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Microalgae for Pigments and Cosmetics
Published in Sanjeet Mehariya, Shashi Kant Bhatia, Obulisamy Parthiba Karthikeyan, Algal Biorefineries and the Circular Bioeconomy, 2022
Nídia S. Caetano, Priscila S. Corrêa, Wilson G. de Morais Júnior, Gisela M. Oliveira, António A.A. Martins, Teresa M. Mata, Monique Branco-Vieira
Chlorophylls are an extraordinary group of green pigments that exist in every microalgae, cyanobacteria, and plants as well (Masuda and Fujita, 2008; Rubio et al., 2003). They are the most abundant and valuable natural pigment, essential for the microalgae life cycle that absorbs and converts solar/light energy into chemical energy through photosynthesis for the functioning of its metabolism and reproduction (Li et al., 2015). Chlorophylls are complex molecules based on tetrapyrroles organized in cycles around a central magnesium atom that is bonded to the four nitrogen atoms of the pyrroles (Fujita et al., 2015). According to variations of the tetrapyrrole structure of the molecule, chlorophylls are identified by letters a, b, c, d, e, and f (Barkia et al., 2019; Li et al., 2012). Other types of chlorophyll that differ in the molecular structure, altering the form of light absorption, have been identified in other microorganisms: Protochlorophyll and Bacteriochlorophyll a, b, c, d, e, and g (Silva and Lombardi, 2020).
Engineering Strategies for Enhancing Photofermentative Biohydrogen Production by Purple Nonsulfur Bacteria Using Dark Fermentation Effluents
Published in Farshad Darvishi Harzevili, Serge Hiligsmann, Microbial Fuels, 2017
Anish Ghimire, Giovanni Esposito, Vincenzo Luongo, Francesco Pirozzi, Luigi Frunzo, Piet N.L. Lens
Bacterial photosynthesis can be divided into two types depending on the presence or absence of oxygen for the metabolism of bacteriochlorophyll, a bacterial photosynthetic pigment. Oxygenic photosynthesis is carried out by cyanobacteria and prochlorophytes, whereas anoxygenic photosynthesis can be generally mediated by purple bacteria, green sulfur bacteria, heliobacteria, and others (Kim and Gadd 2008). Photosynthetic anoxygenic bacteria are a very diverse group of bacteria that carry out bacteriochlorophyll-dependent photosynthesis as a metabolic process (McEwan 1994). The anoxygenic phototrophic bacteria can be broadly grouped into different classes (Figure 8.1), based on their photosynthetic pigments and electron donors (Kim and Gadd 2008; McEwan 1994). Depending on the electron donors used, purple bacteria can be further divided into purple sulfur bacteria (use sulfur compounds as electron donors) and nonsulfur bacteria (use organic substances as electron donors).
Fundamentals of Photosynthetic Microbial Fuel Cell
Published in Lakhveer Singh, Durga Madhab Mahapatra, Waste to Sustainable Energy, 2019
Photosynthetic organisms use pigments, such as chlorophyll and bacteriochlorophyll (Bchl) molecules to harness light from sun as energy source and organic/inorganic carbon material as electron source to lead reaction center of the photosystem. Solar radiations were absorbed by the pigment and channeled to the reaction center. They get promoted from basal state and triggers chain photochemical reactions, provoking a separation of negative and positive charge across the membrane. In anoxygenic photosynthetic bacteria, the Bchl-a shows the energy efficiency of 95 to 99% accessory pigments linked to the reaction center (RC). RC-LH complex has the capability to transform light energy to proton motive force with the role of quinone pool and second membrane-attached e- transporter protein (cytochrome (cyt) bc1 complex) (Chandra et al. 2017). At first, the excited e- from the Bchl-a goes to quinone, followed by cytochrome-complex before exiting across microbial membrane. In this kind of photochemical reactions sunlight offers energy and acetate (organic residue) as the e-. The negative Gibbs free energy of the photo electrochemical reaction and positive emf involves that electrical current can be generated by using organic carbon as the substrate. Separation of charge initiate a series of e- transfer, which are joined to the translocation of protons through the membrane and establish an electrochemical proton gradient that leads to a development of bio potential, and finally to electro-genesis. On the other hand, oxygenic photosynthesis needs the joining of three membrane protein complexes (PSI, PSII, and cytochrome bf complex) working in sequence for the electron transfer from H2O to NADP+ to produce O2 (Venkata Subhash et al. 2013). Plastoquinone and plastocyanin, which are small movable substances, transport electrons between those protein complexes. These small molecules transport electrons above relatively long distances and play a sole role in photosynthetic energy conversion.
Have photosynthetic pigments been formulated for chemical stability? A cursory insight into the reactivity of magnesium porphyrinoids
Published in Journal of Coordination Chemistry, 2018
Łukasz Orzeł, Dorota Rutkowska-Zbik, Mateusz Świrski, Grażyna Stochel
Although the necessity to reduce the pyrrole rings in MgPPIX is obvious from the point of view of the optimization of photosynthetic activity, its effect on some secondary properties of Mg complexes is still not fully recognized. The issue of changing the stability of Mg porphyrinoids on the biosynthetic pathway seems to be of particular interest. Therefore, we undertook experimental and theoretical studies to test the response of three biologically relevant porphyrinoids: magnesium protoporphyrin IX (MgPPIX), chlorophyll a (Chla), and bacteriochlorophyll a (BChla), to factors destabilizing the binding of Mg(II) ion. In this way, we attempted to reveal the effect of the π-electron system on factors capable of causing loss of photosynthetic ability.
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).