1

1

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

2

The Growth Curve

2

3

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

4

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

3

5

Control of Microbial Growth

6

4

7

The Autoclave

8

5

9

10

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

6

11

Nutritional Patterns

12

Overview

of

Metabolism

7

13

The Flow of

Energy

14

The Role of ATP

8

15

Enzyme

Structure

16

Enzyme

Action

9

17

Enzyme Function

18

Re-Dox

Reactions

10

19

Central

Metabolism

20

Glycolysis

11

21

TCA Cycle

(Krebs)

22

Energy

Trapping

12

23

Electron Transport Chain

24

Electron Flow

and Energy

Trapping

13

25

Fermentations

26

Fermentation Products

14

27

28

Energy

Trapping

15

29

Energy

Utilization

30

16

31

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

32

The Central Dogma

17

33

The Central Dogma

34

DNA Structure

18

35

3-Dimensional Model of DNA

36

DNA Replication

19

37

DNA Replication

38

Transcription of DNA

20

39

Transcription & Translation