BIOM 250 1st Edition Lecture 10Outline of Last Lecture I. Physical RequirementsII. Chemical requirementsIII. BiofilmsIV. CommunicationV. Bacterial GrowthVI. Control of GrowthVII. Effectiveness of TreatmentOutline of Current Lecture I. Controlling MicrobesII. Effective DisinfectionIII. PhenolsIV. HalogensV. AlcoholsVI. Chemical Food PreservativesVII. AldehydesVIII. Hydrogen PeroxideIX. DiseaseX. Normal MicrobiotaThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.XI. Opportunistic PathogensXII. EtiologyCurrent LectureI. Controlling Microbes: Damagea. Damaged by alterations of membrane permeabilityi. Makes the microbes more subject to osmotic damage and cell lysisb. Damaging proteins is extremely effective because enzyme structure is critical to cellular functionc. Damage to nucleic acids is usually lethal and causes extensive damage that cannot be repairedd. Heat:i. Heat denatures proteins and enzymes (irreversible)ii. Boiling kills bacterial pathogens, most viruses, fungi and fungal spores—but NOT endosporesiii. Autoclaving—steam under pressure—raises temperatures above boiling point1. This kills endospores2. Liquids sterilize faster due to convection currents3. Solids take longer for heat to penetratee. Pasteurization:i. Mild heatingii. Originally used for preservation of beer and wineiii. Eliminates spoilage or pathogenic bacteria, but not all of itiv. Equivalent treatments1. 63° C for 30 minutes2. High-temperature for a short time: 72° for 15 seconds3. Ultra-high temperature: 140°C for less than 1 second4. Still, some heat resistant organisms survive making spoilage possibleII. Effective Disinfectiona. Based on:i. Concentration of disinfectant1. Most have an optimum effective concentration that is suggested2. May also have a pH optimumii. Organic matter1. Can bind to disinfectant, doesn’t reach targetiii. Time1. How long a disinfectant is used on an agent is based on the structure/size of the agentIII. Phenol and Phenolicsa. Attack and disrupt plasma membranesi. Cause leakages of cellular componentsb. Disk-diffusion method tests effectiveness against specific bacteriumi. Works by placing an infused disk on a lawn of bacterium and observing inhibition of growthIV. Halogensa. Iodine- active against bacteria, endospores, fungi, some parasites, and virusesi. Tinctures: in aqueous alcoholii. Iodophors: in organic molecules; slow releaseiii. Alter protein synthesis and forms a complex with membranes and disrupts functionb. Chlorine- broadly effective and VERY reactivei. Bleach- chlorine + water forms hypochlorous acidii. Penetrates cell walliii. Chlorine is an oxidizing agent and stops enzyme functionsV. Alcoholsa. Ethanol; isopropanoli. Kills bacteria, fungi, enveloped viruses—but NOT endospores and non-enveloped virusesii. Denatures proteins and dissolves lipidsiii. Alcohol requires some water in its solution in order to be effectiveb. Quaternary ammonium compounds (Quats)i. Cationic, likely targets membrane permeabilityii. Targets G+, fungi, amoeba, and enveloped virusesVI. Chemical Food Preservativesa. Organic acidsi. Examples: sorbic acid, benzoic acid, and calcium propionateii. Inhibits metabolism and disrupts plasma membrane in moldsiii. Most effective at the low pH that molds favor to grow inb. Nitrates/nitrites in meat productsi. Nitrates are reduced to nitrites by the bacterium in meat productsii. Nitrites prevent endospore germinationVII. Aldehydesa. Aldehydes inactivate proteins by cross-linking with functional groupsb. Examples: formaldehyde, glutaraldehydei. Preserve biological specimens ii. Sterilize medical instrumentsiii. Bactericidal against tuberculosis bacteriumVIII. Hydrogen peroxidea. Oxidizing agent- produces reactive oxygen and has many cellular targetsb. Best for contaminated surfacesi. Safer option because it degrades into water and oxygenIX. Diseasea. Pathogen- an organism capable of causing diseaseb. Pathogenesis- how a disease developsc. Disease- abnormal state of functiond. Normal flora- microbes that symbiotically interact with an animali. Can be beneficial to hostii. Found on and in many areas of the bodye. Symbiosis- when at least one organism is dependent on anotheri. Mutualism—both organisms benefitii. Commensalism—one organism benefits while the other is unharmediii. Parasitism—one organism lives at the expense of another organism and causes harm to itX. Normal Microbiotaa. Skin acts a barrier to disease because it is a dry surface and has selective secretionsb. Intestines contain MANY resident microbiota that interact with the bodyi. The mucous layer of the intestines is critical for protection and functionc. Reproductive systems have resident populations that are not usually harmfuli. Normal flora is present in the vaginaXI. Opportunistic Pathogensa. Foreign microbe:i. Chance contact with a foreign microbe allows its growthb. Normal microbiota:i. While many resident microbes are not harmful they have the potential to become toxigenic or invasiveii. Example: E.coliXII. Etiologya. How do you identify the cause of a disease? Use Koch’s Postulates:i. The same pathogen must be present in every case of the disease.ii. The pathogen must be isolated from the diseased host and grown in pure culture.iii. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.iv. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.b. Disease Occurrence:i. Incidence- the number of cases in a specific time periodii. Prevalence- the number of people in a population with the disease at a specific timeiii. Endemic- a disease constantly present in a specific populationiv. Epidemic- when many people get a disease in a short period of timec. Development of Diseasei. Acute disease- symptoms develop rapidly1. Ex: diarrheaii. Chronic disease- disease develops slowly1. Ex: tuberculosisiii. Latent disease- disease with a period of no symptoms when the causativeagent is inactive1. Ex: