Lab 19 Goals and Objectives:

Exercise 21: EnumerationCount colonies (30-300 plates) and share data(Sample data/explanations in supplemental packet pages 69-72)

Exercise 58: Bacterial Counts on FoodsPlate pre-made dilutions for the following foods: meat, spinach, and milkUse pre-poured solid plates and spread with beadsEach pair needs: 1:10 of each: meat, spinach, milk (no blending: done!)

1:1000 of each: meat, spinach, milk (no diluting: done!)9 NA plates and 9 tubes of beads

Exercise 59: Bacteriological Examination of WaterIf turbid, pre-filter water with cheese-cloth in funnel into new bottleEach pair set up tubes for one water sample (you need minimum 200ml in your

sample for this exercise and Ex. 60)Each pair needs: 5 DS lactose broth LARGE tubes

10 SS lactose broth normal tubesExercise 60: The Membrane Filter Method

Each pair use the same water sample from Exercise 59Perform according to directions pg 403 except skip step 4, Filter 100ml of sampleEach pair needs: Filter apparatus, Grid filter disc, Absorbent pad,

Petri dish, Endo MF broth

Exercise 21: Enumeration

Count colonies (30-300 plates) and share data(Sample data/explanations in supplemental packet pages 69-72)

0.1

0.2

0.3

0.4

y = mx+b

3.4 X 1062.55 X 105

CFU/mlOnce you can assign real CFU/ml numbers to the OD readings, you have a standard curve and the equation of the line can be used to determine the CFU/ml concentration in a sample from the OD reading

Exercise 58: Bacterial Counts on Foods

Dilutions are already madePlate pre-made according to directions on pg 380 for each of the following foods: meat, spinach, and milkUse pre-poured solid plates and spread with beads

Fig 58.1

Exercise 59: Bacteriological Examination of Water

Pre-filter water with cheese-cloth in funnel into new bottle I (if necessary) Each pair set up tubes for one water sample (you need minimum 200ml in your sample for this exercise and Ex. 60)5 DS lactose broth LARGE tubes 10 SS lactose broth normal tubes

Fig. 59.1

Exercise 60: The Membrane Filter Method

• Each pair use the same water sample from Exercise 59

• Perform according to directions pg 403 except skip step 4, Filter 100ml of sample. Skip step 4

• Filter 100ml of sample

Each pair needs:

Exercise 58: 1:10 of each: meat, spinach, milk (no blending: done!)1:1000 of each: meat, spinach, milk (no diluting: done!)9 NA plates and 9 tubes of beads

Exercise 59: 5 DS lactose broth LARGE tubes

10 SS lactose broth normal tubesExercise 60: Filter apparatus, Grid filter disc, Absorbent pad,

Petri dish, Endo MF broth