environmental control of metabolism Flashcards
microbiology
involves study of micro organisms
microorganism’s
archea, bacteria and eukaryotes
include species that use a variety of substrates for metabolism and produce a range of products from their metabolic pathway
why are microorganisms used
- highly adaptable
- easy to cultivate
- speed of growth
- variety of research
- industrial uses
- can produce useful metabolic pathways: beer, wine, bread
what do microorganisms require
- energy source (derived from chemical substrates or from light in photosynthetic organisms)
- simple chemical compounds for biosynthesis
growth liquids can be…
liquid and semi-solid
how to produce the max yield of a product
maintain optimum environmental conditions such as fertility, temp, oxygen levels, control of pH or addition of acid and alkali
advantage of microorganisms grown in a growth media
can produce complex molc required for biosynthesis eg. vitamins, amino acids
- mothers MOO require these complex compounds to be supplied in growth media
nutritional requirements
chemicals and elements used for bacterial growth
why do MOO need raw materials
to produce cellular building blocks such as amino acids needed in biosynthesis of proteins
how are oxygen levels controlled
by bubbling filtered air through the liquid media in fermenter vessels
why are suitable temps of 30-37*C maintained
to provide the optimum temp for growth of bacterial cultures
advantage of sterile conditions in fermenters
- reduce competition with desired microorganisms for nutrients
- reduce risk of spoilage of product
how is the control go pH achieved
- by using different buffers
- addition of acid and alkali
what are the four phases in growth
- lag
- log/exponential
- stationary
- death
lag
enzymes are induced to metabolise substrates
log/exponential
highest rate of growth of microorganisms due to plentiful nutrients
stationary
- toxic and secondary metabolites are produced
- secondary metabolites confer an ecological advantage to MOO producing them by allowing them to outcompete other MOO
- occurs due to nutrients in culture media becoming depleted
death
- occurs due to toxic accumulation of metabolites
- lack of nutrients in the culture
how can size of MOO populations be estimated
by making viable or total cell counts
viable cell count
involve only counting living MOO
- show a death phase where numbers are decreasing
total cell count
involve counting viable and dead cells
