MICROSCOPE
Purpose: Magnifies microorganisms for observation.
Important Parts:
Ocular Lens
10X magnification
Scanning Objective
4X magnification
Low Power Objective
10X magnification
High Power Objective
40X magnification
Oil Immersion Objective
100X magnification
Coarse Adjustment Knob
Moves stage up and down significantly
Used for initial focusing
Fine Adjustment Knob
Fine tunes focus
Stage
Holds slide
Condenser
Focuses light onto specimen
Iris Diaphragm
Controls amount of light
Illuminator
Light source
Total Magnification Formula
Total Magnification = Ocular Lens × Objective Lens
Examples:
10 × 4 = 40X
10 × 10 = 100X
10 × 40 = 400X
10 × 100 = 1000X
ASEPTIC TECHNIQUE
Purpose: Prevent contamination of cultures, media, and the environment.
Tools:
Inoculating Loop
Used for fishtail streaking
Used for plate inoculation
Inoculating Needle
Used for stab inoculation
Used for butt inoculation
Important Steps:
Flame Loop
Sterilizes loop before and after use
Flame Tube Opening
Reduces contamination
SIMPLE STAIN THEORY
Purpose: Understand how dyes interact with bacterial cells.
Cell Charge:
Bacterial cells have a negative charge
Basic Dyes:
Positively charged
Attracted to bacterial cells
Examples:
Crystal violet
Methylene blue
Acidic Dyes:
Negatively charged
Examples:
Nigrosin
Congo Red
Result:
Opposite charges attract
Basic dyes stain bacterial cells
ORGANISM IDENTIFICATION
Escherichia coli
Gram Reaction:
Gram Negative
Morphology:
Rod
Staphylococcus aureus
Gram Reaction:
Gram Positive
Morphology:
Cocci in clusters
Micrococcus luteus
Gram Reaction:
Gram Positive
Morphology:
Cocci in tetrads
Bacillus subtilis
Gram Reaction:
Gram Positive
Morphology:
Rod
Endospore former
Enterobacter aerogenes
Gram Reaction:
Gram Negative
Morphology:
Rod
LAB TOOLS
Loop
Purpose:
Fishtail streaking
Plate inoculation
Needle
Purpose:
Stab inoculation
Butt inoculation
TSI
Tool Used:
Needle
Procedure:
Stab butt
Fishtail streak slant
SIM
Tool Used:
Needle
Procedure:
Single stab inoculation