Bacterial Growth l Introduction –Population vs. Cellular Growth –Exponential vs. Arithmetic...
26
Bacterial Growth Bacterial Growth Introduction – Population vs. Cellular Growth – Exponential vs. Arithmetic Growth – Bacterial Growth - Binary Fission
-
Upload
ashley-rebecca-rose -
Category
Documents
-
view
222 -
download
0
Transcript of Bacterial Growth l Introduction –Population vs. Cellular Growth –Exponential vs. Arithmetic...
Bacterial GrowthBacterial Growth
Introduction– Population vs. Cellular Growth– Exponential vs. Arithmetic Growth– Bacterial Growth - Binary Fission
Bacterial GrowthBacterial Growth
Gen # Exp. Arith. # Log10 #0 20 1 05 25 32 1.51
10 210 1024 3.0115 215 32768 4.5220 220 1,048,576 6.0225 225 33,554,432 7.53
Bacterial GrowthBacterial Growth
Bacterial Growth Curve– Lag Phase– Log Phase– Stationary Phase– Death Phase
Bacterial GrowthBacterial Growth
Lag
Log
Stationary
Death
Bacterial GrowthBacterial Growth
Calculations - Number of cells
Example:
InitialCells = Number x 2 number of
generations
of cells
Bacterial GrowthBacterial Growth
Sample calculation:
How many cells would be in a culture if the starting number were 100,000 and the culture was allowed to divide 5 times?
Bacterial GrowthBacterial Growth
Calculations - Number of Generations
Example:
Generations = log n2 – log n1/log 2Generations = log n2 – log n1/0.301where n = number of cells at a given time
Bacterial GrowthBacterial Growth
Sample calculation:
How many generations have elapsed if the cell count in a culture went from 3 x 108 to 8 x 1010 in 1.5 hours?
Bacterial GrowthBacterial Growth
Calculations - Generation Time Time for single cell to double Example:
Generation Time
=Elapsed time
Number of Generations
between n1 and n2
Bacterial GrowthBacterial Growth Calculations - Generation Time Time for single cell to double Example:
Generation Time
=5 hours
(Log 1,720,320 – log 100)/.301
=5/((6.23 – 2)/.301)
= .356 hrs or 21 min
Bacterial GrowthBacterial Growth
Measurement of Growth– Biomass– Viable Counts– Total Counts– Most Probable Number (MPN)
Bacterial GrowthBacterial Growth
Biomass– Dry weight– Turbidity– Metabolic Activity
Bacterial GrowthBacterial Growth
Dry Weight– Mass increases in proportion to
growth– Filter onto pre-weighed paper – Dry under vacuum – Time consuming but usually accurate
Bacterial GrowthBacterial Growth
Metabolic Activity– Dissolved oxygen
»Decrease in oxygen as cells increase
– pH»Use indicator change or pH meter
– Monitor a metabolite»Glucose use or ethanol production or
carbon dioxide
Bacterial GrowthBacterial Growth
Viable Counts– Plate counts– Membrane filters
Bacterial GrowthBacterial Growth
Total Counts– Direct Microscopic Count– Most Probable Number– Electronic Counter
Bacterial GrowthBacterial Growth
Most Probable Number– 5 tubes at 10 mL, 1 mL and 0.1 mL
sized inoculum– Use combinations with table to
calculate the most probable number– Confidence limits set range
Bacterial GrowthBacterial Growth
Electronic counter– Cells move past light source in very
narrow tube– Each cell passing is counted– Counts both live and dead cells so
must be used before culture gets to stationary phase
