Bacillus

Spirillum

Staphylococcus

Streptococcus

Clostridium Tetani

Amphitrichous Flagella

Peritrichous Flagella

Capsule Stain

Ubiquity of Microbes - Microorganisms

They are everywhere.  They are free-living and do not need a host.

They are commensal/mutualistic - they benefit/we benefit.

They can also be opportunistic pathogens - if conditions are right they multiply and cause harm.

Colony - each dot

Only takes one cell on nutrient medium to start growing/multiplying.

Eventually you can see an area of growth on the medium = colony.

 Morphology - study of shape

Stains are solutions consisting of a solvent and a dye.

Charged regions of the dye molecule that give color are termed chromophores.

Chromophores stain bacteria through bonds formed with the cell. Bacterial cell surfaces tend to have a - charge so a dye with a + chromophore will adhere to the cell.

Differential Stain - allows us to detect changes between organisms

2 stain process with de-colorization inbetween.
Primary stain - crystal violet

Iodine added as mordant.
Mordant enhances cv stain by forming cv-iodine complexes)

Decolor (alcohol wash).

Gram - will decolor.  Gram + - keep color.

Poor technique and age can give false results.

Shapes of bacteria:

Bacillus - rod shaped

Coccus - spherical shaped

Spirillum - spiral shaped

Staphylo - cluster arrangement

Strepto - chain arrangement

Primary stain in ZN method is Carbolfuschin (red).
This dye is lipid soluble and will penetrate waxy coating.  Steaming allows the dye to penetrate further.

Alcohol is used as a decolorizer in non-acid fast cells.  Acid fast cells will not decolorize.

After decolorizing, another stain is applied to those that lost the carbolfuschin stain.  Methylene blue is used.

Acid fast=red.  Non-acid fast=blue.

Endospore - a dormant form of bacterium.  Not all bacteria form endospores.

If a bacteria produces an endospore it means the conditions around it have deteriorated.

Spores resist heat as well as most chemicals.

Tough outer coating of a spore is made of keratin.

Hanging Drop - wet mount that is inverted on a depression slide.
Used to view bacteria under low light and look for motility. 

Ring of petroleum jelly prevents evaporation of H2O and allows coverslip to adhere to depression slide.

Motility should not be confused with Brownian Motion.
Vibration or evaporation of H2O.

Gram Stain after Heat Fix

1-Cover smear with crystal violet stain for 1 minute.

2-Rinse with distilled H2O.

3-Cover Smear with iodine for 1 minute.

4-Rinse with distilled H2O.

5-Decolorize with alcohol until run-off is clear.

6-Rinse with distilled H2O.

7-Counterstain with safranin for 1 minute.

8-Rinse with distilled H2O.