Microbial Nutrition And Growth Flashcards
What are the 2 broad groups called that are based in carbon source and what are the 2 called based in energy source?
Autotrophs - inorganic source of carbon (CO2)
Heterotrophs - catabolise reduced organic molecules (proteins, CHO, amino acids, fatty acids)
Chemotrophs - energy acquired from redox reactions involving organic and inorganic chemicals
Phototrophs - use light for energy
What are the three requirements for microbial growth?
Carbon source
Energy source source of electrons (or hydrogen atoms)
What are the 2 categories based in electron source called?
Lithotrophs - e from inorganic sources
Organotrophs - e from organic sources
How do most unicellular organisms reproduce?
Binary fission - cell grows to twice its normal size and divides, producing daughter cell of equal size. Asexual process
What is the name given to the time taken for 1 bacterial cell to become 2?
Generation time
What are the four phases of a microbial growth curve?
Lag - no growth
Log - exponential growth
Stationary - nutrients decline death rate = cells produced
Death - cells die due to lack of nutrients
What are 2 ways to count bacteria?
Total count - counts both living and dead organisms
Viable count - counts living organisms
What are the different types of oxygen requirements?
Obligate aerobes - requires O2 to grow
Obligate anaerobes - can live only in the absence of O2
Facultative anaerobes - can use O2 if it is present but can switch to anaerobic if it is absent
Aerotolerant anaerobes - grows poorly in O2, grows better in anaerobic conditions
Microaerophiles - require O2 but are killed by high concentrations of it
Capnophiles - grows best in high concentrations of CO2
What physical factors effect bacterial growth?
Temperature pH Moisture Pressure Radiation
What temperature goes with what bacterial type?
Psychrophile - -5 to 22 (optimum 12 - 15)
Psychrotrophs - 0 to 35 (opt 25-30)
Mesophiles - 10 to 45 (opt 30-39)
Thermophiles - 40 to 70 (opt 50-55)
Hyperthermophiles - 65 to 110+ (opt 80-100)
Features of Psychrophiles?
Arctic and Antarctic environments
Oceans
Unsaturated fatty acids in plasma membrane
Specialised low temperature enzymes
Algae, bacteria and archaea
Ice crystals within cell
Proteins higher proportion of alpha helical structure - allows more flexibility
Features of psychrotrophs?
Grow at moderate and low temperatures
Significant in food spoilage
Bioremediation in temperate climates possibility (breakdown of waste)
Features of mesophiles?
Most Microorganisms
Thermoduric - survive 45*C but do not grow
Includes most human pathogens
Features of thermophiles?
Compost piles, hot springs, water lines
High G+C content in genome
Proteins possess increased thermal stability
Highly saturated fatty acids in membranes
Taq polymerase vital in polymerase chain reaction
Features of Hyperthermophiles?
Occur in volcanic habitats and in deep sea thermal vents
