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Lab 7 - Outline (47, .docx - Lab 7 – Temperature,...

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Lab 7 – Temperature, Antibiotics, AntisepticsTemperature: Lethal Effects Talk (47)Proteins and Enzymes are denatured by heat resulting in irreversible damage.Dna can be damaged/lose structure in heat resulting in loss of nucleic acids. Leading tocell death.NAD+ and other coenzymes can be damaged by heat.Some organisms are more resistant to heat because they form endospores. Bacillus andClostridium form endospores. And these structures are more resistant to hear thanvegetative cells.-Endospores have a lower water content than vegetative cells, bc of this theirmacromolecules are less susceptible to denaturation. Endospore is dehydrated,water is not available for harmful chemical reactions.-Endospores contain calcium dipicolinate which plays a vital role in heatresistance by preventing thermally induced denaturation of proteins. Calciumprovides resistance to oxidizing agents that can destroy proteins, nucleic acids,and macromolecules.-Proteins found in the endospore are capable of binding to nucleic acids andpreventing their denaturation.-All these factors ensure endospore remains dormant and unchanged sothat it will give rise to viable cells when conditions are reestablished forgermination and growth.Methods of comparison:-Thermal death point (TDP):is the lowest temperature at which a population of a targetorganism is killed in 10 minutes.Thermal death time (TDT):is the shortest time required to kill a suspension of cells orspores under defined conditions at a given temperature-Factors such as pH, moisture, medium composition, and age of the cells caninfluence results.-important in food industry because canned foods must be heated totemps that kill endospores of Clostridium botulinum and Clostridium perfringens (foodborne illness pathogens).1.We will not “do” this lab online, but students should know it like a “Do” lab!!!2.The procedure is to inoculate and incubate 3 different bacteria at 3 different HOTtemperatures – to see if/how they survivea.Broth tubes of the 3 cultures are placed into 60°C, 80°C, and 100°C waterbathsb.Every 10 min. you will remove 0.1ml and plate it out to check for viabilityc.++++ = 10, 20, 30, 40 min.

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Term
Fall
Professor
CarlKulow
Tags
Bacteria, staph

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