Microbial Growth: Nutrition and Cultivation

MGI 301

fastidious

a type of microorganism that requires more added nutrients because they are not capable of synthesizing on their own

complex (undefined) media

a semi-solid or liquid preparation used to grow microorganisms where ingredients containing unknown chemical compositions are used

tryptone

the collection of small polypeptides and peptones that are formed when casein protein is digested with the trypsin enzyme

blood agar

common undefined growth medium that includes nutrients that promote the growth of fastidious organisms, enriched with blood

filtration

the passage of air or liquid through a material with pore openings that are smaller than microbes, used to sterilize liquids and reduce the number of microbes/particles

peptone

collection of small polypeptides and peptones that are formed when casein protein is digested with pepsin enzyme

sterilization

killing of all viable forms of microbes

differential medium

growth medium that contains an indicator that allows microbes to be visually distinguished based on the way they react to certain ingredients

selective medium

growth medium that has ingredients that kill/inhibit growth of some organisms while allowing others to grow, used to isolate a specific microbe

minimal medium

nutrient media where the lowest amount of nutrients possible for growth are present, forces cell to synthesize everything by themself, slowing growth rate

agar

gel-like polysaccharide isolated from seaweed that is used as a solidifying agent in media

defined medium

a medium where all exact chemical species are known in their exact concentrations

enriched medium

nutrient media that contains pre-formed essential biochemical building blocks so that the cell doesn’t have to produce it by itself, leads to faster growth

macronutrients

substances used for biosynthesis and energy production that are required for microbial growth and are needed in large amounts

micronutrients

substances used for biosynthesis and energy production that are required for microbial growth, needed in small amounts, also used as confactors for enzymes

casamino acids

amino acids from casein proteins treated with acid used in complex/defined media to assist in growth

autoclave

laboratory instrument that sterilizes by using pressure to super-heat steam

yeast extract

yeast cells are grown, lysed, filtered, and the insoluble cell components are dried. the powder is used for complex/undefined media to provide carbon and nitrogen

casein

milk protein used to make many microbial growth media components