Applied Microbiology (L39-43) Flashcards Preview

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Flashcards in Applied Microbiology (L39-43) Deck (26):

how to bacteria reproduce?

asexually via binary fission


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

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


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

light (photo-) and chemical (chemo-)


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

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


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

- 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


what kind of behaviour do myxobacteria have?

social behaviour (social gliding and fruiting body development)


why have myxobacteria developed their social behaviour?

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


describe the motility of myxobacteria

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


what is the mechanism for the movement of myxobacteria?

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


what happens to myxobacteria when there is no food?

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


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

- 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


how to measure viable count?

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


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

- cells of a species proliferate to form a population
- different populations interact/communicate to form communities


define microbial ecology

study of the interrelationships among microorganisms and their environment


define enrichment culture

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


define mesocosm

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


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

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


what are the gradients that exist in the Winogradsky column?

- oxygen gradient: high at top low at bottom
- H2S gradient, high at bottom low at top


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

green - because it can tolerate higher levels of H2S


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

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


what causes the H2S gradient?

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


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

purple and green sulfur bacteria


what trophic classification are the purple and green sulfur bacteria?



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

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


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

- electron donor is H2S
- reducing power is NADPH


what are the differences between anoxygenic and oxygenic photophosphorylation?

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