higher biology 2.6

what do microorganisms include?

bacteria, eukaryotes and archaea

why are microorganisms used?

speed of growth, ease of cultivation and adaptability

what do growth medias require?

raw materials for biosynthesis and a light source

what do microorganisms use?

wide range of substrates for metabolism and produce a range of products from metabolic pathways

many microorganisms produce

the complex molecules that are required for biosynthesis

eg

amino acids

fatty acids

vitamins

growth media may contain

simple substances suitable for specific microorganisms or complex ingredients such as beef extract

talk about energy sources

an energy source is derived from chemical substrates eg carbohydrates eg. fungi

light - photosynthetic micro organisms

culture conditions

sterility - sterile conditions in fermenters reduce competition with desired microorganisms for nutrients and reduce risk of spoilage of product

temperature - must be controlled as enzymes are involved - growth occurs due to chemical reactions

oxygen - levels may be controlled by aeration

pH - regulated through adding pH buffers or addition of acid/alkali

fermenters

industrial fermenters can be used to culture microorganisms ona large scale. sensors monitor temp, ph and oxygen levels

viable cell count

only counts living micro organisms

total cell counts

count both living and dead cells

lag phase

during lag phase, enzymes are induced to metabolise substrates

log/exponential

contains most rapid growth of micro organisms due to plentiful supply of nutrients

stationary

nutrients in culture are becoming depleted and toxic metabolites are being produced. secondary metabolic are also produced which in the wild allow the metabolites to have an ecological advantage by allowing micro organisms which produce them to outcompete other microorganisms.

death phase

toxic accumulation of metabolites or lack of nutrients in culture