Applied Microbiology 2
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Transcript of Applied Microbiology 2
Applied Microbiology
Applied Microbiology
applied microbiology is the interaction of the microbial world and the rest of the world– genetic variances– microbial effect on soil, water, our
food
microorganisms are present in most every aspect of our lives– microorganisms are critical to our
survival on Earth
to be a successful ecosystem on Earth, you’d best be nice to the microorganisms!
Microbial Ecology: relationship of microorganisms with each
other and their environment
ecosystem: interaction of living and non-living components– oceans, deserts, marshes,
forests, tundra, lakes– microorganisms play a key
role in ecosystem structure
Microbial Ecology: relationship of microorganisms with each other and
their environment
microenvironment: immediately surrounds a microorganism
– relevant to survival and growth of the microorganism
Nutrient Acquisition within an Ecosystem
3 main levels exist in every ecosystem in regards to nutrient acquisition– producer– consumer– decomposer
1. primary producers:
convert CO2 to
organic material
Nutrient Acquisition within an Ecosystem
2. consumers– heterotrophs– utilize organic material
created by producers
Nutrient Acquisition within an Ecosystem
3. decomposers– heterotrophs– digest leftovers of primary
producers and consumers
detritus ( fresh or partially decomposed organic matter)
– bacteria and fungi are key players in the process of decomposition
Low Nutrient Environments: common in nature
bacteria do best in biofilms if nutrition availability is low– biofilms are a polysaccharide
encased community of microorganisms
– microorganisms extract nutrients that are absorbed by water from air or nutrients that are adsorbed onto the biofilm
Microbial competition and antagonism
most environments are suitable to many kinds of microorganisms
only one or a few can actually occupy the environment at a given time
Competition and Antagonism: among microorganisms
competition:– fierce competition for nutrients and water– the faster a microbe reproduces the larger the
population– the larger population competes better
critical, especially if the microorganisms competing utilize similar nutrients
antagonism– bacteriocins: protein produced by bacteria that
destroys similar strains
“WINNER TAKES ALL AND IS KING/QUEEN OF THE MICROBIAL ECOSYSTEM”
Example of Competition
stability of microbial community in human intestine is attributed to competition and antagonism amongst its members– compete nicely for nutrients– produce toxins to limit growth of new microbes
Environmental Change affect microbial population
environmental fluctuations are common and resident microorganisms may respond by– producing enzymes to help adapt to changing
environment
additional or different enzymes may be necessary for survival
– mutation– domination by other species (can’t compete any
more)
Microbial Mat: thick, dense, organized biofilm
generally found attached to a solid substrate or at air-water interfaces
Microbial mat attached to rocks
Microbial mat in stream bed
The Study of Microbial Ecology
somewhat difficult to accomplish– less than 1% of
environmental microorganisms can be successfully cultured in the lab
Microbial Habitat
aquatic– marine:
deep waters are usually stable and consistent
shoreline habitat varies due to nutrient rich run-off
Microbial Habitat
freshwater:– lakes
stratification allows for the mixing of the water seasonally.
Increases the presence of O2 in the deeper H2O
algae
paramecium
Microbial Habitat
moving water– rivers
generally aerobic due to turbulence facilitating O2 circulation
river ostracod
Microbial Habitat
terrestrial– microorganisms are critical to soil habitat
composition of microbes is dependent on soil conditionswet soil: anaerobic conditions due to water filling the pore space in the soil, soil dries and microbes go produce endospores for survival
Endospores
Mutualism with Eukaryotes
mychorrhizae: fungus– assist plants in the uptake of
phosphorous– mychorrizae gain nutrient from plant
Mutualism
nitrogen fixers: fix nitrogen and make it available for the use by their partner plant– most common is
Rhizobium, a microorganism found in many root nodules
Rhizobium in root nodules
Nitrogen Cycle
Mutualism: microorganisms and the world
microorganisms and herbivores– animal with a rumens (cow) or cecums
(horse) need microorganisms to digest the plant food they ingest
Bacillus in a cow rumen
Microorganisms in Sewage Treatment
decreasing biochemical oxygen demand (BOD) decreases impact of sewage on the environment
BOD is the amount of O2 needed for microbial decomposition of the organic material in a sample
Grit chamber
Biological filter
Clarifier
Microorganisms in Sewage Treatment
if not treated the high BOD found in sewage could deplete the O2 level in the receiving water
in other words if raw sewage is deposited into a lake or stream without treatment, it would effectively suck the oxygen out of the water, leaving very little for the fish and other organisms
Microorganisms in Sewage Treatment
sewage treatment is a controlled process that strives to eliminate the excess organic material, thus diminishing the BOD– most of the removal of organic matter is done
by microorganisms
bacterial filaments
Microorganisms and Water Treatment and Testing
municipal water supplies are tested and treated for the removal of pathogenic microorganisms and chemicals– this is done with the
use of chemicals
Microorganisms and Solid Waste Treatment
the elimination of organic waste material can be enhanced by microorganisms– increase cost to separate organic
material from inorganic (glass, metal, plastic)
– composting: natural decomposition of organic solid materiel results in excellent fertilizer
Compost
microorganisms are needed to breakdown the organic material
Bioremediation: use of microorganisms to eliminate or make
harmless pollutants in an environment
pollutants removed can include– organic solvents– toxic chemicals– hydrocarbons
oil spill
Bioremediation
introduces specific organisms to the polluted area– many toxic substances are man-made/new to the
environment (xenobiotics)– no time for naturally occurring microbes to have
evolved biochemical pathways for their degradation
scientists are trying to develop new microbes for the degradation of environmental polluters
Cleaning an oil spill
Bioremediation
scientists are also making use of organisms already found in the environment – enhance their requirements for growth, such as
nutrition or water availability
Bacteria in an oil spill
Why Bioremediation?
current methods of controlling some environmental polluters are incineration or storage in land fills, which result in– more pollution– health risks
bioremediation is– inexpensive– publicly accepted– non-polluting (ideally)– in situ treatment (at the site)
Food Microbiology
food is an ecosystem and microorganisms play a key role in the stability of that ecosystem
microorganisms are introduced to the food ecosystem from the soil, harvesting, handling, storage, and packaging
Food Microbiology
fermentation: good food microbiology– food that have been
intentionally altered such as sour cream, cheese, beer
– any desirable change a microorganism makes to food
Food Microbiologyspoilage: bad food microbiology– undesirable changes to food;
sour milk, moldy bread– preservatives and refrigeration
inhibit the growth of microorganisms
Moldy Spam
Microorganisms in Food
factors that affect the presence of microorganisms in food include– intrinsic– extrinsic
Intrinsic growth factors: naturally present in food
water availability is measured as water activity (aw)
this is the amount available in the food
most microorganisms require an aw of 0.90 or above for growth
fungi can grow with a aw of 0.80
fresh food have an aw 0.98
Intrinsic Growth Factors
pH– many species of bacteria are inhibited by low pH,
including most pathogens
Testing soil pH
Intrinsic Growth Factors
biological barriers: shells, rinds– protect foods from invading
microorganisms
antimicrobial chemicals:– naturally occurring in some
foodsegg whites have lysozyme which will destroy lysozyme susceptible bacteria
Extrinsic Factors: environmental conditions
temperature of storage– below freezing water is unavailable for
microorganisms– low temperatures (above freezing) enzyme reactions
are non-existent or slow– refrigerated food microbial growth is likely
psychrophiles
Extrinsic Factors
atmosphere: presence or absence of O2
– obligate aerobes (need O2) won’t grow in sealed containers
may allow growth of anaerobic microbes
Microorganisms in Food Production
using microorganisms for food production has been done for thousands of years– cheese, yeast, beer
microorganisms used in food often produce an acidic by-product as a result of metabolism– can inhibit growth of many
spoilage microorganisms– can inhibit growth of many
foodborne pathogens
Yeast cells
Food Spoilage: undesirable changes in food
smell bad, taste bad, look badprobably are not harmful– microorganisms that cause food spoilage compete with
pathogens– in the case of food spoilage vs. pathogens, the spoilers
are winningevidence is obvious, though I wouldn’t eat anything that smelled or looked like that
Foodborne Intoxication
illness from microbial exotoxin– microorganism does not cause the illness, the toxin
released by the microorganism does
common exotoxin producing microorganisms
– Staphylococcus aureus
– Clostridium botulinum
Foodborne Infection
requires consumption of microorganismsymptomatic about 1 day following ingestion of contaminated foodcommon foodborne infecting microorganisms– Salmonella and Campylobacter
poultry product infections– Escherichia coli 0157:H7
undercooked hamburger
Campylobacter Salmonella
Food Preservation: preventing growth and metabolic
activities of microorganisms
spices, salting, drying are methods that have been around for years
most common methods of current food preservation are– high temperature treatment– low-temperature storage– antimicrobial chemicals– irradiation