008). In general, the colors are very stable and tolerate high temperatures, pH changes, and light (Sekar and Chandramohan 2008). Moreover, R-phycoerythrin has specialized applications in analytical techniques, such as flow cytometry, cell sorting, and histo-chemistry (Lorbeer et al. 2013). C-phycocyanin, Rand B-phycoerythrin are currently used in the cosmetic industry for production of lipsticks, eye-liners, and other high value cosmetics (Kim et al. 2013).
Biofouling in marine aquaculture: a review of recent research and developments
Published in Biofouling, 2019
Jana Bannister, Michael Sievers, Flora Bush, Nina Bloecher
Fouling species compete with cultured seaweed species for light, space and dissolved nutrients. Studies on the cultured red algae Gracilaria chilensis (Buschmann and Gómez 1993) and Kappaphycus alvarezii (Marroig and Reis 2016) show that biofouling significantly reduces levels of solar irradiance reaching cultured stock, leading to lower photosynthetic rates and photosynthetic efficiency than unfouled stock (Borlongan et al. 2016). Interestingly, higher chlorophyll-a and phycobilin content in heavily fouled stock suggests that some seaweeds can acclimatise to low-irradiance conditions (Borlongan et al. 2016). Furthermore, opportunistic benthic algae growing on cultured seaweed and farm infrastructure, such as cultivation ropes, raceways and rafts, directly compete with cultured seaweed for substratum, space, and dissolved nutrients, such as ammonia, nitrogen and inorganic carbon (Buschmann and Gómez 1993; Fletcher 1995; Veeragurunathan et al. 2015).
Linking biofilm spatial structure to real-time microscopic oxygen decay imaging
Published in Biofouling, 2018
S. Rubol, A. Freixa, X. Sanchez-Vila, A. M. Romaní
CLSM images were analyzed for spatial distribution based on the 2-D projections along the vertical axis of the different color bands for the 10× visualization fields. Intensity values (for each channel) were measured by an ad hoc script in Matlab, the values being a continuous variable rather than a discrete one. The intensity values for each channel (chlorophyll, phycobilin, concanavaline, DNA) varying in a 0–255 scale, were converted to binary sets, after selecting a threshold light intensity, so that at each pixel the variable I(x, y), indicated the presence (I = 1) or no presence (I = 0), based on whether the actual measured light intensity at each pixel exceeded the threshold value. For all channels, the threshold value chosen was set to 10% of the maximum potential intensity (ie corresponding to an intensity value of 25). This threshold was determined by visual inspection between the resulting binary map and that of the original images with intensity color plots. The sensitivity of the threshold choice was tested in the red channel, also using a value of 50, and then comparing the results of the statistical analysis (see Tables S1–S3). Finally, the analyses performed on the green and blue channels indicated no reason to use a threshold different from 25 (again, from visual inspection of the resulting binary maps).