bmic topic 3.3 microbiological media ; physical state

part 1

what is a culture medium?

A mixture of different compounds that provides all the nutrients that are required for microbial growth

what are microbiological media categorized based on?

physical state composition function

what is an example of a liquid media?

nutrient broth

what is an example of a solid media?

nutrient agar

how do we solidify agar?

agar is added up to 2% (v/v) as solidifying agent

agar used as few microorganisms can catabolize agar

agar solidifies at 45 C allowing addition of heat labile substances into molten agar

what is a semi-solid media?

agar added up to 1% (v/v)

what is the growth for solid culture: agar

microorganisms grow as colonies on the surface of the agar

what are the advantages of agar?

useful for isolation to give pure cultures

easier to detect for contamination

what are the disadvantages of agar?

more tedious to prepare, especially in large quantities

smaller yields and more difficult to harvest

what is the growth of liquid culture: broth?

growth appears as turbidity

what is turbidity?

cloudy

what are the advantages of broth?

large quantities of medium can be prepared easily

large quantities of microbial cells can be cultured

easily harvested and diluted

what is the disadvantage of broth?

difficult to tell whether it’s contaminated and impossible to salvage if contaminated.