Microbial Nutrition Flashcards
cold-loving
Psychrophiles
moderate temperatures
Mesophiles
heat-loving
Thermophiles
Most bacteria grow within a limited range of temperatures:
Minimum and maximum growth temperatures are only 30°C apart.
Temperature at which the species can best grow
Optimum temperature
What pH most bacteria grow best?
pH 6.5-7.5
Few bacteria grow below in what pH level?
pH 4
Chemical buffers for bacteria culture.
Phosphate salts and peptones
Microbes obtain nutrients in solution from water.
Osmotic pressure
They do not require high salt concentrations but can grow at concentrations up to 2%.
Facultative halophiles
Structural backbone of living matter; needed for all organic compounds that make up a living cell.
Carbon
It forms the amino group of amino acids.
Nitrogen
Synthesis of sulfur-containing amino acids and vitamins such as thiamine and biotin.
Sulfur
Synthesis of nucleic acids and phospholipids of the cell membrane; also in ATP.
Phosphorus
Essential for some enzymes, sometimes as cofactors. Includes iron, copper, molybdenum, and zinc.
Trace elements
Essential compounds not synthesized which are obtained from the environment. Include enzymes for vitamin synthesis, amino acids, purines, pyrimidines.
Organic growth factors
They can use anaerobic respiration or fermentation when oxygen is absent, e.g. E. coli and yeasts.
Facultatiive anaerobes
They cannot use molecular oxygen for energy yielding reactions, e.g. Clostridium.
Obligate anaerobes
e.g. lactobacilli; they can survive convert harmful forms of oxygen to O2.
Aerotolerant anaerobes
They can only tolerate oxygen concentrations lower than air.
Microaerophiles
Nutrient material prepared for the growth of microorganisms.
Culture media
Microbes that are introduced into a culture medium to initiate growth.
Inoculum
Microbes that grow and multiply in a culture medium.
Culture
Culture media must be initially what?
sterile
A solidifying agent
Agar
At what temperature does agar liquify?
100°C
Agar remains liquid until temperature drops to:
40°C
Agar is not a:
nutrient
Forms of Culture Media:
Broth
Slants
Stab tubes/deep
Plates
A mass of organisms is floating on top of the broth.
Pellicle
The organisms appear as a general cloudiness throughout the broth.
Turbidity
A mass of organisms appears as a deposit at the bottom of the tube.
Sediment
Tubes are held at an angle.
Slants
Bacteria are inoculated by stabbing the medium.
Stab tubes/deeps
Use Petri dishes; commonly used in the culturing, separating, and counting of microorganisms.
Plates
Most commonly used method in obtaining pure cultures.
Streak plate method
Pure culture of microbes is placed in a suspending liquid and quick-frozen at temperatures ranging from -50°C to -95°C.
Deep-freezing
Suspension of microbes is quickly frozen at temperatures ranging from -54°C to -72°C, and the water is removed by a high vacuum.
Lyophilization (freeze-drying)
Five “I”s of Culturing Microbes:
- Inoculation
- Isolation
- Incubation
- Inspection
- Identification
Producing a pure culture.
Inoculation
Colony on media, one kind of microbe, pure culture.
Isolation
Growing microbes under proper conditions.
Incubation
Observation of characteristics (data).
Inspection
Use of data, correlation, to ID organism to exact species.
Identification
Most common mode of reproduction.
Binary fission
