Sanitation work sheet Answer Key Not to be turned in..............

ä.2 Name: ___________________________________________Sanitation work sheetAnswer Key Not to be turned in..............1)What are the four general considerations for effective microbial control? List and describe (8 pts)1) Sterilization: complete removal or destruction of all viable microbes. Used oninanimate objects2) Disinfection: use of physical process or chemical agent to destroy vegetative microbes- not endospores3) Antisepsis - chemical applied to the body surfaces to destroy or inhibit vegetativemicrobes4) Sanitation/degermation - chemical and physical methods that reduce the microbial loadon a surface.2) Does de-germing of skin involve sterilization or sanitation processes and why? (4 pts)De-germing the skin involves a sanitation process and not sterilization. Sterilize the skinwould involve destroying the skin to kill all bacteria hiding in the hair follicles of theskin.3) Describe the five factors that affect microbial death rates? (10 pts)1) The number of organisms: the higher the load of contaminants requires moretime to destroy the microbes.2) The nature of the microorganism in the population3) The temperature and pH of the environment4) the concentration of the agent used to kill the microbe5) the mode of action (MOA) of the agent. How does it kill or inhibit the microbe?

4) Describe the four modes of action for a good antimicrobial agents. (8 pts)1) Cell wall, 2) cell membrane; 3) cellular synthesis processes (DNA RNA);4) Denaturation of Protein1) Cell Wall:a)Blocking cell wall synthesis;b) digesting the cell wall;c) breaking down the cell wall i.e. penicillin, detergents and alcohols2) Cell membranea) surfactants: lower surface tension of cell membranes disrupting phospholipidbi-layer resulting in leaky membranes3) cellular biosynthesis of DNA RNAa) agents irreversibly binds to DNA preventing it transcriptionb) agents can cause mutations in coding genes4) Altered Protein functiona) Denaturation of 3D structureb) Metallic ions bind to active sites of proteins preventing interactions withsubstrates5) Compare and contrast the relative effectiveness of moist heat to that of dry heat?(Please make a Table for this descriptive purpose (12 pts))Moist heat:Dry heat :Steam under pressureAutoclave 121C for 15 min vs. 134C for 3 minNon-pressurized steamTyndallization intermittent sterilization repeated heatingcycles over 60 min time several times repeated.Boiling waterBoiling water (100C for 30 minutes) does not kill resistant sporebe will kill most non-spore forming microbesPasteurization (See table provided during lecture)Oven heat at 121C for 120 minutes vs. 170 for 60 minutesDehydrates cellsDenature cellsOxidizes cells6) What is considered an effective temperature and time for the Pasteurization of milk products withoutdestroying milk favor? (4 pts)Flash method: 71.6C for 15 seconds. This method is preferable beacuse it is lesslikely to change flavor or nutrient content and effective against Coxiella andMycobacterium.

7) Draw, annotate and discuss the following graphs for a good bacteriostatic, bacteriocidal, and bacteriolyticagents upon microbial population. (Label the graph) (12 pts)See attached appendix material8) Ultra violet (U.V.) radiation can be used for sterilization. At what frequency does U.V. radiation work at;What is it’s mode of action; B) limitations and C) where would UV light be used to control microbes? (5 pts)A frequency of 185 and 260~5 nm. Mode of Action (MOA) surface sterilant causingpyrimidine dimers, also causing photochemical products called free radicals. UVradiation passes through air slightly through liquids, and poorly through solids. Used inhospital rooms, operating tables, food preparation areas, and dental offices. Also used tocurtail the growth of microbes in food processing plants and slaughterhouse.9) How is food lyophilizing? Is a food product sterilized by this method? Why or why not? (6 pts)Food is freeze dried at low temperatures low pressure. Microbes require water to live andare not necessarily killed by this method of food preservation. Upon rehydrationmicrobial decay once again begin its activity.10) How does cooling cooked food products down to 3.3C reduce spoilage? Explain! Does freezingtemperature kill microbes such as Clostriduim? Why (6 pts)Most food destroying microbes live best at 37C. Cooling food to 3.3C reduces afavorable environment for microbial growth but does not necessarily stop its growth. Onthe other hand, while freezing stops microbial growth it does not kill microbes such asClostriduim.

11) Provide 3 examples that antiseptic methods can be employed to prevent bacterial entry into the humanblood system in the medical profession (6 pts)1) Preparing the skin before surgical incisions with iodine compounds2) Swabbing an open root canal with hydrogen peroxide3) Ordinary hand washing with a germicidal soap12) What is the mode of action of chorine, soaps, and heavy metals? (9 pts)Chlorineorganic oxidant of sulfhydryl groupsand interferes with disulfide bridges.Highly affect disinfectants andantiseptics Toxic to living tissuessoups sufactants emulsifies microbes anddisrupts their membraneintegrityHeavy metals (Zinc, silver, mercury) Binds to Metals are very toxic to humans iffunctional protein groups ingested, inhaled, or absorbedin-activating them. through the skin. Causes allergicreactionsG:\Tests\Microbiology Test\Work sheet\Sanitation\Micro 231 Lec Test 3 F06 take home_answers B.wpdAppendix

Log ofCellsTotal CountViable CountBacteriostaticTime

Log ofCellsBacteriocidalTime

Log ofCellsBacteriolyticTime