Did you search in complete genomes? Did you search by sequence or by gene name?

Genes might be misnamed, or absent in the case of a draft genomes.

Even the most recent "minimal genome" artificial cell contains MgtE

Article Design and synthesis of a minimal bacterial genome

Thank you Xabier,

Yes. It seems all of creatures need Mg as an essential element. But I am wondering if some bacteria consume more than others?

It doesn't have a rich redox chemistry so it will probably never go further than being a trace element. Said that, there will, likely, be a difference between oligotrophs and copiotrophs but it's not really related just to the Mg.

Otherwise, the only way that this may vary would depend on the number of proteins active at a given time that actually need Mg in their catalytic center.

Hi,

Mg is an essential element for.all known organisms. It is an important co-factor in many pathways.

Not finding Mg transporters is doesn't not mean there aren't.  Most likely they were not sequenced or the bacterium you are working on has a differentgene.

That said, the domain bacteria is so.diverse and most of it hardly stuyied so there might be a small chance of finding bacteria that use another element. 

Mohamad, Magnesium is closely associated with energy production and particularly components with phosphate groups like ATP and DNA. Therefore, I would suspect it is vital to all living things. Many general textbooks of biology make reference to magnesium being a major nutrient.

Plants have a higher requirement because it is the central metal ion in Chlorophyll, making magnesium vital to all living systems.

I have no knowledge of any organism that can grow or function without magnesium.

Andrew