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Lab Report 17 and 18.docx - Running head: b Report 17 & 18...

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Running head: b Report 17 & 181Lab Report 17 & 18Florida Atlantic UniversityAbstract
LAB REPORT 17 & 182The following research on the effects of ultraviolet light on bacteria as well as antiseptics,antibiotics, and disinfectants, Chapter 17’s lab results showed that ultraviolet light affects thegrowth of a bacteria.Staphylococcus aureushad heavy growth most of the time it was spentunder the ultraviolet light as well asEscherichia coli.As for XLI Blue the growth fluctuatedfrom moderate to little/no growth. This means that the ultraviolet light was able to kill the XLIBlue II then the other two bacteria. Chapter 18 measured the zone of inhibition and compared itto known standards. Results were measured in millimeters for chapter 18. The purpose of thisexperiment (chapter 18) is to see determine the effectiveness of the antibiotics and disinfectantson bacteria. If the technique is done appropriately, then the organism could be determinedresistant, susceptible or intermediate to antimicrobial agents and disinfectants based on the zoneof the inhibition. We saw thatEscherichia colishowed no zone of inhibition (0 mm) to bleach,CVS mouthwash, Lavoris mouthwash, penicillin, and bacitracin.Staphylococcus aureushad 0mm of zone of inhibition to ampicillin. This study has shown that disinfectants have no effect onEscherichia colicompared toStaphylococcus aureus.Gram positive bacteria are moresusceptible to chemical disinfectants while mycobacteria or bacterial endospores are moreresistant.Keywords: ultraviolet light, antiseptics, disinfectants, antibiotics
LAB REPORT 17 & 183IntroductionIn both labs chapter 17 and 18, we were introduced to effects of ultraviolet light onbacteria as well as determining as to whether the organism is susceptible, intermediate, orresistant to an agent by measuring zone sizes obtained and measuring them to NCCLS (NationalCommittee for Clinical Laboratory Standards). Firstly, solar ultraviolet (UV) radiation is a non-ionizing radiation which means that it is any type of electromagnetic radiation that does not carryenough energy to ionize atoms or molecules to completely remove an electron from an atom ormolecule. There are three types of solar UV radiation: UV-A, UV-B, and UV-C. UV-A emanates320 – 400 nm and encompasses approximately 95% of solar UV radiation. Furthermore, UV-A ispoorly absorbed by DNA molecule and forms little or no DNA photoaducts, so it indirectlyinduces DNA damage by the activation of certain proteins (photosensitizers). At 290 – 320 nm,UV-B is emitted. For UV-B to form pyrimidine dimers it directly absorbs nucleic acids.Pyrimidine dimers are molecular lesions formed from thymine or cytosine bases in DNA viaphotochemical reactions. Ultraviolet light induces the formation of covalent linkages byreactions localized on the C=C double bonds (Jiang, 2009). The dimers are to two thymine thatare adjacent and covalently crosslinked on the same DNA strand. The distortion caused by the

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Term
Fall
Professor
SMITH
Tags
Bacteria, DNA, Ultraviolet, gram negative bacteria

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