Applied Microbiology (L39-43) Flashcards
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?
photoautotrophs
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
