Plackett-Burman (PB) design and central composite design (CCD) were applied to optimize of xylose fermentation for ethanol production by Candida shehatae HDYXHT-01. The PB results showed that (NH4)2SO4, KH2PO4, yeast extract and inoculum volume were the main affecting factors. With ethanol productivity as the target response, the optimal fermentation was determined by CCD and response surface analysis (RSM). The optimal fermentation conditions were (NH4)2SO4 1.73 g/L, KH2PO4 3.56 g/L, yeast extract 2.62 g/L and inoculum volume 5.66%. Other fermentation conditions were xylose 80 g/L, MgSO47H20 0.1 g/L, pH 5.0 and 250 mL flask containing 100 mL medium and cultivated at 30 degrees C for 48 h and the agitation speed was 140 r/min. Under this fermentation conditions, ethanol productivity was 26.18 g/L, which was 1.15 times of the initial.
Candida ; metabolism ; Ethanol ; metabolism ; Fermentation ; Industrial Microbiology ; Xylose ; metabolism

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 (<100 mg/dL) and 3.4–3.7% (≥100 mg/dL), respectively, and 3.7 mg/dL (<100 mg/dL) and 2.1–2.6% (≥100 mg/dL), respectively. Each coefficient of determination (R2) for linearity of the 3 reagent lots was >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 <100 mg/dL and ≥100 mg/dL, >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.
Biological Science Disciplines ; Blood Glucose* ; Consensus ; Glucose ; Hematocrit ; Humans ; Xylose

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.
Biocatalysis ; Formaldehyde ; chemistry ; Fructose-Bisphosphate Aldolase ; metabolism ; Xylose ; chemical synthesis

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.
Escherichia coli/genetics* ; Hydroxybutyrates ; Lactic Acid ; Polyesters ; Polyhydroxyalkanoates ; Xylose

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.
Biofuels ; Ethanol ; Fermentation ; Metabolic Engineering ; Saccharomyces cerevisiae/genetics* ; Xylose

Metabolic alterations including postprandial hyperglycemia have been implicated in the development of obesity-related diseases. Xylose is a sucrase inhibitor suggested to suppress the postprandial glucose surge. The objectives of this study were to assess the inhibitory effects of two different concentrations of xylose on postprandial glucose and insulin responses and to evaluate its efficacy in the presence of other macronutrients. Randomized double-blind cross-over studies were conducted to examine the effect of D-xylose on postprandial glucose and insulin response following the oral glucose tolerance test (OGTT). In study 1, the overnight-fasted study subjects (n = 49) consumed a test sucrose solution (50 g sucrose in 130 ml water) containing 0, 5, or 7.5 g D-xylose powder. In study 2, the overnight-fasted study subjects (n = 50) consumed a test meal (50 g sucrose in a 60 g muffin and 200 ml sucrose-containing solution). The control meal provided 64.5 g of carbohydrates, 4.5 g of fat, and 10 g of protein. The xylose meal was identical to the control meal except 5 g of xylose was added to the muffin mix. In study 1, the 5 g xylose-containing solutions exhibited significantly lower area under the glucose curve (AUCg) and area under the insulin curve (AUCi) values for 0-15 min (P < 0.0001, P < 0.0001), 0-30 min (P < 0.0001, P < 0.0001), 0-45 min (P < 0.0001, P < 0.0001), 0-60 min (P < 0.0001, P < 0.0001), 0-90 min (P < 0.0001, P < 0.0001) and 0-120 min (P = 0.0071, P = 0.0016). In study 2, the test meal exhibited significantly lower AUCg and AUCi values for 0-15 min (P < 0.0001, P < 0.0001), 0-30 min (P < 0.0001, P < 0.0001), 0-45 min (P < 0.0001, P = 0.0005), 0-60 min (P = 0.0002, P = 0.0025), and 0-90 min (P = 0.0396, P = 0.0246). In conclusion, xylose showed an acute suppressive effect on the postprandial glucose and insulin surges.
Carbohydrates ; Cross-Over Studies ; Glucose ; Glucose Tolerance Test ; Hyperglycemia ; Insulin ; Meals ; Sucrase ; Sucrose ; Xylose

In this study, we investigated the heat effect of digestion-resistant fraction (RF) from soybean on retarding bile acid transport in vitro. The RFs from soybean retarded bile acid transport. A raw, unheated RF of soybean (RRF-SOY) was significantly more effective than the heated RF of soybean (HRF-SOY). The RS1 which physically trapped in milled grains and inaccessible to digestive enzyme after 18 hrs incubation level of content in RRF-SOY was found to be as high as 24.1% and after heating the RS1 of HRF-SOY was significantly reduced to 16.8%. The X-ray diffraction pattern of RF from soybean was altered after heat treatment. The RFs from soybean were characterized by peak at diffraction angles of 12.0degrees and 20.0degrees corresponding to RS content. Cellulose contents of RRF-SOY was 5% higher than that of HRF-SOY and pentosan contents of RRF-SOY was 5% higher than that of HRF-SOY, too. Whereas the hemicellulose content of RRF-SOY was 13% lower than HRF-SOY.
Bile ; Cellulose ; Edible Grain ; Heating ; Hot Temperature ; Polysaccharides ; Soybeans ; X-Ray Diffraction ; Xylose

INTRODUCTION: Small intestinal bacterial overgrowth (SIBO) occurs in varying frequency in irritable bowel syndrome (IBS). We studied the frequency of SIBO in IBS and chronic non-specific diarrhea (CNSD). METHODS: 129 patients with IBS (Manning's criteria), 73 with CNSD (> or = 4 weeks diarrhea with two of these tests normal [urine D-xylose, fecal fat and duodenal biopsy]) and 51 healthy controls (HC) were evaluated for SIBO using glucose hydrogen breath test (GHBT). Diarrhea-predominant IBS (D-IBS) was grouped into CNSD. Rise in breath hydrogen 12 ppm above basal following 100 g glucose was diagnostic of SIBO. RESULTS: Of 129 patients with IBS, 7 were constipation (C-IBS), and 122 were of indeterminate type (I-IBS). Patients with IBS were younger than HC and CNSD (IBS vs. HC: 36.6 yr +/- 11.4 vs. 44.1 yr +/- 13.6, p = 0.001; IBS vs. CNSD: 36.6 yr +/- 11.4 vs. 42 yr +/- 14.5, p = 0.003). Patients with CNSD were comparable to HC in age (42 yr +/- 14.5 vs. 44.1 yr +/- 13.6, p = ns). Patients with IBS were more often male than HC [108/129 (83.7%) vs. 34/51 (66.7%) p = 0.02]; gender of CNSD and HC was comparable [male 39/73 (53.4%) vs. 34/51 (66.7%) p = ns]. SIBO was commoner in CNSD than HC [16 (21.9%) vs. 1 (2%), p = 0.003], but was comparable in IBS and HC [11 (8.5%) vs. 1 (2%), p = 0.18]. Patients with CNSD more often had SIBO than IBS [16 (21.9%) vs. 11 (8.5%), p = 0.007]. CONCLUSIONS: SIBO was more common in CNSD including D-IBS than other types of IBS and HC.
Breath Tests ; Constipation ; Diarrhea ; Glucose ; Humans ; Hydrogen ; Irritable Bowel Syndrome ; Malabsorption Syndromes ; Male ; Xylose

To realize the simultaneous fermentation of xylose and glucose, ptsG (one of the glucose-PTS genes) was deleted from the engineered ethanologenic Escherichia coli SZ470 (deltapflB, deltafrdABCD, deltaackA, deltaldhA), resulting in loss of glucose effect in the mutant SZ470P (deltaptsG). When tested in 5% mixture of glucose (2.5%) and xylose (2.5%), SZ470P simultaneously used glucose (13 g/L) and xylose (20 g/L) whereas the parent strain SZ470 sequentially used glucose (25 g/L) then xylose (5 g/L). Upon completion of the fermentation, both strains achieved similar product yield of 89%. SZ470P produced 15.01 g/L of ethanol, which was 14.32% higher than that produced by SZ470 (12.86 g/L). Deleting ptsG gene enabled the mutant strain SZ470P to simultaneously use both glucose and xylose and achieve better ethanol production.
Escherichia coli ; enzymology ; genetics ; Ethanol ; chemistry ; Fermentation ; Glucose ; chemistry ; Phosphoenolpyruvate Sugar Phosphotransferase System ; genetics ; Xylose ; chemistry

This study aimed to examine the inhibitory effect of rare sugars on Streptococcus mutans (S. mutans) in the presence of sucrose. Xylitol and three rare sugars (D-xylose, D-lyxose and D-mannose) were used in this study. S. mutans KCTC 3065 was cultured in Brain Heart Infusion (BHI) medium containing xylitol, D-xylose, D-lyxose, or D-mannose in the presence of sucrose, and the effect on S. mutans growth was assessed by measuring solution turbidity at different time points after inoculation. To assess effects on pH, sucrose was added at different concentrations, and solution pH was measured at different time points after inoculation. All sugars significantly inhibited the growth of S. mutans in the presence of sucrose. Especially, D-lyxose and D-mannose exhibited significantly greater inhibition than that of xylitol. Furthermore, unlike D-lyxose, D-mannose significantly inhibited the decrement of pH, and its effect was greater than that of xylitol. Taken together, D-mannose has strong inhibitory effect on S. mutans in the presence of sucrose.
Brain ; Carbohydrates ; Dental Caries ; Heart ; Hydrogen-Ion Concentration ; Mannose* ; Streptococcus mutans* ; Streptococcus* ; Sucrose* ; Xylitol ; Xylose