Table 1 General distribution of Ni and Co utilization in the three domains of life

Ni-utilizing organisms

39

319

51

409

Ni User (+)

Ni Transporter* (+)

21

166

49

236

Ni Transporter (-)

& Unassigned transporter (+)

11

81

-

92

Ni Transporter (-)

& Unassigned transporter (-)

7

62

2

71

Ni User (-)

Ni Transporter (+)

-

10

-

10

Co-utilizing organisms

45

410

49

504

B ₁₂ biosynthesis pathway (+)

Co Transporter (+)

15

180

-

195

Co Transporter (-)

& Unassigned transporter (+)

10

16

-

26

Co Transporter (-)

& Unassigned transporter (-)

9

13

-

22

B ₁₂ biosynthesis pathway (-)

Co Transporter (+)

-

-

-

-

Other (using external B ₁₂ )

11

201

49

261

Organisms that use both Ni and Co

38

287

9

335

Organisms that use neither Ni nor Co

1

98

69

168