Partial acid hydrolysis of cellulosic materials as a pretreatment for enzymatic hydrolysis

Knappert, D.; Grethlein, Hans E.; Converse, Alvin O.

doi:10.1002/bit.260220711

Cited by 191 publications

(77 citation statements)

References 9 publications

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“…The removed hemicellulose could be degraded to monosaccharides, which could be used for ethanol production or be further degraded to furfural for chemical use. Another effect of acid hydrolysis on cellulose is the decrease of degree of polymerization, leading to the creation of reducing ends of cellulose (Knappert et al, 1980). A review of the literature reveals that the structural changes of biomass during pretreatment are complex and not completely understood.…”

Section: Introductionmentioning

confidence: 99%

Towards understanding structural changes of photoperiod-sensitive sorghum biomass during sulfuric acid pretreatment

Shi

Wang

2013

Bioresource Technology

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Section: Introductionmentioning

confidence: 99%

Towards understanding structural changes of photoperiod-sensitive sorghum biomass during sulfuric acid pretreatment

Shi

Wang

2013

Bioresource Technology

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“…[3][4][5][6] For cellulase to catalyze the hydrolysis of cellulose there must be direct physical contact between the cellulosic microfibrils and the enzyme complex; therefore the rate of enzymatic hydrolysis of cellulose is profoundly affected by the structural features of the lignocell~loses.~ In this study aspen wood samples have been pretreated with a variety of mechanical and chemical methods. Chief among these has been a method involving hydrothermal decompression which has been showns to greatly increase the enzyme hydrolysis of wood fractions.…”

Section: Introductionmentioning

confidence: 99%

Enzymatic hydrolysis of cellulose and various pretreated wood fractions

Saddler¹,

Brownell²,

Clermont³

et al. 1982

Biotech & Bioengineering

182

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summaryThree strains of Trichodermu-T. reesei C30. T. reesei QM9414. and Trichodernia species ES8-were used to study the enzymatic hydrolysis of pretreated wood substrates. Each of the culture filtrates was incubated with a variety of commercially prepared cellulose substrates and pretreated wood substrates. Solka floc was the most easily degraded commercial cellulose. The enzyme accessibility of steam-exploded samples which had been alkali extracted and then stored wet decreased with the duration of the steam treatment. Air drying reduced the extent of hydrolysis of all the samples but had a greater effect on the samples which had previously shoun the greatest hydrolysis. Mild pulping using 2% chlorite increased the enzymatic hydrolysis of all the samples. Steam explosion was shown to be an excellent pretreatment method for aspen wood and was much superior to dilute nitric acid pretreatment. The results indicate that the distribution of the lignin as well as the surface area of the cellulosic substrate are important features in enzymatic hydrolysis.

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“…(2) Acid Pretreatment The main objective is to solubilise the hemicellulose fraction of the biomass and to make the cellulose more accessible to enzymes. This can be performed with concentrated or diluted acid [16] but utilization of concentrated acid is less attractive due to the formation of inhibiting compounds, equipment corrosion, and high operational and maintenance costs [17]. Dilute acid pretreatment is probably the most commonly applied method among the chemical pretreatment methods.…”

Section: A Physical Pretreatmentsmentioning

confidence: 99%

Biological Pretreatment of Lignocellulosic Substrates for Enhanced Delignification and Enzymatic Digestibility

2011

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Sheer enormity of lignocellulosics makes them potential feedstock for biofuel production but, their conversion into fermentable sugars is a major hurdle. They have to be pretreated physically, chemically, or biologically to be used by fermenting organisms for production of ethanol. Each lignocellulosic substrate is a complex mix of cellulose, hemicellulose and lignin, bound in a matrix. While cellulose and hemicellulose yield fermentable sugars, lignin is the most recalcitrant polymer, consisting of phenyl-propanoid units. Many microorganisms in nature are able to attack and degrade lignin, thus making access to cellulose easy. Such organisms are abundantly found in forest leaf litter/composts and especially include the wood rotting fungi, actinomycetes and bacteria. These microorganisms possess enzyme systems to attack, depolymerize and degrade the polymers in lignocellulosic substrates. Current pretreatment research is targeted towards developing processes which are mild, economical and environment friendly facilitating subsequent saccharification of cellulose and its fermentation to ethanol. Besides being the critical step, pretreatment is also cost intensive. Biological treatments with white rot fungi and Streptomyces have been studied for delignification of pulp, increasing digestibility of lignocellulosics for animal feed and for bioremediation of paper mill effluents. Such lignocellulolytic organisms can prove extremely useful in production of bioethanol when used for removal of lignin from lignocellulosic substrate and also for cellulase production. Our studies on treatment of hardwood and softwood residues with Streptomyces griseus isolated from leaf litter showed that it enhanced the mild alkaline solubilisation of lignins and also produced high levels of the cellulase complex when growing on wood substrates. Lignin loss (Klason lignin) observed was 10.5 and 23.5% in case of soft wood and hard wood, respectively. Thus, biological pretreatment process for lignocellulosic substrate using lignolytic organisms such as actinomycetes and white rot fungi can be developed for facilitating efficient enzymatic digestibility of cellulose.

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Partial acid hydrolysis of cellulosic materials as a pretreatment for enzymatic hydrolysis

Cited by 191 publications

References 9 publications

Towards understanding structural changes of photoperiod-sensitive sorghum biomass during sulfuric acid pretreatment

Towards understanding structural changes of photoperiod-sensitive sorghum biomass during sulfuric acid pretreatment

Enzymatic hydrolysis of cellulose and various pretreated wood fractions

Biological Pretreatment of Lignocellulosic Substrates for Enhanced Delignification and Enzymatic Digestibility

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