62
Table 3 Biochemical reactions in anaerobic fermentative processes
Process stage
Responsible enzymes
Chemical reactions and metabolic products
Reference
Hydrolysis
Esterases, glycosidases, cellulases,
β-glucosidase, β-xylanase, β-xylosidase,
β-mannosidase, α-galactosidase, peptidases,
lipase, etc.
(C
6 H
10 O
5 )n + nH
2 O → n(C
6 H
12 O
6 )
Abbasi et al. [88], Bharathiraja
et al. [81], Deepanraj et al.
[89], Sikora et al. [90] and Van
et al. [83]
Acidogenesis
Glucosidases, dehydrogenase, dehydratases,
decarboxylase, glycine reductase, acetate
kinase
n(C
6 H
12 O
6 ) → 3nCH
3 COOH
C
6 H
12 O
6  + 2H
2 O → 2CH
3 COOH + 4H
2  + CO
2
C
6 H
12 O
6  + 2H
2  → 2CH
3 CH
2 COOH + 2H
2 O
C
6 H
12 O
6  → CH
3 CH
2 CH
2 COOH + 2H
2  + 2CO
2
C
6 H
12 O
6  → 2CH
3 CH
2 OH + 2CO
2
C
6 H
12 O
6  → 2CH
3 CHOHCOOH
Abbasi et al. [88], Deepanraj
et al. [89], Sikora et al. [90]
and Van et al. [83]
Acetogenesis
Decarboxylase, dehydrogenase/acetyl-CoA
synthase, acetate kinase, oxidoreductase,
alcohol dehydrogenase, etc.
CH
3 CH
2 OH + H
2 O → CH
3 COOH + 2H
2
2CH
3 CH
2 OH + 2CO
2  → CH
4  + 2CH
3 COOH
CH
3 CH
2 COOH + 2H
2 O → CH
3 COOH + 3H
2  + CO
2
CH
3 CH
2 CH
2 COOH + 2H
2 O → 2CH
3 COOH + 2H
2
CH
3 CHOHCOOH + H
2 O → CH
3 COOH + CO
2  + 2H
2
2CO
2  + 4H
2  → CH
3 COOH + 2H
2 O
Abbasi et al. [88], Deepanraj
et al. [89], Sikora et al. [90]
and Van et al. [83]
Methanogenesis
Dehydrogenase, methyl-reductase, methyltransferase, acetate kinase, etc.
CH
3 COOH → CH
4  + CO
2
CO
2  + 4H
2  → CH
4  + 2H
2 O
Abbasi et al. [88], Deepanraj
et al. [89], Sikora et al. [90],
Van et al. [83]
C. Mateescu and A.-D. Dima