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Micrococcus Luteus
''Micrococcus luteus'' is a Gram-positive, to Gram-variable, nonmotile, coccus, tetrad-arranging, pigmented, saprotrophic bacterium that belongs to the family Micrococcaceae. It is urease and catalase positive. An obligate aerobe, ''M. luteus'' is found in soil, dust, water and air, and as part of the normal microbiota of the mammalian skin. The bacterium also colonizes the human mouth, mucosae, oropharynx and upper respiratory tract. ''Micrococcus luteus'' is considered a contaminant in sick patients and is resistant by slowing of major metabolic processes and induction of unique genes. It is a high G + C ratio bacterium. ''Micrococcus luteus'' is coagulase negative, bacitracin susceptible, and forms bright yellow colonies on nutrient agar. ''Micrococcus luteus'' has been shown to survive in oligotrophic environments for extended periods of time. Recent work by Greenblatt ''et al.'' demonstrate that ''Micrococcus luteus'' has survived for at least 34,000 to 170,000 ye ... [...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. Gram-positive bacteria take up the crystal violet stain used in the test, and then appear to be purple-coloured when seen through an optical microscope. This is because the thick peptidoglycan layer in the bacterial cell wall retains the stain after it is washed away from the rest of the sample, in the decolorization stage of the test. Conversely, gram-negative bacteria cannot retain the violet stain after the decolorization step; alcohol used in this stage degrades the outer membrane of gram-negative cells, making the cell wall more porous and incapable of retaining the crystal violet stain. Their peptidoglycan layer is much thinner and sandwiched between an inner cell membrane and a bacterial outer membrane, causing them to take up the counterstain (saf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacitracin
Bacitracin is a polypeptide antibiotic. It is a mixture of related cyclic peptides produced by ''Bacillus licheniformis'' bacteria, that was first isolated from the variety "Tracy I" ( ATCC 10716) in 1945. These peptides disrupt Gram-positive bacteria by interfering with cell wall and peptidoglycan synthesis. Bacitracin is primarily used as a topical preparation, as it can cause kidney damage when used internally. It is generally safe when used topically, but in rare cases may cause hypersensitivity, allergic or anaphylactic reactions, especially in patient allergic to neomycin. Medical uses Bacitracin is used in human medicine as a polypeptide antibiotic and is "approved by the U.S. Food and Drug Administration (FDA) for use in chickens and turkeys," though use in animals contributes to antibiotic resistance. As bacitracin zinc salt, in combination with other topical antibiotics (usually polymyxin B and neomycin) as an ointment ("triple antibiotic ointment," with the brand n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultraviolet Light
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionize atoms, it can cause chemical reactions and causes many substances to glow or fluoresce. Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules. Short-wave ultraviolet light damages DNA and sterilizes surfaces with which it comes into contact. For h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Code
The genetic code is the set of rules used by living cells to translate information encoded within genetic material ( DNA or RNA sequences of nucleotide triplets, or codons) into proteins. Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries. The codons specify which amino acid will be added next during protein biosynthesis. With some exceptions, a three-nucleotide codon in a nucleic acid sequence specifies a single amino acid. The vast majority of genes are encoded with a single scheme (see the RNA codon table). That scheme is often referred to as the canonical or standard genetic code, or simply ''the'' genetic code, though variant codes (such as in mitochondria) exist. History Effor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codon
The genetic code is the set of rules used by living cells to translate information encoded within genetic material ( DNA or RNA sequences of nucleotide triplets, or codons) into proteins. Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries. The codons specify which amino acid will be added next during protein biosynthesis. With some exceptions, a three-nucleotide codon in a nucleic acid sequence specifies a single amino acid. The vast majority of genes are encoded with a single scheme (see the RNA codon table). That scheme is often referred to as the canonical or standard genetic code, or simply ''the'' genetic code, though variant codes (such as in mitochondria) exist. History Efforts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M221
M-221 is a short state trunkline highway in the Upper Peninsula (UP) of the US state of Michigan that connects M-28 with the community of Brimley and Brimley State Park. The highway was originally part of M-28 until the 1940s when it was briefly a local road. It has been a state highway again since it was designated as M-221 in 1945. Route description M-221 runs for north from M-28 into the unincorporated community of Brimley in Superior Township. The highway passes through rural fields and woods until it enters downtown. At the corner of Main Street and Lakeshore Drive, the signed portion of M-221 ends, but state maintenance continues on Lakeshore Drive across the Waiska River. The total length of the highway, including the unsigned segment, is . M-221 is maintained by the Michigan Department of Transportation (MDOT) like other state highways in Michigan. As a part of these maintenance responsibilities, the department tracks the volume of traffic that uses the roadways un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Pair
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. Dictated by specific hydrogen bonding patterns, "Watson–Crick" (or "Watson–Crick–Franklin") base pairs (guanine–cytosine and adenine–thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence. The Complementarity (molecular biology), complementary nature of this based-paired structure provides a redundant copy of the genetic information encoded within each strand of DNA. The regular structure and data redundancy provided by the DNA double helix make DNA well suited to the storage of genetic information, while base-pairing between DNA and incoming nucleotides provides the mechanism through which DNA polymerase replicates DNA and RNA polymerase transcribes DNA in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA molecule to maintain its integrity. These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation. Chromosomes are normally visible under a light microscope only during the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). Before this happens, each chromosome is duplicated ( S phase), and both copies are joined by a centromere, resulting either in an X-shaped structure (pictured above), if the centromere is located equatorially, or a two-arm structure, if the centromere is located distally. The joined copies are now called si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinomycetota
The ''Actinomycetota'' (or ''Actinobacteria'') are a phylum of all gram-positive bacteria. They can be terrestrial or aquatic. They are of great economic importance to humans because agriculture and forests depend on their contributions to soil systems. In soil they help to decompose the organic matter of dead organisms so the molecules can be taken up anew by plants. While this role is also played by fungi, ''Actinomycetota'' are much smaller and likely do not occupy the same ecological niche. In this role the colonies often grow extensive mycelia, like a fungus would, and the name of an important order of the phylum, '' Actinomycetales'' (the actinomycetes), reflects that they were long believed to be fungi. Some soil actinomycetota (such as ''Frankia'') live symbiotically with the plants whose roots pervade the soil, fixing nitrogen for the plants in exchange for access to some of the plant's saccharides. Other species, such as many members of the genus '' Mycobacterium'', ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligotrophic
An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates of metabolism, and generally low population density. Oligotrophic environments are those that offer little to sustain life. These environments include deep oceanic sediments, caves, glacial and polar ice, deep subsurface soil, aquifers, ocean waters, and leached soils. Examples of oligotrophic organisms are the cave-dwelling olm; the bacterium " ''Candidatus'' Pelagibacter communis", which is the most abundant organism in the oceans with an estimated 2 × 1028 individuals in total; and the lichens with their extremely low metabolic rate. Etymologically, the word "oligotroph" is a combination of the Greek adjective ''oligos'' (ὀλίγος) meaning "few" and the adjective ''trophikos'' (τροφικός)) meaning "feeding". Plant adaptatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agar Plate
An agar plate is a Petri dish that contains a growth medium solidified with agar, used to culture microorganisms. Sometimes selective compounds are added to influence growth, such as antibiotics. Individual microorganisms placed on the plate will grow into individual colonies, each a clone genetically identical to the individual ancestor organism (except for the low, unavoidable rate of mutation). Thus, the plate can be used either to estimate the concentration of organisms in a liquid culture or a suitable dilution of that culture using a colony counter, or to generate genetically pure cultures from a mixed culture of genetically different organisms. Several methods are available to plate out cells. One technique is known as "streaking". In this technique, a drop of the culture on the end of a thin, sterile loop of wire, sometimes known as an inoculator, is streaked across the surface of the agar leaving organisms behind, a higher number at the beginning of the streak and a l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coagulase
Coagulase is a protein enzyme produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of '' Staphylococcus'' isolates. Importantly, '' S. aureus'' is generally coagulase-positive, meaning that a positive coagulase test would indicate the presence of ''S. aureus'' or any of the other 11 coagulase-positive ''Staphylococci''. A negative coagulase test would instead show the presence of coagulase-negative organisms such as ''S. epidermidis'' or '' S. saprophyticus''. However, it is now known that not all ''S. aureus'' are coagulase-positive. Whereas coagulase-positive ''Staphylococci'' are usually pathogenic, coagulase-negative ''Staphylococci'' are more often associated with opportunistic infection. It is also produced by ''Yersinia pestis''. Coagulase reacts with prothrombin in the blood. The resulting complex is called ''staphylothrombin'', which enables the enzyme to act as a prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
