Question

One of my isolates (WCm1) from the Eastern Shore Winogradsky Column has some interesting properties: it’s a motile bacterium and it can grow in simple media that have only a short list of ingredients. Both PMG and PMD broths support growth of WCm1 in well-aerated culture tubes.

PMG Broth	PMD Broth
10.5 g K2HPO4	10.5 g K2HPO4
4.5 g KH2PO4	4.5 g KH2PO4
1 g MgSO4	1 g MgSO4
10 g Glutamic acid	10 g Dextrose (Glucose)
1 liter H2O	2 g Ammonium chloride
	1 liter H2

Which of the following terms apply to these broths? Briefly explain your answer.

(Complex, Defined, Rich, Minimal)

Complex media: made from digests of microbial, animal, or plant products, such as milk protein (casein), beef (beef extract), soybeans (typically broth), yeast cells (yeast extract),or any number of other highly nutritious substances.

Rich media: used for the culture of nutritionally demanding microbes, many of which are pathogens, in a complex medium to which additionally high nutritious substances such as serum or blood are added

Defined media: prepared by adding precise amounts of pure inorganic or organic chemicals to distilled water, the exact composition of a defined media (in both qualitative and quantitative sense) is known

Minimal media: contain the minimum nutrients possible for a colony to grow, generally without the presence of amino acids

Answer 1

PMD Broth is a minimal media which contains the minimum nutrients possible for the growth of a colony and it does not contain any amino acid. It contains the basic Carbon source (Dextrose), nitrogen source (Ammonium chloride) and salts for the growth of the bacterial colony.

PMG Broth is a defined media which contains precise amounts of inorganic and organic chemicals. Typically, defined media contain a simple sugar as the carbon and energy source, an inorganic nitrogen source, various mineral salts and if necessary growth factors (purified amino acids, vitamins, purines and pyrimidines).