Unit 3: Growth Requirements Flashcards
The requirements for microbial growth can be divide into two main categories:
Physical
Chemical
The requirements for microbial growth can be divide into two main categories:
_____: temperature, pH, and osmotic pressure
_____: sources of carbon, nitrogen, sulfur, phosphorus, oxygen, trace elements, and organic growth factors.
Physical
Chemical
What are the different Physical Requirements
Temperature
pH
Osmolarity
TEMPERATURE affects microorganisms in two opposing ways:
- As temperature rises, enzymatic reactions increase and growth becomes faster.
- Above a certain temperature, proteins or other cell components may be denatured or damaged.
Cardinal Temperature
Minimum
- _____; transport processes so slow that growth cannot occur
Enzymatic reactions occurring at increasingly rapid rates.
Optimum
- Enzymatic reaction occurring at a maximal possible rate.
Maximum
- _____; collapse of the cytoplasmic membrane; thermal lysis
Membrane gelling
Protein denudation
Temperature Classes of Organisms
Psychophile
Psychrotrophs
Mesophile
Thermophile
Hyperthermophile
Temperature Classes of Organisms
_____ 4°C
_____ 39°C
_____ 60°C
_____ 88°C
_____ 106°C
Psychophile
Mesophile
Thermophile
Hyperthermophile
Hyperthermophile
_____
- Optimal growth at 15°C or lower.
_____: act as RNA chaperones that maintain cold- sensitive proteins
Psychrophiles
Cold-shock proteins
Cryoprotectants
Polyunsaturated fatty acids
_____
- Variant of psychrophiles which grows at 0°C but displays an optimum temp in the mesophile range, nearer room temp.
- Between 20 and 30*C (but grows well at lower temperature)
Psychrotrophs
_____
- Between 25 and 45oC
- Optimal growth near 37°C (the body temperature of warm- blooded animals)
Mesophiles
_____
- Between 45 and 70°C, Optimal growth: >45°C
Thermophiles
_____
- between 70 and 110°C
- Have high G+C content in their DNA.
- Have highly saturated fatty acids.
- ______: increased ionic bonds between basic and acidic amino acids
Hyperthermophiles
Heat-stable proteins
Physical Requirements: pH
Acidity or alkalinity of a solution is expressed by its pH on a logarithmic scale in which NEUTRALITY IS PH 7
_____ <7 (less than)
_____: >7 (greater than)
Acidic
Alkaline
Physical Requirements: pH
_____ Organisms that grow optimally at a pH value in the range termed circumneutral (pH 5 to 8)
NEUTROPHILES
_____
- Organisms that grow best below pH 5.5
- Cytoplasmic membrane
- Stability Picrophilus oshimae
_____ Microorganisms showing pH optima of 8.5 or higher.
Acidophiles
Alkaliphiles
_____: near neutrality
Intracellular pH
Physical Requirements: OSMOLARITY
_____ are of interest mainly in habitats with high concentrations of salts.
Osmotic effects
Physical Requirements: OSMOLARITY
_____: Microorganisms that inhabit marine environments that show salt requirement to grow.
_____: microbes that can tolerate some salt concentrations but grows best in the absence of salt.
_____: microbes require very high levels of NaCl, typically 15–30%, for optimum growth (found among Archaea).
Halophiles
Halotolerant
Extremophiles
Chemical Requirements
All organisms require a _____ (make up a living cell)
-_____ use an organic molecule.
-_____ typically use carbon dioxide.
CARBON SOURCE
Chemoheterotrophs
Autotrophs
Chemical Requirements
_____: needed for protein and nucleic acid synthesis.
_____: used to synthesize sulfur-containing amino acids and vitamins such as thiamine and biotin.
_____: essential for the synthesis of nucleic acids and the phospholipids of cell membranes.
NITROGEN
SULFUR
PHOSPHORUS
Chemical Requirements
NUTRITIONAL TYPES
BASED ON ENERGY SOURCE
_____
_____
BASED ON CARBON SOURCE
_____
_____
BASED ON ENERGY SOURCE
1. Phototrophs
2. Chemotrophs
BASED ON CARBON SOURCE
Autotroph
Heterotroph (Organotroph)
Nutritional Types
TABLE
TYPE
1. Photoautotroph
2. Photoheterotroph
3. Chemoautotroph
4. Chemoheterotroph
ENERGY SOURCE
1. Sunlight
2. Sunlight
3. Inorganic chemicals
4. Organic compounds (sugars, amino acids, etc)
CARBON SOURCE
1. CO2
2. Organic compounds
3. CO2
4. Organic compounds
Chemical Requirements: OXYGEN
_____
- Require O2 for growth
- Use O2 as a final electron acceptor in aerobic respiration.
_____
_ Do not need or use O2 as a nutrient
_ O2 is a toxic substance which either kills or inhibits their growth
Obligate Aerobes
Obligate anaerobes (occasionally called aerophobes)
Chemical Requirements: OXYGEN
_____
- Organisms that can switch between aerobic and anaerobic types of
metabolism.
- Anaerobic conditions (no O2) – fermentation or anaerobic respiration
- Presence of O2 – aerobic respiration
_____
- Bacteria with an exclusively anaerobic (fermentation) type of metabolism but insensitive to the presence of O2.
- Live by fermentation alone whether or not O2 is present in their
environment.
Facultative anaerobes (or facultative aerobes)
Aerotolerant anaerobes
