Table 1.

The elements of microbial cells

Element (symbol)	Major functions and uses in microbial cells
	Required for All Cells
C	basis of all organic molecules
H	H2O, organic molecules
N	organic molecules, esp. proteins and nucleic acids
O	H2O, organic molecules
P	nucleic acids, NTPs, metabolites, phospholipids
S	proteins, glutathione and LMW thiols, biotin, lipoic acid, thiamin
Mg	major cation; cofactor for phosphotransferase reactions
Zn	enzyme cofactor, protein folding
	Required for Most Cells
K	major cation, common in cells
Ca	major cation, required by many eukaryotes
Mn	enzyme cofactor, ribonucleotide reductase, SOD, PS II
Fe	heme, iron-sulfur cluster, non-heme enzymes
Co	enzyme cofactor, B12-dependent enzymes
Cu	enzyme cofactor, electron carrier, respiration, SOD
Mo	FeMoCo cofactor (nitrogenase), Mo cofactor enzymes
	Required for Specialized Functions in Some Cells
Se	selenocysteine in proteins
B	plant cell wall, quorum sensing (some AI-2)
Na	used for ion potential in halophiles
Si	some plant cell walls, diatom walls (frustules)
Cl,Br,Fl,I	some bacterial secondary metabolites
V	nitrogenase, haloperoxidases
Ni	urease, SOD (SodN), glyoxalase
Cd	cofactor for carbonic anhydrase (CA) in some marine microbes
W	tungstoenzymes (aldehyde oxidoreductase, formate dehydrogenase, acetyl hydratase)