Optimization of temperature and enzyme concentration in the enzymatic saccharification of steam-pretreated willow

Eklund, Robert; Galbe, Mats; Zacchi, Guido

doi:10.1016/0141-0229(90)90043-p

Cited by 73 publications

(33 citation statements)

References 5 publications

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“…Similarly, there are significant technical and economic difficulties associated with the scale-up of these processes due to the costs of the chemicals and the very dilute enzyme streams obtained after washing with large amounts of buffer s01ution.l~ A much simple enzyme desorption method that has shown some success in the past is the use of direct readsorption of the enzyme onto fresh substrate either in a b a t~h~~,~~,~~,~~,~~,~~ or continuous mode. 13 Previously we found that cellulases associated with residual cellulosic substrates were able to quickly partition themselves between added fresh substrate and the residual substrate.z9 Good sugar yields were reported for a number of substrates, i.e., wheat aspent7 eucalypt~:~,~~ willow,13 and when cellulose containing residual substrate was added to fresh substrate. This work also indicated that the recovery of enzyme activity varied inversely with the lignin content of the sub~t r a t e .…”

Section: Substrate-related Factors Affecting Hydrolysismentioning

confidence: 96%

Factors affecting cellulose hydrolysis and the potential of enzyme recycle to enhance the efficiency of an integrated wood to ethanol process

Gregg

Saddler

2000

Biotechnol. Bioeng.

157

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Past technoeconomic modeling work has identified the relatively large contribution that enzymatic hydrolysis adds to the total cost of producing ethanol from lignocellulosic substrates. This cost was primarily due to the high concentration of enzyme and long incubation time that was required to obtain complete hydrolysis. Although enzyme and substrate concentration and end‐product inhibition influenced the rate of hydrolysis, the effect was less pronounced during the initial stages of hydrolysis. During this time most of the cellulases were adsorbed onto the unhydrolyzed residue. By recycling the cellulases adsorbed to the residual substrate remaining after an initial 24 h, a high rate of hydrolysis, with low overall residence time and minimal cellulase input, could be achieved for several rounds of enzyme recycle. A comparison of the front end (pretreatment, fractionation, and hydrolysis) of a softwood/hardwood to ethanol process indicated that the lignin associated with the softwood‐derived cellulose stream limited the number of times the cellulose containing residue could be recycled. © 1996 John Wiley & Sons, Inc.

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Section: Substrate-related Factors Affecting Hydrolysismentioning

confidence: 96%

Factors affecting cellulose hydrolysis and the potential of enzyme recycle to enhance the efficiency of an integrated wood to ethanol process

Gregg

Saddler

2000

Biotechnol. Bioeng.

157

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“…Steam explosion has generally been recognized as one of the most effective methods for pretreating and fractionating lignocellulosic feedstocks (6)(7)(8)(9)(10)(11). A range of times, temperatures/pressures, and acid catalysts have been used by researchers on various feedstocks (Table 1).…”

Section: Introductionmentioning

confidence: 99%

A Techno-Economic Assessment of the Pretreatment and Fractionation Steps of a Biomass-to-Ethanol Process

Gregg

Saddler

1996

Seventeenth Symposium on Biotechnology for Fuels and Chemicals

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It is generally recognized that the front-end (pretreatment, fractionation, enzymatic hydrolysis) steps of a lignocellulose-to-ethanol process are both technologically immature and represent a large component (-60%) of the total product cost. In the past, we have tried to itemize the process steps and equipment for a complete plant. It was evident that, owing to the complexity and interrelated nature of this process, it was difficult to determine the influence of even minor changes to the process on the overall production cost of the product. We had originally developed a techno-economic model, based on spreadsheets, as a computational and assessment tool. However, our more recent work, which has looked at various process options such as hardwood vs softwoods, 502 pretreatment of softwoods, and enzyme recycling, indicated that the model required greater flexibility if it was to assess a "generic" biomass-to-ethanol process. The model is currently being modified to address both the flexibility issues, through the incorporation of flowsheeting concepts, as well as including the most recent work on the various process options. In this article, we have described some of the pretreatment and fractionation issues that are being addressed in the updated model.

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“…Similarly the temperature for synthesis of enzymes was optimum for the saccharification of agro wastes in all cases to enzymatic hydrolysis can be attributed to lignin content of the material. Many researchers have studied the effect of agrowaste pre-treatment by alkali or steam (Okeke and Obi, 1994;Kirk and Farrel, 1987;Durand et al, 1984;Waldron and Eveleigh, 1986;Ekhlund et al, 1990). PreBaig et al 449 treatment of lignocellulosic material enhances enzymatic studied.…”

Section: Resultsmentioning

confidence: 99%

Saccharification of banana agro-waste by cellulolytic enzymes

Baig

Yasmeen

2004

Afr. J. Biotechnol.

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Banana is major cash crop of this region generating vast agricultural waste after harvest. The agrowaste including dried leaves and psuedostem after harvest was used as substrate for the release of sugars. Saccharification of banana agro waste by cellulases of Trichoderma lignorum was investigated. The steam treated agro-waste yielded 1.34 mg/ml of reducing sugars after 24 hr. The size of substrate affected saccharification where the smaller size (<120 µ) yield more sugars. Maximum sugars were released at pH 6.0 whereas 40°C was the optimum temperature. Thus, under these conditions the agro waste left behind for natural degradation can be utilized affectively to yield fermentable sugars which can be converted into other substances like alcohol.

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Optimization of temperature and enzyme concentration in the enzymatic saccharification of steam-pretreated willow

Cited by 73 publications

References 5 publications

Factors affecting cellulose hydrolysis and the potential of enzyme recycle to enhance the efficiency of an integrated wood to ethanol process

Factors affecting cellulose hydrolysis and the potential of enzyme recycle to enhance the efficiency of an integrated wood to ethanol process

A Techno-Economic Assessment of the Pretreatment and Fractionation Steps of a Biomass-to-Ethanol Process

Saccharification of banana agro-waste by cellulolytic enzymes

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