Skip to main content

Table 2 Effect of different methods for alkaline pretreatment and enzymatic hydrolysis on the Miscanthus hydrolysate composition.

From: Efficient hydrogen production from the lignocellulosic energy crop Miscanthus by the extreme thermophilic bacteria Caldicellulosiruptor saccharolyticus and Thermotoga neapolitana

  

Hydrolysate

  

I

II

III

IVa

Pretreatment

Alkali

Ca(OH)2

Ca(OH)2

NaOH

NaOH

 

g g-1

0.10

0.10

0.12

0.09

 

mM

157

164

334

265

 

pHinitial

10.4

10.2

11.1

11.0

pH adjustment

Acid

H2SO4

H3PO4

CH3COOH

CH3COOH

 

mM

123

88

302

123

 

pHend

4.8

5.1

4.9

4.8

Enzymatic hydrolysis

Enzyme 1

Cellubrix

GC220

Cellubrix

GC220

 

Enzyme 2

Novozym 188

-

Novozym 188

-

Hydrolysate composition

Sugars (g l-1)

Arabinose

1.8

1.5

1.6

1.1

 

Galactose

0.3

0.2

0.2

0.0

 

Glucose

26.3

19.9

33.0

29.0

 

Xylose

11.5

7.6

11.1

10.0

Total carbohydrates

39.9

29.1

46.0

40.1

Organic acids

Acetic acidb

84

62

419

130

(mM)

Lactic acidc

12

10

14

1.1

  1. aDuring preparation of hydrolysate IV the alkali pretreated material was washed 3 times with water (5.5 l l-1) prior to pH adjustment. bAcetic acid was used for pH adjustment and is also a product of biomass deacylation. cLactic acid is formed by contaminating fermentative microorganisms during enzymatic hydrolysis.
  2. Pretreatment of 205–210 g of dry matter of Miscanthus (2 mm sieve) was done at a solid content of 0.125 g g-1 for 16 h at 85°C. Enzymatic hydrolysis was carried out at 50°C for 24 h.