Lab 19 Goals and Objectives: Exercise 21: Enumeration Count colonies ( plates) and share data (Sample data/explanations in supplemental packet pages 69-72) Exercise 58: Bacterial Counts on Foods Plate pre-made dilutions for the following foods: meat, spinach, and milk Use pre-poured solid plates and spread with beads Each 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 Water If turbid, pre-filter water with cheese-cloth in funnel into new bottle Each 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 tubes 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 Each pair needs: Filter apparatus, Grid filter disc, Absorbent pad, Petri dish, Endo MF broth

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

y = mx+b 3.4 X X 10 5 CFU/ml Once 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 made Plate pre-made according to directions on pg 380 for each of the following foods: meat, spinach, and milk Use 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 tubes Exercise 60: Filter apparatus, Grid filter disc, Absorbent pad, Petri dish, Endo MF broth