Applied Microbiology

By Charlie Gonzalez,2014-12-08 15:38
18 views 0
Applied Microbiology

    Applied Microbiology

    Kathy Huschle

    Northland Community and Technical College

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:

     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




    1. primary producers:

     convert CO to 2

     organic material

2. consumers


    utilize organic material created by producers 3. decomposers


    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


    bacteriocins: protein produced by bacteria that destroys similar strains


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


    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

The Study of Microbial Ecology

    ;somewhat difficult to accomplish

    less than 1% of environmental microorganisms can be successfully cultured in the lab

Microbial Habitat



    ;deep waters are usually stable and consistent ;shoreline habitat varies due to nutrient rich run-off ;freshwater:


    ;stratification allows for the mixing of the water seasonally.

    ;Increases the presence of O in the deeper HO 22

    ;moving water


    ;generally aerobic due to turbulence facilitating O 2



    microorganisms are critical to soil habitat ;composition of microbes is dependent on soil conditions ;wet soil: anaerobic conditions due to water filling the pore space in the soil, soil dries and microbes go produce endospores for survival

Mutualism with Eukaryotes

    ;mychorrhizae: fungus

    assist plants in the uptake of phosphorous mychorrizae gain nutrient from plant

    ;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

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

Microorganisms in Sewage Treatment

    ;decreasing biochemical oxygen demand (BOD) decreases impact of sewage on the environment

    ;BOD is the amount of O needed for microbial 2

    decomposition of the organic material in a sample

    ;if not treated the high BOD found in sewage could deplete the O level in the receiving water 2

    ;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

    ;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

    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


    use of microorganisms to eliminate or make harmless pollutants in an environment

    ;pollutants removed can include

    organic solvents

    toxic chemicals


    ;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

    ;scientists are also making use of organisms already found in the environment

    enhance their requirements for growth, such as nutrition or water availability

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


    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 ;fermentation: good food microbiology

    food that have been intentionally altered such as sour cream, cheese, beer

    any desirable change a microorganism makes to food ;spoilage: bad food microbiology

    undesirable changes to food; sour milk, moldy bread preservatives and refrigeration inhibit the growth of microorganisms

    ;factors that affect the presence of microorganisms in food include



    Intrinsic growth factors:

    naturally present in food

    ;water availability is measured as water activity (a) w

    ;this is the amount available in the food

    ;most microorganisms require an aof 0.90 or above for w


    ;fungi can grow with a a of 0.80 w

    fresh food have an a0.98w ;

    Intrinsic Growth Factors


    many species of bacteria are inhibited by low pH, including most pathogens

Intrinsic Growth Factors

    ;biological barriers: shells, rinds

    protect foods from invading microorganisms ;antimicrobial chemicals:

    naturally occurring in some foods

    ;egg 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 atmosphere: presence or absence of O2 ;

    obligate aerobes (need O)won’t grow in sealed containers 2

    ;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

Food Spoilage:

    undesirable changes in food

    ;smell bad, taste bad, look bad

    ;probably are not harmful

    microorganisms that cause food spoilage compete with pathogens

    in the case of food spoilage vs. pathogens, the spoilers are winning

    ;evidence 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 microorganism

    ;symptomatic about 1 day following ingestion of contaminated food

    ;common foodborne infecting microorganisms Salmonella and Campylobacter

;poultry product infections

    Escherichia coli 0157:H7

    ;undercooked hamburger

    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


Report this document

For any questions or suggestions please email