FSHN Lecture 22.pptx - Lecture 22 Introduction to Microbiology Lecture 22 Learning After this lecture you should be able to Goals Distinguish between

FSHN Lecture 22.pptx - Lecture 22 Introduction to...

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Lecture 22: Introduction to Microbiology
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Lecture 22 Learning Goals After this lecture, you should be able to: Distinguish between “good”, “bad”, and “ugly” microorganisms Recall the factors microorganisms need to grow and survive (i.e., FAT TOM) Identify the differences in shape, size, nuclei, reproduction, spore formation, temperature requirements, oxygen requirements, pathology, and by-products when comparing bacteria, yeast, and mold
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Microorganisms found in food A. General classification The "good" microbes are those used to preserve foods and/or provide other desirable properties to food materials The "bad" microbes are those that cause unacceptable defects in the appearance, flavor, and texture of foods, but present no health hazards to consumers The "ugly" microbes are those that cause food- borne illness (food infection or food intoxication)
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What microorganisms need to grow and survive A. Important factors: FAT TOM F ood Nutrient availability A cidity Bacteria (narrowest pH range) < yeast < mold (widest pH range) General rule of thumb: pathogenic organisms cannot develop in foods with pH < 4.6
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What microorganisms need to grow and survive A. Important factors: FAT TOM continued T ime T emperature O xygen M oisture Content (more specifically a w ) The classes of microorganisms differ their a w requirements Requirements Bacteria (~0.90 a w and higher), yeast (~0.86 a w and higher), mold (~0.70 a and higher)
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Classes and characteristics of microorganisms Microorganism Shape Size Nuclei Repro- duction Spore Forma- tion Temp. Require- ments Oxygen Require- ments Pathol- ogy By- Product s Bacteria Rods, Spheres , Spirals Small, typically about 1 micron in length Does not have a nuclei (prokary otic) Asexual, capable of rapid expone ntial growth Yeast Mold This table is intended as a study tool. After reviewing slides 6 – 31, return to this table and complete the table. Highlight unique characteristics of each group.
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A. Bacteria Shape: Rods (bacilli) Spheres (cocci) Spiral Classes and characteristics of microorganisms Figure 22.1. Common bacteria shapes
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Size: small, typically around 1 micron (μm) in length or diameter Nuclei: does not contain a nucleus (prokaryotic organism) Movie 22.1 – Prokaryotes vs. Eukaryotes (RicochetScience) Classes and characteristics of microorganisms
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Reproduction: asexual, capable of very rapid exponential growth (see Figure 22.2) Asexual growth does not refer to the size of the microorganism, but rather the size of the population The size of the population doubles in every phase of growth Classes and characteristics of microorganisms
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