lab quiz #2

• Aerobes: Require oxygen to grow, enzymes use oxygen as an electron acceptor.
• obligate anaerobes: require the absence of oxygen. Can use other molecules like NO3- for the enzyme to use as an electron acceptor.
• Facultative anaerobes: can grow with or without the use of oxygen.
• size: pinpoint, small, moderate, or large 2. (growth on an agar plate)
• Pigmentation is the color of colony.
• Form: the shape of the colony. Can either be circular or irregular.
• Margin: the appearance of the outer edge of the colony.

  Entire: Sharply defined (even)

  Lobate: Marked indentations

  Undulate: wavy indentations

  Serrate: Toothlike appearance

  Filaments: Threadlike, spreading edge.
• Elevation: The degree to which colony growth is raised on the agar surface.

  Flat: flat

  Raised: slightly elevated

  Convex: Dome-shaped elevation

  Umbonate: raised, with elevated convex central region.
• CFU's are not visible.
• isolation of a pure culture is basically a dilution method.
• compound microscope: 2 lens system for magnifying specimens.
• stage: fixed platform with an opening in the center allowing the passage of light.
• mechanical stage: can be moved vertically or horizontally by adjustment controls.
• Light source: light source is positioned in the base of the instrument.
• condenser: Found directly under the stage and contains two sets of lenses.
• Iris diaphragm: shutter controlled by a lever that is used to regulate the amount of light passing.
• Body tube: houses the lens system that magnifies the specimen.
• objective lens goes 4x, 10x, 40x, and 100x.
• Immersion oil increases the resolving power of the microscope by increasing the contrast between the specimen and the background.
• selective media: media used to select specific groups of bacteria.
• Differential/selective media: media that distinguish among morphologically and biochemically related groups of organisms.
• Mannitol salt agar is both differential and selective. It is selective because of its high salt concentration. It is differential because of the mannitol inside. if yellow halo appears, that means that the enzyme was able to cleave mannitol.
• Eosin Methylene blue agar is both selective and differential. It is selective because it is selective for gram-negative bacteria. It is also differential because it has lactose in it. The bacteria has to be able to cleave lactose.
• Blood Agar Plate are enriched NOT selective. They are differential because the microbes need to have the ability to break down red blood cells. (hemolysis)
• Gamma hemolysis: No lysis of red blood cells result in no change in the medium.
• Alpha hemolysis: Incomplete lysis of red blood cells. Reduction of hemoglobin to methemoglobin results in greenish halo.
• Beta hemolysis: lysis of red blood cells with complete destruction and use of hemoglobin. Bright yellow halo will show this.
• Starch is not selective but enriched with starch. It is differential because microbes will need to break down starch into glucose.
• Carbohydrate fermentation test:

  Acid and gas: yellow color and has a gas bubble in tube

  Acid: yellow color

  Negative: pink color
• Negative Urease test: yellow color
• Positive urease test: pink
• Negative bile-esculin test: brown color
• positive bile esculin test: black color
• 1/10 dilution is 10^-1. when you add another 0.1ml of diluted solution to the petri dish you get a dilution of 10^-2.