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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
The Roles of Microorganisms in Food Production
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
The Roles of Microorganisms in Food Production
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
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The beer-brewing process
Figure 26.3
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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
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Food Microbiology
The Causes of Food Spoilage
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
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Food Microbiology
The Causes of Food Spoilage
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
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Industrial canning
Figure 26.4
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Food Microbiology
The Causes of Food Spoilage
The prevention of food spoilage
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
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Food Microbiology
The Causes of Food Spoilage
The prevention of food spoilage
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
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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
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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
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Industrial Microbiology
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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Industrial Microbiology
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 Microbiology
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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Industrial Microbiology
Industrial Products of Microorganisms
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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Industrial Microbiology
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Industrial Microbiology
Industrial Products of Microorganisms
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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Industrial Microbiology
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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Industrial Microbiology
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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Industrial Microbiology
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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Industrial Microbiology
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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Industrial Microbiology
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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Environmental Microbiology
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
Environmental Microbiology
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Environmental Microbiology
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
Environmental Microbiology
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Environmental Microbiology
Microbial Ecology
Role of adaptation in microbial survival
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
Environmental Microbiology
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Environmental Microbiology
Microbial Ecology
Role of adaptation in microbial survival
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
Environmental Microbiology
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Environmental Microbiology
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
Industrial Microbiology
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Industrial Microbiology
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
Industrial Microbiology
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Industrial Microbiology
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
Environmental Microbiology
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Environmental Microbiology
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
Environmental Microbiology
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Environmental Microbiology
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
Environmental Microbiology
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Environmental Microbiology
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
Environmental Microbiology
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Environmental Microbiology
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
Environmental Microbiology
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Environmental Microbiology
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
Environmental Microbiology
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Environmental Microbiology
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
Environmental Microbiology
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Environmental Microbiology
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
Environmental Microbiology
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Environmental Microbiology
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
Environmental Microbiology
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gy
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
Environmental Microbiology
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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
Biological Warfare and Bioterrorism
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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
Biological Warfare and Bioterrorism
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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
Biological Warfare and Bioterrorism
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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
Biological Warfare and Bioterrorism
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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
Biological Warfare and Bioterrorism
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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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Biological Warfare and Bioterrorism
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Known Microbial Threats
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
Biological Warfare and Bioterrorism
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Known Microbial Threats
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
Biological Warfare and Bioterrorism
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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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Biological Warfare and Bioterrorism
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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
Biological Warfare and Bioterrorism
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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
Biological Warfare and Bioterrorism
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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