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Bacteria
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Mesosomes are membranous structures found inside the ctyoplasmic membrane (CM) and may arise as an extension of the CM. Mesosomes consist of subcellular particles that are mainly proteins, nucleoproteins, and lipoproteins. In addition, the cytoplasm contains soluble enzymes, nutrients, ions, and waste products that have not yet been excreted. Finally, the cytoplasm of some cells contains storage polymers such a polyphosphate granules and polyhydroxyalkanoate granules.
Biology of microbes
Published in Philip A. Geis, Cosmetic Microbiology, 2006
Cytoplasm, mesosomes, ribosomes, and other inclusions. A bacterial cell minus its wall is a protoplast. A protoplast includes the plasma membrane, the cytoplasm, and everything within it. The prokaryotic cytoplasm, however, does not have typical unit membrane-bound internal organelles. Within the cytoplasm is the nucleoid where the DNA genetic material is localized. Also, within the cytoplasm are the enzymes needed for growth and metabolism, the machinery for manufacturing those enzymes (ribosomes), and some internal membrane structures called mesosomes. Mesosomes are actually invaginations of the plasma membrane. Finally, some bacteria also contain inclusion bodies consisting of polyphosphate, cyanophycin, and glycogen. These inclusions are not usually membrane-bound. Other bacteria have inclusions bound by a single-layered nonunit membrane. These consist of poly-b-hydroxybutyrate, sulfur, carboxysomes, hydrocarbons, and gas vacuoles.
Bioengineering of Inorganic Nanoparticle Using Plant Materials to Fight Extensively Drug-Resistant Tuberculosis
Published in Richard L. K. Glover, Daniel Nyanganyura, Rofhiwa Bridget Mulaudzi, Maluta Steven Mufamadi, Green Synthesis in Nanomedicine and Human Health, 2021
Mpho Phehello Ngoepe, Maluta Steven Mufamadi
This is prevalent in cases where microbes are exposed to the drug but are not eradicated either by the microbicidal effects of the drug itself or by the microbiostatic effects (inhibit but do not kill microbes) of the drug, where the host immune system plays a key role in killing the microbes (Teixeira et al., 2018). As a result of these acquisitions of antimicrobial resistance, nanoparticles have been proposed as alternative antibiotics because they are capable of overcoming existing antibiotic resistance mechanisms by various means, such as disruption of bacterial membranes and inhibition of biofilm formation (Wang et al., 2017). The mechanism of antimicrobial action of metal oxide nanoparticles is due to (a) electrostatic interaction between the particle and the microbe cell surface causing cell membrane damage; while cell uptake leads to (b) leakage of the proton due to disruption of the chemiosmosis process (dissipation of the proton motive force); (c) damage of organic biomolecules (carbohydrates, lipids, proteins and nucleic acids) due to the generation of reactive oxygen species (ROS) having a microbicidal effect; (d) altering cellular respiration, cell division and DNA replication due to mesosome binding; (e) inhibition of signal transduction and bacterial growth by dephosphorylation of the phosphotyrosine residue and (f) degradation of protein due to protein carbonylation leading to loss of catalytic activity of the enzyme (Fig 7.1) (Mahira et al., 2019).Antimicrobial mechanism of NPs and their ions.
Usnic acid and its derivatives for pharmaceutical use: a patent review (2000–2017)
Published in Expert Opinion on Therapeutic Patents, 2018
Olga A. Luzina, Nariman F. Salakhutdinov
Thus, the evidence indicates potential antimicrobial, anti-inflammatory, analgesic, antioxidant, antiprotozoal, antiviral, larvicidal, and other activities of UA. Two concise but extensive reviews were published almost simultaneously in 2002 [14,15], outlining what was known of the biological potential of UA. During the same period, however, some studies reported liver toxicity [16]. The wide use of UA in food supplements caused several cases of intoxication, and studies were focused on its toxicity. In 2008, Guo et al. published a detailed review of this problem [17]. Studies of toxicity have revealed that UA is toxic in vitro at low micromolar concentrations. Treatment with 5 µM UA for 16 h in mouse primary hepatocytes resulted in 98% cell death [18]. Similar mechanisms mediate the cytotoxic and antibacterial effects. They involve the uncoupling of the oxidative phosphorylation chain by distorting the membrane potential in eukaryotic mitochondria and in Gram-positive bacteria, which have no mitochondria but have mesosomes that perform similar functions. Usnic acid toxicity is provided by the ‘triketone’ moiety of the molecule, which is responsible for the loss of mitochondrial potential. Owing to the acidity of the fragment, the molecule can diffuse through mitochondrial membranes and cause proton leak. The lipophilicity of UA and the usnate anion allows them to permeate the mitochondrial membrane by passive diffusion. Recent investigation of UA toxicity mechanism showed that UA caused cell cycle dysregulation, DNA damage, and oxidative stress and that the Nrf2 signaling pathway was activated in UA-induced cytotoxicity [19].