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.