Ch26 Lecture Outline

8/2/2019 Ch26 Lecture Outline

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Copyright 2011 Pearson Education Inc.

Lecture prepared by Mindy Miller-Kittrell, University of Tennessee, Knoxville

M I C R O B I O L O G YWITH DISEASES BY TAXONOMY, THIRD EDITION

Chapter 26 Applied and Environmental Microbiology


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Food Microbiology

Microorganisms involved in producing many foods and beverages

Fermentation produces characteristic flavors, aromas, andconsistencies of various foods

Microbial metabolism has other functions

Acts as a preservative

Destroys many pathogenic microbes and toxins

Can add nutritional value in form of vitamins or other nutrients

Microbes are used in food production

Microbes can control activity that would result in food spoilage


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Food Microbiology

The Roles of Microorganisms in Food Production

Fermentation (in food microbiology terms)

Any desirable change that occurs to a food or beverage as a

result of microbial growth

Spoilage is unwanted change to a food due to various reasons

Undesirable metabolic reactions

Growth of pathogens

Presence of unwanted microorganisms in the food


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Food Microbiology


Starter cultures used in commercial food and beverageproduction

Composed of known microorganisms that consistently

perform specific fermentations

Many common products result from fermentation of vegetables,

meats, and dairy products


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The cheese-making process

Figure 26.1


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Food Microbiology


Products of alcoholic fermentation

Alcoholic fermentation

Process by which various microorganisms convert simple

sugars into alcohol (ethanol) and carbon dioxide (CO2)

Specific starter cultures used in the large-scale commercial

applications of alcohol fermentation

Various alcoholic products made through fermentation


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The wine-making process

Figure 26.2



The beer-brewing process

Figure 26.3



Food Microbiology

The Causes of Food Spoilage

Food spoilage results from intrinsic or extrinsic factors

Intrinsic factors

Inherent properties of the food itself

Extrinsic factors

Involved with the processing or handling of food



Food Microbiology


Classifying foods in terms of potential for spoilageThree categories based on likelihood of spoilage

Perishable

Nutrient rich, moist, and unprotected by coverings

Semi-perishable

Can store sealed for months without spoiling

Many fermented foods are semi-perishable

NonperishableDry or canned foods that can be stored indefinitely

Often nutrient poor, dried, fermented, or preserved



Food Microbiology


The prevention of food spoilage

Food-processing methods

Industrial canning

Eliminates mesophilic bacteria and endospores

Pasteurization

Lowers microbe numbers but some microbes survive

Lyophilization

A vacuum draws off ice crystals from frozen foods

Gamma radiation

Can achieve complete sterilization



Industrial canning

Figure 26.4



Food Microbiology



Use of preservatives

Salt and sugar remove water from the food

Garlic contains allicin, which inhibits enzyme functionBenzoic acid interferes with enzymatic function

Certain spices and herbs interfere with the functions of

membranes of microorganisms

Chemical preservatives can be purposely added to foods



Food Microbiology



Attention to temperature during processing and storage

High temperatures desirable to prevent food spoilage

Proteins and enzymes become denatured

Low temperatures are desirable for food storage

Cold slows metabolism and retards microbial growth

Listeria monocytogenes can grow in cold storage

Found in certain dairy products



Food Microbiology

Foodborne Illnesses

Due to consumption of spoiled foods or foods containg harmfulmicrobes or their products

Two categories of food poisoning

Food infections

Consumption of living microorganisms

Food intoxications

Consumption of microbial toxins rather than the microbe

Symptoms include nausea, vomiting, diarrhea, fever, fatigue,and muscle cramps



Industrial Microbiology

Important field within the microbiological sciences

Industrial microbiology used in various applications

Microbes in fermentation

Microbes in the production of several industrial products

Treatment of water and wastewaters

Disposal and cleanup of biological wastes

Treatment of mine drainage




The Roles of Microbes in Industrial Fermentations

Industrial fermentations

Large-scale growth of particular microbes for producing

beneficial compounds

Examples include amino acids and vitamins


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The Roles of Microbes in Industrial Fermentations

Primary metabolitesProduced during active growth and metabolism

Required for reproduction or are by-products of metabolism

Secondary metabolites

Produced after the culture has entered stationary growth

Substances are not immediately needed for growth


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Fermentation vats

Figure 26.5


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Industrial Products of Microorganisms

Microorganisms produce array of industrially useful chemicals

Recombinant organisms add to this diversity

Produce substances not normally manufactured by microbial

cells


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Enzymes and other industrial products

Microbial products used as food additives and supplements

Include vitamins, amino acids, organic acids, dyes

Alternative fuels

Some microbes produce carbohydrates used as fuels

Other microbes convert biomass into renewable fuels

Pharmaceuticals

Includes antimicrobials, recombinant hormones, and other

cell regulators


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Pesticides and agricultural productsMicrobes used to help crop management

Biosensors and bioreporters

Use of microorganisms to solve environmental problems

Biosensors

Bacteria or microbial products combined with electronicmeasuring devices

Bioreporters

Composed of microbes with innate signaling capabilities


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Water Treatment

Water pollutionWater pollution can occur three ways

Physically

Presence of particulate matter

Chemically

Presence of inorganic or organic compounds

Biologically

Too many or non-native microorganisms

Polluted waters support a greater than normal microbial load

I d i l Mi bi l


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Water Treatment

Waterborne illnessesConsuming contaminated water can cause various diseases

Diarrheal diseases occur worldwide

Waterborne diseases rare in the United States

Outbreaks are point-source infections

Water treatment removes most waterborne pathogens

I d t i l Mi bi l


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Water Treatment

Treatment of drinking water

Potable water is water considered safe to drink

Water is not devoid of microorganisms and chemicals

Levels are low enough that it is not a health concernPresence of coliforms in water indicates fecal contamination

Increased likelihood disease-causing microbes present

Treatment of drinking water involves four stages

Th t t t f d i ki t


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The treatment of drinking water

Figure 26.7

I d t i l Mi bi l


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Water Treatment

Water quality testingMajority of waterborne illnesses caused by fecally

contaminated water

Indicator organisms signal possible presence of pathogens

E. colior other coliforms used as indicator organisms

E. coliis a good indicator organism

Consistently found in human waste

Survives in water as long as most pathogens

Easily detected by simple tests

T t lit t t


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Two water quality tests

Figure 26.8

I d t i l Mi bi l


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Water Treatment

Treatment of wastewater

Wastewater (sewage)

Water that leaves homes or businesses after use

Wastewater contains a variety of contaminants

Treatment intended to remove or reduce contaminants

Processed to reduce the biochemical oxygen demand (BOD)

Oxygen needed by aerobic bacteria to metabolize wastesin water

Levels reduced so unable to support microbial growth

T diti l t t t


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Traditional sewage treatment

Figure 26.9

A h ti t


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A home septic system

Figure 26.10

Waste ater treatment in an artificial etland


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Wastewater treatment in an artificial wetland

Figure 26.11

Environmental Microbiology


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Studies the microorganisms as they occur in their natural habitats

Microbes flourish in every habitat on Earth

Microbes are important to the cycling of chemical elements



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Microbial Ecology

Study of the interrelationships among microorganisms and the

environment

Two aspects to consider

Levels of microbial associations in the environment

Role of adaptation in microbial survival

Relationship among microorganisms and the environment


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Relationship among microorganisms and the environment

Figure 26.12



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Microbial Ecology


Most microorganisms live in harsh environments

Microbes must be specially adapted to survive

Microbes must adapt to constantly varying conditions

Extremophiles

Adapted to extremely harsh conditions

Can only survive in these habitats



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Microbial Ecology


Biodiversity held in balance by various checks

Competition

Best-adapted microorganisms have advantageoustraits

Antagonism

One microbe actively inhibits the growth of another

Cooperation

One microbe makes environment favorable for others



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Bioremediation

Uses organisms to clean up toxic, hazardous, or recalcitrant

compounds by degrading them to harmless compounds

Most known application is use of bacteria to clean oil spills



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Two Types of Bioremediation

Natural bioremediationMicrobes encouraged to degrade toxic substances in soil or

water

Addition of nutrients stimulate microbe growth

Artificial bioremediation

Genetically modified microbes specifically degrade certain

pollutants



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The Problem of Acid Mine Drainage

Drainage results from exposure of certain metal ores to oxygenand microbial action

Resulting compounds are carried into streams and rivers

Causes decrease in pH

Can kill fish, plants, and other organisms

Acidic water unfit for human consumption

Some microbes flourish in these acidic conditions

The effects of acid mine drainage


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The effects of acid mine drainage

Figure 26.13

An acid-loving microbe


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An acid-loving microbe

Figure 26.14



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Role of Microorganisms in Biogeochemical Cycles

Biogeochemical cycles

Processes by which organisms convert elements from one

form to another

Elements often converted between oxidized and reducedforms

Involve the recycling of elements by organisms



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Role of Microorganisms in Biogeochemical Cycles

Biogeochemical cycling entails three processesProduction

Inorganic compounds converted into organic compounds

ConsumptionOrganisms feed on producers and other consumers

Decomposition

Conversion of organic compounds in dead organisms into

inorganic compounds

Simplified carbon cycle


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Simplified carbon cycle

Figure 26.15

Simplified nitrogen cycle


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Simplified nitrogen cycle

Figure 26.16

Simplified sulfur cycle


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Simplified sulfur cycle

Figure 26.17



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Role of Microorganisms in Biogeochemical Cycle

Phosphorus cycle

Phosphorus undergoes little change in oxidation state in the

environment

Phosphorus converted from insoluble to soluble forms Becomes available for uptake by organisms

Conversion of phosphorus from organic to inorganic forms

Occurs by pHdependent processes



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Role of Microorganisms in Biogeochemical Cycle

The cycling of metals

Metal ions are important microbial nutrients

Primarily involves transition from insoluble to soluble forms

Allows trace metals to be be used by organisms



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Soil Microbiology

Examines the roles played by organisms living in soil

Nature of soils

Soil arises from the weathering of rocks

Soil also produced through the actions of microorganisms

The distribution of microorganisms and nutrients in soil


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The distribution of microorganisms and nutrients in soil

Figure 26.18



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Soil Microbiology

Environmental factors affecting microbial abundance in soilsMoisture content

Moist soils support microbial growth better than dry soils

OxygenOxygen dissolves poorly in water

Moist soils are lower in oxygen than dry soils

pHHighly acidic and highly basic soils favor fungi



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Soil Microbiology

Environmental factors affecting microbial abundance in soils

Temperature

Most soil organisms are mesophiles

Nutrient availability

Microbial community size determined by how much

organic material is available



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Soil Microbiology

Microbial populations in soilsMicrobial populations present in the soil

Bacteria are numerous and diverse inhabitants of soil

Archaea present but are difficult to culture and study

Fungi are also populous group of microorganisms

Algae and protozoa are also present in the soil

Microbes perform a number of functions

Cycle elements and convert them to usable form

Degrade dead organisms

Produce compounds with potential human uses

Selected soilborne diseases of humans and plants


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p

Table 26.7



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Aquatic Microbiology

Study of microbes living in freshwater and marine environments

Water ecosystems support fewer microbes than soil

Due to dilution of nutrients

Types of aquatic habitats

Freshwater systems characterized by low salt content

Marinesystems characterized by a salt content of about

3.5%

Specialized aquatic systems salt lakes, iron springs, andsulfur springs



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Aquatic Microbiology

Types of aquatic habitatsFreshwater systems

Characterized by low salt content

Marinesystems

Characterized by a salt content of about 3.5%

Specialized aquatic systems

Salt lakes, iron springs, and sulfur springs

Vertical zonation in deep bodies of water


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p

Figure 26.19

Biological Warfare and Bioterrorism


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Microbes can be fashioned into biological weapons

Bioterrorism

Uses microbes or their toxins to terrorize human populations

Agroterrorism

Uses microbes to terrorize human populations by destroying thefood supply



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Assessing Microorganisms as Potential Agents of Warfare or

Terror Not all organisms have potential as biological weapons

Governments have criteria to assess biological threats to humans

Established to evaluate the potential of microorganisms to be

weaponized

Helps focus research and defense efforts where needed



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Assessing Microorganisms as Potential Agents of Warfare or

TerrorCriteria for biological threats to humans based on:

Public health impact

Ability of hospitals and clinics to handle the casualties

Delivery potential

How easily agent can be introduced into the population

Public perception

Effect of public fear on ability to control an outbreak

Public health preparedness

Existing response measures



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Assessing Microorganisms as Potential Agents of Warfare or Terror

Criteria for assessing biological threats to livestock and poultry

Criteria similar to those used to evaluate potential human threats

Include agricultural impact, delivery potential, and plausible

deniability



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Assessing Microorganisms as Potential Agents of Warfare or Terror

Criteria for assessing biological threats to agriculture crops

Plant diseases generally not as contagious as animal or human

diseases

Criteria based on several factorsPredicted extent of crop loss

Delivery and dissemination potential

Containment potential



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Known Microbial Threats

Various microorganisms currently considered threats as agentsof bioterrorism

Three types

Human pathogens

Animal pathogens

Plant pathogens

Bioterrorist threats to humans


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Copyright 2011 Pearson Education Inc. Table 26.8



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Animal pathogens

Divided into categories based on level of danger

Some agents could potentially amplify an outbreak

Infect wild animal populations in addition to livestock

Foot-and-mouth disease is most dangerous of the agents

It affects all wild and domestic cloven-hoofed animals



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Plant pathogens

Most potential agents are fungi

Dissemination could easily result in contamination of soils

All agents are naturally present

Detecting difference between a natural outbreak and an

intentional attack would be difficult



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Defense Against Bioterrorism

Much can be done to limit impact of an attack

Key is coupling surveillance with effective response protocols

One aspect of the response to a bioterrorist attack


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Copyright 2011 Pearson Education Inc. Figure 26.20



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Defense Against Bioterrorism

AgroterrorismThere is little security protecting nations agricultural

enterprises

Livestock and poultry often moved around the country

without being tested for disease

Many agricultural facilities are open to the public

Methods to help defend against agroterrorism

Screening of animals

Restricting public access to agricultural facilities



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The Roles of Recombinant Genetic Technology in Bioterrorism

Could use to create new or modify biological threatsTraits of various agents could be combined to create novel

agents

No immunity would exist in the population

Terrorists theoretically could make their own microbes



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The Roles of Recombinant Genetic Technology in Bioterrorism

Could be used to thwart bioterrorism

Scientists can identify unique genetic sequences

May aid in tracking biological agents and determining

their source

Genetic techniques could help develop vaccines, treatments,

and pathogen-resistant crops

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Ch26 Lecture Outline