Microbial Survey and Aseptic Techniques Notes

Microbial Survey Evaluation

Colony Morphology

• Size: Measurement of colony's dimensions, e.g., 4mm.

Colony Morphology - Shape

• Various shapes:

  • Punctiform

  • Circular

  • Filamentous

  • Irregular

  • Rhizoid

  • Spindle

Colony Morphology - Elevation

• Different elevations:

  • Flat

  • Raised

  • Convex

  • Pulvinate

  • Umbonate

• TÜYENIAB is listed, but its relevance isn't specified.

Colony Morphology - Surface

• Surface textures:

  • Smooth

  • Rough

  • Wrinkled

  • Shiny

  • Dull

Colony Morphology - Margin

• Margin types:

  • Entire (even)

  • Undulate (wavy)

  • Filamentous

  • Lobate (lobes)

  • Erose (serrated)

  • Curled

Colony Morphology - Texture, Color, Opacity

• Texture:

  • Moist

  • Mucoid

  • Butyrous

  • Dry

• Color/opacity / translucent are unspecified but listed as A, B, Py

Aseptic Techniques

• Aseptic: Without contamination.

• Culture: Medium containing living microbes.

• Pure culture: Containing a single species.

General Practice for Aseptic Transfers

• Minimize contamination.

• Be organized.

• Take your time.

• Place media tubes in a test tube rack.

• Never hold tubes by the cap.

• Hold the loop like a pencil with proper pressure.

• Adjust the Bunsen burner to create inner & outer cone.

Types of Media

• Broths: Liquid media.

• Agar: Solid media.

  • Agar slants

  • Agar deeps

  • Plated media: used for isolation, differential testing, and quantifying.

Quadrant Streak for Isolation

• Quadrant streak is a method for isolating colonies.

• Examples:

  • Micrococcus luteus

  • Escherichia coli

Quadrant Streak - Procedure

• Streak plate is divided into four quadrants (1, 2, 3, 4).

Lab Evaluations: Streak Plate Isolation

• Observe quadrant streaks to critique lab partner; consider:

  • Isolation?

  • Pattern?

    • Were the first 3 streaks near the edge of the plate?

    • Did any streaks intersect where they should not have?

    • Was the loop too flat?

  • Agar?

    • Was the entire surface used?

    • Was the agar cut by the loop?

  • How can you improve results?

Lab Evaluations: Aseptic Transfer

• Observe sterile NA slant and NB tubes for growth.

• Reflect: Which medium was most difficult to transfer from or to inoculate?

• Observe E. coli (turbidity):

  • Difference in density?

  • Qualitative scoring:

    • +++ Very Turbid

    • ++ Somewhat Turbid

    • + Barely Turbid

    • 0 Not Turbid