Reaction Engineering - PowerPoint PPT Presentation

About This Presentation
Title:

Reaction Engineering

Description:

Reaction Engineering - Aalborg Universitet – PowerPoint PPT presentation

Number of Views:118
Avg rating:3.0/5.0
Slides: 41
Provided by: EvaP3
Category:

less

Transcript and Presenter's Notes

Title: Reaction Engineering


1
Reaction Engineering
2
(No Transcript)
3
Batch culture exponential phase (balanced growth)
Max growth rate -gt smallest doubling time
4
(No Transcript)
5
Michaelis Menten Kinetics
  • Used when microbe population is constant
    non-growing (or short time spans)
  • Derivable from first principles
    (enzyme-substrate binding rates and equilibria
    expressions)
  • Parameter determination methods used for Monod
    calculations (i.e. Lineweaver Burke)

6
(No Transcript)
7
Monod Growth Kinetics
  • Relates specific growth rate, m, to substrate
    concentration
  • Empirical---no theoretical basisit just fits!
  • Have to determine mmax and Ks in the lab
  • Each m is determined for a different starting S

8
Michaelis Menten vs. Monod
  • Michaelis Menten
  • Kinetic expression derived (theoretical)
  • Constant enzyme pool
  • Free enzymes
  • Non-growing microbes
  • v vs. S where v is velocity
  • Km is half saturation constant
  • Monod
  • Empirical expression
  • Growth
  • Enzyme concentration increases with time
  • Relates microbial growth rate constant to S
  • µ vs S
  • Ks is half saturation constant

9
Michaelis Menten vs. Monod
  • Parameters (vmax or µmax Ks or Km) are
    determined by linearization (e.g. Lineweaver
    Burke model) or nonlinear curve fitting.
  • Relationship between dependent variable and S
    determined experimentally, in the lab
  • Range of S
  • Set conditions (T, chemistry, enzyme or microbe)
  • Measure the v or µ for each S
  • Plot v or µ vs. S analyze data for parameter
    estimation

10
Determining Monod parameters
  • Double reciprocal plot (Lineweaver Burke)
  • Commonly used
  • Caution that data spread are often insufficient
  • Other linearization (Eadie Hofstee)
  • Less used, better data spread
  • Non-linear curve fitting
  • More computationally intensive
  • Progress-curve analysis (for substrate
    depletion)
  • Less lab work (1 curve), more uncertainty

11
Where Monod Growth Kinetics Applies
It applies where µ ? 0 -gt exponential growth (µ
µmax ) transition into stationary
  • KS is the half-saturation coefficient mg/L

Monod kinetics -gt Substrate depletion
kinetics
12
Substrate Depletion Kinetics
  • Since
  • And

  • Monod applies!!
  • Then
  • And

Y Yield coefficients
Where k
  • k is the maximum substrate utilization rate
    sec-1
  • KS is the half-saturation coefficient mg/L

13
Substrate Depletion Kinetics
  • Substrate consumption rates have often been
    described using Monod kinetics
  • -gt Substrate controls
  • growth Kinetics
  • S is the substrate concentration mg/L
  • X is the biomass concentration mg/ L
  • k is the maximum substrate utilization rate
    sec-1
  • KS is the half-saturation coefficient mg/L

14
Stoichiometric Coefficients for Growth
Yield coefficients, Y, are defined based on the
amount of consumption of another material.
Because ?S changes with growth condition, YX/S is
not a constant
15
Monod Growth Kinetics
mixed order
S gtgt KS
S ltlt KS
1
3
2
mmax
m, 1/hr
S, mg/L
Expontential growth µ µmax
Stationary phase µ 0
16
Depletion Kinetics
  • 1. Zero-order region, S gtgt KS, the equation can
    be approximated by µ µmax
  • -gt exponential growth
  • 2. Center region, Monod mixed order kinetics
    must be used -gt transition from exponential
    growth to stationary growth caused by S
    limitation
  • 3. First-order region, S ltlt KS, the equation can
    be approximated as
  • µ µmaxS/Ks
  • -gt transition from exponential growth to
    stationary growth caused by S limitation
  • Just before stationary phase starts (stationary
    phase µ 0)

mixed order
S gtgt KS
S ltlt KS
1
3
2
mmax
m, 1/hr
S, mg/L
  • k is the maximum substrate utilization rate
    sec-1
  • KS is the half-saturation coefficient mg/L

17
Modeling Substrate Depletion
  • Three common assumptions
  • Monod kinetics applies (mid range
    concentrations)
  • -gt Substrate depletion kinetics
  • First-order decay (low concentration of S,
    applicable to many natural systems)
  • Zero-order decay (substrate saturated) µ µmax
  • -gt exponential growth

18
Growth and Production Kinetic
  • Cellular growth rate
  • Monod approximation
  • Yield factor
  • Substrate Utilization
  • Product Formation
  • (Beginning of Stationary Phase)

19
Factors Determining Kinetics
  • Rate per microbe, which depends on
  • Species
  • Substrates
  • Environmental factors
  • Total numbers of microbes

20
Quantification of Microbes in the Environment
  • Culture-based (limited 2000 species vs. 13,000
    species of bacteria in soil by DNA-based methods
  • Counting colony forming units (CFUs)
  • Activity assays need cell or biomass count to
    normalize
  • Culture-independent
  • Direct Counts
  • General fluorescent stain, like acridine orange
    or SYBR gold
  • Counting cells in FISH assay
  • Biomass assays
  • Quantification of an element like C or N
  • Chloroform fumigation / incubation or direct
    extraction
  • Total protein or DNA

21
Fermentation Technology
-gt Why is it important to know the kinetics of
the reaction in the fermenter?
22
Fermentation Technology
-gt What is going on in a fermenter? -gt How to
control the process in a fermenter?
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
Stochiometric Coefficients
29
Mass Balance
30
Rates (Kinetics) and Balances
31
Example
-gt Too complex !!!!
32
  • -gt Blackbox effect

substrates cells ? extracellular products
more cells ( ?S X ? ?P
nX)
33
Model to describe what is going on in a
Bio-reactor
Monods model -gt S depletion
  • Mass balance depentend on reactor type -gt S, P,
    X
  • Growth Kinetics -gt Monod model (substrate
    depleting model)
  • -gt Describes what happens in the reactor in
    steady state (constant conditions)

34
(No Transcript)
35
Primary metabolic products
Secondary metabolic products
36
Microbial Products
1. Growth associated products products
appear simultaneoulsy with cells in culture
qp is the specific rate of product formation (mg
product per g biomas per hours
2. Non-growth associated products products
appear during stationary phase of batch growth
3. Mixed-growth associated products
products appear during slow growth and stationary
phase
37
Biotechnological processes of growing
microorganisms in a bioreactor
Mass Balance Fin Fout 0
Fin ? 0 Fout 0 Fin Fout ?
0 V
const. V increases
V const.
38
Batch Reactor
?Closed ?Well-mixed ?Constant volume -gt substrate
growth limiting factor
Mass Balance
Verbal In Out Reaction Accumulation
Math 0 0 rV ?t ?X V
Rearrange r V ?X/?t
V -gt Substrate concentration controls growth
rate
Growth
Growth
39
Growth and Production Kinetic in Batch
  • Cellular growth rate
  • Monod approximation
  • Yield factor
  • Substrate Utilization
  • Product Formation
  • (Beginning of Stationary Phase)

40
Biotechnological processes of growing
microorganisms in a bioreactor
Mass Balance Fin Fout 0
Fin ? 0 Fout 0 Fin Fout ?
0 V
const. V increases
V const.
Write a Comment
User Comments (0)
About PowerShow.com