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Foundations in Microbiology
Seventh Editionss
Chapter 27
Lecture PowerPoint to accompany
Talaro
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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27.1 Applied Microbiology and Biotechnology
• Applied microbiology – microbes are used to treat wastewater and bioremediate damaged environments
• Industrial microbiology – use of microbes in making food, medical, manufacturing, and agricultural products
• Biotechnology – uses microbes for practical applications
• Fermentation – controlled culture of microbes to produce desired organic compounds
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Water and Wastewater Treatment
Water purification• In most cities, water is treated in a stepwise process
before it is supplied to consumers• Impoundment in large, protected reservoir – storage
and sedimentation; treated to prevent overgrowth of cyanobacteria
• Pumped to holding tanks for further settling, aeration, and filtration; chemical treatment with a chlorine, ozone, or peroxide disinfectant
Figure 27.1 Major steps in water purification
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Sewage treatment• Sewage – used wastewater containing chemicals,
debris, and microorganisms• Typically requires 3 phases:
– Primary phase – removes floating, bulky physical objects
– Secondary phase – removes the organic matter by biodegradation, natural bioremediation in a large digester forming sludge which is aerated by injection and stirred
– Tertiary phase – filtration, disinfection, and removal of chemical pollutants
• Gradually released• Anaerobic digesters: turn sludge into a secondary
source of energy
Figure 27.3 The primary, secondary, and tertiary stages in sewage treatment
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Insert figure 26.24Sewage treatment
Figure 27.4 Treatment of sewage and wastewater
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27.2 Microorganisms and Food
• Microbes and humans compete for nutrients in food
• The effects of microorganisms on food can be– Beneficial– Detrimental– Neutral
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Microbial Fermentations in Food Products
Microbes, through fermentation, can impart desirable aroma, flavor, or texture to foods (starter cultures)
• Bread – yeast leaven dough by giving off CO2
• Beer – fermentation of wort• Wine – fermentation of fruit juices• Vegetable products – sauerkraut, pickles• Vinegar – fermentation of plant juices• Milk and dairy products – cheeses, yogurt
Figure 27.5 Hops
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Figure 27.7
Wine making
Figure 27.8 Microbes at work in milk products
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Figure 27.9 Cheese making
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Microorganisms as food
• Mass-produced yeasts, molds, algae, and bacteria
• Single-celled protein and filamentous mycoprotein added to animal feeds
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Microbial Involvement in Food-Borne Diseases
• Food poisoning – diseases caused by ingesting food
• 2 types:– Food intoxication – results from ingesting exotoxins
secreted from bacterial cells growing in food– Food infection – ingestion of whole microbes that
target the intestine – salmonellosis, shigellosis
• Other common agents – Campylobacter, Salmonella, Clostridium, Shigella, Staphylococcus aureus
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Insert figure 26.31Food-borne illnesses
Figure 27.10 Food-borne illnesses
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Prevention Measures for Food Poisoning and Spoilage
• Prevent incorporation of microbes into food– Aseptic technique– Handwashing and proper hygiene
• Prevent survival or multiplication of microbes in food– Heat – autoclaving, pasteurization, cooking– Cold – refrigeration, freezing– Radiation – UV, ionizing– Chemical preservatives – NaCl, organic acids– Dessication– Spraying of bacteriophages
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Figure 27.11 Preventing food poisoning and
spoilage
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Figure 27.12 Pasteurizer
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Figure 27.13 Temperatures and microbial
growth
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27.3 General Concepts in Industrial Microbiology
• Bulk production of organic compounds such as antibiotics, hormones, vitamins, acids, solvents, and enzymes
• Many processes involving fermentation
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• Mutant strains of bacteria and fungi that synthesize large amounts of metabolic intermediates (metabolites)
• Primary metabolites – produced during major metabolic pathways and are essential to microbe’s function – Amino acids, organic acids synthesized during logarithmic
growth
• Secondary metabolites – by-products of metabolism that may not be critical to microbe’s function – Vitamins, antibiotics, and steroids synthesized during
stationary phase
Figure 27.14 Primary and secondary microbial metabolites harvested by industrial
processes
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Tricks to Increase the Amount of Chosen End Product
1. Manipulate growth environment to increase synthesis of metabolite
2. Select strains that genetically lack a feedback system
3. Many syntheses occur in sequential fashion involving more than one organism
– Biotransformation – waste product of one organism becomes the building block of the next
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Figure 27.15 Example of biotransformation
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From Microbial Factories to Industrial Factories
• Produce appropriate levels of growth and fermentation in a carefully controlled environment
• Commercial fermentation carried out in fermentors – a device in which mass cultures are grown, reactions take place, and product develops
Figure 27.17
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Substance Production
• Steps in mass production:1. Introduction of microbes and sterile media into
reaction chamber2. Fermentation3. Downstream processing (recovery, purification,
packaging)4. Removal of waste
• Carried out aseptically and monitored for rate of flow and quality of product
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Figure 27.18Layout for a fermentation plant
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• Batch fermentations – substrate added to system all at once and taken through a limited run until product is harvested
• Continuous feed systems – nutrients are continuously fed into the reactor and product is siphoned off throughout run
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• Pharmaceutical products– Antibiotics– Hormones– Vitamins– Vaccines
• Miscellaneous products– Biopesticides– Enzymes– Amino acids– Organic acids– Solvents– Natural flavor compounds