Adsorption of hemicellulases onto bleached kraft fibers

Gerber, Paul; Heitmann, John A.; Joyce, T. W.; Büchert, Johanna; Siika‐aho, Matti

doi:10.1016/s0168-1656(98)00163-1

Cited by 20 publications

(12 citation statements)

References 16 publications

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“…7). Again, this behavior is expected, and most likely due to "salting out" effects, as has previously been observed in other cellulase-cellulose systems [50][51][52].…”

Section: Initial Enzyme Adsorptionsupporting

confidence: 80%

Enzymatic degradation of model cellulose films

Eriksson

Malmsten

Tiberg

et al. 2005

Journal of Colloid and Interface Science

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“…7). Again, this behavior is expected, and most likely due to "salting out" effects, as has previously been observed in other cellulase-cellulose systems [50][51][52].…”

Section: Initial Enzyme Adsorptionsupporting

confidence: 80%

Enzymatic degradation of model cellulose films

Eriksson

Malmsten

Tiberg

et al. 2005

Journal of Colloid and Interface Science

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“…Furthermore, adsorption capacity increased with residual xylan content in the solids, as shown in Figure 5, for all pretreatments except AFEX. However, xylanase adsorption not only takes place on xylan but on glucan and lignin in biomass as well (Boussaid and Saddler, 1999;Gerber et al, 1999;Ryu and Kim, 1998;Tenkanen et al, 1995), suggesting that either AFEX pretreated lignin had a low xylanase capacity or that xylan in AFEX solids was not as accessible as for other pretreatments. By comparing Tables IV and V, we can see that xylanase had a lower affinity for pretreated solids than cellulase, and among the leading pretreatments, AFEX solids had the greatest xylanase affinity (0.96 g/L) followed by dilute acid (0.43 g/L), ARP (0.21 g/L), and SO 2 (0.21 g/L), while lime solids followed by controlled pH had the least.…”

Section: Xylanase Adsorptionmentioning

confidence: 99%

Cellulase adsorption and relationship to features of corn stover solids produced by leading pretreatments

Kumar

Wyman

2009

Biotech & Bioengineering

206

137

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Although essential to enzymatic hydrolysis of cellulosic biomass to sugars for fermentation to ethanol or other products, enzyme adsorption and its relationship to substrate features has received limited attention, and little data and insight have been developed on cellulase adsorption for promising pretreatment options, with almost no data available to facilitate comparisons. Therefore, adsorption of cellulase on Avicel, and of cellulase and xylanase on corn stover solids resulting from ammonia fiber expansion (AFEX), ammonia recycled percolation (ARP), controlled pH, dilute acid, lime, and sulfur dioxide (SO(2)) pretreatments were measured at 4 degrees C. Langmuir adsorption parameters were then estimated by non-linear regression using Polymath software, and cellulase accessibility to cellulose was estimated based on adsorption data for pretreated solids and lignin left after carbohydrate digestion. To determine the impact of delignification and deacetylation on cellulose accessibility, purified CBHI (Cel7A) adsorption at 4 degrees C and hydrolysis with whole cellulase were followed for untreated (UT) corn stover. In all cases, cellulase attained equilibrium in less than 2 h, and upon dilution, solids pretreated by controlled pH technology showed the greatest desorption followed by solids from dilute acid and SO(2) pretreatments. Surprisingly, the lowest desorption was measured for Avicel glucan followed by solids from AFEX pretreatment. The higher cellulose accessibility for AFEX and lime pretreated solids could account for the good digestion reported in the literature for these approaches. Lime pretreated solids had the greatest xylanase capacity and AFEX solids the least, showing pretreatment pH did not seem to be controlling. The 24 h glucan hydrolysis rate data had a strong relationship to cellulase adsorption capacities, while 24 h xylan hydrolysis rate data showed no relationship to xylanase adsorption capacities. Furthermore, delignification greatly enhanced enzyme effectiveness but had a limited effect on cellulose accessibility. And because delignification enhanced release of xylose more than glucose, it appears that lignin did not directly control cellulose accessibility but restricted xylan accessibility which in turn controlled access to cellulose. Reducing the acetyl content in corn stover solids significantly improved both cellulose accessibility and enzyme effectiveness.

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“…They are, for instance, useful in pulp and paper industries, particularly for the facilitative role they play in the bleaching of craft pulp in order to reduce the amount of chlorine required for target pulp brightness. 2 A recent and exciting application of endoxylanases is the production of xylo-oligosaccharides with huge commercial value, because xylooligosaccharides, especially xylobiose, have been found to have a stimulatory effect on the selective growth of human intestinal Bifidobacteria, and are frequently defined as prebiotics. 3,4 Another economically important application of Xyl-11 deals with animal feeding.…”

Section: Introductionmentioning

confidence: 99%

Immobilization of His-tagged recombinant xylanase fromPenicillium occitanison Nickel-chelate Eupergit C for increasing digestibility of poultry feed

Driss

Châari

et al. 2014

Bioengineered

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Characterization of the immobilized PoXyn2 was further evaluated. The optimum pH was not affected by immobilization, but the immobilized PoXyn2 exhibited more acidic and large optimum pH range (pH 2.0-4.0) than that of the free PoXyn2 (pH 3.0). The free PoXyn2 had an optimum temperature of 50 °C, whereas that of the immobilized enzyme was shifted to 65 °C. Immobilization increased both pH stability and thermostability when compared with the free enzyme. Thermodynamically, increase in enthalpy and free energy change after covalent immobilization could be credited to the enhanced stability. Immobilized xylanase could be reused for 10 consecutive cycles retaining 60% of its initial activity. It was found to be effective in releasing reducing sugar from poultry feed. Immobilization on Eupergit C is important due to its mechanical resistance at high pH and temperature. Hence, considerable stability and reusability of bound enzyme may be advantageous for its industrial application.

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Adsorption of hemicellulases onto bleached kraft fibers

Cited by 20 publications

References 16 publications

Enzymatic degradation of model cellulose films

Enzymatic degradation of model cellulose films

Cellulase adsorption and relationship to features of corn stover solids produced by leading pretreatments

Immobilization of His-tagged recombinant xylanase fromPenicillium occitanison Nickel-chelate Eupergit C for increasing digestibility of poultry feed

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