It shows that it is mostly Actinobacteria, with some firmicules ,and proteobacteria mixed in (Figure 2). Know more about our courses. Micrococcus spp. The negative oxidase result conflicts with M. luteus (Public Health England). . They are generally strict aerobes and can generally reduce nitrate. Micrococcus luteus uses the amino acids and does not grow in the butt of the slant. The differentiation of the Gram-positive cocci encompasses 4 main exercises used to compare and contrast the characteristics of each family: These four tests will, as we shall see, allow for the differentiation of the families of organisms and will guide the laboratorian to other more definitive tests for the identification of the organism. Once the culture was deemed pure enough, I inoculated a slant tube. Micrococcus luteus are Gram-positive cocci mostly arranged in tetrads and larger than Staphylococcus. I kept the plate at room temperature for 7 days, and then selected a colony to purify using the pure culture streak plate method. They are positive for catalase and oxidase ( modified). M. luteus can also cause septic shocks in immuno-compromised people. [7], In 2003, it was proposed that one strain of Micrococcus luteus, ATCC 9341, be reclassified as Kocuria rhizophila. The EMB agar showed no growth or change in color, also indicating the microbe was gram positive and a non-fermenter. The identified reads only made up a total of twenty seven percent of the total reads, but the majority of those reads were for M. luteus. Institute for Quality and Efficiency in Health Care. Habitat Micrococcus lives in a wide range of environments such as water, soil, and the dust whereas, Staphylococcus lives in the animal body. Isolates of the M. luteus have been found to overproduce the riboflavin virus when they are grown on toxic organic pollutants like pyridine. In the presence of atmospheric oxygen, the oxidase enzyme reacts with the oxidase reagent and cytochrome C to form the coloured compound, indophenol indicated as blue or purplish-blue colouration on the disc after the introduction of the bacterial colony on the disc. The nasal cavity microbiome primarily consists of the phyla Actinobacteria, Firmicutes and Proteobacteria (Bassis et al. The third image represents the colony morphology of many of the streptococci and enterococci. Gram Staining. (2019, March 14). This is in agreement with a study by Mohana et al., (2013) who reported that the carotenoid pigments had antioxidant properties of Micrococcus luteus was reported at IC50 of 4.5mg/ml, also the . Staphylococci were distinguished by their ability to form acid from glucose anaerobically and sarcinas by the formation of cubical packets. Positive. They are usually normal flora but can be opportunistic pathogens in certain immunocompromised patients. Micrococcus luteus was formerly known as Micrococcus lysodeikticus. Examples of the colony morphology associated with each family is represented on this slide. Bacteria Detail., The Editors of Encyclopdia Britannica. The first control consisted of plates of agar-agar to test sterility. An interesting remaining family member, Microoccus antarcticus, was isolated from Antarctica, and is capable of growing at 4C. Staphylococci are either producers of the enzyme coagulase or non-producers. I grew my isolated in Tryptic Soy Broth (TSB) for a week to prepare for DNA extraction. Further biochemical tests to identify include the catalase and oxidase test, and typical tests of a "colorful series . So far there are two genome sequences that have been done. 570 . Bacillus megaterium fermented sugars but didn't grow in the anaerobic area of the butt. AACC.org As the microbe is gram positive this means that it has a large peptidoglycan layer and lacks a lipopolysaccharide layer. . Table 1: Graph from Korona showing the percent reads of each organism, and to which taxonomic level. The Micrococcus genus is known to be found on dust particles, in water, on skin and skin glands in vertebrates, and some species can be found in milk. Although it's tempting to write a summary of the entire study but it . Micrococcus luteus ( Scanning electron micrograph ) Micrococcus luteus is a Gram-positive bacterium of the genus Micrococcus. It is essential for differentiating catalase-positive Micrococcaceae from catalase-negative Streptococcaceae. Micrococcus luteus can synthesize the iso-branched and anteiso-branched alkenes by the head-to-head condensation of fatty-acid thioesters. The typical microscopic morphology of the Gram-positive cocci when using the Grams stain is represented in these three images. Mannitol salt agar (MSA) is a selective, differential, and indicator medium used to isolate and identify Staphylococcus aureus from the clinical specimen. The identification of three different biovars within the species M. luteus has the advantage that the three groups can be differentiated without nomenclatural changes having to be introduced. The M. luteus genome encodes about four sigma factors and fourteen response regulators, a finding indicative of the adaptation to a rather strict ecological niche. 2014). Simple biochemical tests like the one above have always been an important aid to identification of bacteria, because the different bacterial groups and species have characteristic metabolic activities. The conflicting results of the metagenome binning and the catalase test influenced this mistake. The two unifying characteristics of these four families are their coccoid shape and the fact that they stain purple in the Grams method for visualizing bacteria microscopically. See answer (1) best answer. These discrepancies could be due to human error, unpure culture, or an old agar plate. The family, Micrococcaceae, has been shrinking. While defining the characteristics of the Micrococcus are the ability to produce acid aerobically from the aesculin hydrolysis, glucose glycerol, arginine dihydrolase, motility, major pigment production, and conversion of nitrate to nitrite. In the case of a negative test, no colour change is observed. Staphylococcus spp. They have a respiratory metabolism, often producing little or no acid from carbohydrates, and are usually halotolerant, growing in 5% NaCl. Gamma or no hemolysis results in no characteristic display in the vicinity of the colony. Micrococcus luteus is a Gram-positive to Gram-variable, nonmotile, tetrad-arranging, pigmented, saprotrophic coccus bacterium in the family Micrococcaceae. CATALASE TEST: Catalases are enzymes that convert hydrogen peroxide (H2O2) into water and oxygen gas. The laboratory assay is performed by mixing a sample of the bacterial colony with a drop(s) of hydrogen peroxide placed on a microscope slide. Retrieved 06:20, April 16, 2019, from https://en.wikipedia.org/w/index.php?title=Micrococcus_luteus&oldid=887698104, Wikipedia contributors. Methods: To start isolating the bacterium, I used a sterile swab wet with deionized water provided by the lab to pick up bacteria from the shower drain. Like MSA, this medium also contains the pH indicator, phenol red. Where the M. luteus can cause severe skin infections and is sometimes clinically mistaken for Staphylococcus aureus. Gram Stain:Gram-positive cocci, arranged in clusters that differ from Staphylococcus. They are indole negative, oxidase-positive, catalase-positive, and citrate negative. Source: Trainee Council in English, Hello, my name is Dr. Karen Krisher. After it was sequenced using an Illumina MiSeq at the UAF Core lab, I used the online program Base Space to analyze the reads that I got from sequencing. Whereas the M. variant has a G-C content of about 66-72mol%. The oxygen class of the microbe, obligate aerobe, matches up with the predictions I had made about it because the bacteria was originally sourced in a nostril. M. luteus is found in the soil, dust, water, and human skin flora. They also produce yellow or pink colonies when they are grown on the mannitol salt agar, micrococcus flavus, M. terreus, and M. yunnanensis. With this almost universal range of survivable living conditions that microbes can live in (particularly bacteria), it would be reasonable to assume that there would be at least one variety living in such a nice, wet, and aerated place as my shower drain. Micrococcus spp. I used Prokka Genome Annotation to identify which genes are present in the bacterium, Kraken Metagenomics to identify what the DNA reads correlated to on different taxonomic levels, and SPAdes Genome Assembler to determine how many contigs were produced from the reads that were produced. The bubbling reaction is almost immediate and distinct in appearance. The staphylococci and micrococci are catalase producers while the streptococci, enterococci, and a variety of other Gram-positive cocci are catalase-negative. It is an opportunistic pathogen, only pathogenic enough to cause disease in weakened immune systems (Medical Laboratories). View Biochemical Tests Lab Report.docx from BIOL 240 at University of Alaska, Anchorage. M. luteus is considered an opportunistic pathogen that can be responsible for some of the nosocomial infections. About half of the Micrococcus luteus gram stain was found to carry plasmids of about one to 100MDa in size. Wikipedia contributors. M. luteus is the majority of reads on the species level. Like all Staphylococci, S. saprophyticus is also clustering Gram-positive cocci, nonmotile, non-spore-forming, and . In Wikipedia, The Free Encyclopedia. The skin infections or chronic cutaneous infections that are caused can result in pruritic eruptions of the skin in some of the areas as well as scattered papule lesions with or without central ulcerations. The pathogen, Staphylococcus aureus, is notably coagulase-positive while most other members of the family are coagulase-negative. Micrococcus luteus was one of the early examples of novel codon usage,[5][6] which led to the conclusion that the genetic code is not static, but evolves. In Wikipedia, The Free Encyclopedia. What are the Diseases that are Caused By Micrococcus? Production of bubbles indicates a positive reaction. Then to actually isolate a bacterium, I chose a colony from the initial plate and did a quadrant streak of it to further isolate the bacterium, and then incubated it at 38 degrees Celsius for a week. My goal in this experiment was to isolate, characterize and identify a bacterial colony that arose from a sample taken from my roommates nose. Although many of the members of these families have low pathogenicity and are classified as causes of opportunistic infections, those organisms most often cited as pathogens are listed on this slide. However, the most promising antibiotic regimen that is proposed for the treatment of the Micrococcus luteus seems to be a combination of amikacin, vancomycin, and rifampicin. Other articles where Micrococcus luteus is discussed: Micrococcus: found in milk, such as M. luteus, M. varians, and M. freudenreichii, are sometimes referred to as milk micrococci and can result in spoilage of milk products. The EMB plate is also selective for gram-negative bacteria which is probably why the bacteria didnt grow on it. They contain cytochromes and are resistant to lysostaphin. The kaiju metagenome binning shows that the microbe sample is not completely pure (Figure 2). The previous classification of these organisms was much simpler; however, with the use of more advanced genetic sequencing methods, these gram-positive cocci have expanded into 4 separate families and their associated genera. [2] It resists antibiotic treatment by slowing of major metabolic processes and induction of unique genes[citation needed]. This is designated as beta ()-hemolysis. Some streptococci also possess unique cell wall carbohydrate antigens that can be identified by reactivity with specific indicator antibodies in an agglutination assay (Lancefield typing). We were aiming to isolate a bacterium from this initial environmental sample by using repeated quadrant streaks to isolate single species colonies, therefore producing a pure culture that we could do a multitude of tests on which include Gram staining, genetic analysis and antibiotic testing along with many other tests. Micrococcus species are oxidase-positive, where these can be used to distinguish them from some other bacteria like most of the Staphylococcus species, which are generally oxidase-negative. M. luteus is an obligate aerobe (Medical Laboratories). Micrococcus luteus is another gram-positive coccus that also is catalase positive. This is likely either a cause of human error, unpure cultures, or not using agar plates that are fresh enough for the test. Note the bright yellow, non-diffusable colony pigment which is a defining characteristic of M. luteus. Colony morphology, the elucidation of the characteristics of the growth of the bacterium on agar medium, in most cases trypticase soy agar containing 5% sheep blood (sBAP). In a temporal study by Kloos and Musselwhite (1975), it was found that micrococci usually constituted from 1 to 20% of the total aerobic bacteria isolated from the skin of the head, legs, and arms, but less than 1% of those isolated from the high bacterial density areas of the nares and axillae. This bacterium is often arranged in the form of circular tetrads and it forms bright yellow colonies on nutrient agar. Care must be taken when using a sample of organism acquired from a sBAP since erythrocytes also produce catalase. Kaiju webserver metagenome binning analysis chart. Sarah D. Perkins., Government of Canada, Public Health Agency of Canada. After you have cultivated your organism on agar media, the next step is the microscopic examination. I then transferred the pure culture into a TSB slant to preserve it, keeping it at around 3 degrees Celsius in the lab refrigerator. A summary table is included which lists the results of the identification criteria discussed in the tutorial. This presentation will focus on the laboratory tests useful for the differentiation among the families as opposed to the more complicated differentiation and identification of the organisms within the different genera. In the case of a negative test, no colour change is observed. Washington, DC 20001 The microbiome of the nasal cavity can also change in response to environmental factors such as geographic location, and hygiene (Rawis et al. In order to determine physiological characteristics of the culture such as cell shape, arrangement, and whether it was gram positive or negative, which helps determine the cell wall type of the microbe, I performed a gram stain. 1 Nevertheless they have been documented to be causative organisms in cases of bacteremia, endocarditis, ventriculitis, peritonitis, pneumonia, endophthalmitis, keratolysis and septic arthritis. Staphylococcus aureus. From four species that have been identify, only Bacillus subtilis and Pseudomonas diminuta that show ability to block pathogen bacteria Edwardsiella tarda.
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