Foundations in

Microbiology Seventh Edition

Chapter 27

Applied and Industrial

Microbiology

Lecture PowerPoint to accompany

Talaro

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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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3

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 26.24 Sewage 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 26.31 Food-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

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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28

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 chamber

2. Fermentation

3. 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 27.18

Layout 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