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These numbers should match your measurements from

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These Numbers should match your Measurements from last Week. Have you caught-on the Size can be an important Factor in the Identification of some Bacteria? 4. Inoculate an IMViC Set-up (Tryptone Broth, MR-VP Broth, Citrate Slant) using the same Colony you used to make your Gram Stain (1 IMViC Set-up per Clan). 5. Incubate your IMViC Set-up at 37°C for 48 Hours . 6. Save one (1) Enteric Mother Plate at 04°C. _______________________________________________________________________________ “Willie, Willie, Willie. What kind of a name is that? Is it short for something”? Willie is my professional name, Indiana .’ Hey, lady! You call him Dr. Jones! My professional name.” © 1984 LucasFilm, Ltd.
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Lab 6 Page 19 Background Information for Lab 7 Exercises Viable Count (Atlas Pages 217 and 218) Microbiologists routinely need to determine the Number of Bacteria in a given Sample. An Industrial Microbiologist might want to monitor a Microbial Fermentation Process, a Public Health Microbiologist might want to monitor the Number of Bacteria in Hamburger from a Central Processing Plant, or an Environmental Microbiologist might want to monitor the Number of Bacteria in a Stream. The Number of Viable Cells (L= living) cannot accurately be determined by Direct Cell Counting using a Hemocytometer (which we’ve already done) or by Turbidity Measurement using Spectrophotometer (which we did with the Growth Curve Lab) because neither of these Methods can distinguish Viable Cells (which like Molly Malone’s Cockles and Mussels are “Alive Alive Oh!”) from Non-Viable Cells (“He’s dead, Jim!”). The Number of Viable Cells can only be determined by performing a Viable Count. A Viable Count involves the dilution and plating of Bacteria onto a Suitable Agar Medium which will support the Growth of these Bacteria. Each Isolated Bacterium will then produce a visible Colony. So a Viable Count requires an appropriate Dilution of the Sample and an appropriate Medium for the Bacteria. Today’s Lab Exercise introduces a Viable Count of Bacteria in a Hamburger Sample. Hamburger is Ground Beef. There are no Bacteria inside the Muscle Tissue of a freshly slaughtered healthy Animal. The Bacteria are introduced by Contamination during the Handling and Grinding of this Meat. And once a Meat Grinder becomes Contaminated, all Hamburger produced by this Meat Grinder will be Contaminated. Any Contamination in the resultant Ground Beef will be exacerbated by improper Refrigeration during the Transport, Storage and Display of the Ground Beef in the Meat Display Counter at the Grocery Store. Each Pair of you will be given a Blended Sample of Hamburger from a Davis Grocery Store diluted to 10 -1 (10 g of Hamburger into 90 ml of Sterile Saline). You and your Lab Partner will make a Series of Dilutions in Sterile Saline out to a Dilution of 10 -7 . Your Aim is to use this Dilution Series to produce Plates containing between 30 and 300 Colonies of Bacteria (a Number of Colonies both easily Countable and Statistically Meaningful).
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