Lipid A is considered as the hydrophobic lipid moiety of the LPS molecule. Lipid A is basically phosphorylated glucosamine disaccharide with many fatty acids attached to it. This portion of the LPS is responsible for its endotoxic activity (Rietschel et al., 1982). Lipid A is the agent capable of inducing various endotoxic reactions such as fever, Shwartzman reaction, activation of immune cells, lethal toxicity etc (Galanos et al 1985; Rietschel et al, 1987). Lipid A is embedded in the lipid bilayer of outer membrane and is necessary for a functional membrane barrier function (Wyckoff et al., 1998). Lipid A generally consists of bisphosphorylated β-(1 6) - linked glucosamine disaccharide substituted with fatty acids ester linked at positions 3 and 3׀ and amide linked at positions 2 and 2’ (Zahringer et.al 199). Lipid A adopts an ordered hexagonal arrangement resulting in a more rigid structure compared with the rest of the molecule (Petsch and Anspach., 2000). Bacteria lacking lipid A are not known (Perola et al., 2007). LPS containing a lipid A and Kdo, a unique sugar along with ...
Because B. pertussis is a gram-negative bacteria, it possesses the endotoxin lipopolysaccharide (LPS). However, its LPS is different from that of the other gram-negative bacteria, in that it is heterogeneous with an alternative form of the Lipid A, called Lipid X. Although not fully understood at the time, it seems that Lipid X has a greater capacity for virulence.
plasma membranes, meaning animals and plants contain lipids. In this paper I will display and
Trabelsi, H., Dendana, F., Sellami, A., Sellami, H., Cheikhrouhou, F., Neji, S., … Ayadi, A. (2012). Pathogenic
Pasteurella multocida is a zoonotic bacterium that infects a range of hosts such as livestock, poultry, domestic pets, and even humans. (1,2) The bacterium is a small, nonmotile, bipolar staining, gram-negative coccobacillus. (2) Classifications of these microorganisms are based on the bacteria capsule type and lipopolysaccharide antigens. Pasteurella multocida have five distinct carbohydrate polymer capsular types which are A, B, D, E, and F. (3) The lipopolysaccharide antigens classifies Pasteurella multocida into 16 Heddleston serovars that produce different lipopolysaccharide structures that help protects the bacteria from host immune response. (3)
Ever since the discovery of antibiotics in the 1920’s, treating bacterial infections in humans, and animals alike, has emerged as a revolutionary possibility. Antibiotics are drugs that are naturally produced by bacteria or fungus to defend against other bacteria via death or inhibiting reproduction (1). Since their detection, antibiotics have been diversified into many different forms and classes which are arranged by mode of action. Glycopeptides are a class of antibiotics which are composed of glycolsylated cyclic or polycyclic nonribosomal peptides that inhibit cell wall synthesis in susceptible bacteria (2). However, it was soon discovered that the use of these antibiotic drugs would lead to antibiotic resistance. This paper will discuss the history, function, and resistance associated with vancomycin, a glycopeptide antibiotic.
The purpose of this investigation was to identify an unknown bacterium. “At any time there are millions of bacteria living around, on, or inside us” (The Plague). Bacterium can’t be identified by merely looking at it. Many bacteria have the similar appearances in growth. “In most cases, detection is based on the reaction of an enzyme with a certain substrate” (Sigma-Aldrich). Identification is usually based on the results of the bacterium’s cells metabolic capacities.
L. pneumophila belongs to the genus Legionella. This genus also causes Pontiac Fever, a milder illness resembling the flu. Infections by Legionella bacterium, separately or together, is sometimes called legionellosis. L. pneumophila is a ubiquitous organism which thrives in warm, moist places – including water pipes. It is thin, pleomorphic, flagellated and Gram-negative. It is the primary human pathogen of its genus. It does not have endospores or a capsule and morphologically it is a rod-like bacteria. Although, it is considered Gram-negative, it stains poorly because of its lipopolysaccharide outer layer of the outer cell membrane. It is non-acid-fast, aerobic and non-fermentative. It is not pigmented but it is oxidase and catalase positive. Its optimum temperature is around 35 degrees Celsius or 95 degrees Fairinheight and it is capable of surviving temperature ran...
Mycobacterium is a bacillus –a rod shaped, cord forming, bacteria. The reason the organism creates problems for its host is due to the fact that its cell wall contains large wax like lipids called mycolic acids. Mycolic acids are strong hydrophobic molecules that form a lipid...
Being a gram-negative bacterium, L. pneumophila has lipopolysaccharides (LPS) that act as endotoxin within a human host. The presence of a flagella is thought to mediate adherence to human lung cells, thereby causing infection, since flagella-less strains do not cause disease. Once attached to human cells, the organism is engulfed by a macrophage where is utilizes the internal environment to multiply.
Yuksel M, Okajima K, Uchiba M, Horiuchi S, Okabe H: Activated protein C inhibits lipopolysaccharide-
Differentiating between fatty acids can be in two main ways: the length of free fatty acid chains and the fatty acids degree of saturation. The number of carbon atoms determine the length of fatty acid chains which often categorized as short chain fatty acids (SCFA), Medium-chain fatty acids (MCFA), Long-chain fatty acids (LCFA), and Very long chain fatty acids (VLCFA) with aliphatic tails longer than 22 carbons, while the number of double bonds between carbon atoms determine their degree of saturation. Fats can be categorized into saturated fats and unsaturated fats. Furthermore, the unsaturated fats divide into monounsaturated fats and polyunsaturated fats. Fatty acid can be saturated if there are no double bonds
Talaro , K., & Chess, B. (2012). Foundations in microbiology. (8th ed., pp. 563-564). New York, NY:
The cell plasma membrane, a bilayer structure composed mainly of phospholipids, is characterized by its fluidity. Membrane fluidity, as well as being affected by lipid and protein composition and temperature (Purdy et al. 2005), is regulated by its cholesterol concentration (Harby 2001, McLaurin 2002). Cholesterol is a special type of lipid, known as a steroid, formed by a polar OH headgroup and a single hydrocarbon tail (Wikipedia 2005, Diwan 2005). Like its fellow membrane lipids, cholesterol arranges itself in the same direction; its polar head is lined up with the polar headgroups of the phospholipid molecules (Spurger 2002). The stiffening and decreasing permeability of the bilayer that results from including cholesterol occurs due to its placement; the short, rigid molecules fit neatly into the gaps between phospholipids left due to the bends in their hydrocarbon tails (Alberts et al. 2004). Increased fluidity of the bilayer is a result of these bends or kinks affecting how closely the phospholipids can pack together (Alberts et al. 2004). Consequently, adding cholesterol molecules into the gaps between them disrupts the close packing of the phospholipids, resulting in the decreased membrane fluidity (Yehuda et al. 2002).
T. pallidum is highly sensitive to oxygen and has a decreased ability to survive when not in human body temperature environments 1. The mode of transmission is through sexual contact or vertical transmission from the mother to the fetus. T. pallidum lacks the lipopolysaccharide which is the endotoxin normally present in gram negative bacteria1. The bacterium does produce many lipoproteins which are thought to prompt the inflammatory mediators through the recognition of toll-like receptors1. T. pallidum has a virulence factor of being highly motile due to its ability to propel itself forward by rotating on a longitudinal axis1. The spirochetes easily penetrate the skin or mucosal membranes and spread throughout the lymph nodes and then the blood circulation, affecting many parts in the body1.
Membranes play an integral function in trapping and securing metabolic products within the borders of a cell within an aqueous environment. Without a selectively permeable border surrounding sites of anabolic function, potential useful products of this metabolism would simply diffuse away in the aqueous environment contained within and surrounding the cell. However, securing metabolites within the cell also comes with a price of not being able to acquire potentially useful compounds from the surrounding environment. Some very small gases and polar uncharged compounds are able to simply diffuse across this membrane, moving to the site of lower concentration on either side of the membrane. However, larger uncharged and charged polar molecules,