Kinetics Flashcards
What does thermodynamics determine?
Determines if the reaction is possible.
Energy of the products has to be less than the reactants. releasing energy.
What does kinetics determine and affect?
Is associated with activation energy.
Affects how fast the reaction will happen.
What are the four stages of the microbial growth curve?
- Lag phase
- Exponential phase
- Stationary phase
- Decline phase
What happens in the lag phase?
Cells are adjusting to the new environment.
Cells will activate and synthesis new enzymes.
Change in cell mass over time (dx/dt) = 0
Change in substrate conc. over time (dS/dt) = 0
What happens in the exponential phase?
Cells growing exponentially.
- Microbial populations are growing by cell division
Change in cell mass over time (dx/dt) > 0
Change in substrate conc. over time (dS/dt) < 0
What happens in the stationary phase?
Cell number remains the same:
- Same number of new cells as cells dying
- Tends to occur due to running out of nutrients and energy sources for growth
Change in cell mass over time (dx/dt) = 0
Change in substrate conc. over time (dS/dt) < 0
What happens in the decline phase?
More cells dying than produced.
Change in cell mass over time (dx/dt) < 0 (doesn’t inc. dead cells)
Change in substrate conc. over time (dS/dt) < 0
What controls microbial growth rates?
- Temp
- Salinity
- pH
- Nutrient availability
- Substrate conc. (PED)
What is the Monod Equation?
Rate of Change of Microbial Biomass
u = u(max) * ( s/(Ks+ s))
Ks = substrate concentration at 1/2u(max)
Tells us if growth rate is dependent on substrate concentration or not.
What happens to microbial growth rates in the real world?
99% slower
- Competition
- Lower water:cell ratio
- Lower nutrient and energy supply
How do cell adapt in the real world?
- Grow slower
- Become smaller, higher SA:V ratio
- Forms spores to preserve key cell components
