MB I
Terms
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- aseptic technique
-
handling microorganisms without
-infecting laboratory worker
-contamination with extraneous ones. - bacterium
- Microorganism classified as procaryote because it lacks a true nucleus.
- colony
- visible population of cells growing on a solid medium and arising from a single cell.
- culture
- growth of microorganisms
- culture (verb)
- to place onto a medium for propagation of microorganisms
- fastidious
- difficult to grow
- medium
- substance or preparation containing essential nutrients for cultivation of living cells.
- microorganism
- seen only through microscop
- sepsis
- microorganisms present; infection
- Properties necessary for sustaining growth on a culture medium:
-
Nutrients
Atmosphere
pH
Sterile
Temperature - Nutrients required by medically important bacteria:
-
Carbon
Nitrogen
Inorganic salts of (Fe, Mg, Ph, K, S)
Water
Growth Factors - what growth factors may be needed by medically important bacteria?
-
Blood
Calcium
Sodium
Carbs
Vitamins
Trace elements - What does Water do for culture media nutrients?
-
provides source of hydrogen
helps transport of nutrients
keeps culture medium fresh. - Proper atmosphere for aerobic bacterial growth:
- free flow of oxygen
- proper ph for bacteria
- 6-8
- what happens in the lag phase?
- bacteria get accustomed to their environment; not so much increase in growth
- what happens in the logarithmic phase?
-
a constant rate of growth;
doubling of bacterial population app. every half hour! - what happens in the stationary phase?
-
bacterial population is constant with rate of growth = rate of death.
nutrient supply gets exhausted; toxed end products accumulate. - What happens in the phase of decline?
-
death occurs at faster rate than multiplication.
colonies still present on medium, but some are not viable anymore. - Which phase do we look at bacteria in?
- 18-24 hrs; stationary phase.
- 3 types of culture media:
- liquid, semi-solid, solid.
- agar solidifies and liquifies at:
- 45 and 98 celcius
- amount of agar in liquid media
-
<0.1%
only in it to enhance growth - amount of agar in semi-solid media
-
.3 - .5%
jelly-like medium for detection of bacterial motility. - amount of agar in solid medium
-
minimum 1.5%
makes a plate, slant, or deep. - 4 types of surface growth in a broth
-
ring
pellicle
flocculant
membraneous - whats a pellicle in a broth?
- thick growth of organism extending across the surface of liquid
- 3 types of subsurface growth in a broth
-
turbid - cloudy
granular - small particles
flocculant - small floating masses - two methods of colony isolation
-
streak plate
pour plate - for counting numbers of colonies - heterotrophs vs. autotrophs
-
hetero - utilize organic carbon sources.
auto - utilize inorganic carbon sources. - photo vs. chemoheterotrophs
-
photo derive energy from sunlight
chemo from chemical reactions (what we study) - essential nutrients for culture medium
-
carbon
nitrogen
MACRONUTRIENTS: inorganic salts of Fe, Mg, P, K, S
Water
Oxygen
Micronutrients: sheeps blood, NaCl, Carbohydrates - What micronutrients are used in culture medium, and for what purpose?
-
NaCl, Carbs, and Sheeps blood.
To enhance growth of fastidious microorganisms. - Passive Transport
- nutrient transport along a concentration gradient (from high to low)
- 3 types of passive transport
-
Diffusion - high to low
Osmosis - diff of H2O
Facilitated diffusion - diffusion via cell-membrane transport proteins, but still with tthe gradient. - 2 energy-requiring transport
-
-requires energy input
1. Active transport - nutrient binds to transport protein which brings it into the cell.
2. Group translocation - nutrient is chemically altered as it is transported into the cell. - 2 aspects of bacterial growth to remember:
-
-Growth curve
-Generation time - What is generation time?
- amt of time it takes to double a bacterial population. app 20-30 min
- How does a culture grow?
- by binary fission
- 3 types of temp classifications
-
Psychrophile
Mesophile
Thermophile - Psychrophile
-
loves cold
tolerates -5 to 30, best at 10-20 - Mesophile
-
loves middle ground
tolerates 10-45
best at 37.5 - Psychrotolerant
- mesophile that tolerates cold temps.
- Thermophiles
-
loves thermos - hot
Tolerates 30-80
best at 50-60. - 3 types of Aerobes
-
Obligate Aerobes
Microaerophiles
Facultative Aerobes - Where do obligate aerobes grow and in what?
- At TOP of tube only; only in oxygen.
- Where do microaerophiles grow and in what?
- just below surface of tube; can't tolerate atmospheric O2, need lower levels.
- Where do facultative anaerobes grow, and in what?
- all over the tube! They like O2 best, but can tolerate lower levels or lack of it.
- 2 types of anaerobes
-
obligate anerobes
aerotolerant anaerobes - Where do obligate anaerobes grow and in what?
- Not in O2; only at bottom of tube.
- Where do aerotolerant anaerobes grow and in what?
- All over in a broth tube, but heaver at bottom because they prefer no O2. In O2 or none. A lot like facultative anaerobes, but they prefer no O2.
- What are capnophiles?
- CO2 loving. like 5-10% enriched medium.