Table 3 Enriched KEGG mappings for the significantly different KO abundances

Pathway

Methane metabolism

173

33

Pyruvate metabolism

113

14

Carbon fixation pathways in prokaryotes

97

12

Fatty acid degradation

25

5

Butanoate metabolism

97

11

Tryptophan metabolism

39

6

Drug metabolism—other enzymes

20

4

Lysine biosynthesis

41

6

Citrate cycle (TCA cycle)

54

7

Nitrogen metabolism

54

7

Arginine biosynthesis

45

6

Module

Methanogenesis, CO2 =  > methane

23

14

F420 biosynthesis, archaea

5

5

Acetyl-CoA pathway, CO2 =  > acetyl-CoA

5

5

Methanogenesis, acetate =  > methane

19

8

Lysine biosynthesis, acetyl-DAP pathway, aspartate =  > lysine

9

4

Benzoyl-CoA degradation, benzoyl-CoA =  > 3-hydroxypimeloyl-CoA

9

4

Dissimilatory sulfate reduction, sulfate =  > H2S

5

3

Lysine biosynthesis, DAP aminotransferase pathway, aspartate =  > lysine

10

4

Denitrification, nitrate =  > nitrogen

10

4

Reductive acetyl-CoA pathway (Wood-Ljungdahl pathway)

16

5

Ornithine biosynthesis, glutamate =  > ornithine

12

4

Lysine biosynthesis, succinyl-DAP pathway, aspartate =  > lysine

13

4

Citrate cycle, second carbon oxidation, 2-oxoglutarate =  > oxaloacetate

25

5

Lysine degradation, lysine =  > saccharopine =  > acetoacetyl-CoA

4

2

Phosphatidylethanolamine (PE) biosynthesis, PA =  > PS =  > PE

4

2

Fumarate reductase, prokaryotes

4

2

Benzoate degradation, cyclohexanecarboxylic acid =  > pimeloyl-CoA

5

2