7 - cultivating bacteria Flashcards
what do bacteria need to grow?
- nutrients
- moisture
- temperature
- oxygen/gas
- space
- pH
- ionic balance
what are catabolic reactions?
energy releasing reactions
what are anabolic reactions?
building energy into food
4 macronutrients
- carbohydrates
- lipids
- proteins
- nucleic acids
main elements needed in cultivation of bacteria in the lab
- carbon - 50%
- oxygen - 17%
- nitrogen - 13%
- phosphorus - 2.5%
any others in trace amounts
what are the 2 types of media?
chemically defined media - very specific
undefined complex media - general mixture
what states can media be in?
liquid broth
solid agar
what do agar plates contain?
agar - extracted from seaweed
undigestible by bacteria - remains as the solid phase
what is generation time?
the time interval required for the cells to grow
g = t/n = time / no. of generations
why is generation time useful?
can compare different bacterial species growing in the same condition
compare 1 species growth in different conditions
extremophiles
grow under harsh conditions
would kill most other organisms
effect of pH on growth
grow in a range but possess an optimum
optimum pH is based on extracellular environment only
cytoplasmic pH is maintained closer to 7
Na2PO4 and KH2PO4 are good buffers
chemostats - continuous culture
known as bioreactors
system is open
fresh media goes in and spent media and cells come out
can grow at a steady state
what happens if the flow rate (F) exceeded the growth rate?
bacteria will be washed out and there will be nothing to replace it
what happens if the flow rate (F) was below the growth rate?
accumulation of bacteria
stationary phase / death phase
