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Microbial Nutrition & Growth
! Requirements for Growth:! Physical: Temperature, O2, pH, Osmotic pressure
! Chemical: Bulk, Ions, Growth Factors
! Culture Media:Liquid vs solid Complex vs defined
Aerobic vs anaerobic Selective vs differential
! Population Growth:
The growth curve
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The Growth Curve
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The Growth Curve
probably more sensitive than
total N or total protein
measurements
Measurement of total cell
yield in cultures
Measurement of dry weight or wet
weight of cells or volume of cells
after centrifugation
Requires a fixed standard to
relate chemical activity to
cell mass and/or cell
numbers
Microbiological assaysMeasurement of Biochemical activity
e.g. O2 uptake CO2 production, ATP
production, etc.
Fast and nondestructive, but
cannot detect cell densities
less than 107 cells per ml
Estimations of large
numbers of bacteria in clear
liquid media and broths
Turbidity measurement
Very sensitive if plating
conditions are optimal
Enumeration of bacteria in
milk, foods, soil, water,
laboratory cultures, etc.
Viable cell count (colony counts)
Cannot distinguish living
from nonliving cells
Enumeration of bacteria in
milk or cellular vaccines
Direct microscopic count
Method Application Comments
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The Growth Curve
Bacterium Medium Generation Time (minutes)Escherichia coli Glucose-salts 17
Bacillus megaterium Sucrose-salts 25
Streptococcus lactis Milk 26
Streptococcus lactis Lactose broth 48
Staphylococcus aureus Heart infusion broth 27-30
Lactobacillus acidophilus Milk 66-87
Rhizobium japonicum Mannitol-salts-yeast extract 344-461
Mycobacterium tuberculosis Synthetic 7 92-932
Treponema pallidum Rabbit testes 1980
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Metabolism
! Introductory ConceptsNutritional patterns, Metabolism, ATP, Enzymes,
Re-Dox reactions, Phosphorylation reactions
! Catabolism
Glycolysis, TCA cycle, Electron transport chain
! Fermentations
Ethanol, Lactic acid
! Anabolism
Biosynthesis
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Microbial Genetics
!Basic Molecular Genetics -The Central Dogma:
Replication, Transcription,Translation
-Gene Expression
Genotype and Phenotype
-The Structure of DNA
Nucleotides and nucleic acids
! Genetic Variability
Mutations, Recombinations, Plasmids
! Genetic Engineering
Terminology and Technology
Products/Benefits of Genetic Engineering
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The Central Dogma