国外微生物学基础实验(三)-英文版.ppt

Getting Ready for Today’s Lab Grab your lab check-in card and the dirty copies of Lab #2 and #3 that we saved from last week. Grab your plastic box of supplies. Put on your lab coat and have your goggles, lab card and dirty copies of lab exercises/reports on the bench next to you. Plug in and turn on your microincinerator. TURN IN: No lab report or Pre-lab due this week. End of Today’s Lab After you have cleaned your lab bench, copy your Lab #2 and #3 material on to a clean copy to take home. I must see you throw out your dirty copy of Lab #2. You may turn in your dirty copy of Lab #3 to save for use next week. Lab Report #2 and #3 due next week, as week, as well as Pre-lab #4. Laboratory 3 Differential Staining Three Main Things We are Doing Today I. Looking at Results from Last Weeks Cultures II. Learning to use an Inoculation Loop for Streak Plate Method III. Differential Stains I. Looking at Results from Last Weeks Cultures Other Types of Media: McConkey’s, Blood Agar Mannitol Salt Look at the plates on your lab bench that are red/pink In color. Blood Agar = very dark red McConkeys = lighter, purplish-pink Mannitol Salt -= orangish-pink MacConkeys (already prepared) MacConkey’s is both a selective differential media. 1. What Does Selective Mean? MacConkey’s is selective media because it inhibits the growth of some organisms [Gram positive bacteria]. 2. What Does Differential Mean? Because “neutral red” has been added to the media, it is also differential. - Bacteria that use lactose (a type of sugar) for food, produce acidic metabolites which causes the pH indicator neutral red to turn red. - These “lactose fermenters” will grow in red colonies while non-lactose fermenters will be colorless and clear. Members of the family Enterobacteriaceae (Gram negative bacilli) are the most frequently encountered bacteria isolated from many types of clinical specimens. They are most commonly lactose fermenters. Blood agar Most specimen