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35 Cards in this Set
- Front
- Back
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microorganisms =
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factories
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Microorganisms are used by industry
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to produce chemicals, antibiotics, organic compounds and pharmaceuticals without much hazardous/toxic waste
bacteria are used to clean up the environment |
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Keep in mind that even though we have all of these applications:
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less than 1% of the world’s microbes have been utilized!
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Fermentation
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an anaerobic process that generates energy by the breakdown of organic compounds
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Indusrtial fermentation (in huge bioreactors):
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Any process that produces biomass (bacteria, fungi, yeast, etc.) as the end product
Transformation of a compound by cells to another commercially valuable compound in a process known as biotransformation • High fructose corn syrup, bioplastics Industrial fermentation attempts to improve the productive performance of microorganisms (efficiency) by optimizing growth conditions Most industrial fermentation is now aerobic because it is more efficient Different applications use different types of fermenters: stirred tank reactors are most common (airlift fermenters also used) Products are collected by two main methods: • Continuous fermentation (treating wastewater) • Batch culturing (antibiotics purified from cells) |
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Microbes as food supplements:
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o have been used as food supplements for several thousand years
o A monoculture of algal, bacterial or fungal cells is 70-80% protein (dry weight) or lipid oil |
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SCP
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Single Cell Protein
•a monoculture grown in large volumes for use as human or livestock feed supplements •SCP has a high content of vitamins, minerals, carbohydrates, lipids, AND essential amino acids (e.g., K & M that are often lacking in plant protein) •SCP is produced from cheap sources of C and N like natural gas and the waste from cheese production and pulp mills (carbohydrates) |
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benifits and drawbacks of SCPs
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benefit: SCP may provide a low cost solution to malnutrition
drawback: Concentration of toxic compounds into SCPs |
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food safety and microorganisms
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• Microorganisms growing on food after production cause spoilage and may produce harmful toxins
Clostridium botulinum produces botulism toxin which causes paralysis • Sensitive diagnostic methods are being developed to detect microbes and their toxic products • PCR, monoclonal antibody assays, and specific DNA probes are used to detect/distinguish harmful bacteria from harmless bacteria Strains of E. coli, Listeria, Salmonella |
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Metabolites
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products of metabolism that have value
Primary and secondary metabolites are synthesized by microbial cells 1°metabolites are synthesized during the growth phase and are essential to an organism’s metabolism (e.g., aa’s, vitamins, nucleotides, etc.) 2°metabolites are NOT essential, but usually confer an advantage; often are the end products of metabolism (e.g., antibiotics, pigments, toxins) |
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Enzymes
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protein catalysts
Used in the production of pharmaceuticals, cosmetics, and foods Often used to convert abundant substrates into commercially valuable products (e.g., α- amylase and the production of high fructose corn syrup) |
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High fructose corn syrup
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• This is an example of Bioconversion
• Uses bacteria Bacillus amyloliquefaciens for amylase, fungus Aspergillusniger for glucoamylase, and additional bacterial species from the genus Arthrobacterfor glucose isomerase! |
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Antibiotics
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metabolites with antimicrobial activity
Enable the producer to compete for resources by killing or inhibiting the growth of competitor microbes Antibiotics have been produced by fermentation since 1929 (A. Fleming & penicillin) Antibiotics act in different ways: • Disrupt the plasma membrane of microbial cells • Inhibit cell wall synthesis • Inhibit synthesis of important 1° metabolites such as proteins, nucleic acids, and folic acid Unfortunately, many bacteria are becoming resistant which is forcing scientists to find new antibiotics |
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Finding new antibiotics:
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Brute force methods
o Screen 2° metabolites for antibiotic activity o Chemically modify existing antibiotics and screen for antibiotic activity Can use Recombinant DNA Technology as well: o Scientists can examine genes coding for different components in pathways and target their products to come up with new antibiotics o Feed unusual substrates to cells containing a pathway from a different organism to yield new “byproduct antibiotics” |
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Fuels from bacteria
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Fuels–CH4 & H2 producing bacteria; Spirulina
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Biopolymers
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bacterial-made substitutes for plastics
Plastics last forever, but are used for seconds Most accumulate in oceanic gyres |
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Biopolymers
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• bacterial-made substitutes for plastics
Plastics last forever, but are used for seconds Most accumulate in oceanic gyres Biopolymers are starting to catch on! Cargil Dow’s biorefinery in Nebraska converts sugars from corn into polylactic acid (PLA) DuPont developed a polymer from corn sugar called Sorona that is used in clothing 100% biodegradable microbial bioplastics like poly(β-hydroxybutyrate) or PHB have importantpotential industrial and medical applications • They can be used as sutures or for constructing artificial blood vessels |
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PLA
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polylactic acid
• PLA is used in packaging, clothing and bedding • PLA is comparable in price to petroleum products |
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more efficient method of bioconversion
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o Sometimes immobilized cells are used to synthesize commercially valuable compounds
• Cells are Crosslinked to a matrix instead of just in a liquid culture • Allows for the cells to be concentrated in a small area • More efficient (enzymes and substrates are closer together) and less expensive method |
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Bioconversions
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o occur when microorganisms modify a given compound to a structurally related compound
o Microbes are “little Swiss army knives” and can use substrates not usually available to make things o Synthesis of these unusual substrates has no value to the cell’s metabolism, but can lead to useful products, chemicals and pharmaceuticals for us o Industrial conversions usually involve a mix of both chemical synthesis and cellular reactions |
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Predisone
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a bioconversion
o an anti-inflammatory drug used to treat allergies and arthritis • Chemical synthesis requires 37 steps! • Substituting microbial conversions at specific points reduces the process to 11 steps |
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Ice-nucleating bacteria
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• Frost-sensitive crops are damaged by wild-type ice nucleating bacteria (e.g., Pseudomonas viridiflava, Erwiniaherbicola, etc.)
• P. syringaepromotes ice formation between 0oC -2oC! • The INA (ice nucleating activity) gene encodes a protein that promotes ice nucleation • INAdeletion strains have been engineered and are sprayed onto plants to outcompete wild-type species |
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Chemical pesticides
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• Chemical pesticides have tremendous drawbacks
Kill off beneficial insects; harm crop plants Not usually biodegradable & accumulate (e.g., DDT) Must be used in massive quantities because pests become resistant over time |
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BT
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B. thuringiensisis a soil bacterium that produces protein endotoxins called insecticidal crystal insecticidal crystal proteins ICPs
ICPs are toxic to insects that eat the bacteria because they are activated once in the insect’s midgut(pH) Insects ingest the bacteria, enzymmatically activate the ICP, and then die of starvation because the ICP paralyzes the insect’s gut Bt toxin doesn’t harm mammals, fish, or birds The spore from the bacteria has been sprayed on plants for over thirty years Genes for Bt toxin have been inserted into other bacteria that colonize the leaf, as well as into the plants themselves Example: Bollgard Insect-Protected Cotton (Monsanto) |
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microbial pesticides
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• Microorganisms and insect viruses may provide a source of insecticides that are biodegradable
• Many fungal, viral and bacterial strains that infect insects have been identified • Only a few have been exploited commercially • Degrade rapidly (unlike DDT!) • Pesticide can break down rapidly in the environment if not consumed by pests • Can use recombinant DNA technology to transfer genes encoding insecticide to crop plants • Many species of corn, potatoes, cotton, etc. have been engineered to produce compounds toxic to specific insects, but not to humans |
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ICPs
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insecticidal crystal proteins
• ICPsare ideal microbial pesticides because the toxin doesn’t last very long in the environment (resistance to it is hard to develop) Helps curtain chemical pesticide use Over fifty subspecies of of B. thuringiensishave been characterized Recombinant DNA technology may possibly create fusion proteins of different toxins that may be effective on other harmful insects |
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Biodegradation
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•process by which bacteria and fungi break down hydrocarbons to produce CO2, water and simple compounds
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Xenobiotics
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chemicals like crude oil, benzene, and PCBs persist in the environment and poison wildlife & humans
100s of species of microorganisms have been discovered that can metabolize Hydrocarbons and some xenobiotics |
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Bioremediation
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process of reclaiming or cleaning up contaminated sites using microorganisms by 2 general methods:
Use of nutrients (fertilizers, trace metals, etc.) to encourage growth / enhance the activity of naturally occurring microorganisms Addition of new bacteria to the polluted site Majority of bioremediation use pre-existing bacteria |
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Oil Spill bioremediation
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Oil is made up a variety of HC’s
Natural biodegradation takes centuries to accomplish Microorganisms with HC-oxidizing enzymes that can attach to the HC’s are useful in bioremediation Major limitation is the availability of P and N Adding fertilizers rich in P and N can greatly speed up the recovery process (weeks-months) Biotechnology soon may produce bacteria that can break down oil more quickly (maybe) |
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Wastewater treatment
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Best known application of bioremediation technology is the microbial aerobic oxidation of wastewater
Bacteria are introduced into domestic sewage / industrial aqueous waste in a controlled environment and supplemented with nutrients for growth Biomass (bacteria) may be free-floating or immobilized on plastic film |
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groundwater remediation
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Soil can be treated many ways; two in situ methods:
• Pumping contaminated water to the surface before adding nutrients to encourage bacterial action • Percolating water & nutrients into the contaminated soil |
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Oil and mineral recovery
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• The potential exists for enhanced recovery of oil and minerals in the future
• Billions of barrels of oil cannot be recovered by conventional methods • Only 5% or less of the total US production of oil has been recovered using alternative technologies like microbial-enhanced oil recovery (MEOR) |
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MEOR techniques
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• Bacteria can be injected into oil reservoirs along with nutrients for growth and colonization; this loosens oil from the rock substratum
• Alternatively, the growth and metabolism of indigenous microbes are stimulated by certain nutrients to likewise loosen the oil from the rock • Microbial products (ie: polysaccharides like xanthangum) may be injected to loosen oil that adheres tightly to rock • Anaerobic microbes can also produce solvents (acetone) that can increase oil mobility and loosen oil on rock • Gasses solubilized by anaerobic bacteria also increase oil mobility |
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drawbacks of MEOR
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• Stimulating natural oil biodegradation
• Losing certain oil fractions because the oil is metabolized • Performing bioremediation instead of mining! • Microbial corrosion and souring of the oil o Increasing hydrogen sulfide content |
