BLG 151 Lecture Notes - Lecture 6: Water Activity, Chemostat, Extremophile
CBLG PPT 6
Measurement of Cell Mass
-1. useful if you are measuring many cells at once
-2. things are constant inside of cells (DNA)
The Continuous Culture of Microorganisms
-batch cultures —> closed container
-continuous cultures —> open, cells are siphoned off
The Chemostat
-fresh medium
-receptacle at bottom to siphon material
-fresh medium comes in, old medium goes out to receptacle
-*need to memorize:
D = dilution rate = flow rate
(ml/hr)/v (vessel volume)
The Turbidostat
-regulate flow rate to maintain a certain turbidity (cell density)
-can change the flow rate —> so dilution rate varies
Importance of Continuous Culture Methods
The influence of Environmental Factors on Growth
-extremophiles —> grow in harsh environments
Solutes and Water
Microbes Adapt to Changes in Osmotic Concentrations
Solutes and Water Activity
-solutes influence water activity
-water —> the amount of water available to organism (so water on sides of container don't
count)
Water Activity Decrease, Limits Growth
Table 6.4
Effects of NaCl on Microbial Growth
-range at which they grow
-they each have a window at which they grow best, then grow worse outside the window
pH
-measure of how many protons there are in the solution
-buffer - prevents change in pH
Temperature
-minimal, optimal, maximum
find more resources at oneclass.com
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Document Summary
1. useful if you are measuring many cells at once. 2. things are constant inside of cells (dna) Continuous cultures > open, cells are siphoned off. Fresh medium comes in, old medium goes out to receptacle. D = dilution rate = ow rate (ml/hr)/v (vessel volume) Regulate ow rate to maintain a certain turbidity (cell density) Can change the ow rate > so dilution rate varies. Water > the amount of water available to organism (so water on sides of container don"t count) They each have a window at which they grow best, then grow worse outside the window ph. Measure of how many protons there are in the solution. Have 3 temperatures for each (min, opt, max) A and g vs. c and t - they have diff number of h bonds. Chaperones - protect other proteins from falling apart in harsh conditions. Oxygen - waste product for microorganism in other forms.
