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Nisin
Nisin is a polycyclic antibacterial peptide produced by the bacterium ''Lactococcus lactis'' that is used as a food preservative. It has 34 amino acid residues, including the uncommon amino acids lanthionine (Lan), methyllanthionine (MeLan), didehydroalanine (Dha), and didehydroaminobutyric acid (Dhb). These unusual amino acids are introduced by posttranslational modification of the precursor peptide. In these reactions a ribosome, ribosomally synthesized 57-mer is converted to the final peptide. The unsaturated amino acids originate from serine and threonine, and the enzyme-catalysed addition of cysteine residues to the didehydro amino acids result in the multiple (5) thioether bridges. Subtilin and epidermin are related to nisin. All are members of a class of molecules known as lantibiotics. In the food industry, nisin is obtained from the culturing of ''L. lactis'' on natural substrates, such as dextrose, and it is not chemically synthesized. It was originally isolated in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactic Acid Bacteria
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bacteria, usually found in decomposing plants and milk products, produce lactic acid as the major metabolic end product of carbohydrate fermentation, giving them the common name lactic acid bacteria (LAB). Production of lactic acid has linked LAB with food fermentations, as acidification inhibits the growth of spoilage agents. Proteinaceous bacteriocins are produced by several LAB strains and provide an additional hurdle for spoilage and pathogenic microorganisms. Furthermore, lactic acid and other metabolic products contribute to the organoleptic and textural profile of a food item. The industrial importance of the LAB is further evidenced by their generally recognized as safe (GRAS) status, due to their ubiquitous appearance in food and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lantibiotics
Lantibiotics are a class of polycyclic peptide antibiotics that contain the characteristic thioether amino acids lanthionine or methyllanthionine, as well as the Saturated and unsaturated compounds, unsaturated amino acids dehydroalanine, and 2-Aminoisobutyric acid, 2-aminoisobutyric acid. They belong to Ribosomally synthesized and post-translationally modified peptides#Lanthipeptides, ribosomally synthesized and post-translationally modified peptides. Lanthionine is composed of two alanine residues that are crosslinked on their β-carbon atoms by a thioether (monosulfide) linkage. Lantibiotics are produced by a large number of Gram-positive bacteria such as ''Streptococcus'' and ''Streptomyces'' to attack other Gram-positive bacteria, and as such, they are considered a member of the bacteriocins. Bacteriocins are classified according to their extent of posttranslational modification. The lantibiotics are a class of more extensively modified bacteriocins, also called Class I bac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Didehydroalanine
Dehydroalanine (Cα,β-didehydroalanine, α,β-di-dehydroalanine, 2-aminoacrylate, or 2,3-didehydroalanine) is a dehydroamino acid. It does not exist in its free form, but it occurs naturally as a residue found in peptides of microbial origin. As an amino acid residue, it is unusual because it has an unsaturated backbone. Structure and reactivity Like most primary enamines, dehydroalanine is unstable. Dehydroalanine hydrolyzes to pyruvate. ''N''-Acylated derivatives of dehydroalanine, such as peptides and related compounds, are stable. For example, methyl 2-acetamidoacrylate is the N-acetylated derivative of the ester. As a residue in a peptide, it is generated by a post translational modification. The required precursors are serine or cysteine residues, which undergo enzyme-mediated loss of water and hydrogen sulfide, respectively. Most amino acid residues are unreactive toward nucleophiles, but those containing dehydroalanine or some other dehydroamino acids are exception ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peptide
Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. Peptides fall under the broad chemical classes of biological polymers and oligomers, alongside nucleic acids, oligosaccharides, polysaccharides, and others. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies. Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each amide bond.. All peptides except cyclic peptides have an N-terminal (amine group) and C-terminal (carboxyl g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salmonella Enterica
''Salmonella enterica'' (formerly ''Salmonella choleraesuis'') is a rod-shaped, flagellate, facultative anaerobic, Gram-negative bacterium and a species of the genus ''Salmonella''. It is divided into six subspecies, arizonae (IIIa), diarizonae (IIIb), houtenae (IV), salamae (II), indica (VI), and enterica (I). A number of its serovars are serious human pathogens; many of them are (more specifically) serovars of ''Salmonella enterica'' subsp. ''enterica''. Epidemiology Most cases of salmonellosis are caused by food infected with ''S. enterica'', which often infects cattle and poultry, though other animals such as domestic cats and hamsters have also been shown to be sources of infection in humans. It primarily resides in the intestinal tract of animals and humans and can be found in feedstuff, soil, bedding, litter, and fecal matter. The primary reservoir for the pathogen is poultry and 70% of human cases are attributed to the consumption of contaminated eggs, chicken, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EDTA
Ethylenediaminetetraacetic acid (EDTA), also called EDTA acid, is an aminopolycarboxylic acid with the formula . This white, slightly water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes even at neutral pH. It is thus used to dissolve Fe- and Ca-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA, but these all function similarly. Uses EDTA is widely used in industry. It also has applications in food preservation, medicine, cosmetics, water softening, in laboratories, and other fields. Industrial EDTA is mainly used to sequester (bind or confine) metal ions in aqueous solution. In the textile industry, it prevents metal ion impurities from modifying colours of dyed products. In the pulp and paper industry, EDTA inhibits the ability of metal ions, especiall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gram-negative
Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists of a thin peptidoglycan cell wall sandwiched between an inner ( cytoplasmic) membrane and an outer membrane. These bacteria are found in all environments that support life on Earth. Within this category, notable species include the model organism '' Escherichia coli'', along with various pathogenic bacteria, such as '' Pseudomonas aeruginosa'', '' Chlamydia trachomatis'', and '' Yersinia pestis''. They pose significant challenges in the medical field due to their outer membrane, which acts as a protective barrier against numerous antibiotics (including penicillin), detergents that would normally damage the inner cell membrane, and the antimicrobial enzyme lysozyme produced by animals as part of their innate immune system. Furthe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clostridium Botulinum
''Clostridium botulinum'' is a Gram-positive bacteria, gram-positive, Bacillus (shape), rod-shaped, Anaerobic organism, anaerobic, endospore, spore-forming, Motility, motile bacterium with the ability to produce botulinum toxin, which is a neurotoxin. ''C. botulinum'' is a diverse group of pathogenic bacteria. Initially, they were grouped together by their ability to produce botulinum toxin and are now known as four distinct groups, ''C. botulinum'' groups I–IV. Along with some strains of ''Clostridium butyricum'' and ''Clostridium baratii'', these bacteria all produce the toxin. Botulinum toxin can cause botulism, a severe Flaccid paralysis, flaccid paralytic disease in humans and other animals, and is the most potent toxin known to science, natural or synthetic, with a lethal dose of 1.3–2.1 ng/kg in humans.(2010). Chapter 19. ''Clostridium'', ''Peptostreptococcus'', ''Bacteroides'', and Other Anaerobes. In Ryan K.J., Ray C (Eds), ''Sherris Medical Microbiology'', 5th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillus Cereus
''Bacillus cereus'' is a Gram-positive bacteria, Gram-positive Bacillus, rod-shaped bacterium commonly found in soil, food, and marine sponges. The specific name, ''cereus'', meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar. Some strains are harmful to humans and cause foodborne illness due to their spore-forming nature, while other strains can be beneficial as probiotics for animals, and even exhibit mutualism with certain plants. ''B. cereus'' bacteria may be Aerobic organism, aerobes or facultative anaerobes, and like other members of the genus ''Bacillus'', can produce protective endospores. They have a wide range of virulence factors, including phospholipase C, cereulide, Metalloproteinase, sphingomyelinase, metalloproteases, and cytotoxin K, many of which are regulated via quorum sensing. ''B. cereus'' strains exhibit Flagellum, flagellar motility. The ''Bacillus cereus'' group comprises seven closely related species: ''B. cereus' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Staphylococcus Aureus
''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive for catalase and nitrate reduction and is a facultative anaerobe, meaning that it can grow without oxygen. Although ''S. aureus'' usually acts as a commensal of the human microbiota, it can also become an opportunistic pathogen, being a common cause of skin infections including abscesses, respiratory infections such as sinusitis, and food poisoning. Pathogenic strains often promote infections by producing virulence factors such as potent protein toxins, and the expression of a cell-surface protein that binds and inactivates antibodies. ''S. aureus'' is one of the leading pathogens for deaths associated with antimicrobial resistance and the emergence of antibiotic-resistant strains, such as methicillin-resistant ''S. aur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Listeria Monocytogenes
''Listeria monocytogenes'' is the species of pathogenic bacteria that causes the infection listeriosis. It is a facultative anaerobic bacterium, capable of surviving in the presence or absence of oxygen. It can grow and reproduce inside the host's cells and is one of the most virulent foodborne pathogens. Twenty to thirty percent of foodborne listeriosis infections in high-risk individuals may be fatal. In the European Union, listeriosis continues an upward trend that began in 2008, causing 2,161 confirmed cases and 210 reported deaths in 2014, 16% more than in 2013. In the EU, listeriosis mortality rates also are higher than those of other foodborne pathogens. Responsible for an estimated 1,600 illnesses and 260 deaths in the United States annually, listeriosis ranks third in total number of deaths among foodborne bacterial pathogens, with fatality rates exceeding even ''Salmonella'' spp. and ''Clostridium botulinum''. Named for Joseph Lister, ''Listeria monocytogenes'' is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gram-positive
In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is used by microbiologists to place bacteria into two main categories, gram-positive (+) and gram-negative bacteria, gram-negative (−). Gram-positive bacteria have a thick layer of peptidoglycan within the cell wall, and gram-negative bacteria have a thin layer of peptidoglycan. Gram-positive bacteria retain the crystal violet stain used in the test, resulting in a purple color when observed through an optical microscope. The thick layer of peptidoglycan in the bacterial cell wall retains the Stain (biology), stain after it has been fixed in place by iodine. During the decolorization step, the decolorizer removes crystal violet from all other cells. Conversely, gram-negative bacteria cannot retain the violet stain after the decolorization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
