9/7/20

1

7- Microbial Nutrition & Growth

Nutrients essential CHONPS macro vs. micro organic vs. inorganic

9/7/20

2

Diffusion Due to molecules in motion Move from areas/volumes of high concentration to low

Osmosis: diffusion of water through a membrane

Biological extra: aquaporins

still later later

9/7/20

3

Tonicity

Facilitated diffusion Group translocation (prok. only)

Active transport (ATP required)

9/7/20

4

Endocytosis receptor-mediated

(Wikipedia)

exocytosis

9/7/20

5

saprobes parasites/predators

9/7/20

6

Singlet oxygen

Toxic forms of oxygen

contains O2 2- (peroxide anion)

Detoxification enzymes

Other antioxidants: carotenoids, glutathione, Vit E & C, etc.

9/7/20

7

Micro-aerophiles

Fluid thioglycollate medium (FTM)

candle jar

for capnophilics

9/7/20

8

Anaerobic jar Glove box

Laminar flow hood (for work with aerobes)

9/7/20

9

Nitrogen cycle Fig 26.7

hyperthermophile

9/7/20

10

acidophiles alkalinophiles/basophiles

Vibrio

neutrophiles

Fig. 2.13

Ferroplasma

Halophiles

obligate

tolerant

Barophiles

Extremophiles

9/7/20

11

Ecological associations

Symbiotic Mutualistic

Commensalistic

Parasitic

Non-symbiotic Antagonistic

Synergistic

Biofilms

Quorum sensing

(on a tooth)

Standard freezer -20oC

Ultra deep freezer -70 to -86oC

Liquid nitrogen -196oC

refrigerator Culture preservation

9/7/20

12

Culture preservation Lyophilization = freeze-drying

Others: desiccation,

crystallization (viruses only)

Reproduction: Binary fission

9/7/20

13

Reproduction:

budding

Reproduction:

fragmentation

Population growth

9/7/20

14

A Viable Plate Count: time-course demonstration showing population increase

Colony counter

Membrane filtration Fig 26.18

9/7/20

15

Cell counter

Direct microscopic count

Look up 4-2-1 pattern in MPN Table

-> 26 cells /100 ml (on average) (see App C)

Most Probable Number (MPN) (used often for water testing)

(serial dilutions)

(replicates)

9/7/20

16

dry weight

Indirect methods

metabolic activity

Turbidity spectrophotometer