Hydrolysis Of Wood Research Articles

Strategies for Reducing Supplemental Medium Cost in Bioethanol Production from Waste House Wood Hydrolysate by Ethanologenic Escherichia coli: Inoculum Size Increase and Coculture with Saccharomyces cerevisiae

In this paper, we report a simultaneous realization of both efficient ethanol production and saving medium nutrient (corn steep liquor [CSL]) during bioethanol fermentation of overliming-treated hydrolysate of waste house wood (WHW) using ethanologenic Escherichia coli KO11. In cultivation using WHW hydrolysate supplemented with 4% (v/v) CSL and 0.2 g-dry cell weight (DCW)/l E. coli KO11 cells, the overall ethanol yield reached 84% of the theoretical value at 61 h. When we conducted the cultivation with 1% CSL to reduce the supplemental medium cost, the overall ethanol yield remained in the range of 66-72% even at 90 h. We proposed two alternative methods for increasing the overall yield even with 1% CSL. The first method involved increasing the inoculum size of E. coli KO11 up to 0.8 g-DCW/l, where 83% of the overall yield was attained at 60 h of cultivation. The second method involved the coculture of 0.2 g-DCW/l E. coli KO11 together with 0.02 g-DCW/l of Saccharomyces cerevisiae TJ1, and the overall yield reached 81% at 47 h of cultivation.

P-227 木材糖化濃硫酸法における硫酸回収法の検討(I) : イオン交換膜電気透析による硫酸の濃縮(ポスター発表)

P-227 木材糖化濃硫酸法における硫酸回収法の検討(I) : イオン交換膜電気透析による硫酸の濃縮(ポスター発表)

Acid in ionic liquid: An efficient system for hydrolysis of lignocellulose

Acid in ionic liquid was demonstrated as an efficient system for hydrolysis of lignocellulosic materials with improved total reducing sugars (TRS) yield under mild conditions. TRS yields were up to 66%, 74%, 81% and 68% for hydrolysis of corn stalk, rice straw, pine wood and bagasse, respectively, in C4mimCl in the presence of 7 wt% hydrogen chloride at 100 °C under atmospheric pressure within 60 min. Different combinations between ionic liquids, such as C6mimCl, C4mimBr, AmimCl, C4mimHSO4, and SbmimHSO4, and acids, including sulfuric acid, nitric acid, phosphoric acid, as well as maleic acid, afforded similar results albeit longer reaction time was generally required comparing with the combination of C4mimCl and hydrochloric acid. FT-IR spectra and elemental analysis of the recovered residues indicated that modification of lignin occurred during sulfuric acid catalyzed hydrolysis. In addition, kinetic modeling based on experimental data suggested that the hydrolysis likely followed a consecutive first-order reaction sequence, where k1 and k2, the rate constants for TRS formation and TRS degradation, were determined as 0.068 min−1 and 0.007 min−1, respectively. This novel system may be valuable to facilitate cost-efficient conversion of biomass into biofuels and biobased products.

Biosynthesis of poly-β-hydroxyalkanoate by Brevundimonas vesicularis LMG P-23615 and Sphingopyxis macrogoltabida LMG 17324 using acid-hydrolyzed sawdust as carbon source

Poly-beta-hydroxyalkanoate (PHA) is a biodegradable polymer accumulated in intracellular granules by different bacterial species. Its physical and chemical properties are similar to those of petroleum-derived plastics. Material generated by the acid hydrolysis of wood was evaluated for use in the bacterial synthesis of PHA. Acid-hydrolyzed sawdust was prepared and adjusted to pH 7. Mineral salts with carbon:nitrogen (C:N) proportions of 100:1, 100:3.5, 100:10, 100:30, or 100:50 and trace elements were added and these solutions were inoculated with a bacterial strain Brevundimonas vesicularis LMG P-23615 or Sphingopyxis macrogoltabida LMG 17324. The percentage of cells accumulating PHA was evaluated by flow cytometry. The hydrolyzed sawdust composition was analyzed by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). The organic material (601.5 mg l(-1)) contained 112.5 mg l(-1) sugars. Over 96% of these sugars were consumed and more than 90% of the bacterial cells accumulated PHA. The 100:3.5 C:N proportion was optimal for growth and PHA synthesis, with yields ranging from 64% to 72% of the dry cell weight. The results suggest that acid-hydrolyzed sawdust can be used by bacteria as a carbon source for growth and PHA production. This forestry by sub-product offers a low-cost alternative for obtaining biodegradable plastics (e.g., PHA) synthesized by bacteria.

Evaluation of biological pretreatment with white rot fungi for the enzymatic hydrolysis of bamboo culms

Biological pretreatment with white rot fungi has shown potential for improving enzymatic hydrolysis of wood and grass. In this study, 34 isolates of white rot fungi were screened for the biological pretreatment of bamboo culms (Phyllostachys pubescence). Echinodontium taxodii 2538 and Trametes versicolor G20 were selected for further evaluation of pretreatment because they caused high lignin loss (>20%) and high selectivity value of lignin degradation (>2) after the 4-week biodegradation. Fermentable sugar yield of bamboo culms pretreated with these two fungi through enzymatic hydrolysis increased with increasing pretreatment time. Sugar yield of bamboo culms pretreated with T. versicolor G20 and E. taxodii 2538 increased 5.15-fold and 8.76-fold, respectively, after 120-day pretreatment. FTIR analysis showed that E. taxodii 2538 preferentially degraded the lignin of bamboo culms. The pretreated bamboo culms showed significant increase of initial adsorption capacity to cellulase (4.20-fold and 6.66-fold for T. versicolor G20 and E. taxodii 2538, respectively, after 120 days) and decrease of lignin content (12.00% and 29.14% for T. versicolor G20 and E. taxodii 2538, respectively, after 120 days) with increasing pretreatment time. Initial adsorption capacity and lignin content of bamboo culms were correlated to fermentable sugar yield. Scientific relevance This paper focused on the biodegradation and pretreatment of bamboo culms with white rot fungi. Bamboo culms pretreatment with white rot fungi was evaluated firstly for energy convention of lignocellulose. This paper studied effects of lignin content and initial adsorption capacity on enzymatic hydrolysis also.

Batch and repeated batch production of l(+)-lactic acid by Enterococcus faecalis RKY1 using wood hydrolyzate and corn steep liquor

Lactic acid production was investigated for batch and repeated batch cultures of Enterococcus faecalis RKY1, using wood hydrolyzate and corn steep liquor. When wood hydrolyzate (equivalent to 50 g l(-1) glucose) supplemented with 15-60 g l(-1) corn steep liquor was used as a raw material for fermentation, up to 48.6 g l(-1) of lactic acid was produced with, volumetric productivities ranging between 0.8 and 1.4 g l(-1 )h(-1). When a medium containing wood hydrolyzate and 15 g l(-1) corn steep liquor was supplemented with 1.5 g l(-1) yeast extract, we observed 1.9-fold and 1.6-fold increases in lactic acid productivity and cell growth, respectively. In this case, the nitrogen source cost for producing 1 kg lactic acid can be reduced to 23% of that for fermentation from wood hydrolyzate using 15 g l(-1) yeast extract as a single nitrogen source. In addition, lactic acid productivity could be maximized by conducting a cell-recycle repeated batch culture of E. faecalis RKY1. The maximum productivity for this process was determined to be 4.0 g l(-1 )h(-1).

Enhanced enzymatic hydrolysis of olive tree wood by steam explosion and alkaline peroxide delignification

Olive tree wood, a renewable low-cost agricultural residue, was submitted to steam explosion pretreatment at 190, 210, 230 and 240 °C for 5 min. To improve enzymatic hydrolysis yields, the water-insoluble fiber was further delignified by an alkaline peroxide treatment. Enzymatic hydrolysis was performed using a commercial cellulolytic complex supplemented with β-glucosidase at 10% (w/v) pretreated material concentration. Delignification did enhance enzymatic hydrolysis yields of steam pretreated olive tree wood. Up to 80% of the lignin in the original wood was solubilized, leaving a cellulose-rich residue that led to a concentrated glucose solution (51.3 g/l after 72 h enzymatic hydrolysis in the best case). The maximum overall process yield, taking into account both sugars present in the liquid from steam pretreatment and glucose from the steamed, delignified and hydrolyzed solid was obtained at the lowest steam pretreatment temperature assayed. As a result, from 100 g of raw material, 28.8 g of sugars were recovered of 54.7 g available (52.6%).

05/00312 Combustion of wood hydrolysis residue in a 150 kW powder burner: Eriksson, G. et al. Fuel, 2004, 83, (11–12), 1635–1641

05/00312 Combustion of wood hydrolysis residue in a 150 kW powder burner: Eriksson, G. et al. Fuel, 2004, 83, (11–12), 1635–1641

Performance of Rhizopus, Rhizomucor, and Mucor in ethanol production from glucose, xylose, and wood hydrolyzates

In searching for ethanol producing microorganisms also capable of fermenting pentoses, nine zygomycetes strains including three strains of Rhizopus oryzae, Mucor corticolous, M. hiemalis, M. indicus, Rhizomucor pusillus, R. miehei, and zygomycete IT were examined. Each strain was cultivated on glucose, xylose or dilute-acid hydrolyzate (DAH) as carbon sources, and the production of ethanol, lactic acid, glycerol, xylitol, and succinic acid were investigated. Great similarities but also conspicuous differences were seen between the species, to some extent linked to the genera. All strains were capable of growing on glucose or xylose as single carbon source. With the exception of the two Rhizomucor strains, all produced ethanol. All the strains produced glycerol as by-product, while Rhizopus and Rhizomucor but not Mucor produced lactic acid in significant amounts. All Mucor and Rhizopus strains and one strain of Rhizomucor produced xylitol in the xylose medium, but no xylitol was detected after growth on DAH. All Mucor and two R. oryzae strains were capable of growing on DAH. Two Mucor species, M. hiemalis and M. indicus showed greater ethanol production than the other strains. The ethanol yields by M. hiemalis on glucose, xylose, and DAH were 0.39, 0.18, and 0.44 g/g, respectively, whereas the corresponding results for M. indicus were 0.39, 0.22, and 0.44 g/g. The strains also rapidly consumed hydroxymethyl furfural present in DAH.

Effect of Acid Hydrolysis of Oak Wood on Its Aroma-Forming Complex

The effect of acid hydrolysis of English oak (Quercus robur. L) wood on its aroma-forming complex was studied. The contents of methanol, acetic and crotonic acids, and furfural increased considerably in the samples treated with hydrochloric acid. In the composition of minor compounds, aromatic hydrocarbons were synthesized de novo, whereas the contents of volatile phenols, such as vanillin, lilac aldehyde, and coniferaldehyde decreased; relative content of guaiacol and syringol elevated; and acetovanillon and propiovanilIon were formed as well as products of degradation of hexoses-levoglucosenone, 1,4:3,6-dianhydroglucose, maltol, and 1,6-dianhydroglucopyran.

Batch and continuous fermentation of succinic acid from wood hydrolysate by Mannheimia succiniciproducens MBEL55E

Batch and continuous cultures of Mannheimia succiniciproducens MBEL55E were carried out in a complex medium containing a NaOH-treated wood hydrolysate for the production of succinic acid. The wood hydrolysate based medium was treated with NaOH before sterilization to reduce the formation of inhibitory compounds. M. succiniciproducens MBEL55E utilized xylose as well as glucose in the wood hydrolysate based medium as a carbon source for the succinic acid production. In batch cultures, the final succinic acid concentration of 11.73 g l −1 was obtained from the pre-treated wood hydrolysate based medium, resulting in a succinic acid yield of 56% and a succinic acid productivity of 1.17 g l −1 h −1, while the corresponding continuous cultures gave the succinic acid yield and productivity of 55% and 3.19 g l −1 h −1, respectively. These results suggest that succinic acid can be produced economically and efficiently by the fermentation of M. succiniciproducens MBEL55E from an inexpensive biomass-based wood hydrolysate.

Effects of cultivation conditions on the growth of the basidiomycete Coriolus hirsutus in a medium with pentose wood hydrolyzate

The effects of physical–chemical parameters of cultivation (temperature, pH, intensity of medium aeration and degree of shear under agitation) and concentration of reducing sugars (RS) on the growth of the wood-rotting basidiomycete Coriolus hirsutus were studied in a medium with pentose wood hydrolyzate. The values of these parameters, which were optimal for mushroom biomass formation, were found. Optimum concentration of hydrolyzate RS for mushroom growth was shown to be 20–25 g/l. The culture under study was able to grow (increasing pH) at high acidity of the medium, although the optimum level of pH was 5.6–5.8. Maximum specific growth rate of mushroom was recorded at high temperatures of 30–36 °C. Due to these particular features, the basidium fungus Coriolus hirsutus can be suitable object for biotechnology. During shake-flask fermentation with the aeration level of 0.9–1.2 g O 2/l h −1 and corresponding to aeration the intensity of shearing forces, the mushroom grew in the form of small loose and fluffy pellets, which had more points of growth on a surface. This probably resulted in an increase of biomass concentration under these conditions and the very high efficiency of substrate utilization ( η x / s = 0.68).

Anti-oxidant activity of isolates from acid hydrolysates of Eucalyptus globulus wood

The ethyl acetate-soluble fraction of Eucalyptus globulus wood hydrolysates was fractionated on a Sephadex LH-20 column, using methanol as the mobile phase to give four fractions, and both the DPPH (α,α-diphenyl-β-picrylhydrazyl) radical-scavenging activity and composition of raw extracts and isolates were determined. One of the fractions isolated (denoted F4) showed a remarkable anti-oxidant activity (EC 50 of 0.15 g/l, in comparison with 0.55 g/l for crude extracts), presenting a comparatively high phenolic content, with ellagic acid as the main component.

Combustion of wood hydrolysis residue in a 150 kW powder burner

A combustion test has been made with residues from hydrolysis of wood for fuel ethanol production. A 150 kW powder burner was used. Fuel feeding and combustion were stable. The average concentration of CO in the stack gas was 8 mg/MJ, the average concentration of NO x was 59 mg/MJ and the average total hydrocarbon concentration was below 1 ppm, at an average O 2-concentration of 4.6%. The low contents of potassium and sodium in the hydrolysis residue make the material attractive as a gas turbine fuel and the conclusion of this test is that direct combustion may be a feasible approach for gas turbine applications.

Biotechnological production of l(+)-lactic acid from wood hydrolyzate by batch fermentation of Enterococcus faecalis

The inhibition of lactic acid fermentation by wood hydrolyzate was decreased (approx. 20%) by adaptation of Enterococcus faecalis RKY1 to wood hydrolyzate-based medium whereby lactic acid productivity and cell growth were enhanced by 0.5 g l(-1) h(-1) and 2.1 g l(-1), respectively. When the diluted or concentrated wood hydrolyzate (equivalent to 25-100 g glucose l(-1)) was supplemented with 15 g yeast extract l(-1), 24-93 g lactic acid l(-1) was produced at a rate between 1.7 g l(-1) h(-1) and 3.2 g l(-1) h(-1).

Enhanced enzymatic hydrolysis of steam-exploded Douglas fir wood by alkali-oxygen post-treatment.

Good enzymatic hydrolysis of steam-exploded Douglas fir wood (SEDW) cannot be achieved owing to the very high lignin content ( >40%) that remains associated with this substrate. Thus, in this study, we investigated the use of alkali-oxygen treatment as a posttreatment to delignify SEDW and also considered the enzymatic hydrolyzability of the delignified SEDW. The results showed that under optimized conditions of 15% NaOH, 5% consistency, 110 degrees C, and 3 h, approx 84% of the lignin in SEDW could be removed. The resulting delignified SEDW had good hydrolyzability, and cellulose-to-glucose conversion yields of over 90 and 100% could be achieved within 48 h with 20 and 40 filter paper units/g of cellulose enzyme loadings, respectively. It was also indicated that severe conditions, such as high NaOH concentration and high temperature, should not be utilized in oxygen delignification of SEDW in order to avoid extensive condensation of lignin and significant degradation of cellulose.

The Fermentation Performance of Nine Strains of Saccharomyces cerevisiae in Batch and Fed-Batch Cultures in Dilute-Acid Wood Hydrolysate

Large differences in colony forming capacity, ethanol production and inhibitor conversion were noted between nine different strains of Saccharomyces cerevisiae in anaerobic batch and fed-batch cultures on dilute acid wood hydrolysate. S. cerevisiae ATCC 96581 was able to metabolize all added glucose and mannose in fed-batch experiments. The choice of production strain will have a significant effect on the performance of a hydrolysate-based ethanol production plant.

The fermentation performance of nine strains of Saccharomyces cerevisiae in batch and fed-batch cultures in dilute-acid wood hydrolysate

Large differences in colony forming capacity, ethanol production and inhibitor conversion were noted between nine different strains of Saccharomyces cerevisiae in anaerobic batch and fed-batch cultures on dilute acid wood hydrolysate. S. cerevisiae ATCC 96581 was able to metabolize all added glucose and mannose in fed-batch experiments. The choice of production strain will have a significant effect on the performance of a hydrolysate-based ethanol production plant.

Comparison of microbial inhibition and enzymatic hydrolysis rates of liquid and solid fractions produced from pretreatment of biomass with carbonic acid and liquid hot water.

This research quantified the enzymatic digestibility of the solid component and the microbial inhibition of the liquid component of pretreated aspen wood and corn stover hydrolysates. Products of liquid hot water and carbonic acid pretreatment were compared. Pretreatment temperatures tested ranged from 180 to 220 degrees C, and reaction times were varied between 4 and 64 min. Both microbial inhibition rates and enzymatic hydrolysis rates showed no difference between pretreatments containing carbonic acid and those not containing no carbonic acid. Microbial inhibition increased as the reaction severity increased, but only above a midpoint severity parameter of 200 degrees C for 16 min. Both the rates and yields of enzymatic hydrolysis displayed an increase from the lowest tested reaction severity to the highest tested reaction severity.

Controlled fed-batch fermentations of dilute-acid hydrolysate in pilot development unit scale.

Inhibitors formed during wood hydrolysis constitute a major problem in fermenting dilute-acid hydrolysates. By applying a fed-batch technique, the levels of inhibitory compounds may be held low, enabling high ethanol productivity. In this study, a previously developed fed-batch strategy was modified and implemented for use in pilot development unit (PDU) scale. The rate of total gas formation, measured with a mass flow meter, was used as input variable in the control algorithm. The feed rate in the PDU-scale experiments could be properly controlled based on the gas evolution from the reactor. In fed-batch experiments utilizing TMB 3000, an inhibitor-tolerant strain of Saccharomyces cerevisiae, close to 100% of the hexoses in the hydrolysate was converted.