Micorbiology lab notes 9-8-09

Lab- September 9, 2009

1. Place 1 mL of sterile broth into a test tube
2. Grab 1 isolated colony from previous plate and suspend in the test tube
3. use the streaking technique and streak for isolated colonies on Emosin Methylene Blue (EMB) agar plate and on a Mannitol Salt Agar (MSA) plate

Kirby -Bauer test
- test antibiotic susceptibility
1. Make "lawn" of bacteria with broth and bacteria on Mueller-Hinton Agar plate
a. use a cotton swab and dip it in broth previously made
b. rub the broth-swab all over the plate covering the entire thing
2. Use flame and alcohol sterilized tweezers to place antibiotic disks on the bacteria lawns
a. use 5 different antibiotic disks and one negative control disk
b. place three in each plate about 1.5 inches apart in a triangular shape
3. Dip tweezers in alcohol then over flame 2 or more times before grabbing each disk
4. grab each disk with the tweezers and tap each one into the agar

Sterile dilution
- count live bacteria in liquid sample
1. start with original sample
2. place 0.9 mL of sterile broth in 6 different labeled test tubes
3. Take 0.1 mL of original sample and place it in the 1st test tube
-flick each tube after mixing solutions
4. Take 0.1 mL of the 1st test tube and place it in the second test tube
5. Repeat this process until you are at the end of the series
6. grab 7 plates and label them 1-7
7. pipet 0.1 mL of test tube 6 into plate 6
8. place hockey stick in alcohol then in flame
9. move hockey stick back and forth while spinning the plate
10. repeat this process until you are done with the series
11. incubate and wait for results

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