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Enzyme recovery in high-solids enzymatic hydrolysis of steam-pretreated willow: Requirements for the enzyme composition

Pristavka, AA; Salovarova, VP; Zacchi, Guido LU ; Berezin, IV and Rabinovich, ML (2000) In Applied Biochemistry and Microbiology 36(3). p.237-244
Abstract
In order to reduce the total enzyme consumption in high-solids static hydrolysis of nonwashed steam-exploded willow Salix caprea by mixed cellulase of Trichoderma reesei + Aspergillus foetidus, two different approaches were proposed. In the first case, the enzyme activity adsorbed on residual solids after extended hydrolysis was used for hydrolysis of the newly added substrate. The initial mixing of fresh and hydrolyzed substrates was sufficient for the adsorbed enzyme redistribution and conversion of the new substrate portion, and constant mechanical stirring was not required. Feeding of two additional portions of the exploded hardwood adjusted to pH 4 with dry caustic into the reactor with simultaneous replacement of accumulated sugars... (More)
In order to reduce the total enzyme consumption in high-solids static hydrolysis of nonwashed steam-exploded willow Salix caprea by mixed cellulase of Trichoderma reesei + Aspergillus foetidus, two different approaches were proposed. In the first case, the enzyme activity adsorbed on residual solids after extended hydrolysis was used for hydrolysis of the newly added substrate. The initial mixing of fresh and hydrolyzed substrates was sufficient for the adsorbed enzyme redistribution and conversion of the new substrate portion, and constant mechanical stirring was not required. Feeding of two additional portions of the exploded hardwood adjusted to pH 4 with dry caustic into the reactor with simultaneous replacement of accumulated sugars with fresh buffer (pH 4.5) resulted, on average, in a 90% conversion of cellulose at the final enzyme loading of 8 IFPU per g ODM substrate, an average sugar concentration of 12%, and a glucose/xylose ratio of 5 : 1. In the second approach, weakly adsorbed cellulase fractions were used for static high-solids hydrolysis followed by their ultrafiltration recovery from the resultant sugar syrup. In contrast to the initial cellulase mixture whose residual activity in a syrup did not exceed 5-10% at the end of hydrolysis (48 h), up to 60% of weakly adsorbed enzyme fraction could be separated from sugar syrups by ultrafiltration and then reused. Weakly adsorbed enzymes displayed a hydrolysis efficiency of not less than 80% per IFPU enzyme consumed in extended hydrolysis of pretreated willow as compared to the original enzyme mixture. An electrophoretic study of the weakly adsorbed enzyme fraction identified T. reesei cellobiohydrolase II as the predominant component, whereas clear domination of T. reesei cellobiohydrolase I was found by electrophoresis of proteins tightly bound to residual hydrolysis solids. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Applied Biochemistry and Microbiology
volume
36
issue
3
pages
237 - 244
publisher
MAIK Nauka/Interperiodica
external identifiers
  • wos:000087156200006
  • scopus:0034178823
ISSN
0003-6838
DOI
10.1007/BF02742572
language
English
LU publication?
yes
id
75160b26-9bb3-43d2-80c4-83db90a468dd (old id 3911346)
date added to LUP
2013-07-01 08:18:54
date last changed
2017-01-01 06:42:26
@article{75160b26-9bb3-43d2-80c4-83db90a468dd,
  abstract     = {In order to reduce the total enzyme consumption in high-solids static hydrolysis of nonwashed steam-exploded willow Salix caprea by mixed cellulase of Trichoderma reesei + Aspergillus foetidus, two different approaches were proposed. In the first case, the enzyme activity adsorbed on residual solids after extended hydrolysis was used for hydrolysis of the newly added substrate. The initial mixing of fresh and hydrolyzed substrates was sufficient for the adsorbed enzyme redistribution and conversion of the new substrate portion, and constant mechanical stirring was not required. Feeding of two additional portions of the exploded hardwood adjusted to pH 4 with dry caustic into the reactor with simultaneous replacement of accumulated sugars with fresh buffer (pH 4.5) resulted, on average, in a 90% conversion of cellulose at the final enzyme loading of 8 IFPU per g ODM substrate, an average sugar concentration of 12%, and a glucose/xylose ratio of 5 : 1. In the second approach, weakly adsorbed cellulase fractions were used for static high-solids hydrolysis followed by their ultrafiltration recovery from the resultant sugar syrup. In contrast to the initial cellulase mixture whose residual activity in a syrup did not exceed 5-10% at the end of hydrolysis (48 h), up to 60% of weakly adsorbed enzyme fraction could be separated from sugar syrups by ultrafiltration and then reused. Weakly adsorbed enzymes displayed a hydrolysis efficiency of not less than 80% per IFPU enzyme consumed in extended hydrolysis of pretreated willow as compared to the original enzyme mixture. An electrophoretic study of the weakly adsorbed enzyme fraction identified T. reesei cellobiohydrolase II as the predominant component, whereas clear domination of T. reesei cellobiohydrolase I was found by electrophoresis of proteins tightly bound to residual hydrolysis solids.},
  author       = {Pristavka, AA and Salovarova, VP and Zacchi, Guido and Berezin, IV and Rabinovich, ML},
  issn         = {0003-6838},
  language     = {eng},
  number       = {3},
  pages        = {237--244},
  publisher    = {MAIK Nauka/Interperiodica},
  series       = {Applied Biochemistry and Microbiology},
  title        = {Enzyme recovery in high-solids enzymatic hydrolysis of steam-pretreated willow: Requirements for the enzyme composition},
  url          = {http://dx.doi.org/10.1007/BF02742572},
  volume       = {36},
  year         = {2000},
}