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Introduction to cyanobacteria
Published in Ingrid Chorus, Martin Welker, Toxic Cyanobacteria in Water, 2021
Leticia Vidal, Andreas Ballot, Sandra M. F. O. Azevedo, Judit Padisák, Martin Welker
A key characteristic distinguishing cyanobacteria from other bacteria is that they possess chlorophyll-a like plant chloroplasts, their major photosynthetic pigment and a variety of carotenoids, the latter acting primarily as photoprotectants to reduce oxidative damage to chlorophyll-a. In addition, cyanobacteria possess specific accessory pigments, the phycobilins (Tandeau de Marsac, 2003). These pigments are bound to water-soluble proteins, the phycobiliproteins, and occur in variants with different optical properties. Phycocyanin is common for all cyanobacteria and appears blue, giving a blue-green colour to many cyanobacteria, hence the classic name “blue-green algae”. The blueish colour is especially prominent when cyanobacterial cells have lysed and dissolved phycocyanin stains the water blue. Phycoerythrin appears red and is responsible for the reddish or brownish colour of many cyanobacteria, such as Planktothrix rubescens. Within the cells, phycocyanins and phycoerythrins absorb certain wavelengths of photosynthetically active radiation (PAR) and transfer the light energy to chlorophyll-a in photosystem II, thus extending the wavelength range of light available for photosynthesis (Berman-Frank et al., 2003). In some species, phycobilins are also present in the antenna of photosystem I where they are thought to serve the energy demand of nitrogen fixation (Watanabe et al., 2014).
Extraction of natural pigments from marine macroalgae waste
Published in Cândida Vilarinho, Fernando Castro, Margarida Gonçalves, Ana Luísa Fernando, Wastes: Solutions, Treatments and Opportunities III, 2019
S.L. Pardilhó, M.F. Almeida, J.M. Dias, S. Machado, S.M.F. Bessada, M.B.P.P. Oliveira
In the last years, MM have been considered as an important source of bioactive natural compounds, being highlighted the production of bioplastics, biostimulants, biofuels and pigments (Haryatfrehni et al., 2015, Pangestuti and Kim, 2011). Their richness in Natural Pigments (NPs) and the need to replace the synthetic pigments makes the extraction of NPs promising. There are three classes of NPs in MM, namely chlorophylls (Chls), carotenoids and phycobilins (Haryatfrehni et al., 2015, Pangestuti and Kim, 2011). Chl is the major pigment in most of photosynthetic organisms, and there are four kinds (Chl a, Chl b, Chl c, Chl d) in MM, with predominance of Chl a (Haryatfrehni et al., 2015). Carotenoids are considered accessory pigments, and they can be divided into carotenes and xanthophylls (Haryatfrehni et al., 2015). Fucoxanthin, a brown pigment especially present in brown algae, is one of the most abundant carotenoid (Pangestuti and Kim, 2011). Phycobilin is usually found in red algae and it has a more unstable structure, which can be easily damaged by light, heat or chemicals (Haryatfrehni et al., 2015). In short, in red MM (Rhodophyta) the dominant pigments are Chl a and phycobilin, green MM (Chlorophyta) is known to contain Chl a and Chl c and brown MM (Ochrophyta-Phaeophyceae) has fucoxanthin (Fucox) and Chl c (Haryatfrehni et al., 2015).
Fucoxanthin
Published in M. Jerold, V. Sivasubramanian, Biochemical and Environmental Bioprocessing, 2019
Algae contain a wide variety of pigments that absorb light for photosynthesis. Seven different types of chlorophylls are reported in algae. They are Chl a (present in all groups of algae), Chl b (found in green algae), Chl c (seen in brown algae and diatoms), Chl d (present in red algae and cyanobacterium (Miyashita et al., 1996)), and Chl f (present in cyanobacterium (Chen et al., 2012)). Carotenoid is also a fat-soluble yellow pigment which is present in almost all algal groups. They are found in close association with chlorophyll and protect chlorophyll from photo damage by passing absorbed energy to chlorophyll. Chlorophyll molecules are used in pharmacies as a photosensitizer for cancer therapy (Mishra et al., 2011). Carotenoids are also called accessory pigments. Fucoxanthin is a brown pigment which gives color to brown algae as well as diatoms. Phycobilins are water-soluble pigments which are found in the cytoplasm or in the stroma of the chloroplast. Phycocyanin is responsible for the bluish color of cyanobacteria and phycoerythrin for the red color of red algae. Major pigments in the class Phaeophyceae are β carotene, zeatin, violaxanthin, fucoxanthin, chlorophyll a, and chlorophyll c (Takaichi, 2011). Algal pigments have great commercial value as natural colorants in nutraceutical, cosmetics, and pharmaceutical industry, besides their health benefits (Prasanna et al., 2007).
Phytochemicals, chlorophyll pigments, antioxidant activity, relative expansion ratio, and microstructure of dried okra pods: swell-drying by instant controlled pressure drop versus conventional shade drying
Published in Drying Technology, 2021
Sabah Mounir, Atef Ghandour, Carmen Téllez-Pérez, Ahmed A. Aly, Arun S. Mujumdar, Karim Allaf
Figure 3 shows that the processing parameters of DIC-texturing (P, t) had an insignificant impact on carotenoids of SD okra pods; although a negative correlation (-0.51) was observed between saturated steam pressure of DIC-texturing and carotenoids (Table 3). The carotenoids of SD okra pods ranged from 1.47 to 2.26 mg/ml depending on the conditions of DIC-texturing against 2.17 mg/ml for SHD okra pods. The highest carotenoids content (2.26 mg/ml) was found in SD okra pods textured at 0.3 MPa for 43 s followed by the samples textured at 0.4 MPa for 50 s which were close to SHD okra pods (2.15 mg/ml) (Table 2). The increase of carotenoids in SD okra pods textured under conditions of 0.3 MPa for 43 s may be due to the liberation of bound phytochemicals in okra pods matrix as a result of breaking down their cell walls. While, the high saturated steam pressure (high temperature) of DIC-texturing degrades these compounds; the negative correlation between the saturated steam pressure and carotenoids content of SD okra pods confirms this hypothesis. Phenolic compounds such as carotenoids are accessory pigments that help chlorophyll-a to capture light energy during photosynthesis. So, it is worth mentioning a positive correlation (0.61) between carotenoids content and chlorophyll-a which also correlated with TPC (0.58) and TFC (0.82) (Table 3). The higher the TPC, TFC, and carotenoids, the higher the chlorophyll-a content of SD okra pods.
Iron plaque formation in the roots of Pistia stratiotes L.: importance in phytoremediation of cadmium
Published in International Journal of Phytoremediation, 2019
Kambam Tamna Singha, Abin Sebastian, Majeti Narasimha Vara Prasad
Photosynthetic pigments considered as a biomarker of Cd toxicity (Ferhad et al. 2015). The decrease in chlorophyll during Cd treatment occurred due to oxidative stress (Guo et al. 2016). It was noticed that more chlorophyll and carotenoid present in the leaves of the plaque formed plants (Figure 6a–d). The increase in chlorophyll a and b was in the rage of 10.0%–100.0% (Figure 6a,b). Chlorophyll a is part of the reaction center of the photosystems, and therefore this pigment is critical for the harvest of light energy (Fromme and Grotjohann 2008). Therefore, it is predicted that plants with Fe plaque had better photosynthetic light harvest efficiency under Cd stress. Chlorophyll b and carotenoids are known as accessory pigments that help in the channeling of light energy to reaction center with the dissipation of excess light energy. The increase in carotenoid content was in the range of 14.0%–58.0% among the Fe plaque formed plants during Cd treatments (Figure 6d). More light harvest resulted in an increase of accessory pigments in plants (Trees et al. 2000). Therefore, the increase in accessory pigments observed in the study considered as a response to increase in light harvest due to more chlorophyll among plaque-induced plants. Total chlorophyll content in the plant was used as an indicator of Fe nutrition status of the plants (Terry and Low 1982; Rafael et al. 2013). Therefore, the higher total chlorophyll content among plaque formed plants indicates that Cd-induced Fe deficiency did not occur in plants with plaque (Figure 6c). This finding also confirmed with more Fe accumulation observed in the leaves of plaque formed plants (Figure 4b).
Green hydrogen production by Rhodobacter sphaeroides
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Dahbia Akroum-Amrouche, Hamza Akroum, Hakim Lounici
Carotenoids have three main functions, the participation in antenna-level light collection in the 400-550nm spectral region, complementary to that of bacteriochlorophyll that effectively absorbs infrared radiation, The protection of the photosynthetic apparatus of reactive entities generated by photo-oxidation and the coloration of the bacteria and their absorption spectrum is not only related to bacteriochlorophylls, but also accessory pigments such as carotenoids contribute significantly (Ma, Guo, and Yang 2012).