Term
| What do microorganisms generally need to gorw? |
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Definition
Macronutrients to build Macromolecules: C,N,P,S,O
Micronutrients for protein structure/activity Na+, Mg2+, Mn2+, etc |
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Term
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Definition
Most commonly required growth factors
Most function as coenzymes |
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Term
| Acquisition of nutrients: autotrophs |
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Definition
| Assimilate carbon from inorganic sources |
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Term
| Acquisition of nutrients: heterotrophs |
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Definition
| Assimilate carbon in preexisting organic form |
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Term
| Acquisition of energy: phototrophs |
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Definition
| Capture light energy to produce ATP |
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Term
| Acquisition of energy: chemotrophs |
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Definition
| Capture energy from oxidation of reduced organic or inorganic compounds |
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Term
| Electron sources: organotrophs |
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Definition
| Electrons from organic molecules (ie: glucose) |
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Term
| Electron sources: lithotrophs (aka “rock eaters”) |
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Definition
| Electrons from inorganic sources (ie: H2 gas and elemental S) |
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Term
| What affects microbial growth? |
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Definition
| Nutrient type, nutrient concentration, oxygen, pH, osmotic pressure, water availability, and temperature |
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Term
| How does nutrient type affect microbial growth? |
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Definition
| Depends on what the microbe can use: prototrophs vs. auxotrophs |
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Term
| Prototrophs: nutrient type |
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Definition
| Can synthesize all needed macromolecular precursors from a single carbon source and inorganic molecules |
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Term
| Auxotrophs: nutrient type |
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Definition
| Cannot synthesize all needed precursors from a single carbon source |
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Term
| How does nutrient concentration affect microbial growth? |
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Definition
Growth rate depends on the amounts of nutrients in the environment
One key nutrient, available in the lowest amount, will dictate how much growth can occur over time (limiting factor) |
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Term
| How does oxygen affect microbial growth? |
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Definition
| Aerobes (obligate, microaerophiles) vs anaerobes (aerotoerant, obligate, facultative) |
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Term
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Definition
| Grow in the presence of oxygen |
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Term
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Definition
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Term
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Definition
| Grow best when there is less oxygen than normal |
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Term
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Definition
| Aren’t harmed by oxygen, but don’t use it either |
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Term
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Definition
| Cannot grow when oxygen is present |
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Term
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Definition
| CAN use oxygen but can also grow in the absence of oxygen |
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Term
| How do we determine aerobic vs anaerobic? |
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Definition
| Based on what defenses are available against oxygen / negative effects on the cell |
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Term
| How does pH affect microbial growth? |
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Definition
| Affects macromolecule structures and transmembrane electrochemical gradients |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| How does osmotic pressure affect microbial growth? |
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Definition
| Different solute concentrations can result in influx of water into or efflux of water out of the cell. This causes the cell to swell or shrink, respectively. |
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Term
| How does water availability affect microbial growth? |
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Definition
| It must be present for biochemical reactions (measured in terms of water availability, aw)Most bacteria require aw > 0.9 |
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Term
| What affects the value of aw? |
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Definition
Interactions with solute can decrease it.
Pure water: aw = 1.0 … seawater: aw = 0.98 … honey aw = 0.6 |
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Term
| How does temperature affect microbial growth? |
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Definition
Affects macromolecular structure, membrane fluidity, and enzyme function
Different microbes have different optimal temperatures |
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Term
| What is one use of a semisolid medium? |
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Definition
| Counting phages; we don’t usually grow organisms in a semisolid medium |
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Term
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Definition
| Unknown chemical composition |
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Term
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Definition
| Precisely defined chemical composition |
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Term
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Definition
| Solid vs. liquid … undefined vs defined … function |
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Term
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Definition
| Selective, differential, enriched |
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Term
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Definition
| Allows for the isolation of microbes with specific properties (ie: salt tolerance) |
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Term
| Example of specialized media: Gram negative enteric |
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Definition
| Selects gram negative and differentiates E-coli |
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Term
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Definition
| Allows certain microbes to be organized based on visual reactions in the medium (ie: E. coli lactose fermentation, fecal indicator) |
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Term
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Definition
| Can be used to increase a particular population of microbes with a specific property from a mixture of cell types (ie: sabouraud dextrose agar for fungi) |
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Term
| Enriched media: Blood agar plate |
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Definition
Diagnostic tool only; 5% sheep RBC’s
Some microorganisms lyse sheep RBC’s so you can identify it: color change
This does NOT mean it will lyse YOUR cells |
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Term
| Types of lysis for blood agar plate |
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Definition
Beta-hemolysis: lyses RBC’s; turns the plate clear
Alpha-hemolysis: partial lysis; turns plate greenish-yellow |
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Term
| Benefit of a solid medium |
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Definition
| Cells are held in place on the surface and can be isolated |
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Term
| Three methods for separating cells |
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Definition
| Streak plate, spread plate, pour plate |
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Term
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Definition
| Limited in colony of recovery. Suspended in media. |
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Term
| Cultivation independent methods of doing something |
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Definition
DNA from unculturable bacteria can be amplified & sequenced using PCR
The sequences can be used to produce fluorescent probes that will bind to the complementary DNA |
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Term
| Unculturable Bacteria: Metagenomics |
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Definition
DNA is isolated & sequenced; genetic content can be examined and compared from an organism in one area to one in another
NCBI & BLAST N are databases used for the comparison of DNA |
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Term
| Unculturable bacteria: microbial consortia |
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Definition
| Some microbes may be too accustomed to growing with others so they cannot be isolated. Enriched media must be made that includes whatever products that second bacteria would produce in order to get growth. |
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Term
| How can we measure and count microbes? |
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Definition
| Direct count, viable cell counting, turbidity |
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Term
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Definition
Using a slide with an etched grid to count cells under a light microscope
Cheap, fast, easy, BUT can’t differentiate living vs dead |
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Term
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Definition
| Serial dilutions and CFUs (so: how many colonies on the plate?) |
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Term
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Definition
| Using a spectrophotometer to analyze the cloudiness and a standard curve to determine a concentration |
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Term
| What are some things a growth curve can tell us? |
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Definition
| Generation time, growth rate, and growth yield |
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Term
| Why is growth rate important? |
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Definition
| Tells you went to check for results / when to harvest the products an organism is producing |
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Term
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Definition
A chemostat flows in fresh medium and takes out old medium to keep the organisms growing. We would do this commercially to harvest their by-products
Replicates real-life environment scenarios, including the human body. |
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Term
| How can we eliminate microbes and prevent their growth? |
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Definition
| Removal by filtration, heat, electromagnetic radiation, and chemicals |
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Term
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Definition
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Term
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Definition
Nylon/Teflon filters; 0.2-4.5 microns
Problems: large molecules can clog the filter |
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Term
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Definition
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Term
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Definition
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Term
| Heat for control of bacteria |
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Definition
Denatures proteins and nucleic acids; 100 C kills most microbes
Autoclave also adds pressure to keep the fluids from evaporating
Problem: endospores, some materials can’t be heated (milk) |
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Term
| Cold for control of bacteria: Pasteurization |
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Definition
| Low temperature & then heat |
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Term
| Cold for control of bacteria: Freezing |
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Definition
Problem: can damage cells by forming ice crystals
Good for long-term preservation |
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Term
| Electromagnetic radiation to control bacteria |
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Definition
| UV radiation of 260 to 280 nm can damage DNA, forming thymine dimers |
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Term
| Chemical methods for controlling microbes |
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Definition
| Disinfectants, anticeptics, ethanol, triclosen, bleach (sodium hypochlorite), benzalknoium chloride, gluteraldeyde |
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Term
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Definition
| Chemicals used on non-living surfaces to kill microbes |
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Term
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Definition
| Chemicals that can be used on living tissues |
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Term
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Definition
Hand sanitizers 60-95% Ethanol
Only works if there isn’t visible grime |
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Term
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Definition
No evidence that it’s better than soap & water
Endocrine disruptor, amplifies testosterone, reduces muscle strength, may harm the immune system |
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Term
| What makes a good chemical method for control of bacteria? |
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Definition
Does it kill a wide range without being overly corrosive/toxic? Is it cheap and temperature stable? :D
Does it leave a residue? Doe it emit bad smelling fumes? D: |
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Term
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Definition
| What microbes are present? Endospores? How many microbes? Do they all need to die? How powerful does it have to be and for how long does it need to be applied? Do we need to worry about toxicity? |
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Term
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Definition
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Term
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Definition
| Irradiation, MAP, Hurdle Technology |
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Term
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Definition
Food does NOT become radioactive itself
Strength of microbe elimination depends on type of radiation (but all cause damage to microbe DNA) |
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Term
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Definition
Surface level only, not strong
UV |
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Term
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Definition
Gamma/x-rays
Stronger, more penetrating |
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Term
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Definition
Modified atmosphere packaging
Vacuum packing takes oxygen out of the package. Sometimes, also flooded with CO2 |
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Term
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Definition
| Can be packaged in a HIGH oxygen environment to reduce growth of harmful anaerobic microbes and keep meat a desirable color |
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Term
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Definition
Multiple levels of antimicrobial control in food
Often works synergistically - overall protection is better than a single method |
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Term
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Definition
| Can be used to produce different types of food |
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Term
| Food Fermentation: Process |
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Definition
Starter cultures of microbes are added to food to begin the fermentation process.
It is monitored and controlled for a desirable outcome of flavors and textures |
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Term
| Fermentation: Milk Products |
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Definition
| Lactic acid bacteria (LAB) produce cheese and yogurt |
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Term
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Definition
| Milk product, sauerkraut, salami, sausage |
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Term
| Fermentation: What can go wrong? |
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Definition
Wrong microbe mixes & produces the wrong product
Infection of microbes by lytic bacteria phages can stop fermentation
Starter microbes lose plasmids |
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Term
| Fermentation Problems: Wrong Bacterial Products |
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Definition
Lactic acid instead of ethanol in wine
Production of CO2 gas instead of lactic acid |
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Term
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Definition
Asia
Miso - fermented soybean paste; Tempeh - fermented soy/bean; Soy sauce; Sake |
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Term
| Fementation: Koji starter cultures & Aspergillus species |
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Definition
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Term
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Definition
| Food contaminated with microbes can cause illness in humans and animals |
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Term
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Definition
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Term
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Definition
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Term
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Definition
Consumption of one thing by many people
Ex: Salmonellosis (food poisoning); botulism |
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Term
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Definition
| Spread through water or food |
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Term
| How can we keep our water supplies safe? |
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Definition
3% freshwater - not all can be consumed
Dirty water can build up and run off into water (sewage) |
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Term
| Goals for treating wastewater (sewage) |
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Definition
Reducing total organic carbon (TOC)
Removal or inactivation of harmful microbes in wastewater
Reduction of inorganic compounds
Reduce persistent organic pollutant levels (POP) |
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Term
| Inorganic compounds to reduce via sewage treatment |
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Definition
| Ammonium, nitrogen, phosphorous |
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Term
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Definition
| Harfum to fish and mammal reproduction and development |
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