Lab Procedures Part I. Staining and Colony Morphology

Ex. 1-1 Types of Media

Nutrient agar and nutrient broth are common media used in maintaining bacterial cultures. They contain nutrients such as proteins, carbohydrates (sugars), and various lipids. Solid media contains agar, a thickening agent that does not melt at high temperatures (this allows us to incubate the bacteria to facilitate growth); bacteria grow on the surface of solid media. Preparation of media involves making solutions and then autoclaving them at 121oC, 15 psi, for 15 minutes to kill all bacteria including thermophiles (heat loving bacteria) and those that produce resistant endospores (the increased pressure gets the temperature above boiling). This will insure that the media is sterile before inoculation. After autoclaving, media can be dispensed into petri dishes/test tubes and cooled.

Examine different kinds of media: nutrient broth tubes, nutrient agar slants, nutrient agar deeps, agar plates

What would be the advantage of growing bacteria on a slant, rather than on a deep?

Ex. 2-1 Ubiquity

Work in groups of 4

Each group needs 4 agar plates

Label each plate on edge of plate with: name, date, experiment #, type of exposure

Plate 1 – open and place on top of bench; expose to air for 30 minutes.

Plate 2 – Divide plate in half (write on bottom of plate with sharpie marker; label one half of plate with a “B” (before);

label the other half with an “A” (after); touch agar on “B” side with a dirty finger; wash hands with antibacterial soap, then touch agar on “A” side with clean finger

Plate 3 – kiss agar

Plate 4 – dip a sterile swab in sterile water (found in test tubes); swab bench top; dispose of swab in trash.

Incubate: Plates 1 & 4 at 30oC; Incubate: Plates 2 & 3 at 37oC.

Ex. 3-1 Introduction to the Light Microscope

Read/discuss Intro. Microscope Handout

Clean microscope before viewing slides


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