Sugarcane Bagasse Hemicellulosic Hydrolysate Research Articles

Evaluation of novel xylose-fermenting yeast strains from Brazilian forests for hemicellulosic ethanol production from sugarcane bagasse.

Bioconversion of hemicellulosic hydrolysates into ethanol with the desired yields plays a pivotal role for the overall success of biorefineries. This paper aims to evaluate the ethanol production potential of four native strains of Scheffersomyces shehatae (syn. Candida shehatae) viz. S. shehatae BR6-2AI, CG8-8BY, PT1-1BASP and BR6-2AY, isolated from Brazilian forests. These strains were grown in commercial d-xylose-supplemented synthetic medium and sugarcane bagasse hemicellulose hydrolysate. S. shehatae BR6-2AY showed maximum ethanol production [0.48 ± 0.019 g g−1, 95 ± 3.78 % fermentation efficiency (FE)] followed by S. shehatae CG8-8BY (0.47 ± 0.016 g g−1, 93 ± 3.12 % FE), S. shehatae BR6-2AI (0.45 ± 0.01 g g−1, 89 ± 1.71 % FE) and S. shehatae PT1-1BASP (0.44 ± 0.02 g g−1, 86 ± 3.37 % FE) when grown in synthetic medium. During the fermentation of hemicellulose hydrolysates, S. shehatae CG8-8BY and S. shehatae BR6-2AY showed ethanol production (0.30 ± 0.05 g g−1, 58 ± 0.02 % FE) and (0.21 ± 0.01 g g−1, 40 ± 1.93 % FE), respectively.

Ultrasonic pretreatment and acid hydrolysis of sugarcane bagasse for succinic acid production using Actinobacillus succinogenes

Immense interest has been devoted to the production of bulk chemicals from lignocellulose biomass. Diluted sulfuric acid treatment is currently one of the main pretreatment methods. However, the low total sugar concentration obtained via such pretreatment limits industrial fermentation systems that use lignocellulosic hydrolysate. Sugarcane bagasse hemicellulose hydrolysate is used as the carbon and nitrogen sources to achieve a green and economical production of succinic acid in this study. Sugarcane bagasse was ultrasonically pretreated for 40 min, with 43.9 g/L total sugar obtained after dilute acid hydrolysis. The total sugar concentration increased by 29.5 %. In a 3-L fermentor, using 30 g/L non-detoxified total sugar as the carbon source, succinic acid production increased to 23.7 g/L with a succinic acid yield of 79.0 % and a productivity of 0.99 g/L/h, and 60 % yeast extract in the medium could be reduced. Compared with the detoxified sugar preparation method, succinic acid production and yield were improved by 20.9 and 20.2 %, respectively.

Rice bran extract: an inexpensive nitrogen source for the production of 2G ethanol from sugarcane bagasse hydrolysate.

Selection of the raw material and its efficient utilization are the critical factors in economization of second generation (2G) ethanol production. Fermentation of the released sugars into ethanol by a suitable ethanol producing microorganism using cheap media ingredients is the cornerstone of the overall process. This study evaluated the potential of rice bran extract (RBE) as a cheap nitrogen source for the production of 2G ethanol by Scheffersomyces (Pichia) stipitis NRRL Y-7124 using sugarcane bagasse (SB) hemicellulosic hydrolysate. Dilute acid hydrolysis of SB showed 12.45 g/l of xylose and 0.67 g/l of glucose along with inhibitors. It was concentrated by vacuum evaporation and submitted to sequential detoxification (neutralization by calcium hydroxide and charcoal adsorption). The detoxified hydrolysate revealed the removal of furfural (81 %) and 5-hydroxymethylfurfural (61 %) leading to the final concentration of glucose (1.69 g/l) and xylose (33.03 g/l). S. stipitis was grown in three different fermentation media composed of detoxified hydrolysate as carbon source supplemented with varying nitrogen sources i.e. medium #1 (RBE + ammonium sulfate + calcium chloride), medium #2 (yeast extract + peptone) and medium #3 (yeast extract + peptone + malt extract). Medium #1 showed maximum ethanol production (8.6 g/l, yield 0.22 g/g) followed by medium #2 (8.1 g/l, yield 0.19 g/g) and medium #3 (7.4 g/l, yield 0.18 g/g).

Evaluation of ethanol production by a new isolate of yeast during fermentation in synthetic medium and sugarcane bagasse hemicellulosic hydrolysate

A new xylose fermenting yeast was isolated from over-ripe banana by enrichment in xylose-containing medium. The phylogenetic analysis of ITS1-5.8S-ITS2 region sequences of ribosomal RNA of isolate BY2 revealed that it shows affiliation to genus Pichia and clades with Pichia caribbica. In batch fermentation, Pichia strain BY2 fermented xylose, producing 15 g l−1 ethanol from 30 g l−1 xylose under shaking conditions at 28°C, with ethanol yield of 0.5 g g−1 and volumetric productivity of 0.31 g l−1 h−1. The optimum pH range for ethanol production from xylose by Pichia strain BY2 was 5–7. Pichia strain BY2 also produced 6.08 g l−1 ethanol from 30 g l−1 arabinose. Pichia strain BY2 can utilize sugarcane bagasse hemicellulose acid hydrolysate for alcohol production, efficiency of fermentation was improved by neutralization, and sequential use of activated charcoal adsorption method. Percent total sugar utilized and ethanol yield for the untreated hydrolysate was 17.14% w/v and 0.33 g g−1, respectively, compared with 66.79% w/v and 0.45 g g−1, respectively, for treated hemicellulose acid hydrolysate. This new yeast isolate showed ethanol yield of 0.45 g g−1 and volumetric productivity of 0.33 g l−1 h−1 from sugarcane bagasse hemicellulose hydrolysate detoxified by neutralization and activated charcoal treatment, and has potential application in practical process of ethanol production from lignocellulosic hydrolysate.

Influence of the use of rice bran extract as a source of nutrients on xylitol production

Xylose-to-xylitol bioconversion using 2.5 or 10% (v/v) rice bran extract was performed to verify the influence of this source of nutrients on Candida guilliermondii metabolism. Semisynthetic medium (SM) and sugarcane bagasse hemicellulosic hydrolysate detoxified with ion-exchange resins (HIE) or with alteration in pH combined with adsorption onto activated charcoal (HAC) were fermented in 125 mL Erlenmeyer flasks at 30 ºC and 200 rpm for 72 hours. Activated charcoal supplemented with 2.5% (v/v) rice bran extract was fermented by C. guilliermondii in a MULTIGEN stirred tank reactor using pH 5.0 and 22.9/hour oxygen transfer volumetric coefficient. Higher values of xylitol productivity (0.70, 0.71, and 0.62 g.Lh-1) and xylose-to-xylitol conversion yield (0.71, 0.69, and 0.63 g.g-1) were obtained with 2.5% (v/v) rice bran in semisynthetic medium, ion-exchange resins, and activated charcoal, respectively. Moreover, during batch fermentation, the xylitol volumetric productivity and fermentation efficiency values obtained were 0.53 g.Lh-1 and 61.1%, respectively.

A novel use for sugarcane bagasse hemicellulosic fraction: Xylitol enzymatic production

The excess of sugarcane bagasse (SCB) from the sugar-alcohol industry is considered a by-product with great potential for many bioproducts production. This work had as objective to verify the performance of sugarcane bagasse hemicellulosic hydrolysate (SCBHH) as source of sugars for enzymatic or in vitro xylitol production. For this purpose, xylitol enzymatic production was evaluated using different concentrations of treated SCBHH in the commercial reaction media. The weak acid hydrolysis of SCB provided a hydrolysate with 18 g L−1 and 6 g L−1 of xylose and glucose, respectively. Considering the reactions, changes at xylose–xylitol conversion efficiency and volumetric productivity in xylitol were not observed for the control experiment and using 20 and 40% v.v−1 of SCBHH in the reaction media. The conversion efficiency achieved 100% in all the experiments tested. The results showed that treated SCBHH is suitable as xylose and glucose source for the enzymatic xylitol production and that this process has potential as an alternative for traditional xylitol production ways.

Effect of Dissolved Oxygen and Inoculum Concentration on Xylose Reductase Production from <i>Candida guilliermondii</i> Using Sugarcane Bagasse Hemicellulosic Hydrolysate

This work evaluated the effect of dissolved oxygen and the initial inoculum concentration on xylose reductase (XR) production by Candida guilliermondii from sugarcane bagasse hemicellulosic hydrolysate. Both the parameters were studied under an experimental design 22 with triplicate at central point. The statistical analysis of the results indicated a significant negative effect on XR production from the variable inoculum. The variable dissolved oxygen also showed a negative effect on XR production. We found the maximum enzyme activity (2.5 U?mg?1) when both the factors were applied at their lowest levels. The yeast showed to be potentially capable for xylose reductase production when sugarcane bagasse hemicellulosic hydrolysate was used as carbon source. Also, the results presented important information for further optimization of xylose reductase attainment.

Succinic acid production from sugarcane bagasse hemicellulose hydrolysate by Actinobacillus succinogenes

Succinic acid, a four-carbon diacid, has been the focus of many research projects aimed at developing more economically viable methods of fermenting sugar-containing natural materials. Succinic acid fermentation processes also consume CO(2), thereby potentially contributing to reductions in CO(2) emissions. Succinic acid could also become a commodity used as an intermediate in the chemical synthesis and manufacture of synthetic resins and biodegradable polymers. Much attention has been given recently to the use of microorganisms to produce succinic acid as an alternative to chemical synthesis. We have attempted to maximize succinic acid production by Actinobacillus succinogenes using an experimental design methodology for optimizing the concentrations of the medium components. The first experiment consisted of a 2(4-1) fractional factorial design, and the second entailed a Central Composite Rotational Design so as to achieve optimal conditions. The optimal concentrations of nutrients predicted by the model were: NaHCO(3), 10.0 g l(-1); MgSO(4), 3.0 g l(-1); yeast extract, 2.0 g l(-1); KH(2)PO(4). 5.0 g l(-1); these were experimentally validated. Under the best conversion conditions, as determined by statistical analysis, the production of succinic acid was carried out in an instrumented bioreactor using sugarcane bagasse hemicellulose hydrolysate, yielding a concentration of 22.5 g l(-1).

Application of Response Surface Methodology for Optimization of Xylitol Production from Lignocellulosic Hydrolysate in a Fluidized Bed Reactor

AbstractThis work aims to contribute to the development of a viable technology for the production of xylitol from sugarcane bagasse hemicellulose hydrolysate, using a fluidized bed bioreactor with yeast cells of Candida guilliermondii FTI 20037. To evaluate the technical viability of this biotechnological process, simple batch fermentations were realized according to a 23 factorial design with three center points. Furthermore, the influence of the variables fluidization flux, hydrolysate concentration factor and air flow on process yield and volumetric productivity were evaluated. The results obtained showed that only an increase in fluidization flux had a positive influence on process yield and volumetric productivity. This is due to better oxygen transfer to the inside of the cell, leading to increased xylose consumption and xylitol production rates.

Evaluation of hexose and pentose in pre-cultivation of Candida guilliermondii on the key enzymes for xylitol production in sugarcane hemicellulosic hydrolysate

The evaluation of hexose and pentose in pre-cultivation of Candida guilliermondii FTI 20037 yeast on xylose reductase (XR) and xylitol dehydrogenase (XDH) enzymes activities was performed during fermentation in sugarcane bagasse hemicellulosic hydrolysate. The xylitol production was evaluated by using cells previously growth in 30.0 gl(-1) xylose, 30.0 gl(-1) glucose and in both sugars mixture (30.0 gl(-1) xylose and 2.0 gl(-1) glucose). The vacuum evaporated hydrolysate (80 gl(-1)) was detoxificated by ion exchange resin (A-860S; A500PS and C-150-Purolite®). The total phenolic compounds and acetic acid were 93.0 and 64.9%, respectively, removed by the resin hydrolysate treatment. All experiments were carried out in Erlenmeyer flasks at 200 rpm, 30°C. The maximum XR (0.618 Umg (Prot) (-1)) and XDH (0.783 Umg (Prot) (-1)) enzymes activities was obtained using inoculum previously growth in both sugars mixture. The highest cell concentration (10.6 gl(-1)) was obtained with inoculum pre-cultivated in the glucose. However, the xylitol yield and xylitol volumetric productivity were favored using the xylose as carbon source. In this case, it was observed maximum xylose (81%) and acetic acid (100%) consumption. It is very important to point out that maximum enzymatic activities were obtained when the mixture of sugars was used as carbon source of inoculum, while the highest fermentative parameters were obtained when xylose was used.

Scale-up of diluted sulfuric acid hydrolysis for producing sugarcane bagasse hemicellulosic hydrolysate (SBHH)

Sugarcane bagasse was pretreated with diluted sulfuric acid to obtain sugarcane bagasse hemicellulosic hydrolysate (SBHH). Experiments were conducted in laboratory and semi-pilot reactors to optimize the xylose recovery and to reduce the generation of sugar degradation products, as furfural and 5-hydroxymethylfurfural (HMF). The hydrolysis scale-up procedure was based on the H-Factor, that combines temperature and residence time and employs the Arrhenius equation to model the sulfuric acid concentration (100 mg acid/g dm) and activation energy (109 kJ/mol). This procedure allowed the mathematical estimation of the results through simulation of the conditions prevailing in the reactors with different designs. The SBHH obtained from different reactors but under the same H-Factor of 5.45 ± 0.15 reached similar xylose yield (approximately 74%) and low concentration of sugar degradation products, as furfural (0.082 g/L) and HMF (0.0071 g/L). Also, the highest lignin degradation products (phenolic compounds) were ρ-coumarilic acid (0.15 g/L) followed by ferulic acid (0.12 g/L) and gallic acid (0.035 g/L). The highest concentration of ions referred to S (3433.6 mg/L), Fe (554.4 mg/L), K (103.9 mg/L). The H-Factor could be used without dramatically altering the xylose and HMF/furfural levels. Therefore, we could assume that H-Factor was directly useful in the scale-up of the hemicellulosic hydrolysate production.

Ethanol Production from Sugarcane Bagasse Hydrolysate Using Pichia stipitis

The objective of this study was to evaluate the ethanol production from the sugars contained in the sugarcane bagasse hemicellulosic hydrolysate with the yeast Pichia stipitis DSM 3651. The fermentations were carried out in 250-mL Erlenmeyers with 100 mL of medium incubated at 200 rpm and 30 degrees C for 120 h. The medium was composed by raw (non-detoxified) hydrolysate or by hydrolysates detoxified by pH alteration followed by active charcoal adsorption or by adsorption into ion-exchange resins, all of them supplemented with yeast extract (3 g/L), malt extract (3 g/L), and peptone (5 g/L). The initial concentration of cells was 3 g/L. According to the results, the detoxification procedures removed inhibitory compounds from the hemicellulosic hydrolysate and, thus, improved the bioconversion of the sugars into ethanol. The fermentation using the non-detoxified hydrolysate led to 4.9 g/L ethanol in 120 h, with a yield of 0.20 g/g and a productivity of 0.04 g L(-1) h(-1). The detoxification by pH alteration and active charcoal adsorption led to 6.1 g/L ethanol in 48 h, with a yield of 0.30 g/g and a productivity of 0.13 g L(-1) h(-1). The detoxification by adsorption into ion-exchange resins, in turn, provided 7.5 g/L ethanol in 48 h, with a yield of 0.30 g/g and a productivity of 0.16 g L(-1) h(-1).

Bio-hydrogen production from the fermentation of sugarcane bagasse hydrolysate by Clostridium butyricum

Sugarcane bagasse (SCB) used in hydrogen production by Clostridium butyricum was hydrolyzed using H 2SO 4 at various concentrations (0.25–7.0% volume) and reaction times (15–240 min) at 121 °C, 1.5 kg/cm 2 in autoclave. Optimal conditions obtained were 0.5% H 2SO 4 and 60 min which yielded 24.5 g-COD/L of total sugar. At these conditions, 11 g glucose/L; 11.29 g xylose/L; 2.22 g arabinose/L; 2.48 g acetic acid/L and 0.12 g/L furfural were obtained. Effects of initial pH and substrate concentration on the bio-hydrogen production from SCB hemicellulose hydrolysate by C. butyricum were then investigated. The best hydrogen yield of 1.73 mol H 2/mol total sugar and the hydrogen production rate of 1611 mL H 2/L/day were obtained at the initial pH 5.5 and initial sugar concentration 20 g-COD/L and compared very favorably with those reported in literature. Results suggested the possibility of using SCB hemicellulose hydrolysate as a fermentation media for hydrogen production by C. butyricum.

PVA-Hydrogel Entrapped Candida Guilliermondii for Xylitol Production from Sugarcane Hemicellulose Hydrolysate

Viable cells of Candida guilliermondii were immobilized by inclusion into polyvinyl alcohol (PVA) hydrogel using the freezing-thawing method. Entrapment experiments were planned according to a 2(3) full factorial design, using the PVA concentration (80, 100, and 120 g L(-1)), the freezing temperature (-10, -15, and -20 degrees C), and the number of freezing-thawing cycles (one, three, and five) as the independent variables, integrated with three additional tests to estimate the errors. The effectiveness of the immobilization procedure was checked in Erlenmeyer flasks as the pellet capability to catalyze the xylose-to-xylitol bioconversion of a medium based on sugarcane bagasse hemicellulosic hydrolysate. To this purpose, the yield of xylitol on consumed xylose, xylitol volumetric productivity, and cell retention yield were selected as the response variables. Cell pellets were then used to perform the same bioconversion in a stirred tank reactor operated at 400 rpm, 30 degrees C, and 1.04 vvm air flowrate. At the end of fermentation, a maximum xylitol concentration of 28.7 g L(-1), a xylitol yield on consumed xylose of 0.49 g g(-1) and a xylitol volumetric productivity of 0.24 g L(-1) h(-1) were obtained.

Semi-continuous xylose-to-xylitol bioconversion by Ca-alginate entrapped yeast cells in a stirred tank reactor

Candida guilliermondii FTI 20037 cells were entrapped in Ca-alginate beads and used for xylose-to-xylitol bioconversions during five successive batches in a stirred tank reactor. Supplemented sugarcane bagasse hemicellulosic hydrolysate was used as the fermentation medium. The average volume of the Ca-alginate beads was reduced by about 30% after the 600 h taken to perform the five bioconversion cycles, thus demonstrating physical instability under the conditions prevailing in the reactor vessel. In spite of this, almost steady bioconversion rates and yields were observed along the repeated batches. In average values, a production of 51.6 g l(-1), a productivity of 0.43 g l(-1 )h(-1) and a yield of 0.71 g g(-1) were attained in each batch, variation coefficients being smaller than 10%.

Sugarcane bagasse hemicellulose hydrolysate for ethanol production by acid recovery process

In order to increase the reducing sugar concentration in the sugarcane bagasse hemicellulose acid hydrolysate and recover the acid, the acid hydrolysis was carried out in an acid recycle process and detoxification of hydrolysate was performed by electrodialysis. Two cycles of acidic treatments increased the reducing sugar concentration from 28 to 63.5 g l −1 and sulphuric acid consumption decreased to 0.056 g g −1 bagasse. After treatment by electrodialysis, 90% of acetic acid in hydrolysate was removed and the recovery ratio of sulphuric acid was 88%. The pretreated hydrolysates, supplemented with nutrient materials, were fermented to ethanol using Pachysolen tannophilus DW06. A batch culture with pretreated hydrolysate as substrate was developed giving 19 g ethanol l −1 with a yield of 0.34 g g −1 sugar and productivity of 0.57 g l −1 h −1.

Semi-continuous xylitol bioproduction in sugarcane bagasse hydrolysate: effect of nutritional supplementation

Xylose-to-xylitol bioconversion by Ca-alginate entrapped Candida guilliermondii cells in sugarcane bagasse hemicellulosic hydrolysate was carried out in erlenmeyer flasks using the repeated-batch mode of fermentation. The hydrolysate was supplemented or not with ammonium sulfate and/or rice bran extract at the beginning of each repeated batch. Altogether, six sets of three repeated-batches were carried out, the immobilized cells being reused at the end of each batch. The best results were achieved when the hydrolysate was supplemented with both nutrients in all the three repeated batches, which provided xylitol productions of 25.9, 46.8, 48.7 gL-1, productivities of 0.27, 0.49, 0.51 gL-1h-1, and yields of 0.45, 0.58, 0.55 gg-1, respectively. In the absence of nutrients, the xylitol production, productivity and yield did not exceed 12.1 gL-1, 0.13 gL-1h-1 and 0.30 gg-1, respectively.

A study on the recovery of xylitol by batch adsorption and crystallization from fermented sugarcane bagasse hydrolysate

AbstractXylitol was recovered from fermented sugarcane bagasse hemicellulosic hydrolysate by adsorption and crystallization procedures. Silica gel adsorption was employed to purify the broth containing xylitol. In this step, different mixtures of the solvents ethyl acetate, ethanol and acetone were used as eluent, and different proportions of fermented broth volume incorporated per gram of silica gel (Vb/Msg, varying from 1.0 to 2.0 cm3 g−1) were used to pack the column employed as stationary phase bed. The xylitol purification efficiency varied for each mixture of solvent, and for each Vb/Msg ratio used. The purified broth was submitted to different crystallization procedures (cooling, concentration and supplementation with commercial xylitol) aiming to recover xylitol crystals. The best result (60% crystallization yield and 33% total recovery of xylitol from fermented broth) was obtained when the column was packed with a Vb/Msg ratio of 2 cm3 g−1, and the broth was purified with a mixture of ethyl acetate and ethanol, concentrated 6.5‐fold, and supplemented with commercial xylitol to force the precipitation. Copyright © 2006 Society of Chemical Industry

Xylitol production in a bubble column bioreactor: Influence of the aeration rate and immobilized system concentration

This work evaluated the xylitol production from sugarcane bagasse hemicellulosic hydrolysate in a bubble column bioreactor using cells of the yeast Candida guilliermondii immobilized in calcium-alginate. The fermentation runs were performed according to a 2 2 full factorial design with three replicates at the center point in order to determine the effect of the variables: aeration rate (0.66–1.33 vvm) and immobilized system concentration (20–40% v/v), on the efficiency of xylose-to-xylitol conversion and on the xylitol volumetric productivity. The results indicated a significant influence of both variables on xylitol production. The highest conversion efficiency (41%) was attained using 1.33 vvm aeration rate and 40% immobilized system. Under these conditions, the volumetric productivity was 0.21 g l −1 h −1.

MÉTODOS DE PURIFICACIÓN DE HIDROLIZADOS DE BAGAZO DE CAŃA DE AZÚCAR PARA LA OBTENCIÓN DE XILITOLPURIFICATION METHODS OF SUGARCANE BAGASSE HYDROLYSATES FOR XYLITOL OBTAINING

Three treatments methods for sugarcane bagasse hemicellulosic hydrolysate were tested in order to minimize its toxicity for the biological production of xylitol; using ionic exchange resins (TH1 and TH2) and activated charcoal (TH3). The treated hydrolysates were fermented in shaker flasks by the yeast Candida guilliermondii FTI 20037. The statistical analysis showed that TH1 and TH2 were the best treatments. Concerning to the fermentation process, it was observed that there was a significant difference (P = 0.05) among the treatments and it was detected the highest xylitol productivity and yield with TH1 (0.66 g/Lh, 0.73 g/g) and the lowest with TH3 (0.48 g/Lh; 0.59 g/g). These results showed that the ionic exchange resins increase the efficiency of the fermentative process more than the treatment of adsorption with activated charcoal. Resumen Se probaron tres métodos de tratamiento del hidrolizado hemicelulósico de bagazo de caña de azúcar con el objetivo de minimizar su toxicidad para la producción biotecnológica de xilitol; dos usando resinas de intercambio iónico (TH1 y TH2) y uno usando carbón activado (TH3). Los hidrolizados tratados fueron fermentados en agitador rotatorio por la levadura Candida guilliermondii FTI 20037. Los resultados de los tratamientos se analizaron estadísticamente detectándose que los mejores tratamientos fueron TH1 y TH2. En relación al proceso fermentativo se observó que existen diferencias significativas (P≤0,05) entre los tratamientos, y se detectaron las mayores productividades y rendimientos en xilitol con el tratamiento TH1 (0,66 g/Lh, 0,73 g/g) y las menores con TH3 (0,48 g/Lh; 0,59 g/g). Demostrándose que los tratamientos usando resinas de intercambio iónico aumentan la eficiencia de los procesos fermentativos en mayor medida que el tratamiento por adsorción con carbón activo. Palabras clave: xilitol, hidrolizado hemicelulósico de bagazo de caña de azúcar, resinas de intercambio iónico, carbón activado