Microorganisms Fermentation - Defining Microorganisms...

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Defining Microorganisms Free-living single or small number of cells or spores (with at least one exception). Viruses (not cells) take over reproductive mechanisms of cells to replicate virus Single bacteria cells that reproduce (vegetative) Yeasts Molds (fungi) Parasites (multi cell) Prions (protein particles)
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Microorganisms in Foods Desirable (e.g. fermentative) The Good Those causing spoilage The Bad Those causing disease The Ugly Those of no consequence The Nerds
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Defining Fermentation Strict; Anaerobic breakdown of carbohydrates to form CO2, ethanol, and heat. General; aerobic or anaerobic breakdown of chemical components to form a variety of products. Ex: conversion of ethanol to acetic acid by aerobic acetobacter. (oxidation) CH3-CH2-OH CH3-COOH
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Microorganisms: How many? and what type? 0.1-10
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Undesirable microorganisms Related to Foods Those causing disease Those causing spoilage Factors Sources Conditions Outcome/result Severity of outcome Number affected How to control
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Disease causing (pathogenic) Forms 1. Infections: Growth within the host for disease to occur a. b. Cross G.I. lumen invading and growing within the host. 2. Intoxications: Growth within the host is not necessary for disease
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Food-Borne Pathogens
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Transmission of food borne pathogens from feces to humans
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Estimates of Food Borne Disease in the US (annual) 76 million “cases” 325,000 hospitalizations * 5,000 deaths World-wide, diarrhea is leading killer of children (est. 12 million/year) * “Cases” = confirmed individuals “outbreak” = 2 or more confirmed “cases”
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Steps in Host Invasion Survive acidic stomach (pH 2-4) Attach to or colonized intestinal walls Resistance to host defenses Compete against other organisms Produce toxins and/or cross epithelium and enter/infect somatic cells Means that there is likely an “infectious dose or number” that must be consumed.
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Human defenses against food borne pathogens
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Sites of action
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Most common foodborne infections (CDCP, 2008) Campylobacter : bacterial; fever, diarrhea, and abdominal cramps. most common bacterial cause of diarrhea in the world; Source: intestines of healthy birds: most raw poultry has Campylobacter. undercooked chicken, or cross contaminated food. Salmonella : intestines of birds, reptiles and mammals; fever, diarrhea and abdominal cramps. In Immuno compromised, cause sepsis and life- threatening infections. E. coli O157:H7: cattle and similar animals; cow feces; severe and bloody diarrhea, cramps, without fever. 3% to 5% of cases, hemolytic uremic syndrome (HUS) occurs several weeks after initial symptoms. anemia, profuse bleeding, and kidney failure.
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This note was uploaded on 02/16/2010 for the course NS 3450 at Cornell University (Engineering School).

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Microorganisms Fermentation - Defining Microorganisms...

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