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Depyrogenation by Inactivation and Removal
Published in James Agalloco, Phil DeSantis, Anthony Grilli, Anthony Pavell, Handbook of Validation in Pharmaceutical Processes, 2021
Karen Zink McCullough, Allen Burgenson
LPS is an amphipathic molecule, meaning that it has a hydro-phobic portion, Lipid A, that is embedded in the cell membrane, and a hydrophilic portion, called the oligosaccharide or O-antigen, that is exposed to the organism’s external environment (Silhavy et al., 2010). The molecule is comprised of three distinct regions: The O antigen that confers immunological specificity on the organism, the inner/outer core oligosaccharides, and the Lipid-A moiety, which is the biologically active portion of the molecule. Lipid A is a diphosphorylated di-glucosamine that may contain from four to seven acylations of varying length depending on the genus, species, and growth conditions of the microorganism (Ribi et al., 1962; Raetz, 1990; Trent et al., 2006). For example, the Lipid A from the gram-negative bacterium Escherichia coli has six acyl chains, each 12–14 carbons long, and is a powerful pyrogen (Figure 17.2). However, E. coli, the organism from which the calibration standard is derived, is an enteric microorganism that is prevalent in livestock pens but not in pharmaceutical manufacturing facilities.
Characterization of Microorganisms by Pyrolysis-GC, Pyrolysis-GC/MS, and Pyrolysis-MS
Published in Karen D. Sam, Thomas P. Wampler, Analytical Pyrolysis Handbook, 2021
Stephen L. Morgan, Bruce E. Watt, Randolph C. Galipo
Gram-negative cell envelopes usually have a thin PG layer (Figure 9.1B). PG is attached to the outer membrane by lipoprotein containing phospholipids and other hydrophobic substances. A variety of phospholipids and proteins are found on the inner side of the outer membrane; some of these (porins) spanning the outer membrane. The external surface of the outer membrane of Gram-negative bacteria contains its primary endotoxin, a unique lipopolysaccharide (LPS) consisting of an outer O-antigen, a middle core, and an inner lipid A region [27]. The lipid A region contains a glucosamine disaccharide with covalently bound 2- and 3-hydroxy fatty acids. Glucosamine is common, but 3-hydroxy and 2-hydroxy fatty acids are unusual. Although the fatty acid composition of LPS varies among Gram-negative bacteria, -hydroxymyristic acid is a chemical marker for LPS.
Cyanobacterial toxins
Published in Ingrid Chorus, Martin Welker, Toxic Cyanobacteria in Water, 2021
In particular, LPS is known to bind to one type of so-called toll-like receptors, namely, TLR4 (Bryant et al., 2010), triggering a cascade of cellular reactions that involve the regulation of the expression of a large number of genes (Akira & Takeda, 2004). In healthy individuals, the recognition of LPS by TLR4 triggers innate and adaptive immune responses as part of the normal defence against invasive microbes (Takeda et al., 2003), and only a massive reaction in response to LPS in the bloodstream leads to a critical health status. The strength of the binding of LPS to TLR4 is dependent on the structure of lipid A, explaining varying strength of reactions in patients but also in bioassays. The cascading host response to LPS rather than the toxic properties of LPS itself therefore accounts for the potentially lethal consequences (Opal, 2010). For this reason, LPS (or endotoxin) has been discussed to be classified rather as an (exogenous) hormone than as a toxin in a strict sense (Marshall, 2005). Arguably, LPS is not a secondary metabolite like the known cyanotoxins but a highly variable fraction of a cellular constituent rather than a defined structure.
Plant responses to per- and polyfluoroalkyl substances (PFAS): a molecular perspective
Published in International Journal of Phytoremediation, 2023
Ayesha Karamat, Rouzbeh Tehrani, Gregory D. Foster, Benoit Van Aken
In their study focusing on the metabolome of lettuce plants exposed to PFOA and PFOS, Li et al. (2020a, 2020b) reported an alteration of the lipid composition and the fatty acid metabolism. They proposed that the observed reduction of linoleic acid was indicative of PFAS-induced membrane modification to improve stress adaptability and ROS removal. Studying the effects of PFOA and PFOS on lettuce roots, Li et al. (2020b) reported a decrease in linolenic acid derivatives (17-hydroxylinolenic acid) which they interpreted as a repair mechanism of damaged membranes. Alteration of the fatty acid metabolism was also observed at the transcriptomic level, as it was reported by Li et al. (2020c) in their study of aquatic plants exposed to PFOS in a constructed wetland.
Impact of color of light and nitrogen concentration on Pavlova sp. biomass, cells size and biochemical composition
Published in Biofuels, 2022
H. El bakraoui, M. Slaoui, D. Hmouni, F. El aamri
The influence of N-limitation on the lipid content and fatty acid profiles in different lipid classes of Phaeodactylum tricornutum, Isochrysis aff. galbana clone T-Iso, Rhodomonas baltica, and Nannochloropsis oceanica showed that in response to severe nitrogen deficiency, all four species accumulated lipids mostly in the form of TAG [44]. The genera of Pavlova has the ability to produce large amounts of eicosapentaenoic and docosahexaenoic acids and it has been proved that Pavlova lutheri accumulated lipid in the form of SFA and MUFA under nitrate limitation [42, 45]. As a reason, our next study will focus on the cultivation of Pavlova sp. under various restrictive circumstances to determine how this species accumulates lipids and carbohydrates.
Effect of harvesting time in the methane production on the anaerobic digestion of microalgae
Published in Environmental Technology, 2022
Fernando G. Fermoso, Catalina Hidalgo, Angeles Trujillo-Reyes, Juan Cubero-Cardoso, Antonio Serrano
Biorefinery based on microalgae cultures has gained a lot of attention in the last years due to the possibility of obtaining interesting compounds, such as amino acids, fine chemicals, or pigments, as well as the generation of fuels such as biogas, biodiesel, or biohydrogen [1, 2]. The yield of these microalgae-based biorefineries is related to the composition of the microalgae cells, which depends on the stimulus received from surroundings such as carbon dioxide, water, nutrients deficit, light intensity, pH, and temperature [3, 4]. For example, lipid content, fatty acid, and lipid class compositions of microalgae are strongly influenced by the culture age [5], light intensity, and photoperiod [6]. Other compounds such as photosynthetic pigments, proteins, and carbohydrates have been reported to be also influenced by light [7].