Extraction and characterization of wax from sugarcane bagasse and the enzymatic hydrolysis of dewaxed sugarcane bagasse

Extraction of high-value products from agricultural wastes is an important component for sustainable bioeconomy development. In this study, wax extraction from sugarcane bagasse was performed and the beneficial effect of dewaxing pretreatment on the enzymatic hydrolysis was investigated. About 1.2% (w/w) of crude sugarcane wax was obtained from the sugarcane bagasse using the mixture of petroleum ether and ethanol (mass ratio of 1:1) as the extraction agent. Results of Fourier-transform infrared characterization and gas chromatography–mass spectrometry qualitative analysis showed that the crude sugarcane wax consisted of fatty fractions (fatty acids, fatty aldehydes, hydrocarbons, and esters) and small amount of lignin derivatives. In addition, the effect of dewaxing pretreatment on the enzymatic hydrolysis of sugarcane bagasse was also investigated. The digestibilities of cellulose and xylan in dewaxed sugarcane bagasse were 18.7 and 10.3%, respectively, compared with those of 13.1 and 8.9% obtained from native sugarcane bagasse. The dewaxed sugarcane bagasse became more accessible to enzyme due to the disruption of the outermost layer of the waxy materials.     

An approach to cellulase recovery from enzymatic hydrolysis of pretreated sugarcane bagasse with high lignin content

The possibility of recovering the cellulases used for enzymatic hydrolysis of sugarcane bagasse was evaluated. A strategy was adopted to maximize the enzyme recovery: desorption of the enzymes adsorbed in the solid residue after hydrolysis, and re-adsorption of the enzymes from the liquid medium onto a fresh substrate. The use of surfactant during the enzymatic hydrolysis was important to improve the glucose release from the material structure and also to facilitate the enzyme desorption from the solid residue after hydrolysis. The temperature and pH used during desorption influenced the enzymes recovery, with the best results (90% adsorbed cellulase) being achieved at 45?°C and pH 5.5. The enzymes present in the liquid medium after enzymatic hydrolysis were partially recovered (77%) by adsorption onto the fresh substrate and used in new enzymatic hydrolysis batches. It was concluded that it is possible to recycle cellulases from an enzymatic medium for use in subsequent hydrolysis processes.     

Adsorption of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions by sugarcane bagasse and mercerized sugarcane bagasse chemically modified with succinic anhydride

This work describes the preparation of new chelating material from mercerized sugarcane bagasse. The first part treats the chemical modification of non-mercerized sugarcane bagasse (SCB) and twice-mercerized sugarcane bagasse (MMSCB) with succinic anhydride. Mass percent gains (mpg) and degrees of succinylation (DS) of succinylated non- and twice-mercerized sugarcane bagasse 1 (SCB 1 and MMSCB 1) were calculated. MMSCB 1 exhibited an increase in mpg and DS of 49.2% and 0.9 mmol/g in relation to SCB 1. SCB 2 and MMSCB 2 were obtained by treatment of MMSCB 1 and SCB 1 with bicarbonate solution to release the carboxylate functions and characterized by FTIR. The second part evaluates and compares the adsorption capacity of SCB 2 and MMSCB 2 for Cu²⁺, Cd²⁺ and Pb²⁺ ions in an aqueous single metal solution. Adsorption isotherms were developed using Langmuir model. MMSCB 2 exhibited an increase in Q_max for Cd²⁺ (43.6 mg/g) and Pb²⁺ (83.3 mg/g) in relation to SCB 2.     

化学改性甘蔗渣对固定化细胞发酵产丁醇的影响

旨在研究化学改性的甘蔗渣作为固定化载体对丙酮丁醇梭菌Clostridium acetobutylicum XY16发酵制备生物丁醇的影响。首先利用不同浓度的聚乙烯亚胺(PEI)和1 g/L戊二醛(GA)对甘蔗渣表面进行化学改性,增强甘蔗渣对Clostridium acetobutylicum XY16的附载能力。经4 g/L聚乙烯亚胺和1 g/L戊二醛改性的甘蔗渣(添加量10 g/L)应用到固定化批次发酵中,发酵36 h后丁醇和总溶剂浓度最高,分别达到了12.24 g/L和21.67 g/L,同时溶剂的生产速率达到0.60 g/(L·h),生产速率比游离细胞和未改性甘蔗渣固定化细胞分批发酵分别提高了130.8%和66.7%。在此基础上对改性甘蔗渣固定化的细胞进行6次重复批次发酵,丁醇和总溶剂的产量稳定,溶剂生产速率逐渐提高至0.83 g/(L·h),同时转化率也提高至0.42 g/g。     

Xylanase and feruloyl esterase from actinomycetes cultures could enhance sugarcane bagasse hydrolysis in the production of fermentable sugars

The addition of enzymes that are capable of degrading hemicellulose has a potential to reduce the need for commercial enzymes during biomass hydrolysis in the production of fermentable sugars. In this study, a high xylanase producing actinomycete strain (Kitasatospora sp. ID06-480) and the first ethyl ferulate producing actinomycete strain (Nonomuraea sp. ID06-094) were selected from 797 rare actinomycetes, respectively, which were isolated in Indonesia. The addition (30%, v/v) of a crude enzyme supernatant from the selected strains in sugarcane bagasse hydrolysis with low-level loading (1 FPU/g-biomass) of Cellic® CTec2 enhanced both the released amount of glucose and reducing sugars. When the reaction with Ctec2 was combined with crude enzymes containing either xylanase or feruloyl esterase, high conversion yield of glucose from cellulose at 60.5% could be achieved after 72 h-saccharification.     

Enzymatic hydrolysis of chemithermomechanically pretreated sugarcane bagasse and samples with reduced initial lignin content

Chemithermomechanical (CTM) processing was used to pretreat sugarcane bagasse with the aim of increasing cell wall accessibility to hydrolytic enzymes. Yields of the pretreated samples were in the range of 75-94%. Disk refining and alkaline-CTM and alkaline/sulfite-CTM pretreatments yielded pretreated materials with 21.7, 17.8, and 15.3% of lignin, respectively. Hemicellulose content was also decreased to some extent. Fibers of the pretreated materials presented some external fibrillation, fiber curling, increased swelling, and high water retention capacity. Cellulose conversion of the alkaline-CTM- and alkaline/sulfite-CTM-pretreated samples reached 50 and 85%, respectively, after 96 h of enzymatic hydrolysis. Two samples with low initial lignin content were also evaluated after the mildest alkaline-CTM pretreatment. One sample was a partially delignified mill-processed bagasse. The other was a sugarcane hybrid selected in a breeding program. Samples with lower initial lignin content were hydrolyzed considerably faster in the first 24 h of enzymatic digestion. For example, enzymatic hydrolysis of the sample with the lowest initial lignin content (14.2%) reached 64% cellulose conversion after only 24 h of hydrolysis when compared with the 30% observed for the mill-processed bagasse containing an initial lignin content of 24.4%.     

Enhancement of the enzymatic digestibility of sugarcane bagasse by steam pretreatment impregnated with hydrogen peroxide

Sugarcane bagasse was subjected to steam pretreatment impregnated with hydrogen peroxide. Analyses were performed using 2³ factorial designs and enzymatic hydrolysis was performed at two different solid concentrations and with washed and unwashed material to evaluate the importance of this step for obtaining high cellulose conversion. Similar cellulose conversion were obtained at different conditions of pretreatment and hydrolysis. When the cellulose was hydrolyzed using the pretreated material in the most severe conditions of the experimental design (210°C, 15 min and 1.0% hydrogen peroxide), and using 2% (w/w) water‐insoluble solids (WIS), and 15 FPU/g WIS, the cellulose conversion was 86.9%. In contrast, at a milder pretreatment condition (190°C, 15 min and 0.2% hydrogen peroxide) and industrially more realistic conditions of hydrolysis (10% WIS and 10 FPU/g WIS), the cellulose conversion reached 82.2%. The step of washing the pretreated material was very important to obtain high concentrations of fermentable sugars. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012     

Isolation of a gastroprotective arabinoxylan from sugarcane bagasse

After industrial processing, one-third of sugarcane culms is converted into residual bagasse. The xylan-rich hemicellulose components of the bagasse were extracted with hot aqueous alkali (AX-CRUDE). Approximately 82% of the extracted hemicelluloses was precipitated with ethanol (AX-PET). Both AX-CRUDE and AX-PET contained an arabinoxylan as confirmed by 13C NMR and methylation analysis. Fraction AX-PET was fed to female Wistar rats with ethanol-induced gastric lesions. Oral administrations of 30, 100, and 300 mg/kg reduced the gastric lesion area by over 50%, and replenished ethanol-induced depletion of glutathione. The polysaccharide also increased mucus production by over 70%, indicating its cytoprotective action on experimentally induced gastric ulcers. These findings are significant, since a biologically active compound can be extracted in high yields from an abundant, readily available residue.     

Valorization of an industrial organosolv–sugarcane bagasse lignin: Characterization and use as a matrix in biobased composites reinforced with sisal fibers

In the present study, the main focus was the characterization and application of the by‐product lignin isolated through an industrial organosolv acid hydrolysis process from sugarcane bagasse, aiming at the production of bioethanol. The sugarcane lignin was characterized and used to prepare phenolic‐type resins. The analysis confirmed that the industrial sugarcane lignin is of HGS type, with a high proportion of the less substituted aromatic ring p‐hydroxyphenyl units, which favors further reaction with formaldehyde. The lignin–formaldehyde resins were used to produce biobased composites reinforced with different proportions of randomly distributed sisal fibers. The presence of lignin moieties in both the fiber and matrix increases their mutual affinity, as confirmed by SEM images, which showed good adhesion at the biocomposite fiber/matrix interface. This in turn allowed good load transference from the matrix to the fiber, leading to biobased composites with good impact strength (near 500 J m^?1 for a 40 wt% sisal fiber‐reinforced composite). The study demonstrates that sugarcane bagasse lignin obtained from a bioethanol plant can be used without excessive purification in the preparation of lignocellulosic fiber‐reinforced biobased composites displaying high mechanical properties. Biotechnol. Bioeng. 2010;107:612–621. © 2010 Wiley Periodicals, Inc.     

Metabolic behavior of immobilized Candida guilliermondii cells during batch xylitol production from sugarcane bagasse acid hydrolyzate

Candida guilliermondii cells, immobilized in Ca-alginate beads, were used for batch xylitol production from concentrated sugarcane bagasse hydrolyzate. Maximum xylitol concentration (20.6 g/L), volumetric productivity (0.43 g/L. h), and yield (0.47 g/g) obtained after 48 h of fermentation were higher than similar immobilized-cell systems but lower than free-cell cultivation systems. Substrates, products, and biomass concentrations were used in material balances to study the ways in which the different carbon sources were utilized by the yeast cells under microaerobic conditions. The fraction of xylose consumed to produce xylitol reached a maximum value (0.70) after glucose and oxygen depletion while alternative metabolic routes were favored by sub-optimal conditions.     

甘蔗渣接枝四乙烯五胺制备治理印染废水的新型吸附剂

论文通过在甘蔗渣(sugarcane bagasse,SB)中引入四乙烯五胺获得改性甘蔗渣(modified sugarcane bagasse,MSB),制备出对有机染料伊红和重金属离子Cu²⁺、Cr³⁺均有较好吸附能力的吸附剂,并研究了pH、温度、初始浓度等因素对吸附的影响.结果表明当伊红溶液pH为6时,MSB的吸附量比SB提高了18倍,对金属Cu²⁺ 、Cr³⁺的吸附量也大大高于SB.染料伊红的吸附过程可以用Langmuir 型吸附等温线较好地模拟,由方程可得25℃下伊红的最大吸附量为399.04 mg·g^-1,MSB对伊红的吸附行为符合伪二级吸附动力学模型.实验结果显示改性甘蔗渣(modified sugarcane bagasse,MSB)是一种吸附性能优异的吸附剂,用于处理印染废水与制革废水有较好的应用前景.     

Production and characterization of cellulolytic and xylanolytic enzymes from the ligninolytic white-rot fungus Phanerochaete chrysosporium grown on sugarcane bagasse

The ligninolytic white-rot fungus Phanerochaete chrysosporium BKM-F-1767 produced extracellular cellulolytic enzymes (carboxymethylcellulase, CMCase and -glucosidase) and xylanolytic enzymes (xylanase and -xylosidase) in liquid medium containing 1.0% sugarcane bagasse with or without 1.0% glucose. The changes in pH and soluble protein content were monitored in the culture filtrates. The results obtained showed that the pH decreased after 3 days and then increased. The soluble protein content increased and reached the maximum value after 12 days. The results showed that the activities of enzymes were higher in the case of sugarcane bagasse without glucose. The characterization study indicated that the optimum pH values were 4.6, 4.2, 5.0 and 5.0 for CMCase, -glucosidase, xylanase and -xylosidase, respectively and the optimum temperatures were 60, 70, 65 and 60 °C for the investigated enzymes, respectively. The results showed also that after prolonged heating (5 h) at 60 °C, CMCase, -glucosidase, xylanase and -xylosidase retained 81.2, 86.8, 51.5 and 27.4% activity, respectively.     

Coupling of bioaugmentation and phytoremediation to improve PCBs removal from a transformer oil-contaminated soil

This study was carried out to assess the dissipation of 17 selected polychlorinated biphenyl (PCB_i) congeners in a transformer oil-contaminated soil using bioaugmentation with 2 PCB-degrading bacterial strains, i.e., Pseudomonas spp. S5 and Alcaligenes faecalis, assisted or not by the maize (Zea mays L.) plantation. After 5 and 10 weeks of treatment, the remaining concentrations of the target PCB_i congeners in the soil were extracted and measured using GC-MS. Results showed that the bacterial augmentation treatments with Pseudomonas spp. S5 and A. faecalis led to 21.4% and 20.4% reduction in the total concentration of the target PCBs (ΣPCB_i), respectively, compared to non-bioaugmented unplanted control soil. The ΣPCB_i decreased by 35.8% in the non-bioaugmented planted soil compared with the control. The greatest degradation of the PCB congeners was observed over a 10-week period in the soil inoculated with Pseudomonas spp. S5 and cultivated with maize. Under this treatment, the ΣPCB_i decreased from 357 to 119 ng g^?1 (66.7% lower) and from 1091 to 520 ng g^?1 (52.3% lower). Overall, the results suggested that the combined application of phytoremediation and bioaugmentation was an effective technique to remove PCBs and remediate transformer oil-contaminated soils.     

Removal of phenanthrene from soil by co-cultures of bacteria and fungi pregrown on sugarcane bagasse pith

Sixteen co-cultures composed of four bacteria and four fungi grown on sugarcane bagasse pith were tested for phenanthrene degradation in soil. The four bacteria were identified as Pseudomonas aeruginose, Ralstonia pickettii, Pseudomonas sp. and Pseudomonas cepacea. The four fungi were identified as: Penicillium sp., Trichoderma viride, Alternaria tenuis and Aspergillus terrus that were previously isolated from different hydrocarbon-contaminated soils. Fungi had a statistically significant positive (0.0001相似文献   

Immobilized cells cultivated in semi-continuous mode in a fluidized bed reactor for xylitol production from sugarcane bagasse

Summary Xylitol production from sugarcane bagasse hemicellulosic hydrolyzate was evaluated in a fluidized bed reactor operated in semi-continuous mode, using cells immobilized on porous glass. The fermentative process was performed during five successive cycles of 72 h each one. The lowest xylitol production occurred in the first cycle, where a high cell concentration (12 g l⁻¹) was observed. In the subsequent cycles the xylitol concentration was ever increasing due to the cells adaptation to the medium. In the last one, 18 g xylitol l⁻¹ was obtained with a yield factor of 0.44 g g⁻¹ and volumetric productivity of 0.32 g l⁻¹ h⁻¹.     

Biostimulation for the Treatment of an oil-contaminated Coastal Salt Marsh

A field study was conducted on a coastal salt marsh in Nova Scotia, Canada, during the summer of 2000. The objective of the study was to assess the effectiveness of biostimulation in restoring an oil-contaminated coastal marsh dominated by Spartina alterniflora under north-temperate conditions. Three remediation treatments were tested with two additional unoiled treatments, with and without added nutrients, serving as controls. This research determined the effectiveness of nitrogen and phosphorus addition for accelerating oil disappearance, the role of nutrients in enhancing restoration in the absence of wetland plants, and the rate at which the stressed salt marsh recovered. Petroleum hydrocarbons were analyzed by gas chromatography/mass spectrometry (GC/MS). Statistically significant treatment differences were observed for alkanes but not aromatics in sediment samples. No differences were evident in above-ground vegetation samples. GC/MS-resolved alkanes and aromatics degraded substantially (>90% and >80%, respectively) after 20 weeks with no loss of TPH. Biodegradation was determined to be the main oil removal mechanism rather than physical washout.     

Fractional and physico-chemical characterization of hemicelluloses from ultrasonic irradiated sugarcane bagasse

The present study was undertaken to investigate the extractability of the hemicelluloses from bagasse obtained by ultrasound-assisted extraction methods. The results showed that the ultrasonic treatment and sequential extractions with alkali and alkaline peroxide under the conditions given led to a release of over 90% of the original hemicelluloses and lignin. This fact as well as the sugar composition and structural features of the isolated seven hemicellulosic fractions indicated that ultrasonication attacked the integrity of cell walls, cleaved the ether linkages between lignin and hemicelluloses, and increased accessibility and extractability of the hemicelluloses. Increasing alkali concentration from 0.5 to 2M and alkaline peroxide percentage from 0.5% to 3.0% resulted in degradation of hemicellulosic backbone as shown by a decrease in their molecular weights from 43,580 to 14,470 and 30,180 to 18,130gmol(-1), respectively. However, there were no significant differences in the structural features of the seven sequential alkali- or alkaline peroxide-soluble hemicellulosic fractions, which are composed mainly of L-arabino-(4-O-methyl-D-glucurono)-D-xylans. Ferulic and p-coumaric acids were found to be chemically linked with hemicelluloses.     

Characterization of the cellulolytic secretome of Trichoderma harzianum during growth on sugarcane bagasse and analysis of the activity boosting effects of swollenin

This study demonstrates the production of an active enzyme cocktail produced by growing Trichoderma harzianum on sugarcane bagasse. The component enzymes were identified by LCMS‐MS. Glycosyl hydrolases were the most abundant class of proteins, representing 67% of total secreted protein. Other carbohydrate active enzymes involved in cell wall deconstruction included lytic polysaccharide mono‐oxygenases (AA9), carbohydrate‐binding modules, carbohydrate esterases and swollenin, all present at levels of 1%. In total, proteases and lipases represented 5 and 1% of the total secretome, respectively, with the rest of the secretome being made up of proteins of unknown or putative function. This enzyme cocktail was efficient in catalysing the hydrolysis of sugarcane bagasse cellulolignin to fermentable sugars for potential use in ethanol production. Apart from mapping the secretome of T. harzianum, which is a very important tool to understand the catalytic performance of enzyme cocktails, the gene coding for T. harzianum swollenin was expressed in Aspergillus niger. This novel aspect in this work, allowed increasing the swollenin concentration by 95 fold. This is the first report about the heterologous expression of swollenin from T. harzianum, and the findings are of interest in enriching enzyme cocktail with this important accessory protein which takes part in the cellulose amorphogenesis. Despite lacking detectable glycoside activity, the addition of swollenin of T. harzianum increased by two‐fold the hydrolysis efficiency of a commercial cellulase cocktail. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:327–336, 2016     

Potential of Bioaugmentation and Biostimulation for Enhancing Intrinsic Biodegradation in Oil Hydrocarbon-Contaminated Soil

Studies were conducted using a 10-chamber Micro-Oxymax (Columbus, OH, USA) respirometer to determine the effect of bioaugmentation and biostimulation (by diverse ways of O₂ supply) on enhancing biodegradation of oil hydrocarbons to reduce risk at a former military airport in Kluczewo, Poland. Indigenous or exogenous bacteria bioaugmentation was used to degrade hydrocarbons. Aerated water and/or aqueous solutions of H₂O₂ or KMnO₄ were used to supply O₂. The intrinsic and enhanced biodegradation was evaluated by the O₂ uptake and CO₂ production rates obtained using a linear regression of the cumulative O₂ uptake and CO₂ production curves. Generally, in all cases biodegradation rates enhanced by bioaugmentation were two to four times higher than the rates of intrinsic biodegradation. Moreover, application of indigenous bacteria was more efficient in comparison to the exogenous consortia. The highest CO₂ production rates were achieved when aqueous solution of KMnO₄ was applied, as the increase of CO₂ production rates were about 71% to 97% higher compared to a control. The aqueous solution of H₂O₂ did not cause any significant improvement of the biodegradation rates. Compared to a control, the addition of aerated water resulted in a decrease of CO₂ production rates. Most probably the excessive soil moisture could reduce the air-filled porosity and, consequently, the oxygen contents in soil.