chapter 3 micro

mixing bacteria with an acidic acid or dye called chromogen such as nigrosin, india ink, or eosin then spreading out the mixture on a slide to form a film

• 1. add two drops of culture
• 2. add 2 drops of nigrosin 
• 3. slide second slide across to spread out
• 4. let air dry

• 1. drop of water and bacteria 
• 2. spread out mixture
• 3. air dry 
• 4. heat fix

a dried preperation of bacterial cells on a glass slide

1. add stain (crystal violet 20 sec, carbolfuchsin 5-10 sec, methylen blue 1 min)

• 2. water off
• 3. blot off

one individual cell shape

groups ways you find multiple together.

several aggents

allows for two or more outcomes

thick walls retain primary Purple

looses primary an becomes clear. stains red

divides into two groups. Gram positive and negative

first step crystal violet dye

iodine solution

sahranin will stain colorless gram negative bacteria pink  does not alter th positive

might have + and - do many tries

• 1. prepare a heat fixed smear
• 2. place slide on rack
• 3. flood the smear with crystal violet for 30 sec
• 4. rince with water for 5 seconds
• 5. cover with iodine for one minute
• 6. rinse
• 7. docolorize for 15- 30 seconds
• 8. rinse
• 9. add safranin for about 60- 80 seconds 
• 10 rinse 
• 11. blot dry.