1. Introduction, Lab Safety Quiz, And Environmental Plates
Mic 224
Introduction, Lab Safety Quiz,
And Environmental Plates

2. Microorganisms in the Environment
Microbes are ubiquitous
From the Antarctic to Hydrothermal vents
Found in either 2 stages of development
Active- water is available, organisms are dividing
Dormant-spores

3. Tools of the Trade Petri Dishes-used to grow organisms of interest
3 parts: lid, bottom, media (located in bottom of dish)
Organisms must be transferred directly to the media, NEVER TO THE LID

4. Petri Dish

5. Culture Media Contains nutrients organisms need to survive
Proteins, carbohydrates, vitamins, minerals, water
Media is available in two forms: broth or solid
Broth-liquid, usually in a test tube
Solid-deeps, slants, plates
Solid media contains agar (the solidifying agent)
Normal concentration is 1.5% agar

6. Culture Media May be chemically defined or complex Todays media:
Defined: one in which the exact chemical composition is known
Complex: exact composition is not known: contains products such as blood, etc
Todays media:
Nutrient agar: general purpose-supports the growth of a wide range of organisms
Potato Dextrose Agar: selective media- selects for Fungi

7. Colony Morphology
Colony- result of a single organism dividing into millions of organisms that become visible
Colonial Morphology- consists of size-diameter of colony (mm); elevation-raised/lowered; margin (edge)-rough, variegated, etc; pigment-color; and texture-smooth, rough,etc

8. Colony Morphology
Size of Colony:

9. Colony Morphology
Shape refers to the overall appearance of the colonies. The descriptors here are punctiform, circular, irregular, filamentous (has individual thin projections), or rhizoid (has thin, branching projections).

10. Colony Morphology Height/Elevation
The colony height, or elevation, is a description of how the colony grows vertically. To see the elevation of the colonies, it may be helpful to look through the side of the petri dish. The descriptors here are flat, raised, convex (sloping up from the edges), pulvinate (sloping steeply from the edges and very high in the center), and umbonate (has a raised center)

11. Colony Morphology
Edge, or margin, describes the borders of the colony. The edge can be entire (smooth, with no projections), undulate (wavy), lobate (lobed), filamentous, or rhizoid.

12. Colony Morphology Color/Pigment Texture
Some bacteria produce pigments, giving the colony a distinct color. Pigments can span the entire color spectrum. Recording the color is the first step. In addition to describing the color, this is also the time to identify if the colony is opaque (you can't see through it), translucent (you can see through it), dull, or shiny.
Texture
Texture refers to the characteristics of the colony surface. Colonies can be dry, mucoid (thick, stringy, and wet), moist, smooth, rough, rugose (wrinkled), or contain concentric rings.

13. Useful Terminology
Normal Flora: microorganisms that are typically present in a particular environment
Ex: Staphylococcus epidermidis is found on essentially every surface of the human body
Contaminants: transients organisms that are often invaders in a particular environment