Applied Microbiology (L39-43)

Question 1

how to bacteria reproduce?

Answer 1

asexually via binary fission

Question 2

what are the things bacteria need to grow? why do they need them? (3)

Answer 2

- energy source
in order to make ATP
- carbon source
in order to make precursor metabolites for amino acids
- reducing power

Question 3

what are the kinds of energy sources in the cell? (prefix)

Answer 3

light (photo-) and chemical (chemo-)

Question 4

what are the two types of carbon sources? (prefix)

Answer 4

Carbon dioxide from atmosphere (auto-) and organic compounds (hetero-)

Question 5

what are the 4 trophic groups? briefly describe their details?

Answer 5

• chemoautotrophic
  make organic molecule for energy from carbon dioxide, energy from inorganic molecules
• chemoheterotrophs
  carbon and energy from organic molecule (glucose)
• photoautotrophs
  carbon from carbon dioxide, energy from light
• photoheterotrophs
  carbon from organic molecule, energy from light

Question 6

what kind of behaviour do myxobacteria have?

Answer 6

social behaviour (social gliding and fruiting body development)

Question 7

why have myxobacteria developed their social behaviour?

Answer 7

because when the cells germinate they are in groups which makes feeding of these microbial scavengers more efficient

Question 8

describe the motility of myxobacteria

Answer 8

• social gliding motility

- can go forward and backward by reversing polarity (no u-turn)

Question 9

what is the mechanism for the movement of myxobacteria?

Answer 9

they have two engines: S (social) engine which allows pulling and A (adventurous) engine which allows pushing movement

Question 10

what happens to myxobacteria when there is no food?

Answer 10

they develop a fruiting body:

• cells aggregate by coordinated movement mediated by cell signalling
• aggregation causes mounds to form
• form myxospores which are very resistant to starvation
• myxospores germinate when nutrients become available and vegetative growth cycle begins again

Question 11

what are the phases in the pattern of growth of a closed batch culture system? briefly describe what happens in each phase

Answer 11

• lag phase
  no appearance of change, cells preparing metabolic reactions
• exponential phase
  cells are actively dividing and nothing is limiting to growth
• stationary phase
  bacteria have run out of nutrients and stop growing
• death phase
  90% of culture dies

Question 12

how to measure viable count?

Answer 12

plate culture onto agar and measure the number of cfu (colony forming units) = number of viable colonies

Question 13

what is the ecological relationship between cells, population, and community?

Answer 13

• cells of a species proliferate to form a population

- different populations interact/communicate to form communities

Question 14

define microbial ecology

Answer 14

study of the interrelationships among microorganisms and their environment

Question 15

define enrichment culture

Answer 15

providing the temperature and chemical conditions in the laboratory that encourage the growth of specific groups of microbes

Question 16

define mesocosm

Answer 16

an experimental system that simulates real-life conditions as closely as possible

Question 17

what are the layers from bottom to top of the Winogradsky column?

Answer 17

• fermentative and sulfur reducing bacteria (chemoheterotrophic)
• green sulfur and purple sulfur bacteria
• colourless sulfur bacteria
• cyanobacteria

Question 18

what are the gradients that exist in the Winogradsky column?

Answer 18

• oxygen gradient: high at top low at bottom

- H2S gradient, high at bottom low at top

Question 19

which sulfur bacterium is located closer to the bottom of the winogradsky column? why?

Answer 19

green - because it can tolerate higher levels of H2S

Question 20

what are the reactions that chemoheterotrophs are responsible for in the Winogradsky column and which bacteria?

Answer 20

• fermentative bacteria
  break down cellulose into acetate
• sulfur reducing bacteria
  use SO4(2-) for respiration (reduce it to H2S) and oxidise acetate to CO2

Question 21

what causes the H2S gradient?

Answer 21

the production of H2S from sulfur reducing bacteria at the bottom of the column

Question 22

what are the types of anoxygenic photosynthetic bacteria in the Winogradsky column?

Answer 22

purple and green sulfur bacteria

Question 23

what trophic classification are the purple and green sulfur bacteria?

Answer 23

photoautotrophs

Question 24

what is the process of reactions that occurs in the Winogradsky column?

Answer 24

- fermentation
cellulose -> acetate
- acetate to CO2
SO4(2-) -> H2S
- H2S -> S
- H -> NADPH
- CO2 -> (CH2O)n

Question 25

what is the electron donor and what is the reducing power in anoxygenic photosynthesis?

Answer 25

• electron donor is H2S

- reducing power is NADPH

Question 26

what are the differences between anoxygenic and oxygenic photophosphorylation?

Answer 26

• anoxygenic
  is cyclic, doesnt use oxygen
• oxygenic
  is not cyclic, does use oxygen