Why are trace elements or vitamins not included in some of the bacterial minimal media like Bushnell Hans media?
Are trace elements not essential for bacterial growth?
If, for example, any carbon source like Tryptophan is used in such a minimal media without any trace element, will the Tryptophan degrading bacteria will grow in it?
In addition to what Amjad Tarawneh and Alexander Galushko said, It depends on the aim of using certain minimal media for special purpose, the trace elements generally work as cofactors for the reactions of many crucial enzymes in the cell. It also depends on wether the bacteria are prototrophic or auxotrophic and what some elements serve as either a structural or functional role in the cells.
Minimal media are generally used to detect the ability of some microbes to use some particular chemical compound as carbon source. Hence, minimal media are free from any carbon sources. The chemical of interest is mixed with the media and the bacteria that grows on it are capable using (or degrading) the chemical as carbon source.
Thanks Sutanu Karmakar . But there are many other minimal media like MM3Y, M9 etc. which include trace elements, yeast extract etc. So I am wondering if I use any carbon source like tryptophan in a minimal media without trace elements, will Trp degrading bacteria still grow?
It depends. That is the reason of using different minimal media. Because some bacteria needs some co-facor or co-substrate for degrading certain compound while other may directly degrade and use it.
In general All microorganisms need trace elements! The requirement of trace elements for growth depends on the presence of metal-dependent enzymes in the pathway of the particulat organic compound degradation.
yeast extract etc are NOT trace elemtsfree...
Thanks a lot Dr. Alexander Galushko for your kind reply.
So I am still confused why some minimal media do not include trace elements or yeast extract?
Minimal media contains the minimum possible nutrients for colonial growth, generally, without the presence of amino acids. This media are often used to grow "wild-type" microorganisms, also, can be used as selective media for or against recombinants or exconjugants.
Typically, Minimal media contains: Water, carbon source, and various salts, to provide essential elements such as magnesium, nitrogen, phosphorus, and sulfur.
But, supplementary minimal media contains a single selected agent, usually an amino acid or a sugar, which allows for the culturing of specific lines of auxotrophic recombinants.
In addition to what Amjad Tarawneh and Alexander Galushko said, It depends on the aim of using certain minimal media for special purpose, the trace elements generally work as cofactors for the reactions of many crucial enzymes in the cell. It also depends on wether the bacteria are prototrophic or auxotrophic and what some elements serve as either a structural or functional role in the cells.
It is true that many bacteria can grow in minimal medium like M9 and others that do not have trace elements added to it. They seem to grow just fine, so you can probably go ahead and do your tryptophan selection without worry. I have always assumed that the tiny amount of real trace elements needed for reactions as Khaled Khleifat points out, are present because generally we don't use the highest quality chemicals for growth medium or the highest purity of water. So the tiny fraction of contaminating other elements provides the trace elements needed. Remember that using something that is 99% pure still has about 1% of other stuff, which in this case is plenty.
Some components like yeast extract containg trace amounts of trace elements, which generally suffices.
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