Poster
Presentation 1B-53
Enzymatic
Bleaching of Organosolv Sugarcane Bagasse Pulps with Recombinant Xylanase of
the fungus Humicola grisea and
comercial xylanase Cartazyme HS
1Departamento de
Biotecnologia
FAENQUIL, CP 116, CEP 12600-970
Lorena-SP, Brazil
E-mail: adilson@debiq.faenquil.br
2Universidade Federal de
Goiás-Goiânia, Brazil
Sugarcane
bagasse was submitted to delignification with a mixture of acetic acid and
water 93% (v/v) and HCl as catalyst for 2 h at 110°C. The ethanol/water pulping of sugarcane bagasse
was carried out using ethanol/water 1:1 (v/v) at 185°C for 2.5 h. The organosolv pulps obtained were biobleached
for 4 h, 8 h and 12 h at 50°C with 18 U/I per gram of dried pulp with comercial
xylanase Cartazyme HS and compared with the pulps treated with xylanase of the
fungus Humicola grisea produced in
yeast Pichia pastoris. After the enzymatic treatment the pulps were
submited to alkaline extraction with NaOH 1 mol.L-1 at 65°C for 1 h.
The biobleaching was evaluated by viscosity, kappa number and the chemical
composition of the pulps. Among the three times studied, 4h was the best time
for the pulp treatment and the results are in table 1 for the ethanol/water
pulps and in table 2 for the acetosolv pulp:
Table 1. Results of viscosity, kappa number and
chemical composition for the ethanol/water pulps.
|
Enzyme |
Treatment |
Viscosity (cP) |
Kappa Number |
Glucan (%) |
Xilan (%) |
Residual Lignin (%) |
|
Cartazyme |
X |
11,10 ± 0.26 |
38.35 ± 3.01 |
72.20 ± 0.68 |
6.79 ± 0.02 |
18.54 ± 1.54 |
|
XE |
20.09 ± 3.76 |
9.15 ± 0.16 |
87.83 ± 0.54 |
5.00 ± 0.06 |
6.51 ± 0.25 |
|
|
Humicola
grisea |
X |
7.98 ± 2.21 |
39.88 ± 2.18 |
66.84 ± 4.82 |
9.59 ± 0.47 |
20.15 ± 0.73 |
|
XE |
12.30 ± 1.56 |
13.84 ± 1.20 |
86.49 ± 2.13 |
5.45 ± 0.10 |
7.14 ± 0.62 |
X = Xylanase, XE = Xylanase followed by alkaline
extraction.
Table 2. Results of viscosity, kappa number and
chemical composition for the acetosolv pulps.
|
Enzyme |
Treatment |
Viscosity (cP) |
Kappa Number |
Glucan (%) |
Xilan (%) |
Residual Lignin (%) |
|
Cartazyme |
X |
5.50 ± 0.12 |
13.25 ± 3.07 |
61.27 ± 0.35 |
10.98 ± 0.08 |
20.67 ± 0.38 |
|
XE |
7.23±
0.15 |
8.33 ± 0.78 |
79.32 ± 3.51 |
9.41 ± 1.40 |
9.10 ± 3.35 |
|
|
Humicola
grisea |
X |
5.32 ± 0.26 |
23.46 ± 2.44 |
68.66 ± 1.22 |
6.61 ± 0.09 |
19.08 ± 2.45 |
|
XE |
5.32 ± 1.82 |
16.19 ± 1.41 |
88.99 ± 0.61 |
5.33 ± 0.37 |
5.37 ± 1.33 |
X = Xylanase, XE = Xylanase followed by alkaline
extraction.
The alkaline extraction of the pulps
increased the viscosity, decreased the kappa number and the residual lignin.
Ethanol/water and acetosolv pulps are chemically distinct and the xylanases
from the two sources act differently on the pulps.