BIOS 242 Week 6 Lab 1 Bacteria of the skin Chamberlain

Lab11:BacteriaoftheSkin LearningObjectives: • Identifythegrowthofskinbacteriaondifferenttypesofselectiveanddifferentialmedia. • Identifypathogenicfromnon-pathogenicbacteria Introduction: Our skin forms the first line of defense. It has several characteristics that makes it an inhospitable environment for the growth of most microbes. Some of thesecharacteristics of skin include: high percentage of salt, low pH from 4-5.5, sebum, antimicrobial chemicals; an outer layer of dead skin cells that acts as a barrierto pathogens; mechanical defenses such as continuous sloughing off of skin, and dendritic macrophages. Skin also harbors a range of resident microbiotaincludingStaphylococcusandDiptheriaespeciesthatactasnormalantagonistmicrobiota…..Continue Materials: MSAplates,nutrientagarplates,sterilewater,sterileswabs,marker,ruler,pureculturesofB.subtilis,E.coli,S.marcescensandS.epidermidis,inoculatingloops,incinerators Method: 1. Forthisexperiment,youwillworkinateamof4students. 2. ObtaintwoMSAplatesandtwonutrientagarplatesperteam. 3. TakeoneMSAplateanddivideitinfourparts. 4. Labeleachquadrantcorrectlywiththenameofthebacteria.Don’tforgettowriteinitialsofyournamesoneachplate. 5. Forthegivenbrothcultures,useaseptictechniqueandstreakbacteriaontheplateappropriatelyaslabeled. 6. TakethesecondMSAplateanddivideitinthreeparts.Labeleachpartcorrectlywiththenameofthebacteria. 7. Swabyourskinandstreaktheappropriatearea. 8. Repeattheabovelistedstepsforthetwonutrientagarplates. 9. Incubatetheplatesat37◦Covernight. 10. Observethesealedplateforgrowthandrecordyourobservationsinthelabreportandanswerallquestions. 11. Onceobservationiscompleted,immediatelyputtheplatesinappropriatewastecontainerforautoclaving. LabReport: Purpose:Describethepurposeofthislab. Results: SourceofSkininoculum:_____ Questions 1. Whyismannitolsaltagarusedasaselectivemediumfornormalskinmicrobiota? 2. HowisMSAadifferentialmedia? 3. Listthreefactorsthatprotecttheskinfrominfection. 4. Which organisms did not grow on MSA plate?6