Module 4 Flashcards
(17 cards)
Environmental conditions for bacterial growth - 2 main components
- Temperature
2. Atmosphere - CO2 or O2
Temperature limits of bacteria - 3
Minimum - no growth - lowest temp at which a bacterial species will grow
Optimum - temp giving optimum growth
Maximum - no growth - highest temp at which a bacterial species will grow
3 groups of bacteria based on temperature
Psychrophilic
Mesophilic
Thermophilic
Psychrophilic
Cold-loving bacteria
Range: 15-20 C
Mesophilic
Middle-loving bacteria
Range: 25 - 40 C
Most bacteria found in the human body are mesophilic
Thermophilic
Heat-loving bacteria
Range: 45 - 50 C
Capnophilic
CO2 loving bacteria
Require a CO2 concentration higher than that found in ambient air (3-10%)
Methods of providing increased CO2 (3)
Candle extinction jar
Chemical generation (GasPak)
CO2 incubator
CO2 concentration in ambient air
about 0.03%
Candle extinction jar - conditions
CO2 concentration is about 2.5%
Moist environment
Anaerobic conditions are NOT provided
Obligate aerobes
Require atmospheric O2 for growth, no growth in absence of O2
Eg. Pseudomonas aeruginosa
Obligate anaerobes
Only grow in absence of O2, growth inhibited by molecular O2, some are killed by exposure to O2
Eg. Bacteriodes fragilis
Cold loving bacteria - grow between 15-20C
Psychrophilic
“Middle loving” bacteria - grow at 25-40C
Mesophilic
Heat loving bacteria - grow at 45-50+ C
Thermophilic
Facultative anaerobes
Organisms that can grow anaerobically but grow better in the presence of oxygen
Most human pathogens are this type
Eg. Staph, strep
Microaerophilic
Require oxygen for growth but in a concentration lower than that found in ambient air
Can grow in candle jar conditions
