Bio 455 Lab Test 2 – Flashcards
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| EMB Plate |
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| Selective for Gram Negative, Differential for bacteria that ferment lactose, E.coli appears as a green sheen |
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| SBA |
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| Sheep Blood Agar. Enriched media, Differential for Alpha (incomplete), Beta (complete) and Gamma (none) hemolysis. |
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| Tellurite-Glycine Plate |
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| Identifies coagulase-positive staphylococci. Contains peptones(nitrogen & AAs), yeast(nut), mannitol(carb), White media produces black colonies within 24 hours. |
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| DNase Plate |
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| Teal agar plate detects presence of DNase. Presence of colorless zones is a positive result. |
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| Eugon (Luxuriant) Plates |
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| White media used to grow fastidious organisms. Grows organisms used in Catalase test. Includes peptones (nitrogen, vit, AAs) dextrose (high energy source)Cystine & Sodium Sulfite (stimulate growth) NaCl (osmotic balance) |
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| Catalase Test |
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| H2O2->H20+O2, observed by bubbles upon adding hydrogen peroxide. Staplylococci & Micrococci are positive. Streptococci & Enterococci are negative. |
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| Staphylococcus aureus |
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| yellow/gold on SBA. Opportunistic pathogen--acne, boils, infections, food poisoning. Gram + Clusters Strong Beta Hemolysis Growth & Black Colonies on Tellurite Glycine DNase + Catalase + |
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| Staphylococcus epidermidis |
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| White Colonies on SBA. Lesser virulent opportunistic pathogen. Gram + Clusters, dicocci, chains Weak Beta hemolysis Growth on Tellurite Glycine DNase - Catalase + |
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| Streptococcus pyogenes |
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| Harmful upper repiratory infections & scarlet fever, strep throat, tonsillitis. Gram + Long Chains Gamma Hemolysis Tellurite Glycine - DNase + Catalase - |
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| Enterococcus faecalis |
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| Lives in gut of mammals. Common pro-biotic. Non-motile, ferments lactose w/o gas production. Causes endocarditis, bladder, prostate infections. Becoming increasingly resistant. Gram + 3-4 cell chains Gamma Hemolysis Growth @ 48 hours on Tellurite Glycine DNase - Catalase - |
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| Neisseria subflava |
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| Inhabits mucus membrane of upper respiratory tract. Usually non-pathogenic. Gram - Dicocci Gamma Hemolysis Tellurite Glycine - DNase - Catalase + |
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| Sarcina lutea |
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| mostly harmles saprophytes on dead organic matter. Yellow colonies. Gram + Packets (sarcina) Gamma Hemolysis Growth&Colonies @ 48hrs on Tellurite Glycine DNase - Catalase + |
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| MBRT Test |
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| Methylene Blue Reductase Test. Used to test milk quality. The Methylene Blue indicates presence of O2. If microorganisms are present, they will use up the O2 and the milk will not hold the blue color very long. <2 hrs=poor, 2-6hrs=fair, 6-8=good, >8hrs=excellent |
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| Koch's Postulates |
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| 1)Microbe must be present in ALL cases of the disease & absent in healthy individuals 2)Must be able to isolate the microbe and grow in pure culture 3)Same disease must result when healthy individual is infected 4)Must be able to isolate again from newly infected host |
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| Conjugation |
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| The passage of plasmids between bacterial species. |
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| Plasmid |
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| Extra-chromosomal circular DNA that encodes for non-essential but often beneficial traits such as resistance to antibiotics. |
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| Transformation |
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| Uptake of free DNA from the environment. Possibly from other dead organisms. |
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| Transduction |
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| Passage of genetic material between bacteria via phage (virus) |
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| Generalized Transduction |
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| A lytic virus fails to dissolve all of the hosts DNA. While incorporating the viral DNA into its capsid before lysis, some of these DNA pieces get put in too. They are then transferred via phage into part of a new host's chromosome. |
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| Specialized Transduction |
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| A lysogenic phage excises incorrectly and carries bits of host DNA on its ends. When the phage infects a new host, this DNA is incorporated. More efficient. |
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| Lytic Cycle |
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| Virus attaches, inserts genome, makes enzymes that dissolve host DNA, uses viral genome to replicate and make protein capsids, packages them together and then lyses the cell. |
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| Lysogenic Cycle |
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| Temperate phage attaches and inserts. It then incorporates its DNA into the host's DNA and remains dormant, replicating vertically. At some trigger, such as a weak immune system, it excises and enters the lytic cycle. |
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| Plaque |
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| An empty spot on a bacteria lawn that indicates phages killed the cells. |
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| UV light experiment |
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| UV can cause pyrimidine dimers in the DNA. Increased exposure increases DNA damage. The main repair mechanism is photolyase which requires light to activate. A dark repair process can occur in cases of extreme damage or when light isn't available. This method is much less effective. |
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| Plasmid Transfer Experiment |
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| E. faecalis was studied. Each strain had one or more plasmid encoding for Tetracycline resistance, Conjunctive factor, or Streptomycin resistance. Conjunctive strains should be both Tet. and Strep. resistant. Plate on BHI (Brain Heart Infusion) because it contains Tetracycline and Streptomycin. |
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| Enterics |
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| Gram negative bacilli found in the gut of animals and make up to 60% of fecal matter. |
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| Spirit Blue Plate |
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| Tests for Lipase. Confirmed by forming colonies with halos. |
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| YLA plate |
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| Yogurt Lactic Agar |
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| Skim Milk (Casein) plate |
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| Used to detect the presence of proteases. Confirmed with clear halo around colonies. |
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| Spore Staining |
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| Involves steaming the specimen while submerged in Malachite green to increase the spores permeability. |
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| Negative Staining |
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| Uses India Ink to stain the background, leaving those bacteria with a capsule clear. |
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| PEA Plate |
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| Phenylethyl Alcohol plate. Selective for Gram + bacteria by inhibiting DNA synthesis in Gram - |
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| Lophotrichous Bactera |
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| Those with flagellum at one end. |
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| Starch Plate |
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| Tests for Amylase. |
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| Peritrichous |
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| Bacteria with flagella on all sides. |
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| Water Quality Test |
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| Tests for coliforms. 1)Presumptive Test-Test for lactose fermentation by presence of bubbles and yellow color indicating reduced pH. 2)Confirmed Test-Streak on EMB plate to ensure that the bacteria is not Gram + 3)Isolate single colony from EMB and Streak on a NUT slant and innoculate the green bile tube. Look for turbidity, gas formation, Gram stain. |
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| Serratia marcescens |
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| Red pigmented bacteria used in UV testing. |
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| Snyder Agar Test |
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| Used to test for susceptibility to tooth decay. Contains glucose and the pH indicator bromcresol green. Bacteria will ferment glucose and produce lactic acid which will turn the indicator yellow. |
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| Simmons Citrate Agar slant |
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| Selects for organisms that can use Citrate as sole carbon source and ammonium for nitrogen. Contains bromotymol blue to indicate pH (<6.9 is green; >7.6 is blue). In using the ammonium, the bacteria turn the solution basic therefore blue. |
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| Indole Test |
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| Determines if bacteria can split tryptophan into indole aka Tryptophanase. Must be in sterile indole solution for 24 hours. Add Kovac's reagent after. Positive result is red/red violet color. |
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| MRVP tests |
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| Methyl Red Voges-Proskauer tests. Initially in a broth that contaiins peptone, glucose, and phosphate buffer, some bacteria will ferment into just acetic acid, others into a variety of acids, and some not at all. Methyl Red shows that they fermented the mixed acids by being red in acidic environment. The VP test shows that it fermented only acetic acid because it will not overcome the buffer. Rather, will give a pH of roughly 6.2 Positive result is a maroon band that reacts with the acetic acid mixture. |
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| TSI slants |
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| Triple Sugar Iron. Tests for those that ferment sugars and produce hydrogen sulfide. Differential media based upon ability to reduce sulfur and ferment carbohydrates. Judge by the position of color change whether it fermented glucose, lactose, or sucrose. If they reduce their terminal electron acceptor to sulfide, H2S reacts with the ferrous sulfate to form ferrous sulfide, black precipitate. If anaerobic microbes at the butt use H+ as terminal electron acceptor, they'll release gas, cracking the agar. |
