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GROWTH AND CULTURING OF BACTERIA

CHAPTER 6

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Growth and Cell Division

Growth

Binary fission

3

4

Cell Division

Budding

5

Bacterial Growth Curve

Lag phase

Log phase

Stationary phase

Death phase

6

Measuring Bacterial Growth Serial dilution/

Standard plate counts

7

Measuring Bacterial Growth

Direct microscopic counts

8

Measuring Bacterial Growth Most probable

number

9

Measuring Bacterial Growth

Filtration

Turbidity (Spectrophotometric)

10

Filtration

11

Turbidity

12

Physical Factors Affecting Bacterial Growth

pH Temperature

13

Oxygen

Moisture

Physical Factors Affecting Bacterial Growth

14

Hydrostatic pressure

Osmotic pressure

Radiation

Physical Factors Affecting Bacterial Growth

15

Radiation:

Ionizing (gamma radiation)

Ultraviolet radiation: DNA absorbs 260 nm light

“Thymine dimers”

16

Nutritional Factors Affecting Bacterial Growth

Carbon source

Nitrogen source NH4 best, but NO3 and NO2 can work

too.

Sulfur/ phosphorusPO4

3- SO42-

C6H12O6 best but many sugarsCO2 for autotrophs

17

Nutritional Factors Affecting Bacterial Growth

Trace elements

Vitamins

Nutritional complexity

18

Tab. 5-1

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Locations of Enzymes

Extracellular

Periplasmic kinases and phosphatases

Cytoplasmic

Proteases and cellulases (hydrolases)

Foldases , dehydrogenases

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Sporulation

Endospores

Other sporelike bacterial structures

21

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Bacillus subtilis spore stain

23

Culturing Bacteria — Streak Plates

Streak plate method

24

Culturing Bacteria — Pour Plates

Pour plate method

25

Culture Media Types

– Defined

– ComplexLB (Luria-Bertani)TSA

26

Culture Media Purposes

Selective media

Differential media

Enrichment media

McConkey’s

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Detection of Carbon source fermenters

McConkey’s agar

28

Culture Conditions — O2

Controlling oxygen content

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Culture conditions

Maintaining cultures

Preserved cultures

Diagnostic tests

Limitations

30