Artículos de revistas: "Xylitol Production"

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Hong, Yuanyuan, Mehdi Dashtban, Greg Kepka, Sanfeng Chen y Wensheng Qin. "Overexpression of D-Xylose Reductase (xyl1) Gene and Antisense Inhibition of D-Xylulokinase (xyiH) Gene Increase Xylitol Production inTrichoderma reesei". BioMed Research International 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/169705.

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T. reeseiis an efficient cellulase producer and biomass degrader. To improve xylitol production inTrichoderma reeseistrains by genetic engineering, two approaches were used in this study. First, the presumptive D-xylulokinase gene inT. reesei(xyiH), which has high homology to known fungi D-xylulokinase genes, was silenced by transformation ofT. reeseiQM9414 strain with an antisense construct to create strain S6-2-2. The expression of thexyiHgene in the transformed strain S6-2-2 decreased at the mRNA level, and D-xylulokinase activity decreased after 48 h of incubation. This led to an increase in xylitol production from undetectable levels in wild-typeT. reeseiQM9414 to 8.6 mM in S6-2-2. TheT. reeseiΔxdh is a xylose dehydrogenase knockout strain with increased xylitol production compared to the wild-typeT. reeseiQM9414 (22.8 mM versus undetectable). The copy number of the xylose reductase gene (xyl1) inT. reeseiΔxdh strain was increased by genetic engineering to create a new strain Δ9-5-1. The Δ9-5-1 strain showed a higherxyl1 expression and a higher yield of xylose reductase, and xylitol production was increased from 22.8 mM to 24.8 mM. Two novel strains S6-2-2 and Δ9-5-1 are capable of producing higher yields of xylitol.T. reeseihas great potential in the industrial production of xylitol.

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T.N. Bhagat, A. G. Pathade y G. R. Pathade. "Xylitol: Production and its applications – A Review". Ecology, Environment and Conservation 30, Suppl (2024): 228–33. http://dx.doi.org/10.53550/eec.2024.v30i02s.048.

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Xylitol is important chemical due to its various applications. The use of xylitol as a sweetener for diabetic patients has made it a high valuable special chemical. As xylitol is present in low concentrations in fruits and vegetables, therefore its extraction is unaffordable from these sources. Thus, xylitol can be produced chemically by reduction of xylose in presence of suitable reducing agents and microbial route method. Although several species of yeast, fungi and bacteria synthesize xylitol by the species of the genus Candida, Saccharomyces, Pichia, Debaryomyces, Trichosporon, Enterobacter, Corynebacterium, Mycobacterium etc. The chemical synthesis of xylitol from xylose is the dominant production method of xylitol production. The industrial process to produce xylitol involves the chemical hydrolysis of D-xylose followed by the hydrogenation of the resultant hemicellulose hydrolysate by catalysts including palladium and nickel. For the chemical synthesis of xylitol, high temperatures and high pressure are required. These processes are very expensive which makes the production costs of synthesizing xylitol because of the highly energy intensive, high temperature, pressure and metal catalyst used for a sustained period of time. Therefore, in this review article we study the microbial route of xylitol production from agricultural residues.

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Kumar, Kuldeep, Ekta Singh y Smriti Shrivastava. "Microbial xylitol production". Applied Microbiology and Biotechnology 106, n.º 3 (28 de enero de 2022): 971–79. http://dx.doi.org/10.1007/s00253-022-11793-6.

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Hor, Sreyden, Mallika Boonmee Kongkeitkajorn y Alissara Reungsang. "Evaluation of Xylose-Utilising Yeasts for Xylitol Production from Second-Generation Ethanol Vinasse and Effect of Agitation Intensity in Flask-Scale Xylitol Production". Sains Malaysiana 52, n.º 1 (31 de enero de 2023): 175–85. http://dx.doi.org/10.17576/jsm-2023-5201-14.

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This study aimed to select a yeast strain that effectively utilises xylose to produce xylitol from the vinasse of ethanol broth obtained from the fermentation of sugarcane bagasse hydrolysate. Eleven strains of xylose-fermenting yeasts were evaluated for their abilities to utilise xylose and produce xylitol. Two strains that showed outstanding performance in the semi-defined xylose medium were selected for further testing with a vinasse medium. Candida guilliermondii TISTR 5068 showed a superior xylitol production of 7.03 ± 0.08 g/L with the xylitol yield of 0.70 g/gxylose when cultured in bagasse-based ethanol vinasse. The strain was further tested for its xylitol production performance when cultured at four different agitation intensities. Excessive agitation resulted in a rapid xylitol production rate but caused xylitol consumption once the xylose was depleted. Moderate agitation resulted in the highest xylitol yield of 0.79 g/gxylose. The results of this study have provided important information for the development of the xylitol production process using waste streams from cellulosic ethanol production.

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Hor, Sreyden, Mallika Boonmee Kongkeitkajorn y Alissara Reungsang. "Sugarcane Bagasse-Based Ethanol Production and Utilization of Its Vinasse for Xylitol Production as an Approach in Integrated Biorefinery". Fermentation 8, n.º 7 (19 de julio de 2022): 340. http://dx.doi.org/10.3390/fermentation8070340.

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Biorefinery of sugarcane bagasse into ethanol and xylitol was investigated in this study. Ethanol fermentation of sugarcane bagasse hydrolysate was carried out by Saccharomyces cerevisiae. After ethanol distillation, the vinasse containing xylose was used to produce xylitol through fermentation by Candida guilliermondii TISTR 5068. During the ethanol fermentation, it was not necessary to supplement a nitrogen source to the hydrolysate. Approximately 50 g/L of bioethanol was produced after 36 h of fermentation. The vinasse was successfully used to produce xylitol. Supplementing the vinasse with 1 g/L of yeast extract improved xylitol production 1.4-fold. Cultivating the yeast with 10% controlled dissolved oxygen resulted in the best xylitol production and yields of 10.2 ± 1.12 g/L and 0.74 ± 0.04 g/g after 60 h fermentation. Supplementing the vinasse with low fraction of molasses to improve xylitol production did not yield a positive result. The supplementation caused decreases of up to 34% in xylitol production rate, 24% in concentration, and 24% in yield.

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West, Thomas P. "Xylitol Production by Candida Species from Hydrolysates of Agricultural Residues and Grasses". Fermentation 7, n.º 4 (28 de octubre de 2021): 243. http://dx.doi.org/10.3390/fermentation7040243.

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Xylitol is an industrially important chemical due to its commercial applications. The use of xylitol as a sweetener as well as its utilization in biomedical applications has made it a high value specialty chemical. Although several species of yeast synthesize xylitol, this review focusses on the species of the genus Candida. The importance of the enzyme xylitol reductase present in Candida species as it relates to their ability to synthesize xylitol was examined. Another focus of this work was to review prior studies examining the ability of the Candida species to synthesize xylitol effectively from hydrolysates of agricultural residues and grasses. An advantage of utilizing such a hydrolysate as a substrate for yeast xylitol production would be decreasing the overall cost of synthesizing xylitol. The intent of this review was to learn if such hydrolysates could substitute for xylose as a substrate for the yeast when producing xylitol. In addition, a comparison of xylitol production by Candida species should indicate which hydrolysate of agricultural residues and grasses would be the best substrate for xylitol production. From studies analyzing previous hydrolysates of agricultural residues and grasses, it was concluded that a hydrolysate of sugarcane bagasse supported the highest level of xylitol by Candida species, although corncob hydrolysates also supported significant yeast xylitol production. It was also concluded that fewer studies examined yeast xylitol production on hydrolysates of grasses and that further research on grasses may provide hydrolysates with a higher xylose content, which could support greater yeast xylitol production.

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Meilany, Diah, Dewinka Anugeraheni, Abdul Aziz, Made Tri Ari Penia Kresnowati y Tjandra Setiadi. "The Effects of Operational Conditions in Scaling Up of Xylanase Enzyme Production for Xylitol Production". Reaktor 20, n.º 1 (13 de marzo de 2020): 32–37. http://dx.doi.org/10.14710/reaktor.20.1.32-37.

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The biological route to produce xylitol from Oil Palm Empty Fruit Bunches (EFBs) comprises of EFBs pretreatment, enzymatic hydrolysis, fermentation, and downstream separation of the produced xylitol. Due to the specificity in the hemicellulose composition of EFBs, a xylanase enzyme that has a high affinity to EFBs is required to hydrolyze the EFBs into xylose. In this research, the influences of aeration, humidity, and mixing in xylanase production were mapped. The xylanase production was performed by Aspergillus fumigatus ITBCCL170 in a solid-state fermentation using a tray fermenter with EFBs as the substrate. The optimal configuration was further scaled up into xylanase production using 1000 g of EFBs as the substrate. The results showed that the highest enzyme activity was 236.3 U/g EFB, obtained from the use of humid air airflow of 0.1 LPM, and mixing was performed once a day. The scaling up resulted in a lower xylanase activity and call for a better design of the fermenter.Keywords: aeration, humidity, mixing, OPEFBs, tray fermenter, xylanase, xylitol

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Rahayu, E., N. Hidayah y R. S. Adiandri. "Production of Xylitol from Corn Biomass using Candida sp. As Microbial Agent". IOP Conference Series: Earth and Environmental Science 1024, n.º 1 (1 de mayo de 2022): 012075. http://dx.doi.org/10.1088/1755-1315/1024/1/012075.

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Abstract Xylitol, C5H12O5, is a white and odorless crystalline powder of sweetening agents that included as low-calorie sweetener. It could be used as a healthy ingredient for food and pharmaceutical. Natural sources of xylitol are fruit and vegetable, even in minute quantities. At industrial scale, xylitol is produced through hydrolysis and hydrogenation process of lignocellulosic materials. The aim of this research was to study the production of xylitol from corn biomass using Candida sp. as a microbial agent. The research was conducted using different species of Candida sp. (C. guilliermondii and C. tropicalis) and supplement media growth (with or without glucose). Xylitol concentration was examined after fermentation for 3 and 5 days. The results showed that corncob is a promising material to use in producing xylitol from lignocellulosic biomass. The longer fermentation time, the higher xylitol concentration, ranged from 0.049 to 0.088 g/L. However, compare to another microbe species, the treatment using Candida tropicalis showed that long fermentation resulted in a lower xylitol concentration. The addition of glucose as co-substrate increased xylose consumption rate and xylitol productivity. These results provide useful information to develop further study about xylitol production using agricultural biomass.

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Mardawati, Efri, Budi Mandra Harahap, Emilda Ayu Febrianti, Agus Try Hartono, Natasha Putri Siahaan, Anting Wulandari, Silvia Yudiastuti, Sri Suhartini y Kasbawati Kasbawati. "Integrated and partial process of xylitol and bioethanol production from oil palm empty fruit bunches". Advances in Food Science, Sustainable Agriculture and Agroindustrial Engineering 5, n.º 1 (31 de julio de 2022): 49–67. http://dx.doi.org/10.21776/ub.afssaae.2022.005.01.5.

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Oil palm empty fruit bunches (OPEFBs) are highly abundant in Indonesia and have been highlighted as a potential feedstock for bioethanol and xylitol production. However, the efficacy of the fermentation technology to convert OPEFBs to bioethanol and xylitol, either in partial (i.e. mono-production) or integrated (i.e. co-production) process, still needs further improvement. This study aimed to evaluate the partial and integrated process for xylitol and bioethanol production from OPEFBs. In the integrated process, the remaining solid residues after xylitol extraction are used as feedstock for bioethanol due to their high cellulose compounds. This solid residue is more susceptible to be degraded by cellulase enzymes into glucose and further transformed into bioethanol. In the partial process of xylitol production, xylanase enzyme was used to hydrolyze xylan into xylose, which was then converted into xylitol using Debaryomyces hansenii. While in the partial process of bioethanol production, the hydrolysis of cellulose in the OPEFB into glucose was carried out using cellulase enzymes, followed by fermentation using Saccharomyces cerevisiae. The results show that the partial process produced xylitol yield (Yp/s) of 0.10 g-xylitol/g-xylose, while bioethanol at yield (Yp/s) of 0.32 g-bioethanol/g-glucose, respectively. The integrated process generates xylitol yield (Yp/s)of 0.298 g-xylitol/g-xylose, with bioethanol yield from the remaining solid at 0.051 g-bioethanol/g-OPEFB (or 0.078 g-bioethanol/g-glucose). These findings, therefore, confirmed that the integrated process of xylitol with bioethanol production might offer higher efficacy of OPEFB utilization into high value-added products.

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Ambarsari, Laksmi, Suryani Suryani, Steffanus Gozales y Puspa Julistia Puspita. "The Addition Effects of Glucose as a Co-substrate on Xylitol Production by Candida guilliermondii". Current Biochemistry 2, n.º 1 (20 de abril de 2015): 13–21. http://dx.doi.org/10.29244/cb.2.1.13-21.

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High cost production is one of the constraints of the commercial xylitol production due to high energy needed and pure raw materials. Therefore, it is necessary to improve the xylitol production eficiently with lower production cost by using microorganisms. The research objectives were to determine the optimum xylitol production from xylose by metabolism of C. guilliermondii and effect of glucose as a co-substrate in fermentation medium. The ratio of glucose : xylose (g/L) was 1:25, 1:12, 1:5 and 1:2.5 respectively. The xylitol concentration was measured by spectrophotometer method (D-sorbytol/D-xylitol kit). The result showed that the exponential phase of Candida guilliermondii was 12 h to 36 of incubation and optimum of incubation time to produce the highest xylitol was 72 h. The best ratio- of glucose : xylose to produce xylitol was 9 g/L glucose : 45 g/L xylose (1 : 5). The xylitol concentration produced from medium with the addition of glucose was 2.85 g/L. This concentration increased five times compared to that in the medium without addition of glucose that only reached 2.85 g/L. According to this study, the addition of glucose as a co-substrate could increase the xylitol production.

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Niranjan, Rashmi, Vishal Ahuja y Arvind Kumar Bhatt. "Optimization of Xylose Reductase production from Citrobacter sp." Research Journal of Biotechnology 16, n.º 8 (25 de julio de 2021): 90–97. http://dx.doi.org/10.25303/168rjbt9021.

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Xylitol is a poly-hydroxy straight-chain five-carbon alcohol that can replace sugar in daily uses without any side effects. Lowered risk of dental carries and bone demineralization further support its involvement in a healthy lifestyle. In addition, its role in the synthesis of various commercial products like glycol, ethanol, and resins etc. increases its market value and makes it one of the most valuable bio-products. Microbial fermentation is a cost-effective and eco-friendly method for xylitol production from agricultural residues as available xylose is reduced to xylitol by Xylose reductase (XR) using an equivalent amount of NADPH as a mediator for electron transfer. Previous literature emphasized the use of fungi and yeast for xylitol production rather than bacteria. In contrast to available reports, the potential of the bacterial isolate was evaluated for xylitol production. The effect of process parameters was observed on xylitol yield in terms of XR activity. Out of sixty-eight bacterial isolates obtained, XYLBV-05 was selected for XR production after screening and was identified as Citrobacter sp. based on morphological, microscopic, and biochemical characteristics. Parametric analysis increased the XR production by 4.12 folds (36.61 U/ml). Preliminary results also proved its efficiency in conversion of biomass hydrolysate to xylitol at lab scale but further efforts are needed for xylitol production using agro-industrial lignocellulosic biomass at a large scale which will not only aid in the generation of revenue as a result of value-added products but will also help in environment conservation.

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Dahiya, Jagroop S. "Xylitol production by Petromyces albertensis grown on medium containing D-xylose". Canadian Journal of Microbiology 37, n.º 1 (1 de enero de 1991): 14–18. http://dx.doi.org/10.1139/m91-003.

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Petromyces albertensis produced xylitol and D-xylulose when cultivated on a medium containing D-xylose. These fermentative products were identified by high-performance liquid chromatography. A large amount of xylitol was obtained from a D-xylose medium containing ammonium acetate and yeast extract at an initial pH of 7.0. Maximum production of xylitol and of the enzymes concerned with its production was observed after 10 days of cultivation. A D-xylose (100 g/L) medium supplemented with 1% (v/v) methanol gave the highest yields of xylitol (39.8 g/L) and D-xylulose (2.8 g/L). Key words: Petromyces albertensis, D-xylulose, xylitol.

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Abdullah, Noradilin, Rosli Md Illias, Low Kheng Oon, Nardiah Rizwana Jaafar, Norhamiza Mohamad Sukri y Roshanida Abdul Rahman. "METABOLIC PATHWAY MODIFICATION FOR PRODUCTION OF XYLITOL FROM GLUCOSE IN ESCHERICHIA COLI". Jurnal Teknologi 84, n.º 3 (31 de marzo de 2022): 151–62. http://dx.doi.org/10.11113/jurnalteknologi.v84.18228.

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Glucose is a cheap and readily available substrate for production of large-scale chemicals. Synthesis of xylitol, a high demand chemical in global market is currently done by using xylose, which contributes to its high operational cost. Studies on production of xylitol from glucose have explored several approaches, from sequential fermentation to multiple and single gene expression. Xylitol-5-phosphate dehydrogenase (XPDH), is an enzyme that enables conversion of glucose to xylitol in a single step fermentation. This study explores conversion of xylitol from glucose in E. coli by the expression of xpdh from Clostridium difficile with modifications in metabolic pathways to enhance xylitol production. The xpdh gene was carried by pACYC-Duet-1 expression vector and induced by the addition of IPTG. Initial screening of E. coli expressing xpdh (NA116) was done by shake-flask fermentation for 24 hours and its metabolites were analyzed by HPLC. NA116 was able to produce 0.273 g/L xylitol from 4.33 g/L consumed glucose in 24 hours. Further metabolic pathway modification to eliminate competing pathways yielded four mutants, NA207 (∆rpiA), NA208 (∆rpiB), NA209 (∆pgi) and NA211 (∆rpi∆Apgi). Screening of mutants for xylitol production showed that highest xylitol production from glucose was achieved by NA211 with almost double the amount of the original strain, 0.585 g/L. This showed successful xylitol conversion from glucose in a single fermentation in E. coli with improved yield through metabolic pathway modification.

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Noorain Mohmad Yousoff, Siti, ‘Amirah Baharin y Afnizanfaizal Abdullah. "Deep Neural Network Method for the Prediction of Xylitol Production". Indonesian Journal of Electrical Engineering and Computer Science 5, n.º 3 (1 de marzo de 2017): 691. http://dx.doi.org/10.11591/ijeecs.v5.i3.pp691-696.

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<p>Bio-based chemical products such as xylitol have achieved remarkable attentions both in pharmaceutical and food industries due to their several advantages such as sugar substitute that can help diabetic patients and help in preventing tooth decay problem. To produce xylitol, recently, microbial host such as E. Coli often used as it is predicted that E. Coli can produce high level of xylitol. Therefore, metabolic engineering need to be done towards E. Coli and powerful tools are needed to manipulate, simulate and analyse the E. Coli metabolic pathway. Artificial intelligence methods such as deep neural network offer an efficient and powerful approach to be used to analyse the xylitol production value and at the same time to predict which genes and pathway that give biggest effect in the process to produce xylitol in E. Coli. Results show that, with an absence of genes pgi, tkt and tala, xylitol production can be boosted up to the higher level.</p>

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Ramesh, S., R. Muthuvelayudham, Rajesh Kannan y T. Viruthagiri. "Response surface optimization of medium composition for xylitol production by Debaryomyces hansenii var hansenii using corncob hemicellulose hydrolysate". Chemical Industry and Chemical Engineering Quarterly 19, n.º 3 (2013): 377–84. http://dx.doi.org/10.2298/ciceq120315072r.

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Optimization of the culture medium for xylitol production using Debrayomyces hansenii var hansenii was carried out. The optimization of xylitol production using corncob hemicelluloses hydrolysate as substrate was performed with statistical methodology based on experimental designs. The screening of nine nutrients for their influence of xylitol production to achieved using a Plackett-Burman design. MgSO4.7H2O, KH2PO4, (NH4)2SO4, yeast extract were selected for based on their positive influence on xylitol production. The selected components were optimized using Response Surface Methodology (RSM). The optimum conditions are: MgSO4.7H2O - 1.02 g/l, (NH4)2SO4 - 3.94 g/l, KH2PO4- 2.74 g/l and yeast extract - 3.45 g/l. These conditions are validated experimentally which revealed an enhanced xylitol yield of 0.76 g/g.

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Faradila Ayu, Near Putri, N. Nurhayati, Ahmad Thontowi, Endang Kusdiyantini, Atit Kanti y Euis Hermiati. "Produksi Xilitol Menggunakan Hidrolisat Tongkol Jagung (Zea mays) Oleh Meyerozyma caribbica InaCC Y67". Bioma : Berkala Ilmiah Biologi 23, n.º 1 (2 de junio de 2021): 71–77. http://dx.doi.org/10.14710/bioma.23.1.71-77.

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Xylitol (C5H12O5) is a non-carcinogenic polyalcoholic sugar. Xylitol is beneficial for diabetics because it can be metabolized without insulin. Corn cobs contain 30% xylose which can be fermented into xylitol by microorganisms. Xylitol can be produced by fermentation of xylose and few microorganisms. Meyerozyma caribbica is a yeast that has been proven to produce xylitol and inhibitor’s resistant. The aim of this research is to test the xylitol productivity by Meyerozyma caribbica InaCC Y67 using corn cobs hydrolyzate and the effect of the volume of fermentation media on xylitol productivity by Meyerozyma caribbica InaCC Y67. The method was carried out by culturing Meyerozyma caribbica InaCC Y67 as a starter on YPD media. Fermentation using 100 mL Erlenmeyer with the variation of fermentation volume is 10 ml and 75 ml, agitation 175 rpm and 30 oC. Parameters were measured based on the dry weight of cells, xylose and xylitol. Data were analyzed using fermentation kinetics. The results of analysis showed that the higher xylitol production was found in the fermentation volume 75 ml with an efficiency value of 7,171%. The highest xylitol production was at the 48th hour with production value of 2.050 g/L. Results from research shows that Meyerozyma caribbica InaCC Y67 can produce xylitol with corn cobs hydrolyzate. The right volume of fermentation in the fermentation process can also increase the productivity of xylitol.

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López-Linares, Juan Carlos, Encarnación Ruiz, Inmaculada Romero, Eulogio Castro y Paloma Manzanares. "Xylitol Production from Exhausted Olive Pomace by Candida boidinii". Applied Sciences 10, n.º 19 (5 de octubre de 2020): 6966. http://dx.doi.org/10.3390/app10196966.

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In this work, the production of xylitol from a hemicellulosic hydrolysate of exhausted olive pomace (EOP), a residue originated in the olive oil production process by Candida boidinii, was assessed. The hydrolysate was obtained by dilute acid pretreatment of EOP at 170 °C and 2% H2SO4 (w/v). A previous detoxification step of the hydrolysate was necessary, and its treatment with activated charcoal and ion-exchange resin was evaluated. Prior to fermentation of the hydrolysate, fermentation tests in synthetic media were performed to determine the maximum xylitol yield and productivity that could be obtained if inhibitory compounds were not present in the medium. In addition, the glucose existing in the media exerted a negative influence on xylitol production. A maximum xylitol yield of 0.52 g/g could be achieved in absence of inhibitor compounds. Fermentation of the hemicellulosic hydrolysate from EOP after detoxification with ion-exchange resin resulted in a xylitol yield of 0.43 g/g.

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Qi, Xiang Hui, Yan Luo, Jing Fei Zhu, Huan Huan Zhang, Xu Wang, Jing Lin, Fang Chen, Zhao Ju y Liang Wang. "Microbial Bioconversion Process of Glucose for the Production of Xylitol". Key Engineering Materials 636 (diciembre de 2014): 149–52. http://dx.doi.org/10.4028/www.scientific.net/kem.636.149.

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Xylitol is the first rare sugar that has global market because of its excellent properties. Considering its superiority to chemosynthesis, biosynthesis of xylitol became hot issue in recent studies. The production of xylitol from glucose experienced a development from three-step process to two-step process, or even only one-step process. The microbial and enzymatic process involving key enzymes, molecular cloning and expression and transgenic bacteria construction is introduced in this paper. This study may provide novel thought to explore new resource for better control of biological reaction conditions and obtainment of higher xylitol yield.

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Ou, Chung-Mao, Tien-Yang Ma, Wei-Lin Tu, Yu Chao y Gia-Luen Guo. "Xylitol production from non-detoxified Napiergrass hydrolysate using a recombinant flocculating yeast strain". BioResources 15, n.º 4 (29 de octubre de 2020): 9575–83. http://dx.doi.org/10.15376/biores.15.4.9575-9583.

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Xylose derived from lignocellulose can be utilized to produce ethanol and other high-value chemicals, such as xylitol. The xylitol production through fermentation of lignocellulosic hydrolysate by microorganisms offers advantages of high product yield, high selectivity, and efficacy in mild conditions. In this study, non-detoxified hemicellulose hydrolysate from napiergrass was used for xylitol production by a recombinant flocculating strain of Saccharomyces cerevisiae. An optimization study was conducted with the strain at 35 °C. A promising xylitol yield of 0.96 g/g xylose with no addition of glucose required during the fermentation process, which suggests an extensive potential improvement for the economics of lignocellulosic xylitol production.

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Bedő, Soma, Anikó Fehér, Panwana Khunnonkwao, Kaemwich Jantama y Csaba Fehér. "Optimized Bioconversion of Xylose Derived from Pre-Treated Crop Residues into Xylitol by Using Candida boidinii". Agronomy 11, n.º 1 (1 de enero de 2021): 79. http://dx.doi.org/10.3390/agronomy11010079.

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Crop residues can serve as low-cost feedstocks for microbial production of xylitol, which offers many advantages over the commonly used chemical process. However, enhancing the efficiency of xylitol fermentation is still a barrier to industrial implementation. In this study, the effects of oxygen transfer rate (OTR) (1.1, 2.1, 3.1 mmol O2/(L × h)) and initial xylose concentration (30, 55, 80 g/L) on xylitol production of Candida boidinii NCAIM Y.01308 on xylose medium were investigated and optimised by response surface methodology, and xylitol fermentations were performed on xylose-rich hydrolysates of wheat bran and rice straw. High values of maximum xylitol yields (58–63%) were achieved at low initial xylose concentration (20–30 g/L) and OTR values (1.1–1.5 mmol O2/(L × h)). The highest value for maximum xylitol productivity (0.96 g/(L × h)) was predicted at 71 g/L initial xylose and 2.7 mmol O2/(L × h) OTR. Maximum xylitol yield and productivity obtained on wheat bran hydrolysate were 60% and 0.58 g/(L × h), respectively. On detoxified and supplemented hydrolysate of rice straw, maximum xylitol yield and productivity of 30% and 0.19 g/(L × h) were achieved. This study revealed the terms affecting the xylitol production by C. boidinii and provided validated models to predict the achievable xylitol yields and productivities under different conditions. Efficient pre-treatments for xylose-rich hydrolysates from rice straw and wheat bran were selected. Fermentation using wheat bran hydrolysate and C. boidinii under optimized condition is proved as a promising method for biotechnological xylitol production.

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Mardawati, Efri, Andi Trirakhmadi, MTAP Kresnowati y Tjandra Setiadi. "Kinetic study on Fermentation of xylose for The Xylitol Production". Journal of Industrial and Information Technology in Agriculture 1, n.º 1 (13 de agosto de 2017): 1. http://dx.doi.org/10.24198/jiita.v1i1.12214.

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Xylitol is a natural sugar that has the sweetness level similar to sucrose, but has lower calorie. It is an important sugar alternate for diabetics people. Reduction of xylose is a normally method to produce the xylitol. It Conducted via chemical hydrogenation of xylose at high pressures and temperatures by reacting pure xylose with hydrogen gas using a metal catalyst. This process requires pure xylose as the raw material. Alternatively, the reduction process can be carried out via fermentation. This process does not require high purity of xylose as the raw material, and thus the oil palm empty fruit bunch (EFB) hydrolysate, without any prior pretreatment, can be used. In order to scale up the xylitol production via fermentation, kinetic study of xylitol fermentation including growth and xylitol formation kinetic using the synthetic xylose as substrate will be required. Data used in the kinetic model development were obtained from series of batch fermentations of Debaryomycess hansenii ITB CCR85 varying the initial xylose and glucose concentrations. Yeast growth could be sufficiently modeled using the Monod kinetics, whereas xylitol production could be reasonably well modelled by Luedeking Piret kinetics.

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Muhamad Fuzi, Siti Fatimah Zaharah, Farhana Adilah Zahari, Ong Hong Puay, Low Kheng Oon y Iskandar Abdullah. "Screening Effect of Amino Acid on Xylitol Production By Recombinant Escherichia coli System". Journal of Bioprocessing and Biomass Technology 2, n.º 1 (29 de junio de 2023): 43–47. http://dx.doi.org/10.11113/bioprocessing.v2n1.23.

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Numerical studies have been conducted to sources for safer biological methods to produce xylitol. In view of these concerns and the benefits of xylitol, a fermentation process that is formulated to yield highest xylitol is both favourable and profitable. In this study, recovery of xylitol production from xylose by recombinant Escherichia coli system was conducted by modulating both carbon source and amino acid composition of the media for the relative growth delay of the strain. The key enzyme for xylitol production in this recombinant system is xylose reductase, XR which utilize NADPH to reduce D-xylose to xylitol. By adding 20 types of amino acids individually and substituting glycerol as the carbon source each time, showed an increase of xylitol to 5.24 g/L and yield biomass production to 1.536. It is hypothesize that supply of single amino acid act as a tool to enhance (NAD(P)H)/(NADP+) ratio. Reduced NAD(P)H competition from other bioprocesses help the cell replenishes the reduced cofactor pool. Xylitol has a remarkable benefits as a healthy replacement of table sugar. Therefore, the success of this study will definitely bring forward advance in the production technology and act as a reference for future research.

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Silva, S. S., A. Quesada-Chanto y M. Vitolo. "Upstream Parameters Affecting the Cell Growth and Xylitol Production by Candida guilliermondii FTI 20037". Zeitschrift für Naturforschung C 52, n.º 5-6 (1 de junio de 1997): 359–63. http://dx.doi.org/10.1515/znc-1997-5-614.

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Abstract The effects of yeast extract (0-10g/l), methanol (0-10%v/v), acetic acid (0-1.0g/l), furfural (0-0.5g/l), glucose (0-30g/l), inoculum age (15-70h) and product concentration (18-230g/l) on the xylose-xylitol conversion by Candida guilliermondii FTI 20037 were studied. The xylitol specific productivity increased about 35% at a yeast extract concentration of 1.0g/l, whereas glucose showed a strong inhibitory effect on the xylitol production and a stimulating effect on the growth of C. guilliermondii. Methanol, acetic acid and furfural under the employed concentrations did not show any positive effect neither on the growth or on the xylose-xylitol conversion by the yeast. The inoculum age showed a strong influence on xylitol formation and the best fermentative parameters were attained using a 40-h inoculum age. A xylitol concentration in the fermentation medium higher than 80g/l inhibited markedly the xylitol productivity by the yeast C. guilliermondii.

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Khudhair, Raed S. y Elham I. Tami. "Xylitol Production from Agricultural Wastes by Candida tropicalis". Basrah Journal of Agricultural Sciences 32 (22 de noviembre de 2019): 1–6. http://dx.doi.org/10.37077/25200860.2019.251.

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Xylan produced various agricultural residues including wheat (Furat, Abugraib and Abaa), Papyrus and Sunflower stalks in different ways, including the use of diluted acid, dilute base and self-degradation. The results showed that the acidic method in the production of xylan from various agricultural residues compared with other methods was superior, the highest quantity of xylan 187.6 µg.ml-1 was obtained from the agricultural waste of Papyrus, while it was 157.6, 157.6, 161.6 and 161.3 µg.ml-1 of wheat category of furat, wheat Abu Ghraib, wheat Abaa and sunflower stalks respectively, based on the results obtained, the xylan produced by the acidic method of the different agricultural residues was selected to determine the optimal carboon source for production of xylanase using bacteria Bacillus subtilis strain RS1 locally isolated. After the production of xylitol, the descriptive diagnosis was performed using an HPLC device, depending on the time of the 38.4 minute time lapse reaction of the standard Xylitol and compared with the time of the production of Candida tropicalis, the amount of the processed xylitol was 8.3 µg.ml-1, the calculated xylitol was compared standard xylitol

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25

Sokolov, Filipp S., Konstantin G. Gurevich, Natella I. Kriheli, Andrey V. Zaborovskiy y Viktor M. Glinenko. "Xylitol: production, metabolism and safety of use (literature review)". Hygiene and sanitation 102, n.º 1 (15 de febrero de 2023): 77–81. http://dx.doi.org/10.47470/0016-9900-2023-102-1-77-81.

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The review article provides information on a common sweetener - xylitol, ranging from methods of production and purification, to metabolism in the body and practical applications in medicine and other industries. Considering some prejudice with which xylitol is treated in the Russian Federation, safety of use and low prevalence, it was decided to consider the relevance of use in medicine and related industries, affecting the effectiveness of use as one of the preventive measures in diseases of dental caries. Literature search: according to the Scopus, CyberLeninka, PubMed databases, selective, analytical-synthetic, typological. Xylitol is a polyhydric sugar alcohol; it is found in small amounts in fruits and vegetables. For industrial production, xylitol can be obtained by chemical and biotechnological methods. Chemical production is financially costly mainly due to the complex product purification process. In biotechnological production, agricultural and vegetable raw materials are used as raw materials, which makes it possible to reduce the cost of production and its energy intensity. The safety of xylitol has been well studied by the international community since the late 70s and it is included in various WHO recommendations, numerous studies confirm the safety of use during the metabolic processes of the body. Conclusion. Xylitol is used in at least three industries, namely in food (dietary, confectionery, chewing gum), pharmaceutical (xylitol properties are relevant in the production of nasal sprays, syrups, in combination with other medicines) and in dentistry due to its anti-caries effect, suppression growth of pathogenic microflora of the oral cavity and participation in the remineralization of hard tissues of the tooth. In addition, it is actively used among diabetics.

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Carneiro, de Paula e Silva y Almeida. "Xylitol Production: Identification and Comparison of New Producing Yeasts". Microorganisms 7, n.º 11 (23 de octubre de 2019): 484. http://dx.doi.org/10.3390/microorganisms7110484.

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Xylitol is a sugar alcohol with five carbons that can be used in the pharmaceutical and food industries. It is industrially produced by chemical route; however, a more economical and environmentally friendly production process is of interest. In this context, this study aimed to select wild yeasts able to produce xylitol and compare their performance in sugarcane bagasse hydrolysate. For this, 960 yeast strains, isolated from soil, wood, and insects have been prospected and selected for the ability to grow on defined medium containing xylose as the sole carbon source. A total of 42 yeasts was selected and their profile of sugar consumption and metabolite production were analyzed in microscale fermentation. The six best xylose-consuming strains were molecularly identified as Meyerozyma spp. The fermentative kinetics comparisons on defined medium and on sugarcane bagasse hydrolysate showed physiological differences among these strains. Production yields vary from YP/S = 0.25 g/g to YP/S = 0.34 g/g in defined medium and from YP/S = 0.41 g/g to YP/S = 0.60 g/g in the hydrolysate. Then, the xylitol production performance of the best xylose-consuming strain obtained in the screening, which was named M. guilliermondii B12, was compared with the previously reported xylitol producing yeasts M. guilliermondii A3, Spathaspora sp. JA1, and Wickerhamomyces anomalus 740 in sugarcane bagasse hydrolysate under oxygen-limited conditions. All the yeasts were able to metabolize xylose, but W. anomalus 740 showed the highest xylitol production yield, reaching a maximum of 0.83 g xylitol/g of xylose in hydrolysate. The screening strategy allowed identification of a new M. guilliermondii strain that efficiently grows in xylose even in hydrolysate with a high content of acetic acid (~6 g/L). In addition, this study reports, for the first time, a high-efficient xylitol producing strain of W. anomalus, which achieved, to the best of our knowledge, one of the highest xylitol production yields in hydrolysate reported in the literature.

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Rudrangi, Samatha S. R. y Thomas P. West. "Effect of pH on xylitol production by Candida species from a prairie cordgrass hydrolysate". Zeitschrift für Naturforschung C 75, n.º 11-12 (26 de noviembre de 2020): 489–93. http://dx.doi.org/10.1515/znc-2020-0140.

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AbstractUsing hydrolysates of the North American prairie grass prairie cordgrass buffered at pH 4.5, 5.0, 5.5 or 6.0, xylitol production, xylitol yield, cell biomass production and productivity were investigated for three strains of yeast Candida. Of the three strains, the highest xylitol concentration of 20.19 g xylitol (g xylose consumed)−1 and yield of 0.89 g xylitol (g xylose consumed)−1 were produced by Candida mogi ATCC 18364 when grown for 120 h at 30° C on the pH 5.5-buffered hydrolysate-containing medium. The highest biomass level being 7.7 g cells (kg biomass)−1 was observed to be synthesized by Candida guilliermondii ATCC 201935 after 120 h of growth at 30° C on a pH 5.5-buffered hydrolysate-containing medium. The highest xylitol specific productivity of 0.73 g xylitol (g cells h)−1 was determined for C. guilliermondii ATCC 20216 after 120 h of growth at 30°C on a pH 5.0-buffered hydrolysate-containing medium. Xylitol production and yield by the three Candida strains was higher on prairie cordgrass than what was previously observed for the same strains after 120 h at 30° C when another North American prairie grass big bluestem served as the plant biomass hydrolysate indicating that prairie cordgrass may be a superior plant biomass substrate.

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Wei, Na, Haiqing Xu, Soo Rin Kim y Yong-Su Jin. "Deletion ofFPS1, Encoding Aquaglyceroporin Fps1p, Improves Xylose Fermentation by Engineered Saccharomyces cerevisiae". Applied and Environmental Microbiology 79, n.º 10 (8 de marzo de 2013): 3193–201. http://dx.doi.org/10.1128/aem.00490-13.

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ABSTRACTAccumulation of xylitol in xylose fermentation with engineeredSaccharomyces cerevisiaepresents a major problem that hampers economically feasible production of biofuels from cellulosic plant biomass. In particular, substantial production of xylitol due to unbalanced redox cofactor usage by xylose reductase (XR) and xylitol dehydrogenase (XDH) leads to low yields of ethanol. While previous research focused on manipulating intracellular enzymatic reactions to improve xylose metabolism, this study demonstrated a new strategy to reduce xylitol formation and increase carbon flux toward target products by controlling the process of xylitol secretion. Using xylitol-producingS. cerevisiaestrains expressing XR only, we determined the role of aquaglyceroporin Fps1p in xylitol export by characterizing extracellular and intracellular xylitol. In addition, whenFPS1was deleted in a poorly xylose-fermenting strain with unbalanced XR and XDH activities, the xylitol yield was decreased by 71% and the ethanol yield was substantially increased by nearly four times. Experiments with our optimized xylose-fermenting strain also showed thatFPS1deletion reduced xylitol production by 21% to 30% and increased ethanol yields by 3% to 10% under various fermentation conditions. Deletion ofFPS1decreased the xylose consumption rate under anaerobic conditions, but the effect was not significant in fermentation at high cell density. Deletion ofFPS1resulted in higher intracellular xylitol concentrations but did not significantly change the intracellular NAD+/NADH ratio in xylose-fermenting strains. The results demonstrate that Fps1p is involved in xylitol export inS. cerevisiaeand present a new gene deletion target,FPS1, and a mechanism different from those previously reported to engineer yeast for improved xylose fermentation.

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Ko, Byoung Sam, Jinmi Kim y Jung Hoe Kim. "Production of Xylitol from d-Xylose by a Xylitol Dehydrogenase Gene-Disrupted Mutant of Candida tropicalis". Applied and Environmental Microbiology 72, n.º 6 (junio de 2006): 4207–13. http://dx.doi.org/10.1128/aem.02699-05.

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ABSTRACT Xylitol dehydrogenase (XDH) is one of the key enzymes in d-xylose metabolism, catalyzing the oxidation of xylitol to d-xylulose. Two copies of the XYL2 gene encoding XDH in the diploid yeast Candida tropicalis were sequentially disrupted using the Ura-blasting method. The XYL2-disrupted mutant, BSXDH-3, did not grow on a minimal medium containing d-xylose as a sole carbon source. An enzyme assay experiment indicated that BSXDH-3 lost apparently all XDH activity. Xylitol production by BSXDH-3 was evaluated using a xylitol fermentation medium with glucose as a cosubstrate. As glucose was found to be an insufficient cosubstrate, various carbon sources were screened for efficient cofactor regeneration, and glycerol was found to be the best cosubstrate. BSXDH-3 produced xylitol with a volumetric productivity of 3.23 g liter−1 h−1, a specific productivity of 0.76 g g−1 h−1, and a xylitol yield of 98%. This is the first report of gene disruption of C. tropicalis for enhancing the efficiency of xylitol production.

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30

Hidayah, N., RS Adiandri y E. Rahayu. "Microbial xylitol production from corn cob using Candida guilliermondii". IOP Conference Series: Earth and Environmental Science 1024, n.º 1 (1 de mayo de 2022): 012077. http://dx.doi.org/10.1088/1755-1315/1024/1/012077.

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Abstract Xylitol is a polyol that is widely used in the food industries as an alternative sweetener due to some health benefits. The microbial production of xylitol based on corn cobs was potential to be developed due to the abundant availability of corn cobs in Indonesia. In addition, it is an alternative process that is a higher yield and environmentally friendly. This study was conducted to assign the optimum process in the xylitol production based on corn cobs using Candida guilliermondii. The hydrolysis of corn cobs used sulfuric acid 1% at a temperature of 121°C for 60 minutes. The hydrolysate was then added with calcium hydroxide and activated charcoal to remove inhibitors. The design of experimental used was a factorial completely randomized design with three factors included corn cobs hydrolysate concentration (50% and 66%), glucose (0 g l-1 and 5 g l-1), and incubation period (120 h and 168 h). The result showed that concentration of hydrolysate, glucose, and incubation period had an effect on the xylitol produced. The highest xylitol was 144.09 ppm that was produced by the hydrolysate of 66%, glucose of 5 g l-1 and incubation period of 168 h, meanwhile the residual xylose was 2081.87 ppm.

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Ahuja, Vishal, Markéta Macho, Daniela Ewe, Manoj Singh, Subhasish Saha y Kumar Saurav. "Biological and Pharmacological Potential of Xylitol: A Molecular Insight of Unique Metabolism". Foods 9, n.º 11 (2 de noviembre de 2020): 1592. http://dx.doi.org/10.3390/foods9111592.

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Xylitol is a white crystalline, amorphous sugar alcohol and low-calorie sweetener. Xylitol prevents demineralization of teeth and bones, otitis media infection, respiratory tract infections, inflammation and cancer progression. NADPH generated in xylitol metabolism aid in the treatment of glucose-6-phosphate deficiency-associated hemolytic anemia. Moreover, it has a negligible effect on blood glucose and plasma insulin levels due to its unique metabolism. Its diverse applications in pharmaceuticals, cosmetics, food and polymer industries fueled its market growth and made it one of the top 12 bio-products. Recently, xylitol has also been used as a drug carrier due to its high permeability and non-toxic nature. However, it become a challenge to fulfil the rapidly increasing market demand of xylitol. Xylitol is present in fruit and vegetables, but at very low concentrations, which is not adequate to satisfy the consumer demand. With the passage of time, other methods including chemical catalysis, microbial and enzymatic biotransformation, have also been developed for its large-scale production. Nevertheless, large scale production still suffers from high cost of production. In this review, we summarize some alternative approaches and recent advancements that significantly improve the yield and lower the cost of production.

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Yulianto, Wisnu Adi, Kapti Rahayu Kuswanto, Tranggono Tranggono y Retno Indrati. "Pengaruh Konsentrasi Xilosa dan Kosubstrat Terhadap Produksi Xilitol oleh Candida shehatae Way 08". agriTECH 25, n.º 3 (23 de febrero de 2017): 143. http://dx.doi.org/10.22146/agritech.13352.

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The objectives of the research were to determine the optimum cultivation condition of initial xylose concentration, type of cosubstrate and ratio of cosubstrate to substrate (xylose) for xylitol production by Candida shehatae WAY 08. The initial xylose concentrations were varied within the range of 2-14 %. The cosubstrates were arabinose, galactose, glucose, and mannose. Ratios of cosubstrate to xylose were the range of 1:6 - 3:6 %. The fermentation was performed at 30`C in a 500 ml Erlenmeyer flask placed in a shaker incubator at 200 rpm for 72 h. Biomass concentration was determined by drying method. Xylose, cosubstrate and xylitol concentrations were determined using HPLC. The result indicated that with the medium containing 6 % xylose produced the highest product yield ( 0,75 g/g) and xylitol volumetric productivity was 0,73 g/Lh. The addition of cosubstrate of arabinose increased xylitol production, while the addition of glucose, galactose, and mannose decreased its productions.

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Carvalho, Filipa, Francisca Duarte, Laura Pedreiras, Vanessa Posada y Margarida Brito. "Xylitol". U.Porto Journal of Engineering 8, n.º 5 (27 de septiembre de 2022): 158–74. http://dx.doi.org/10.24840/2183-6493_008.005_0014.

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The main purpose of this project was the eco-valorisation of the tomato plant residues. The chemical product design method was used to select the best idea based on 4 steps: needs, ideas, selection, and manufacturing.Liquid xylitol is here proposed for the valorisation of tomato plant residues, which is an alternative sweetener with a lower glycemic index that can be produced from the hemicellulose found in leaves and stems. Its production would require an alkaline extraction with sodium hydroxide, enzymatic hydrolyses using endo-1,4-β-xylanase, and yeast fermentation with Candida tropicalis.Liquid sweetener with 72% xylitol and other components (D-glucose, D-mannose, D-galactose, L-arabinose, and lignin), commercialised as NITS - Natural Incredible Tomato Sweetener, could be sold for 2.25 €·L-1 for companies and the same price per bottle of 500 mL for individual consumption.

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Lim, Kean Long, Wai Yin Wong, Nowilin James Rubinsin, Soh Kheang Loh y Mook Tzeng Lim. "Techno-Economic Analysis of an Integrated Bio-Refinery for the Production of Biofuels and Value-Added Chemicals from Oil Palm Empty Fruit Bunches". Processes 10, n.º 10 (29 de septiembre de 2022): 1965. http://dx.doi.org/10.3390/pr10101965.

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Lignocellulose-rich empty fruit bunches (EFBs) have high potential as feedstock for second-generation biofuel and biochemical production without compromising food security. Nevertheless, the major challenge of valorizing lignocellulose-rich EFB is its high pretreatment cost. In this study, the preliminary techno-economic feasibility of expanding an existing pellet production plant into an integrated bio-refinery plant to produce xylitol and bioethanol was investigated as a strategy to diversify the high production cost and leverage the high selling price of biofuel and biochemicals. The EFB feedstock was split into a pellet production stream and a xylitol and bioethanol production stream. Different economic performance metrics were used to compare the profitability at different splitting ratios of xylitol and bioethanol to pellet production. The analysis showed that an EFB splitting ratio below 40% for pellet production was economically feasible. A sensitivity analysis showed that xylitol price had the most significant impact on the economic performance metrics. Another case study on the coproduction of pellet and xylitol versus that of pellet and bioethanol concluded that cellulosic bioethanol production is yet to be market-ready, requiring a minimum selling price above the current market price to be feasible at 16% of the minimum acceptable return rate.

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Miura, Masahiro, Tomoaki Seo, Yasutaka Shimotori, Masakazu Aoyama, Hisayuki Nakatani y Masatomo Nishikoori. "Microbial xylitol production from culm of Sasa kurilensis using the yeast Candida magnoliae". Holzforschung 67, n.º 8 (1 de diciembre de 2013): 881–85. http://dx.doi.org/10.1515/hf-2013-0040.

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Abstract A sugar solution containing 31 g l-1 xylose was prepared from the culm of Sasa kurilensis by hydrolysis with 2% sulfuric acid with a liquor-to-solid ratio of 6 (g g-1) at 121°C for 1 h. During acid hydrolysis, also some byproducts were generated, such as acetic acid, furfural, 5-hydroxymethylfurfral, and low molecular weight phenolics, which inhibit bioconversion of xylose to xylitol. Except for acetic acid, these inhibitors were successfully removed from the hydrolysate by contacting with a steam-activated charcoal (15 g l-1 dose) for 24 h. Bioconversion of the detoxified hydrolysate to xylitol by the yeast, Candida magnoliae, was investigated under various microaerobic conditions. The oxygen transfer rate (OTR) varied from 8.4 to 27.6 mmol-O2 l-1 h-1. The maximum xylitol yield (0.62 g-xylitol g-xylose-1) was attained at the OTR of 1.2 mmol-O2 l-1 h-1. An additional increase in the OTR brought about cell growth, which consumed xylose. A proper control of the oxygen supply is necessary to produce efficiently xylitol from the culm hydrolysate.

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Araújo, Diana, Tatiana Costa y Filomena Freitas. "Biovalorization of Lignocellulosic Materials for Xylitol Production by the Yeast Komagataella pastoris". Applied Sciences 11, n.º 12 (15 de junio de 2021): 5516. http://dx.doi.org/10.3390/app11125516.

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The main goal of this study was to screen different lignocellulosic materials for their ability to support the cell growth of the yeast Komagataella pastoris and the production of xylitol. Several lignocellulosic materials, namely banana peels, brewer’s spent grains (BSGs), corncobs, grape pomace, grape stalks, and sawdust, were subjected to dilute acid hydrolysis to obtain sugar rich solutions that were tested as feedstocks for the cultivation of K. pastoris. Although the culture was able to grow in all the tested hydrolysates, a higher biomass concentration was obtained for banana peels (15.18 ± 0.33 g/L) and grape stalks (14.58 ± 0.19 g/L), while the highest xylitol production (1.51 ± 0.07 g/L) was reached for the BSG hydrolysate with a xylitol yield of 0.66 ± 0.39 g/g. Cell growth and xylitol production from BSG were improved by detoxifying the hydrolysate using activated charcoal, resulting in a fourfold increase of the biomass production, while xylitol production was improved to 3.97 ± 0.10 g/L. Moreover, concomitant with arabinose consumption, arabitol synthesis was noticed, reaching a maximum concentration of 0.82 ± 0.05 g/L with a yield on arabinose of 0.60 ± 0.11 g/g. These results demonstrate the feasibility of using lignocellulosic waste, especially BSG, as feedstock for the cultivation of K. pastoris and the coproduction of xylitol and arabitol. Additionally, it demonstrates the use of K. pastoris as a suitable microorganism to integrate a zero-waste biorefinery, transforming lignocellulosic waste into two high-value specialty chemicals with high market demand.

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Takahashi, N. y J. Washio. "Metabolomic Effects of Xylitol and Fluoride on Plaque Biofilm in Vivo". Journal of Dental Research 90, n.º 12 (22 de septiembre de 2011): 1463–68. http://dx.doi.org/10.1177/0022034511423395.

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Dental caries is initiated by demineralization of the tooth surface through acid production from sugar by plaque biofilm. Fluoride and xylitol have been used worldwide as caries-preventive reagents, based on in vitro-proven inhibitory mechanisms on bacterial acid production. We attempted to confirm the inhibitory mechanisms of fluoride and xylitol in vivo by performing metabolome analysis on the central carbon metabolism in supragingival plaque using the combination of capillary electrophoresis and a time-of-flight mass spectrometer. Fluoride (225 and 900 ppm F−) inhibited lactate production from 10% glucose by 34% and 46%, respectively, along with the increase in 3-phosphoglycerate and the decrease in phosphoenolpyruvate in the EMP pathway in supragingival plaque. These results confirmed that fluoride inhibited bacterial enolase in the EMP pathway and subsequently repressed acid production in vivo. In contrast, 10% xylitol had no effect on acid production and the metabolome profile in supragingival plaque, although xylitol 5-phosphate was produced. These results suggest that xylitol is not an inhibitor of plaque acid production but rather a non-fermentative sugar alcohol. Metabolome analyses of plaque biofilm can be applied for monitoring the efficacy of dietary components and medicines for plaque biofilm, leading to the development of effective plaque control.

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Golubkov, Viktor Aleksandrovich, Yuliya Nikolaevna Zaitseva, Sergej Dmitrievich Kirik, Anna Olegovna Eremina, Valentin Vladimirovich Sychev y Oksana Pavlovna Taran. "XYLITOL PRODUCTION FROM XYLOSE OVER ZIRCONIA-DOPED SILICA SBA-15 SUPPORTED RUTHENIUM CATALYSTS". chemistry of plant raw material, n.º 4 (15 de diciembre de 2023): 397–405. http://dx.doi.org/10.14258/jcprm.20230414105.

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Xylitol is an important product of xylan valorization — the main hemicellulose of birch and aspen wood. Xylitol is obtained by direct hydrogenation of xylose. In present study, the xylose was obtained by acid hydrolysis of birch wood xylan. The industrial catalyst for the xylitol production process is Raney nickel. Pyrophoricity, tendency to sintering, Ni leaching and contamination of the product are actual problems of its use. We have developed new supported ruthenium catalysts based on mesoporous silicate SBA-15 doped with zirconia. The proposed method of modification of SBA-15 by doping with zirconia improves the hydrothermal stability. The deposited Ru is present in the form of highly dispersed RuO2 particles and is distributed evenly. The catalysts are stable, safe and environmentally friendly. Their high catalytic activity allows the process to be carried out in very mild conditions – in pure water at 70 °C and a pressure of 5.5 MPa H2. While the catalysts provide 96-99% selectivity for xylitol. The introduction of the developed catalysts into the xylitol production might reduce the product purification cost of and the process energy consumption, thereby improving ecological and economic indicators of deep chemical processing of plant raw materials.

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Neirinck, Leonard G., C. S. Tsai, John L. Labelle y Henry Schneider. "Xylitol as a carbon source for growth and ethanol production by Pachysolen tannophilus". Canadian Journal of Microbiology 31, n.º 5 (1 de mayo de 1985): 451–55. http://dx.doi.org/10.1139/m85-084.

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A number of yeasts that produce ethanol from D-xylose also coproduce xylitol. Such coproduction is undesirable if ethanol is the desired product because of the detrimental effect on yield. The utilization of xylitol, thought to be the first catabolite of D-xylose, has been reported not to lead to the formation of appreciable amounts of ethanol. As part of an effort to improve the yield of ethanol, the use of xylitol for growth and ethanol formation by Pachysolen tannophilus under aerobic conditions was reinvestigated. The polyol was found to be used for ethanol formation. However, the conditions required for this process, as well as for growth, were more stringent than with D-xylose. Notably, xylitol supported growth only when its concentration was relatively high, while ethanol formation occurred over a range of concentrations, provided high cell densities were used.

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Mardawati, Efri, Agus T. Hartono, Bambang Nurhadi, Hana Nur Fitriana, Euis Hermiati y Riksfardini Annisa Ermawar. "Xylitol Production from Pineapple Cores (Ananas comosus (L.) Merr) by Enzymatic and Acid Hydrolysis Using Microorganisms Debaryomyces hansenii and Candida tropicalis". Fermentation 8, n.º 12 (30 de noviembre de 2022): 694. http://dx.doi.org/10.3390/fermentation8120694.

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Hydrolysis and fermentation processes are key stages in xylitol production from lignocellulosic materials. In this study, pineapple cores, one of the wastes from the canned pineapple industry, were used as raw material for xylitol production. Two methods was used for hydrolysis: enzymatically using commercial enzyme Cellic HTec2, and acid hydrolysis using 4% H2SO4. In contrast, the fermentation process was carried out with two selected yeasts commonly employed in xylitol fermentation, Debaryomycess hansenii, and Candida tropicalis. Before these two processes, the pineapple cores were characterized using the Van Soest method to determine their lignocellulosic content. The hemicellulose content was 36.06%, the cellulose content was 14.20%, and the lignin content was 10.05%. This result indicates that the hemicellulose content of pineapple cores has the potential to be used as a raw material in the production of xylitol. The hydrolysis efficiency of enzymatic hydrolysis was 21% higher than that of acid hydrolysis. The highest xylitol and biomass yield of 0.371 gxylitol/gxylose and 0.225 gcell/gxylose were observed by C. tropicalis using an enzymatic hydrolysate.

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Aigner, Danuta Joanna, Lena Hinterholzer, Lukas Almhofer, Robert H. Bischof y Tanja Wrodnigg. "Conversion of xylose into D-xylitol using catalytic transfer hydrogenation with formic acid as H-donor". BioResources 18, n.º 4 (31 de octubre de 2023): 8631–52. http://dx.doi.org/10.15376/biores.18.4.8631-8652.

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d-Xylitol, a biomass-derived sweetener, is increasingly used in cosmetics and pharmaceutical products. The raw material for d-xylitol production, d-xylose, is easily accessible from dissolving pulp production. d-xylitol production involves the heterogeneously catalyzed hydrogenation of d-xylose; this process is energy intensive, as the use of H2 requires high pressure and temperature. This work examined catalytic transfer hydrogenation for xylose conversion into xylitol. Formic acid (FA) was used to replace H2 as the H-donor, as it is easily available, inexpensive, may be obtained from renewable sources, and it avoids the risks associated with the use of high-pressure inflammable gas. A variety of commercially available catalysts were screened to reveal the one enabling the highest yield. The experiments were performed at 40, 80, and 140 °C, with pure xylose as a model compound. Triethylamine (Et3N) was added to ensure sufficient conversion rates. Based on the preliminary studies an experimental design was created (Design Expert®), including the two best performing catalysts Ru/Al2O3 and Ru/C, to investigate the influence of temperature and H-donor and base concentration on xylitol yield. Ru/C resulted in maximum d-xylitol yield of 73.2 % at 100 °C, FA to d-xylose ratio 5:1 and Et3N to FA ratio 0.4.

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42

Carvalho, Walter de, Silvio Silvério da Silva, Michele Vitolo y Ismael Maciel de Mancilha. "Use of Immobilized Candida Cells on Xylitol Production from Sugarcane Bagasse". Zeitschrift für Naturforschung C 55, n.º 3-4 (1 de abril de 2000): 213–17. http://dx.doi.org/10.1515/znc-2000-3-412.

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Abstract In this study we used the yeast Candida guilliermondii FTI 20037 immobilized by entrapment in Ca-alginate beads (2 .5 -3 mm diameter) for xylitol production from concentrated sugarcane bagasse hemicellulosic hydrolysate in a repeated batch system. The fermentation runs were carried out in 125- and 250-ml Erlenmeyer flasks placed in an orbital shaker at 30 °C and 200 rpm during 72 h, keeping constant the proportion between work volume and flask total volume. According to the results, cell viability was substantially high (98%) in all fermentative cycles. The values of parameters xylitol yield and volumetric productivity increased significantly with the reutilization of the immobilized biocatalysts. The highest values of xylitol final concentration (11.05 g/1), yield factor (0.47 gig) and volumetric productivity (0.22 g/lh) were obtained in 250-ml Erlenmeyer flasks containing 80 ml of medium plus 20 mi of immobilized biocatalysts. The support used in this study (Ca-alginate) presented stability in the experimental conditions used. The results show that the use of immobilized cells is a promising approach for increasing the xylitol production rates.

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43

Deng, Li-Hong, Yong Tang y Yun Liu. "Detoxification of Corncob Acid Hydrolysate with SAA Pretreatment and Xylitol Production by ImmobilizedCandida tropicalis". Scientific World Journal 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/214632.

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Xylitol fermentation production from corncob acid hydrolysate has become an attractive and promising process. However, corncob acid hydrolysate cannot be directly used as fermentation substrate owing to various inhibitors. In this work, soaking in aqueous ammonia (SAA) pretreatment was employed to reduce the inhibitors in acid hydrolysate. After detoxification, the corncob acid hydrolysate was fermented by immobilizedCandida tropicaliscell to produce xylitol. Results revealed that SAA pretreatment showed high delignification and efficient removal of acetyl group compounds without effect on cellulose and xylan content. Acetic acid was completely removed, and the content of phenolic compounds was reduced by 80%. Furthermore, kinetic behaviors of xylitol production by immobilizedC. tropicaliscell were elucidated from corncob acid hydrolysate detoxified with SAA pretreatment and two-step adsorption method, respectively. The immobilizedC. tropicaliscell showed higher productivity efficiency using the corncob acid hydrolysate as fermentation substrate after detoxification with SAA pretreatment than by two-step adsorption method in the five successive batch fermentation rounds. After the fifth round fermentation, about 60 g xylitol/L fermentation substrate was obtained for SAA pretreatment detoxification, while about 30 g xylitol/L fermentation substrate was obtained for two-step adsorption detoxification.

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44

Barathikannan, Kaliyan y Paul Agastian. "Xylitol: Production, Optimization and Industrial Application". International Journal of Current Microbiology and Applied Sciences 5, n.º 9 (10 de septiembre de 2016): 324–39. http://dx.doi.org/10.20546/ijcmas.2016.509.036.

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45

Pourmir, Azadeh, Samaneh Noor-Mohammadi y Tyler W. Johannes. "Production of xylitol by recombinant microalgae". Journal of Biotechnology 165, n.º 3-4 (junio de 2013): 178–83. http://dx.doi.org/10.1016/j.jbiotec.2013.04.002.

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46

Saha, B. C. y R. J. Bothast. "Production of xylitol by Candida peltata". Journal of Industrial Microbiology and Biotechnology 22, n.º 6 (1 de junio de 1999): 633–36. http://dx.doi.org/10.1038/sj.jim.2900674.

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47

Hallborn, Johan, Mats Walfridsson, Ulla Airaksinen, Heikki Ojamo, Bärbel Hahn-Hägerdal, Merja Penttilä y Sirkka Keränen. "Xylitol Production by Recombinant Saccharomyces Cerevisiae". Bio/Technology 9, n.º 11 (noviembre de 1991): 1090–95. http://dx.doi.org/10.1038/nbt1191-1090.

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48

Uittamo, Johanna, Mikko T. Nieminen, Pertti Kaihovaara, Paul Bowyer, Mikko Salaspuro y Riina Rautemaa. "Xylitol inhibits carcinogenic acetaldehyde production byCandidaspecies". International Journal of Cancer 129, n.º 8 (1 de abril de 2011): 2038–41. http://dx.doi.org/10.1002/ijc.25844.

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49

Carvalho, W., J. C. Santos, L. Canilha, S. S. Silva, P. Perego y A. Converti. "Xylitol production from sugarcane bagasse hydrolysate". Biochemical Engineering Journal 25, n.º 1 (agosto de 2005): 25–31. http://dx.doi.org/10.1016/j.bej.2005.03.006.

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50

Mussatto, Solange Inês y Inês Conceição Roberto. "Evaluation of nutrient supplementation to charcoal-treated and untreated rice straw hydrolysate for xylitol production by Candida guilliermondii". Brazilian Archives of Biology and Technology 48, n.º 3 (mayo de 2005): 497–502. http://dx.doi.org/10.1590/s1516-89132005000300020.

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Xylitol was produced by Candida guilliermondii from charcoal-treated and untreated rice straw hemicellulosic hydrolysate with or without nutrients (ammonium sulphate, calcium chloride, rice bran extract). Both, xylitol yield and volumetric productivity decreased significantly when the nutrients were added to treated and untreated hydrolysates. In the treated hydrolysate, the efficiency of xylose conversion to xylitol was 79% when the nutrients were omitted. The results demonstrated that rice straw hemicellulosic hydrolysate treated with activated charcoal was a cheap source of xylose and other nutrients for xylitol production by C. guilliermondii. The non-necessity of adding nutrients to the hydrolysate media would be very advantageous since the process becomes less costly.

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