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1.
Chinese Journal of Biotechnology ; (12): 1042-1057, 2021.
Article in Chinese | WPRIM | ID: wpr-878613

ABSTRACT

Effective utilization of xylose is a basis for economic production of biofuels or chemicals from lignocellulose biomass. Over the past 30 years, through metabolic engineering, evolutionary engineering and other strategies, the metabolic capacity of xylose of the traditional ethanol-producing microorganism Saccharomyces cerevisiae has been significantly improved. In recent years, the reported results showed that the transcriptome and metabolome profiles between xylose and glucose metabolism existed significant difference in recombinant yeast strains. Compared with glucose, the overall process of xylose metabolism exhibits Crabtree-negative characteristics, including the limited glycolytic pathway activity, which reduces the metabolic flux of pyruvate to ethanol, and the enhanced cytosolic acetyl-CoA synthesis and respiratory energy metabolism. These traits are helpful to achieve efficient synthesis of downstream products using pyruvate or acetyl-CoA as precursors. This review provides a detailed overview on the modification and optimization of xylose metabolic pathways in S. cerevisiae, the characteristics of xylose metabolism, and the construction of cell factories for production of chemicals using xylose as a carbon source. Meanwhile, the existed difficulties and challenges, and future studies on biosynthesis of bulk chemicals using xylose as an important carbon source are proposed.


Subject(s)
Biofuels , Ethanol , Fermentation , Metabolic Engineering , Saccharomyces cerevisiae/genetics , Xylose
2.
Chinese Journal of Biotechnology ; (12): 580-592, 2021.
Article in Chinese | WPRIM | ID: wpr-878583

ABSTRACT

A novel β-glucosidase BglD2 with glucose and ethanol tolerant properties was screened and cloned from the deep-sea bacterium Bacillus sp. D1. The application potential of BglD2 toward polydatin-hydrolyzing was also evaluated. BglD2 exhibited the maximal β-glucosidase activity at 45 °C and pH 6.5. BglD2 maintained approximately 50% of its origin activity after incubation at 30 °C and pH 6.5 for 20 h. BglD2 could hydrolyze a variety of substrates containing β (1→3), β (1→4), and β (1→6) bonds. The activity of β-glucosidase was enhanced to 2.0 fold and 2.3 fold by 100 mmol/L glucose and 150 mmol/L xylose, respectively. BglD2 possessed ethanol-stimulated and -tolerant properties. At 30 °C, the activity of BglD2 enhanced to 1.2 fold in the presence of 10% ethanol and even remained 60% in 25% ethanol. BglD2 could hydrolyze polydatin to produce resveratrol. At 35 °C, BglD2 hydrolyzed 86% polydatin after incubation for 2 h. Thus, BglD2 possessed glucose and ethanol tolerant properties and can be used as the potential candidate of catalyst for the production of resveratrol from polydatin.


Subject(s)
Enzyme Stability , Glucose , Glucosides/pharmacology , Hydrogen-Ion Concentration , Stilbenes/pharmacology , Substrate Specificity , Temperature , Xylose , beta-Glucosidase/genetics
3.
Chinese Journal of Biotechnology ; (12): 196-206, 2021.
Article in Chinese | WPRIM | ID: wpr-878554

ABSTRACT

Polyhydroxyalkanoates (PHAs) have obtained much attention in biomaterial fields due to their similar physicochemical properties to those of the petroleum-derived plastics. Poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)] is one member of the PHAs family, and has better toughness and transparency compared to existing polylactic acid (PLA) and poly[(R)-3-hydroxybutyrate] [P(3HB)]. First, we confirmed the one-step biosynthesis of P(LA-co-3HB) with the lactate fraction of 23.8 mol% by introducing P(3HB-co-LA) production module into Escherichia coli MG1655. Then, the lactate fraction was increased to 37.2 mol% in the dld deficient strain WXJ01-03. The genes encoding the thioesterases, ydiI and yciA, were further knocked out, and the lactate fraction in the P(3HB-co-LA) was improved to 42.3 mol% and 41.1 mol% respectively. Strain WXJ03-03 with dld, ydiI and yciA deficient was used for the production of the LA-enriched polymer, and the lactate fraction was improved to 46.1 mol%. Notably, the lactate fraction in P(3HB-co-LA) from xylose was remarkably higher than from glucose, indicating xylose as a potent carbon source for P(3HB-co-LA) production. Therefore, the deficiency of thioesterase may be considered as an effective strategy to improve the lactate fraction in P(3HB-co-LA) in xylose fermentation.


Subject(s)
Escherichia coli/genetics , Hydroxybutyrates , Lactic Acid , Polyesters , Polyhydroxyalkanoates , Xylose
4.
Electron. j. biotechnol ; 44: 60-68, Mar. 2020. tab, graf, ilus
Article in English | LILACS | ID: biblio-1087705

ABSTRACT

Background: Oleaginous yeasts can be grown on different carbon sources, including lignocellulosic hydrolysate containing a mixture of glucose and xylose. However, not all yeast strains can utilize both the sugars for lipogenesis. Therefore, in this study, efforts were made to isolate dual sugar-utilizing oleaginous yeasts from different sources. Results: A total of eleven isolates were obtained, which were screened for their ability to utilize various carbohydrates for lipogenesis. One promising yeast isolate Trichosporon mycotoxinivorans S2 was selected based on its capability to use a mixture of glucose and xylose and produce 44.86 ± 4.03% lipids, as well as its tolerance to fermentation inhibitors. In order to identify an inexpensive source of sugars, nondetoxified paddy straw hydrolysate (saccharified with cellulase), supplemented with 0.05% yeast extract, 0.18% peptone, and 0.04% MgSO4 was used for growth of the yeast, resulting in a yield of 5.17 g L−1 lipids with conversion productivity of 0.06 g L−1 h−1 . Optimization of the levels of yeast extract, peptone, and MgSO4 for maximizing lipid production using Box­Behnken design led to an increase in lipid yield by 41.59%. FAME analysis of single cell oil revealed oleic acid (30.84%), palmitic acid (18.28%), and stearic acid (17.64%) as the major fatty acids. Conclusion: The fatty acid profile illustrates the potential of T. mycotoxinivorans S2 to produce single cell oil as a feedstock for biodiesel. Therefore, the present study also indicated the potential of selected yeast to develop a zero-waste process for the complete valorization of paddy straw hydrolysate without detoxification


Subject(s)
Trichosporon/metabolism , Oryza , Xylose/isolation & purification , Trichosporon/chemistry , Oils/chemistry , Lipogenesis , Biofuels , Fermentation , Glucose/isolation & purification , Hydrolysis , Lignin/metabolism , Lipids/biosynthesis
5.
Chinese Journal of Biotechnology ; (12): 942-948, 2020.
Article in Chinese | WPRIM | ID: wpr-826882

ABSTRACT

It is of great significance to use biosynthesis to transform the inorganic substance formaldehyde into organic sugars. Most important in this process was to find a suitable catalyst combination to achieve the dimerization of formaldehyde. In a recent report, an engineered glycolaldehyde synthase was reported to catalyze this reaction. It could be combined with engineered D-fructose-6-phosphate aldolase, a "one-pot enzyme" method, to synthesize L-xylose using formaldehyde and the conversion rate could reach up to 64%. This process also provides a reference for the synthesis of other sugars. With the increasing consumption of non-renewable resources, it was of great significance to convert formaldehyde into sugar by biosynthesis.


Subject(s)
Biocatalysis , Formaldehyde , Chemistry , Fructose-Bisphosphate Aldolase , Metabolism , Xylose
6.
Braz. arch. biol. technol ; 62: e19180728, 2019. tab, graf
Article in English | LILACS | ID: biblio-1055382

ABSTRACT

Abstract The biological assimilation of the sugars present in lignocellulosic residues has gained prominence since these residues are the most abundant and economic residues in nature. Thus, the objective of this work was to determine whether the use of D-xylose and L-arabinose as sources of carbon in Synechococcus nidulans and Spirulina paracas cultures affects the growth and production of proteins and carbohydrates. Kinetic growth parameters, pentose consumption, protein content and carbohydrates were evaluated. Synechococcus nidulans and Spirulina paracas consumed all concentrations of pentose used. The highest cellular concentration (1.37 g.L-1) and the highest protein productivity (54 mg.L-1.d-1) were obtained for Spirulina paracas, which was submitted to the addition of 38.33 mg.L-1 D-xylose and 1.79 mg.L-1 L-arabinose. The use of pentose promoted the accumulation of proteins for the studied microalgae. This is one of the first works to report protein bioaccumulation as a result of pentose addition.


Subject(s)
Arabinose/administration & dosage , Xylose/administration & dosage , Carbohydrates , Proteins/drug effects , Synechococcus
7.
Article in English | WPRIM | ID: wpr-760609

ABSTRACT

BACKGROUND/OBJECTIVES: Myocardial infarction (MI) is caused by extensive myocardial damage attributed to the occlusion of coronary arteries. Our previous study in a rat model of ischemia/reperfusion (I/R) demonstrated that administration of arabinoxylan (AX), comprising arabinose and xylose, protects against myocardial injury. In this study, we undertook to investigate whether psyllium seed husk (PSH), a safe dietary fiber containing a high level of AX (> 50%), also imparts protection against myocardial injury in the same rat model. MATERIALS/METHODS: Rats were fed diets supplemented with PSH (1, 10, or 100 mg/kg/d) for 3 d. The rats were then subjected to 30 min ischemia through ligation of the left anterior descending coronary artery, followed by 3 h reperfusion through release of the ligation. The hearts were harvested and cut into four slices. To assess infarct size (IS), an index representing heart damage, the slices were stained with 2,3,5-triphenyltetrazolium chloride (TTC). To elucidate underlying mechanisms, Western blotting was performed for the slices. RESULTS: Supplementation with 10 or 100 mg/kg/d of PSH significantly reduces the IS. PSH supplementation (100 mg/kg/d) tends to reduce caspase-3 generation and increase BCL-2/BAX ratio. PSH supplementation also upregulates the expression of nuclear factor erythroid 2-related factor 2 (NRF2), and its target genes including antioxidant enzymes such as glutathione S-transferase mu 2 (GSTM2) and superoxide dismutase 2 (SOD2). PSH supplementation upregulates some sirtuins (NAD+-dependent deacetylases) including SIRT5 (a mitochondrial sirtuin) and SIRT6 and SIRT7 (nuclear sirtuins). Finally, PSH supplementation upregulates the expression of protein kinase A (PKA), and increases phosphorylated cAMP response element-binding protein (CREB) (pCREB), a target protein of PKA. CONCLUSIONS: The results from this study indicate that PSH consumption reduces myocardial I/R injury in rats by inhibiting the apoptotic cascades through modulation of gene expression of several genes located upstream of apoptosis. Therefore, we believe that PSH can be developed as a functional food that would be beneficial in the prevention of MI.


Subject(s)
Animals , Apoptosis , Arabinose , Blotting, Western , Caspase 3 , Coronary Vessels , Cyclic AMP Response Element-Binding Protein , Cyclic AMP-Dependent Protein Kinases , Diet , Dietary Fiber , Functional Food , Gene Expression , Glutathione Transferase , Heart , Infarction , Ischemia , Ligation , Models, Animal , Myocardial Infarction , Psyllium , Rats , Reperfusion , Sirtuins , Superoxide Dismutase , Xylose
8.
Chinese Journal of Biotechnology ; (12): 254-262, 2019.
Article in Chinese | WPRIM | ID: wpr-771381

ABSTRACT

Escherichia coli was metabolically engineered to produce poly(glycolate-co-lactate-co-3-hydroxybutyrate) using glucose and xylose as carbon sources. The combinatorial biosynthetic route was constructed by the overexpression of a series of enzymes including D-tagatose 3-epimerase, L-fuculokinase, L-fuculose-phosphate aldolase, aldehyde dehydrogenase, propionyl-CoA transferase, β-ketothiolase, acetoacetyl-CoA reductase, and polyhydroxyalkanoate synthase. Overexpression of polyhydroxyalkanoate granule associated protein significantly improved biopolymer synthesis, and the recombinant strain reached 3.73 g/L cell dry weight with 38.72% (W/W) biopolymer content. A co-culture engineering strategy was developed to produce biopolymer from a mixture of glucose and xylose, achieving 4.01 g/L cell dry weight containing 21.54% (W/W) biopolymer. The results of this work offer an approach for simultaneously utilizing glucose and xylose and indicate the potential for future biopolymer production from lignocellulosic biomass.


Subject(s)
3-Hydroxybutyric Acid , Escherichia coli , Glucose , Glycolates , Lactates , Metabolic Engineering , Polyesters , Xylose
9.
Braz. j. microbiol ; 49(1): 162-168, Jan.-Mar. 2018. tab, graf
Article in English | LILACS | ID: biblio-889200

ABSTRACT

ABSTRACT For the implementation of cellulosic ethanol technology, the maximum use of lignocellulosic materials is important to increase efficiency and to reduce costs. In this context, appropriate use of the pentose released by hemicellulose hydrolysis could improve de economic viability of this process. Since the Saccharomyces cerevisiae is unable to ferment the pentose, the search for pentose-fermenting microorganisms could be an alternative. In this work, the isolation of yeast strains from decaying vegetal materials, flowers, fruits and insects and their application for assimilation and alcoholic fermentation of xylose were carried out. From a total of 30 isolated strains, 12 were able to assimilate 30 g L-1 of xylose in 120 h. The strain Candida tropicalis S4 produced 6 g L-1 of ethanol from 56 g L-1 of xylose, while the strain C. tropicalis E2 produced 22 g L-1 of xylitol. The strains Candida oleophila G10.1 and Metschnikowia koreensis G18 consumed significant amount of xylose in aerobic cultivation releasing non-identified metabolites. The different materials in environment were source for pentose-assimilating yeast with variable metabolic profile.


Subject(s)
Pentoses/metabolism , Xylose/metabolism , Yeasts/metabolism , Vegetables/microbiology , Xylitol/metabolism , Yeasts/isolation & purification , Yeasts/classification , Yeasts/genetics , Ethanol/metabolism , Fermentation
10.
Electron. j. biotechnol ; 31: 67-54, Jan. 2018. ilus, tab, graf
Article in English | LILACS | ID: biblio-1022118

ABSTRACT

Background: Pretreatment of lignocellulosic biomass is essential for using it as a raw material for chemical and biofuel production. This study evaluates the effects of variables in the chemical pretreatment of the Arundo biomass on the glucose and xylose concentrations in the final enzymatic hydrolysate. Three pretreatments were tested: acid pretreatment, acid pretreatment followed by alkaline pretreatment, and alkaline pretreatment. Results: The amounts of glucose and xylose released by the enzymatic hydrolysis of the Arundo biomass obtained from acid pretreatment ranged from 6.2 to 19.1 g/L and 1.8 to 3.1 g/L, respectively. The addition of alkaline pretreatment led to a higher yield from the enzymatic hydrolysis, with the average glucose concentration 3.5 times that obtained after biomass hydrolysis with an acid pretreatment exclusively. The use of an alkaline pretreatment alone resulted in glucose and xylose concentrations similar to those obtained in the two-step pretreatment: acid pretreatment followed by alkaline pretreatment. There was no significant difference in 5-hydroxymethylfurfural, furfural, or acetic acid concentrations among the pretreatments. Conclusion: Alkaline pretreatment was essential for obtaining high concentrations of glucose and xylose. The application of an alkaline pretreatment alone resulted in high glucose and xylose concentrations. This result is very significant as it allows a cost reduction by eliminating one step.


Subject(s)
Ethanol/metabolism , Poaceae/chemistry , Acids/chemistry , Xylose/analysis , Cellulose/chemistry , Biomass , Biofuels , Glucose/analysis , Hydrolysis , Lignin
11.
Article in Korean | WPRIM | ID: wpr-715913

ABSTRACT

BACKGROUND: The performance of the self-monitoring of blood glucose in patients with diabetes should be properly evaluated to ensure strict glycemic control. This study evaluated the self-testing Blood Glucose Monitoring System GlucoDr.S™ (All Medicus Co., Ltd., Korea). METHODS: This study recruited 120 patients. Use of the glucometer was evaluated according to ISO 15197:2013 guidelines. The YSI 2300 STAT PLUS Glucose Analyzer (YSI Life Sciences, USA) was used as the reference device. RESULTS: The standard deviation and coefficients of variation ranges for measurement repeatability and intermediate measurement precision conducted with 10 meters and 3 reagent lots on the same day were 2.7–3.2 mg/dL (0.99. The influence effect of hematocrit and the 24 interference agents was not significant, except for xylose. A system accuracy test was conducted with 100 subjects taking duplicate measurements from each of the 3 reagent lots. When glucose levels were 95% of the samples were within ±15 mg/dL and within ±15% of the average measured values of the reference measurement, respectively. In Consensus Error grid analysis, all results were distributed in zone A and B. The results of the user performance evaluation using 115 lay persons were also included in the acceptance range. CONCLUSION: The GlucoDr.S™ showed acceptable performance according to the ISO 15197:2013 guidelines and could be a clinically useful self-testing glucometer.


Subject(s)
Biological Science Disciplines , Blood Glucose , Consensus , Glucose , Hematocrit , Humans , Xylose
12.
Braz. j. microbiol ; 48(4): 648-655, Oct.-Dec. 2017. tab, graf
Article in English | LILACS | ID: biblio-889169

ABSTRACT

ABSTRACT Producing biofuels such as ethanol from non-food plant material has the potential to meet transportation fuel requirements in many African countries without impacting directly on food security. The current shortcomings in biomass processing are inefficient fermentation of plant sugars, such as xylose, especially at high temperatures, lack of fermenting microbes that are able to resist inhibitors associated with pre-treated plant material and lack of effective lignocellulolytic enzymes for complete hydrolysis of plant polysaccharides. Due to the presence of residual partially degraded lignocellulose in the gut, the dung of herbivores can be considered as a natural source of pre-treated lignocellulose. A total of 101 fungi were isolated (36 yeast and 65 mould isolates). Six yeast isolates produced ethanol during growth on xylose while three were able to grow at 42 °C. This is a desirable growth temperature as it is closer to that which is used during the cellulose hydrolysis process. From the yeast isolates, six isolates were able to tolerate 2 g/L acetic acid and one tolerated 2 g/L furfural in the growth media. These inhibitors are normally generated during the pre-treatment step. When grown on pre-treated thatch grass, Aspergillus species were dominant in secretion of endo-glucanase, xylanase and mannanase.


Subject(s)
Animals , Ethanol/metabolism , Fungi/isolation & purification , Fungi/metabolism , Manure/microbiology , Biofuels/analysis , Biofuels/microbiology , Fermentation , Fungi/classification , Fungi/genetics , Herbivory , Lignin/metabolism , Manure/analysis , Plants/metabolism , Xylose/metabolism
13.
Braz. j. microbiol ; 48(4): 791-800, Oct.-Dec. 2017. graf
Article in English | LILACS | ID: biblio-889166

ABSTRACT

ABSTRACT Lignocellulose-derived inhibitors have negative effects on the ethanol fermentation capacity of Saccharomyces cerevisiae. In this study, the effects of eight typical inhibitors, including weak acids, furans, and phenols, on glucose and xylose co-fermentation of the recombinant xylose-fermenting flocculating industrial S. cerevisiae strain NAPX37 were evaluated by batch fermentation. Inhibition on glucose fermentation, not that on xylose fermentation, correlated with delayed cell growth. The weak acids and the phenols showed additive effects. The effect of inhibitors on glucose fermentation was as follows (from strongest to weakest): vanillin > phenol > syringaldehyde > 5-HMF > furfural > levulinic acid > acetic acid > formic acid. The effect of inhibitors on xylose fermentation was as follows (from strongest to weakest): phenol > vanillin > syringaldehyde > furfural > 5-HMF > formic acid > levulinic acid > acetic acid. The NAPX37 strain showed substantial tolerance to typical inhibitors and showed good fermentation characteristics, when a medium with inhibitor cocktail or rape straw hydrolysate was used. This research provides important clues for inhibitors tolerance of recombinant industrial xylose-fermenting S. cerevisiae.


Subject(s)
Saccharomyces cerevisiae/drug effects , Xylose/metabolism , Glucose/metabolism , Phenols/metabolism , Phenols/pharmacology , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Acids/metabolism , Acids/pharmacology , Industrial Microbiology , Fermentation , Furans/metabolism , Furans/pharmacology
14.
Article in English | WPRIM | ID: wpr-51185

ABSTRACT

BACKGROUND/OBJECTIVES: Vascular dementia (VaD) caused by reduced blood supply to the brain manifests as white matter lesions accompanying demyelination and glial activation. We previously showed that arabinoxylan consisting of arabinose and xylose, and arabinose itself attenuated white matter injury in a rat model of VaD. Here, we investigated whether larch arabinogalactan (LAG) consisting of arabinose and galactose could also reduce white matter injury. MATERIALS/METHODS: We used a rat model of bilateral common carotid artery occlusion (BCCAO), in which the bilateral common carotid arteries were exposed and ligated permanently with silk sutures. The rats were fed a modified AIN-93G diet supplemented with LAG (100 mg/kg/day) for 5 days before and 4 weeks after being subjected to BCCAO. Four weeks after BCCAO, the pupillary light reflex (PLR) was measured to assess functional consequences of injury in the corpus callosum (cc). Additionally, Luxol fast blue staining and immunohistochemical staining were conducted to assess white matter injury, and astrocytic and microglial activation, respectively. RESULTS: We showed that white matter injury in the the cc and optic tract (opt) was attenuated in rats fed diet supplemented with LAG. Functional consequences of injury reduction in the opt manifested as improved PLR. Overall, these findings indicate that LAG intake protects against white matter injury through inhibition of glial activation. CONCLUSIONS: The results of this study support our hypothesis that cell wall polysaccharides consisting of arabinose are effective at protecting white matter injury, regardless of their origin. Moreover, LAG has the potential for development as a functional food to prevent vascular dementia.


Subject(s)
Animals , Hypoxia , Arabinose , Brain , Carotid Arteries , Carotid Artery, Common , Cell Wall , Corpus Callosum , Dementia, Vascular , Demyelinating Diseases , Diet , Functional Food , Galactose , Larix , Models, Animal , Optic Tract , Polysaccharides , Rats , Reflex , Silk , Sutures , White Matter , Xylose
15.
Electron. j. biotechnol ; 19(6): 21-25, Nov. 2016. ilus
Article in English | LILACS | ID: biblio-840308

ABSTRACT

Background: Xylitol is a five carbons polyol with promising medical applications. It can be obtained from chemical D-xylose reduction or by microbial fermentation of Sugarcane Bagasse Hemicellulosic Hydrolysate. For this last process, some microbial inhibitors, as furfural, constitute severe bottleneck. In this case, the use of strains able to produce xylitol simultaneously to furfural neutralization is an interesting alternative. A wild-type strain of Geotrichum sp. was detected with this ability, and its performance in xylitol production and furfural consumption was evaluated. Furthermore, were analyzed its degradation products. Results: Geotrichum sp. produced xylitol from D-xylose fermentation with a yield of 0.44 g-g-1. Furfural was fully consumed in fermentation assay and when provided in the medium until concentration of 6 g-L-1. The furfural degradation product is not an identified molecule, presenting a molecular weight of 161 g-mol-1, an uncommon feature for the microbial metabolism of this product. Conclusion: This strain presents most remarkable potential in performing furfural consumption simultaneous to xylitol production. Subsequent efforts must be employed to establish bioprocess to simultaneous detoxification and xylitol production by Geotrichum sp.


Subject(s)
Furaldehyde/metabolism , Geotrichum/metabolism , Polysaccharides/metabolism , Xylitol/biosynthesis , Xylose/metabolism , Fermentation
16.
Braz. j. microbiol ; 47(3): 680-690, July-Sept. 2016. tab, graf
Article in English | LILACS | ID: lil-788964

ABSTRACT

ABSTRACT A new strain of Thermomyces lanuginosus was isolated from the Atlantic Forest biome, and its β-xylosidases optimization in response to agro-industrial residues was performed. Using statistical approach as a strategy for optimization, the induction of β-xylosidases activity was evaluated in residual corn straw, and improved so that the optimum condition achieved high β-xylosidases activities 1003 U/mL. According our known, this study is the first to show so high levels of β-xylosidases activities induction. In addition, the application of an experimental design with this microorganism to induce β-xylosidases has not been reported until the present work. The optimal conditions for the crude enzyme extract were pH 5.5 and 60 °C showing better thermostability at 55 °C. The saccharification ability of β-xylosidase in the presence of hemicellulose obtained from corn straw raw and xylan from beechwood substrates showed a xylo-oligosaccharide to xylose conversion yield of 80 and 50%, respectively, at 50 °C. Our data strongly indicated that the β-xylosidases activities was not subjected to the effects of potential enzyme inhibitors often produced during fermentation process. These data suggest the application of this enzyme studied for saccharification of hemicellulose, an abundant residue in the American continents, thus providing an interesting alternative for future tests for energy production.


Subject(s)
Ascomycota/enzymology , Xylosidases/metabolism , Fermentation , Polysaccharides/metabolism , Polysaccharides/chemistry , Substrate Specificity , Temperature , Xylose/metabolism , Biomass , Zea mays/chemistry , Enzyme Activation , Hydrogen-Ion Concentration , Hydrolysis
17.
Braz. j. microbiol ; 47(2): 489-496, Apr.-June 2016. tab, graf
Article in English | LILACS | ID: lil-780830

ABSTRACT

Abstract Sugarcane straw has become an available lignocellulosic biomass since the progressive introduction of the non-burning harvest in Brazil. Besides keeping this biomass in the field, it can be used as a feedstock in thermochemical or biochemical conversion processes. This makes feasible its incorporation in a biorefinery, whose economic profitability could be supported by integrated production of low-value biofuels and high-value chemicals, e.g., xylitol, which has important industrial and clinical applications. Herein, biotechnological production of xylitol is presented as a possible route for the valorization of sugarcane straw and its incorporation in a biorefinery. Nutritional supplementation of the sugarcane straw hemicellulosic hydrolyzate as a function of initial oxygen availability was studied in batch fermentation of Candida guilliermondii FTI 20037. The nutritional supplementation conditions evaluated were: no supplementation; supplementation with (NH4)2SO4, and full supplementation with (NH4)2SO4, rice bran extract and CaCl2·2H2O. Experiments were performed at pH 5.5, 30 °C, 200 rpm, for 48 h in 125 mL Erlenmeyer flasks containing either 25 or 50 mL of medium in order to vary initial oxygen availability. Without supplementation, complete consumption of glucose and partial consumption of xylose were observed. In this condition the maximum xylitol yield (0.67 g g-1) was obtained under reduced initial oxygen availability. Nutritional supplementation increased xylose consumption and xylitol production by up to 200% and 240%, respectively. The maximum xylitol volumetric productivity (0.34 g L-1 h-1) was reached at full supplementation and increased initial oxygen availability. The results demonstrated a combined effect of nutritional supplementation and initial oxygen availability on xylitol production from sugarcane straw hemicellulosic hydrolyzate.


Subject(s)
Xylitol/biosynthesis , Candida/metabolism , Saccharum/microbiology , Xylose/metabolism , Plant Stems/metabolism , Plant Stems/microbiology , Plant Stems/chemistry , Culture Media/metabolism , Saccharum/metabolism , Saccharum/chemistry , Fermentation , Hydrolysis
18.
Mycobiology ; : 48-53, 2016.
Article in English | WPRIM | ID: wpr-729454

ABSTRACT

Lenzites betulinus, known as gilled polypore belongs to Basidiomycota was isolated from fruiting body on broadleaf dead trees. It was found that the mycelia of white rot fungus Lenzites betulinus IUM 5468 produced ethanol from various sugars, including glucose, mannose, galactose, and cellobiose with a yield of 0.38, 0.26, 0.07, and 0.26 g of ethanol per gram of sugar consumed, respectively. This fungus relatively exhibited a good ethanol production from xylose at 0.26 g of ethanol per gram of sugar consumed. However, the ethanol conversion rate of arabinose was relatively low (at 0.07 g of ethanol per gram sugar). L. betulinus was capable of producing ethanol directly from rice straw and corn stalks at 0.22 g and 0.16 g of ethanol per gram of substrates, respectively, when this fungus was cultured in a basal medium containing 20 g/L rice straw or corn stalks. These results indicate that L. betulinus can produce ethanol efficiently from glucose, mannose, and cellobiose and produce ethanol very poorly from galactose and arabinose. Therefore, it is suggested that this fungus can ferment ethanol from various sugars and hydrolyze cellulosic materials to sugars and convert them to ethanol simultaneously.


Subject(s)
Animals , Arabinose , Basidiomycota , Biomass , Carbohydrates , Cellobiose , Ethanol , Fruit , Fungi , Galactose , Gills , Glucose , Mannose , Trees , Xylose , Zea mays
19.
Chinese Journal of Biotechnology ; (12): 457-467, 2016.
Article in Chinese | WPRIM | ID: wpr-337451

ABSTRACT

Ensilage is a traditional way of preserving fresh biomass. However, in order to apply ensilage to the ethanol biorefinery, two parameters need to be evaluated: quantity and quality changes of the biomass; and its effects on bioconversion process. To study these two aspects, switchgrass harvested on three different time points (Early, mid and late fall) were used as feedstock. The early fall harvested biomass was ensiled at 5 moisture levels ranging from 30% to 70%. Silage of 40% moisture and 3 other raw switchgrass were pretreated with liquid hot water, followed by enzymatic hydrolysis as well as simultaneous saccharification and fermentation. After 21 days storage pH values of all silages decreased below 4.0 and the dry matter losses were less than 2.0%, and structural sugars contents did not change dramatically. Liquid hot water caused more hemicellulose dissolution in the silage than in unensiled switchgrass. However, ensilage also increased the risk of releasing more sugar degradation products; After enzymatic hydrolysis, silage obtained higher total glucose, xylose and galactose yields than raw materials; After simultaneous saccharification and fermentation, ethanol concentration in silage was 12.1 g/L, higher than the unensiled switchgrass (10.3 g/L, 9.7 g/L and 10.6 g/L for early, mid and late fall respectively). Our results suggest that ensilage helps increase pretreatment efficiency and sugar yield, which increases final ethanol production.


Subject(s)
Biomass , Ethanol , Chemistry , Fermentation , Galactose , Chemistry , Glucose , Chemistry , Hot Temperature , Hydrolysis , Panicum , Chemistry , Polysaccharides , Chemistry , Silage , Water , Xylose , Chemistry
20.
Chinese Journal of Biotechnology ; (12): 185-194, 2016.
Article in Chinese | WPRIM | ID: wpr-242302

ABSTRACT

Lignin degradation products are toxic to microorganisms, which is one of the bottlenecks for fuel ethanol production. We studied the effects of phenolic ketones (4-hydroxyacetophenone, 4-hydroxy-3-methoxy-acetophenone and 4-hydroxy-3,5-dimethoxy-acetophenone) derived from lignin degradation on ethanol fermentation of xylose and cellular lipid composition of Pichia stipitis NLP31. Ethanol and the cellular fatty acid of yeast were analyzed by high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). Results indicate that phenolic ketones negatively affected ethanol fermentation of yeast and the lower molecular weight phenolic ketone compound was more toxic. When the concentration of 4-hydroxyacetophenone was 1.5 g/L, at fermentation of 24 h, the xylose utilization ratio, ethanol yield and ethanol concentration decreased by 42.47%, 5.30% and 9.76 g/L, respectively, compared to the control. When phenolic ketones were in the medium, the ratio of unsaturated fatty acids to saturated fatty acids (UFA/SFA) of yeast cells was improved. When 1.5 g/L of three aforementioned phenolic ketones was added to the fermentation medium, the UFA/SFA ratio of yeast cells increased to 3.03, 3.06 and 3.61, respectively, compared to 2.58 of the control, which increased cell membrane fluidity and instability. Therefore, phenolic ketones can reduce the yeast growth, increase the UFA/SFA ratio of yeast and lower ethanol productivity. Effectively reduce or remove the content of lignin degradation products is the key to improve lignocellulose biorefinery.


Subject(s)
Acetophenones , Chemistry , Ethanol , Chemistry , Fermentation , Industrial Microbiology , Ketones , Chemistry , Lignin , Chemistry , Lipids , Chemistry , Phenols , Chemistry , Pichia , Chemistry , Xylose , Chemistry
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