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163 Cards in this Set
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facts about bacteria growth (4)
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facts:
*bacteria divide quickly by binary fission *under optimal conditions for growth a few bacteria can become large in number in a short time *by knowing the requirements for growth, we can encourage the growth of wanted bacteria we wish to study *we can discourage the growth of unwanted bacteria (infections, contaminant, pathogenic) |
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requirements for bacteria growth (3)
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physical requirements:
a) temperature b) pH c) osmotic pressure |
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bactericidal (biocidal); germicide
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agents that result in the cell being killed
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bacteriostatic
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agents that inhibit bacterial growth that do not kill, when the agent is removed, growth resumes.
ex. colds, hypertonic solution, dessication (drying) |
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mesophiles
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bacteria with an optimal temp range of 25-40*C (37-98.6*F)
- most common including: a) normal microbiota b) most pathogens c) unknown bacteria, in BCC labs |
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psychrophiles
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- 'cold-loving'
- can grow at 0*C - optimum growth temp 15*C - found in polar regions deep in the oceans; on top of high mountains |
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psychrotrophs
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-can grow at 0*C
-high optimum temp 20-30*C -CANNOT grow above 40*C - found in refrigerator food spoilage |
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thermophiles
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- heat-loving bacteria
- extreme high temp - optimum growth temp 50-60*C -optimum temp 121*C=245*F |
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pH
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-most microorganisms grow at pH7
-the wrong pH, the unfavorable pH, denatures enzymes or BACTERICIDAL -low pH inhibits most bacteria, not fungi |
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buffers
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in the microbiological media prevent sudden, drastic chnages in pH and maintain a specific pH
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acidophiles
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-acid-loving
-microorganisms that can grow at a low (acidic) pH |
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basophiles
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alkaline (acid)-loving
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osmotic pressure
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the amount of water outside the cell as there is inside
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hypertonic
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-less water outside the cell than inside
-water leaves the cell |
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plasmolysis
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-the shrinkage of a cell's contents in a hypertonic solution
-the cell membrane, collapses but not the entire cell because of its rigid external cell wall. BACTERIOSTATIC |
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halophiles
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-salt-loving
-live in very salty (HYPERTONIC) environment due to rigid cell walls |
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nutrients
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-chemicals released when large complex food molecules are broken
1) energy source 2) building blocks of macromolecules 3) regulated & control cellular functions (vitamins & minerals) |
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macronutrients
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- >10%
-carbon, nitrogen, phosphorus, sulphur |
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micronutrients
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- <1%
-trace elements (inorganic metallic ions) -organic growth factors (vitamins & minerals) |
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carbon
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-makes ALL organic compounds the backbone of living matter (cells)
-50% of a cell's dry weight |
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autotrophs
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organisms that use inorganic compounds (Co2 gas used)
-ie. photosynthetic organisms -5% of the cell |
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heterotrophs
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-fed by others
-organisms that obtain their carbon from pre-formed organic molecules -95% of the cell |
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nitrogen
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-synthesis of proteins (amino acids)
-synthesis of nucleotides (DNA, RNA, ATP) (CHONPS) -14% of the cell |
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sulfur
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- make amino acids
-4% of the cell |
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phosphorus
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-make phospholipids for DNA, RNA, ATP (nucleotides)
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oxygen
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a highly reactive element that cause formation of free-radicals
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reducing media
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a microbiological growth medium that chemically reacts with dissolved gaseous oxygen & removes oxygen from the medium
ie. sodium glycolate broth, "fluid thio" |
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obligate aerobe
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growth occurs only where high levels of oxygen have diffused into the medium
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obligate anaerobes
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growth occus only where there is no oxygen
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facultative anaerobes
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growth is best wehre most oxygen present, but occurs throughout the tube, although not evenly
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aerotolerant anaerobes
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growth occurs evenly; oxygen has no effect
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microaerophiles
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growth occurs only where a low concentration of oxygen has diffused into medium
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free-radicals
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chemically wastable molecules extensive lethal cellular damage (cause oxydation; electrons)
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trace elements
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- inorganic growth factors
- co-factors: iron copper molybdenum zinc |
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co-factors
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inorganic metallic ions that attach to enzymes and make the enzyme function
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culture
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microorganisms growing in or on a nutrient substance (medium)
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medium
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any nutrient substance that can support microbial growth
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agar
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-a carbohydrate found in red sea weeds
*no microorganism can break down agar *it melts at 100*C/212*F *incubation is 37*C *hardens at 45*C (warm but still melted agar won't kill heat-sensitive microorganisms) |
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organic growth factors
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organic non-protein molecules ie. vitamins: ABCDEK
-act as co-enzymes |
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co-enzymes
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organic non-protein molecules such as vitamins that attach to enzymes and make the enzyme functional
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criteria for a useful medium
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1) must supply all the physical and chemical requirements for microbial growth
2) able to be sterilized (without breakdown) 3) able to be incubated |
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chemically-defined medium
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exact chemical composition is known (every ingredient to an exact amount )
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selective medium
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inhibits growth of unwanted microorganisms BUT allows the growth of wanted microorganisms
ie. pH, salt, EMB dyes, antibiotics |
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complex medium
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a microbial growth medium whose exact chemical compositions isn't known
-is made up of extracts or digests from plants, meats, or yeasts the batch differs if it is not uniform ie. heterotrophic |
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differential medium
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indicates color change due to some unique metabolic process or product
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enrichment culture
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-selective medium that is designed to grow to small microorganisms to become large in inoculum
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reducing medium
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chemically reacts with dissolved oxygen remove to gaseous oxygen from the medium to create an anaerobic environment
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pure culture
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only that one specific species (type of microorganisms)
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streak plate method
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physically separating bacteria out on the surface of solid media far enough apart so that individual cells can grow in to pure colonies
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standard plate count
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serial dilution (setting a series of sterile water blanks, and diluting the bacteria and the pour plate method so that you have individual cells that can grow into pure colonies)
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deep-freezing
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the bacteria has to be suspended in an anti-freeze so ice crystals don't form
ie glycerine, ethylene glycol -50*C-95*C (bacteriostatic) |
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freeze-drying
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fast-freezing, then in a vacuum, the ice sublimates, turns to a gas, not a liquid
(LYSPHILIZATION) (BACTERIOSTATIC) |
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binary fission
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an asexual form of reproduction in which one cell splits into two genetically identical cell
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generation time
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-the time needed for a cell to divide; or a population to double
-or a population to double -vary by species (20' propagate) -vary by physical or chemical requirements |
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lag phase
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-occurs after the inoculum is put into sterile media
-no cells are drying but no new cells are forming a) the cells are adjusting to the new media b) this is a biochemically acive stage in which the cells are preparing for rapid, intense growth |
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log phase (logarithm)
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-exponential growth phase
- a period of rapid cell division (cell growth) -all cells are metabolically active and dividing. -the shortest generation time -all cels are sensitive to any physical or chemical agents that could interfere with growth -all cells can be producing a product |
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stationary phase
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-occurs when microorganisms begin to use up the nutrients in the media
-the accumulation of metabolic wastes are beginning to affect bacterial growth -the phase of the bacterial growth where # of new cells = # of dying cells |
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death phase
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-decline phase
-because the nutrients on the media have now been used up and the accumulation of metabolic wastes has reached dealy toxin levels; more cells are dying then forming endospores |
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1) direct method
2) indirect method |
methods of counting bacteria
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direct method
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-standard plate count
-serial dilution: pour plate (+) viable cell count - very accurate because living cells that grow into viable colonies are counted (-) too many steps, each a risk for contamination (-) uses a lot of lab equipment (-) takes 24 hrs. for results |
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indirect method
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-aseptic technique is critically applied
-many tubes, pipette, timing (secs to min), dilution factor (1:10) (1:100) (1:1000), etc. (+) immediate results (+) only one step procedure, essentially no possible contamination (-) not as accurate because living cells, dirt, fingerprints can contribute to light absorbency |
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turbidity
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refers to cloudiness in the broth, usually due to the number of cells. "the more turbid, the more cells"
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spectrophotometer
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an instrument that measures light absorption
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light transmittance
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the amount of light that goes thru the sample and is not absorbed
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light absorbance
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the amount of light that does not leave the sample
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sterilization
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the complete physical or chemical destruction or removal of all forms of microbial life, including endospores
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-commercial sterilization
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-sufficient heat treatment to kill the heat-sensitive endospores of a specific deadly bacteria (clostridium botulism)
-any endospores of thermophilic bacteria that may survive, do not germinate under normal storage conditions |
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disinfection
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the destruction of vegetative pathogens on non-living surfaces and objects
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disinfection
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the destruction of vegetative pathogens on non-living surfaces and objects
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antisepsis
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the destruction of vegetative pathogens on living tissues, skin, mucous membranes
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degerming
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-physically remove microorganisms from a limited area of the skin
-mechanically removing them by scrubbing soap and water as an alcohol swab |
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sanitization
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treatment intended to lower microbial counts on eating and drinking utensils to safe public health levels
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bactericidal
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treatments that result in the killing of the cell
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biocide (germicide)
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kill microorganisms
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sporocide
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kills endospores
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fungicide
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kills fungi
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viruside
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kills viruses
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tuberculocide
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kills mycobacterium tuberculosis (TB)
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sepsis
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-decay, putrification
-the presence of microorganisms in normally sterile tissues -the presence of bacteria in blood multiplying |
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asepsis
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any procedure, treatment that prevents contamination, infection
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factors that influence the effectiveness of antimicrobial treatments (physical and chemical methods of control)
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1) the number of microorganisms
2) environmental influences: the presence of organic material (ie body fluids - can weaken and even reduce completely the actions of these methods) 3)time of exposure: autoclave 15psi=121*C/245*F=15mins 4) microbial characteristics: from least resistant to most resistant |
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microbial characteristics (factors that influence the effectiveness of antimicrobial treatments)
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from the least resistant to most resistant
1) endospores 2)mycobacteria: TB can't gram-stain 3) Gram (-) 4) Gram (+) - least resistant because pores are open |
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actions of antimicrobial agents
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1)alteration of cell membrane permeability-damage to the cell membrane and it loses selective permeability
-LYSE - destruction of cell wall 2) damage to proteins - denature (coagulation) precipitation 3) damage to nucleic acids (DNA) especially: (DNA=RNA=Proteins) makes new chromosomes BAD!!! |
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physical methods of microbial control
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A. Heat
1. moist heat 2. dry heat a. flaming b. dry heat 3. Pasteurization B. Filtration C. Dessication D. Osmotic pressure E. Radiation a. non-ionizing radiation b. ionizing radiation |
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heat
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very old, but still widely used type of microbial control
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moist heat
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very effective because water is a good conductor of heat
a) boiling water - limited to 212*F b) autoclave - a device that uses steam under pressure 15 psi=245*F+15mins=sterilize (121*C) |
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dry heat
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air acts as an insulator so a larger exposure time and higher temp as needed
a) flaming - Bunsen-burner incineration; denatures proteins b) dry heat sterilization (hot-air) |
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Pasteurization
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a brief mild heating of a liquid such as milk, beer, wine, cider to kill the heat-sensitive pathogens and or spoilage without destroying the flavor or quality of that liquid
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filtration
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a physical method of control by physically preparing microorganism from suspending liquid or gas (air) by passage through screen-like device
*doesn't use heat so that heat-sensitive (heat labile) solutions media, etc. can be sterilized |
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dessication
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drying by evaporation (bacteriostatic)
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osmotic pressure
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bacteria in a hypertonic solution loses water, plasmolysis occurs, (bacteriostatic)
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radiation
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physical method of microbial control to sterilize
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non-ionizing radiation
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-long wavelengths = 265nm
-slow, low energy particles -not very penetrating -damages cellular DNA ex. UV light (in lab) |
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ionizing radiation
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-short wave lengths
-fast-moving particles, high energy -very penetrating -ionizes water to make free-radicals -does extensive lethal cellular damage ex. x-rays, gamma rays |
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free-radicals
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chemically-unstable molecules
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chemical methods of control
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1) concentration
2) temperature 3) organic material can reduce the effectiveness of some chemical agents 4) pH |
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concentration
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dilution
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temperature
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has an effect on exposure time
room temp (20*C = 68*F) |
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what happens if the chemical come into contact with the material to be disinfected?
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oils, organic material can reduce the effectiveness if some chemical agents
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disc diffusion method
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- a way to evaluate the effectiveness of disinfectants/antiseptics
-uses sterile paper discs dipped in a chemical agent and placed on an agar (TSA) that had previouly been swabbed with - E. Coli = pseudomonas aerginousa (G-) - Staph a (G+) |
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BPME disc test that displays zone of inhibition
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B- bleach
P - phenol M - mouthwash E - ethanol |
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bleach
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best, full-spectrum disinfectant; works on all G+ and G- bacteria
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zone of inhibition
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an area of no growth around a paper disc on an agar plate
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phenol
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the first accepted and widely used chemical agent for aseptic surgery
- used by Joseph Lister -acts to denature proteins not weakend or neutralized by organic material -source was carbolic acid |
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why phenol isn't generally used anymore?
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1) disagreeable odor
2) irritating to the skin 3) kills WBC -used as a standard of comparison |
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phenolics
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-compounds derived from phenol
-it reduces the irritating & disagreeable properties of phenol but retains the killing properties -denature proteins/disrupt cell membrane -not affected by organic material ex. lysol or Cresol (to preserve wood) |
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bis-phenols
"bis" = bridge |
a compound derived from two phenolics bridged together
-disrupts cell membrane ex. hexachlorophene (phisoHex) - once used as a topical antiseptic triclosan - use on cutting boards; overuse means bacterial resistance -effective against G+, G- |
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Chemical Agents
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1) phenol
2) phenolics 3) bis-phenols 4) halogens 5) alcohols 6) heavy metals & their compounds 7) surface active agents 8) quartenary ammonium compounds 9) aldehydes 10) gaseous chemosterilizers 11) peroxygens and other oxygens |
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halogens
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- are powerful oxidizers
- inhibit protein functions -alter cellular components ie. chlorine - gas is used in water disinfection -calcium hypochlorite (chloride of lime use by Semmelweiss) -sodium hypochlorite (bleach) |
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iodine
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-tincture -an aqueous solution in alcohol
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iodophore
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iodine with an organics detergent
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alcohols
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are a goood degermer
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degermer
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agent that physically remove microorganisms from a limited area of the skin
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what a good degermer does
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-evaporates quickly
-doesn't leave residue |
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why alcohols are bad antiseptics
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-evaporates quickly
-doesn't leave residue -denature/coagulate proteins |
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heavy metals & their compounds
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-metals form cations (+) ions
-metallic elements are attracted to acid will bind to enzymes |
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oligodynamic action
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the ability of small amounts of heavy metal ions to exhibit antimicrobial activity
ex. silver zinc, copper, mercury, mercurochrome - mercury compound |
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surface active agents
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-surfactants
-soaps & detergents -lower the surface tension of water -also act as emulsifier |
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emulsification
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breaking down lipids (oils) into small droplets (globules) that go into solution
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quarternary ammonium compounds
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-a group of detergents derived from the ammonium ion
-disrupt cell membranes of bacteria -odorless -colorless -stable -easily diluted in water -non-toxic -works well against G+ bacteria -tasteless *does NOT work against G- bacteria bec of outer cell membrane |
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aldehydes
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-group of liquid chemical agents
-formalin, formaldehyde, gluteraldehyde -inactive proteins -gluteraldehyde is one of the few liquid chemical sterilents (long exposure time leaves a residue) -preserve specimens |
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sterilents
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means long exposure time leaves a residue
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gaseous chemosterilizers
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-device that uses a gas to sterilize
-sterilizing gas is ethylene oxide - very penetrating, -doesn't use heat, -denatures proteins, -sporocidal, -used to sterilize heat-sensitive equipment -doesn't leave a residue |
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explosive gas
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mix it with an inert gas
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peroxygens and other forms of oxygen
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-hydrogen peroxide ozone
-peralcitic acid -powerful oxidizers that do extensive lethal cellular damage -forms free radicals -chemical sterilant |
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microbial characteristics
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an important influence on the effectiveness of physical and chemical methods of microbial control
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endospores
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most resistant bacteria
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G-
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less resistant (has an outermembrane)
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G+
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least resistant
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metabolism
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all the chemical reactions within a cell or organism; a life process
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catabolism
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decomposition,
exergonic exothermic (A-B = A+B+energy) |
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anabolism
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synthesis
endergonic endothermic (A+B+energy = A-B) |
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ATP
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-is energy-carrying molecule of cells
-ATP can't make another ATP -energy is transferred from one substance to ATP (the energy-carrying molecule) -heat -work -ATP supplies the energy to drive most anabolic reactions |
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ATP: metabolic pathways
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1. aerobic respiration
2. anaerobic respiration 3. fermentation |
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metabolic pathways
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energy is transferred to ATP in a series of biochemical metabolic steps
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activation energy
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the amoung of energy needed to begin a chemical reaction
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substrate
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the substance that is catalyzed by the enzyme
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apoenzyme
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protein part of an enzyme
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co-factor
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inorganic metallic ione that binds to an enzyme
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co-enzyme
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a non-protein organic molecule that binds to an enzyme
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holoenzyme
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the complete functional enzyme
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active site
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area on an enzyme where a specific substance binds
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factors influencing enzymatic activity
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temp-optimal 37*C: "low slow; high die"
pH- optimal pH7 substrate concentration-saturation pt of enzyme activity vs substrate concentration inhibitors-chemicals that bind to enzymes and stop enzyme activity |
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oxidation
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the loss of electrons from an atom or molecule
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reduction
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the gain of electrons by an atom or molecule
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oxidation-reduction (redox) reactions
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energy is transferred from the molecule to ATP in a series of redox reactions (ie glucose to ATP)
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phosphorilation
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adding a phosphorus group to a molecule
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substrate level phosphorilation
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the phosphate is directly transferred from one compound to ADP
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oxidative phosphorilation
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glucose is used to make ATP from redox reactions
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glycolysis
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doesn't end product; pyruvate acid (2) added
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aerobic respiration
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final electron is oxygen; water is end product
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anaerobic respiration
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final electron is inorganic and molecule cannot make water; not efficient
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fermentation
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final electron is organic molecule to energy-reduced organic compound
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phototrophs
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light as energy source
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chemotrophs
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oxidation of chemical compounds as energy source
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autotrophs
"self-feeding" |
make own organic molecules CO2 gas = inorganic
5% |
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heterotrophs
"fed by others" |
use pre-formed organic molecules
95% |
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photoautotrophs
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light + carbon
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chemoheterotrophs
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organic compounds (glucose)
(ie animals, protozoans, fungi, most bacteria) |
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chemoautotrophs
"rock-eaters or litotrophs" |
inorganic chemical compounds + inorganic CO2 gas
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saprophytes
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decomposers; energy from dead organic materials
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parasites
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nutrients from a living host
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photoheterotrophs
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light + organic compounds (fatty acids, organic acids, carbohydrates, alcohols)
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