BIOS 242 Week 7 Lab 1; Bacteria of Digestive System

Lab13:BacteriaoftheDigestiveSystem LearningObjectives • Identifyhowselectiveanddifferentialmediacanbeusedintheidentificationofbacteriathatcaninhabit the digestive tract. • Identifythegrowthofsamplesofpresumedfecalbacteriafromrestroomswabs. Introduction The human intestinal tract is inhabited from birth by a variety of microorganisms acquired, at first, fromthe mother. Later, microbes are ingested in food and water, and from hands and objects placed in themouth. Many of those do not survive the acidic pH of the stomach, which helps prevent infection frompathogens. However, those that do survive find the environment in the small intestine and colon morehospitable………..Continue MaConkey agar (MAC) Eosin Methylene Blue agar (EMB) InapreviouslaboratoryCarbohydrateFermentation Environmental Sampling (MUST be set-up as a demonstration by the instructor): Exercise1:Growingknownbacteriaonavarietyofgrowthmedia Inthisexercise,wewillgrowpureculturesofknownbacteriainavarietyofsolidandliquidmedia. Materials: Method: Exercise2:DemonstrationofGrowthofGIbacteriaonavarietyofgrowthmediabyCollectingSpecimenfrom toiletrim Instructorwillcarryoutthelistedstepsandshowstudentstheresults. LabReport: Purpose:Pleasedescribeincompletesentencesandinyourownwords,thepurposeofthisexperiment. Observations: Exercise1:Growingknownbacteriaonavarietyofgrowthmedia Exercise2:DemonstrationofGrowthofGIbacteriaonavarietyofgrowthmediabyCollectingSpecimenfrom toiletrim Questions: 1. Explainthepurposeofthefollowingingredients. a. LactoseinMacConkeyagar b. Eosinandmethylenebluedyesineosin-methyleneblueagar. 2. Do all the bacteria samples grow on Eosin Methylene Blue and MacConkey agar? If not, whynot? 3. WhatdoesametallicgreensheenindicateonanEosinMethyleneBlueplate? 4. Whatadditionalinformationdidthelactosefermentationtubesprovide? 5. Whycouldn’tweexamineanyanaerobicbacteriathatarepartofthenormaldigestivesystem?