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Lecture 6: Bacterial Growth

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Text: pages 88-90, 95-103, 108-109 Growth and nutrition. Text: pages 541-544 E. coli ... 4 Septum cell wall synthesis 'Fts' proteins. 5 Cell wall separation ... – PowerPoint PPT presentation

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Title: Lecture 6: Bacterial Growth


1
Lecture 6 Bacterial Growth
Reading assignments in Text Lengeler et al.
1999 Text pages 88-90, 95-103, 108-109 Growth
and nutrition Text pages 541-544 E. coli
symmetric division Text pages 571-574
Caulobacter asymmetric cell division Text pages
882-884 Making MSG Lecture 5 Text pages
205-214, 229-232 Examples of organotrophy Text
pages 234-244, 267-268 Lithotrophs in
general Text pages 245-259, 911-12 Lithotroph
specifics Text pages 327-340 Phototrophs Text
pages 67 Photophosphorylation Lecture 4 Text
pages 116-122 Assimilation Text pages 177-182
Assimilation reactions Text pages 155-157
Storage compounds
2
Last lecture
(get their energy)
All organisms
Fix CO2
Assimilate C
?
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4
Lecture Overview
Bacterial populations (lab conditions)
Food/ Media
Sterilization
Growth measurement
Changes during growth
Applications Making MSG
Bacteria as single cells (cell cycles)
E. coli divides symmetrically
Caulobacter crescentus divides asymmetrically
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6
Food/ Media
undefined from organisms
defined from chemicals
E. coli LB (Luria Bertani)
M9
per liter water
5 g Yeast Extract
3 g KH2 PO4
10 g NaCl
0.5 g NaCl
(15 g Agar for plates)
1 g NH4Cl
Autoclave
(steam pressure)
MgSO4 1 mM
CaCl2 0.1 mM
The truth is seldom simple, but never
pure. -Oscar Wilde
?
Done ?
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8
Sterilization
Why sterilize?
What is Pasteurization?
Methods
Autoclaving
Filtration
Radiation
Chemicals
?
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10
Bacterial growth and measurement
Exponential growth
Log growth
DT Doubling Time
11
Measuring N
1 Viable cell counting
Sample
Dilute (note dilution factor)
One cell One colony 106 cells
2 Direct counts
side
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Measuring N
3 Automated flow cell/ cytometry
Volume (flow) x (time)
4 Absorbency or Optical Density (OD)
OD logI0/I(cells)
OD log10/1
1.0
109 cells / ml
I (cells)
Useful linear range OD 0.1 to 1.0
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Changes during growth
?
1 Induce survival genes
ss
2 Fewer ribosomes
3 Smaller cells (gt8-fold range)
4 Modified fatty acids in P-lipids
5 High mutation rates in sub-population (?)
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17
Making Mono-Sodium Glutamate (MSG)
(see Course Pack lecture 6, Text pages 882-4)
800,000 tons / year
What is MSG ?
Industrial production principles
Central metabolism
Food Glucose Ammonium Salts
MSG (secreted)
?
Synthetic PW Glutamate Dehydrogenase (GD)
Biotin
Growth control ?
18
Making MSG from Central Metabolism
Growing bacteria Biotin
Cells MSG Factories
19
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20
Single cell growth Cell division cycles
Continuous processes
Most biosynthesis (including cell wall)
Ribosome assembly
Punctuated events
Chromosome replication
Cell/wall division
Chromosome Replication
1 Commitment (?)
Critical cell mass trigger
2 Start (assemble) replication factories
Timing (?)
Place oriC
Assemble replication factories (?)
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E. coli Chromosome replication (continued)
3a DNA synthesis
2 x 2x106 bp
3b Polar orientation of oriC and chromosome
movement (?)
4 Termination
6 ter sites pause sites
balance replication
Mechanism
5 Resolution and separation
Gyrase Topo IV unlink
Topological DNA linkage
Covalent linkage problems
23
5 Resolution and separation
Homologous recombination (RecA, BCD)
Even X-over
Steps 1-5 C period 40 min best time
Paradox ?
24
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25
Site-specific DNA resolution
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27
E. coli cell division
1 Commitment (?)
Chromosome-free mini-cell
FtsZ mono-mer (GTP) tubulin-like protein
PBP3
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Staggered projects 2, 4, 8, 16 chromosomes inside
one large cell
Feast or famine strategy
30
Caulobacter crescentus
31
Asymmetric strategies
Stays and makes more Swarmers
32
Cell cycle with swarmer differentiation
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Symmetric and Asymmetric protein distribution
C. crescentus early division
35
Caulobacter applications
Fish farming
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Michaelis-Menton -like analysis of growth
R growth rate
0
C Conc. of limiting nutrient
Where on the curve ?
In batch cultures ?
In a turbido-stat ? a chemo-stat ?
In nature ?
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Controlled growth conditions
Batch cultures or Fermentation cultures
Continuous cultures
Turbido-stat
C gtgt Km
Dilution rate must growth rate (needs extra
feedback control)
Chemo-stat
C Km, C lt Km
Cell conc. constant x C
Growth rate R Media flow rate
(i.e. adjust Y-axis and slope)
Reflect natural growth-limiting environments
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