Xylitol production from xylose mother liquor: a novel strategy that combines the use of recombinant Bacillus subtilis and Candida maltosa

<p>Abstract</p> <p>Background</p> <p>Xylose mother liquor has high concentrations of xylose (35%-40%) as well as other sugars such as L-arabinose (10%-15%), galactose (8%-10%), glucose (8%-10%), and other minor sugars. Due to the complexity of this mother liquor, further isolation of xylose by simple method is not possible. In China, more than 50,000 metric tons of xylose mother liquor was produced in 2009, and the management of sugars like xylose that present in the low-cost liquor is a problem.</p> <p>Results</p> <p>We designed a novel strategy in which <it>Bacillus subtilis </it>and <it>Candida maltosa </it>were combined and used to convert xylose in this mother liquor to xylitol, a product of higher value. First, the xylose mother liquor was detoxified with the yeast <it>C. maltosa </it>to remove furfural and 5-hydromethylfurfural (HMF), which are inhibitors of <it>B. subtilis </it>growth. The glucose present in the mother liquor was also depleted by this yeast, which was an added advantage because glucose causes carbon catabolite repression in <it>B. subtilis</it>. This detoxification treatment resulted in an inhibitor-free mother liquor, and the <it>C. maltosa </it>cells could be reused as biocatalysts at a later stage to reduce xylose to xylitol. In the second step, a recombinant <it>B. subtilis </it>strain with a disrupted xylose isomerase gene was constructed. The detoxified xylose mother liquor was used as the medium for recombinant <it>B. subtilis </it>cultivation, and this led to L-arabinose depletion and xylose enrichment of the medium. In the third step, the xylose was further reduced to xylitol by <it>C. maltosa </it>cells, and crystallized xylitol was obtained from this yeast transformation medium. <it>C. maltosa </it>transformation of the xylose-enriched medium resulted in xylitol with 4.25 g L^-1·h^-1volumetric productivity and 0.85 g xylitol/g xylose specific productivity.</p> <p>Conclusion</p> <p>In this study, we developed a biological method for the purification of xylose from xylose mother liquor and subsequent preparation of xylitol by <it>C. maltosa</it>-mediated biohydrogenation of xylose.</p

Loss of Smad7 Promotes Inflammation in Rheumatoid Arthritis

Objective: Smad7 is an inhibitory Smad and plays a protective role in many inflammatory diseases. However, the roles of Smad7 in rheumatoid arthritis (RA) remain unexplored, which were investigated in this study.Methods: The activation of TGF-β/Smad signaling was examined in synovial tissues of patients with RA. The functional roles and mechanisms of Smad7 in RA were determined in a mouse model of collagen-induced arthritis (CIA) in Smad7 wild-type (WT) and knockout (KO) CD-1 mice, a strain resistant to autoimmune arthritis induction.Results: TGF-β/Smad3 signaling was markedly activated in synovial tissues of patients with RA, which was associated with the loss of Smad7, and enhanced Th17 and Th1 immune response. The potential roles of Smad7 in RA were further investigated in a mouse model of CIA in Smad7 WT/KO CD-1 mice. As expected, Smad7-WT CD-1 mice did not develop CIA. Surprisingly, CD-1 mice with Smad7 deficiency developed severe arthritis including severe joint swelling, synovial hyperplasia, cartilage damage, massive infiltration of CD3+ T cells and F4/80+ macrophages, and upregulation of proinflammatory cytokines IL-1β, TNFα, and MCP-1. Further studies revealed that enhanced arthritis in Smad7 KO CD-1 mice was associated with increased Th1, Th2 and, importantly, Th17 over the Treg immune response with overactive TGF-β/Smad3 and proinflammatory IL-6 signaling in the joint tissues.Conclusions: Smad7 deficiency increases the susceptibility to autoimmune arthritis in CD-1 mice. Enhanced TGF-β/Smad3-IL-6 signaling and Th17 immune response may be a mechanism through which disrupted Smad7 causes autoimmune arthritis in CD-1 mice

A Meta-Analysis Study on the Use of Biochar to Simultaneously Mitigate Emissions of Reactive Nitrogen Gases (N2O and NO) from Soils

Nitrous oxide (N2O) and nitric oxide (NO) are detrimental reactive gaseous oxides of nitrogen. Excessive application of nitrogen fertilizers in cropping systems has significantly increased the emissions of these gases, causing adverse environmental consequences. Previous studies have demonstrated that biochar amendment can regulate soil-N dynamics and mitigate N losses, but they lacked simultaneous assessments of soil N2O and NO emissions. Thus, the factors influencing the emissions of nitrogen oxides are still unclear. Therefore, this study examined the impact of biochar application on simultaneous N2O and NO emissions based on 18 peer-reviewed papers (119 paired observations). A machine learning model (boosted regression tree model) was adopted to assess the potential influencing factors, such as soil properties, biochar characteristics, and field management conditions. The addition of biochar reduced N2O and NO emissions by 16.2% and 14.7%, respectively. Biochar with a high total carbon content and pH, from woody or herbaceous feedstock, pyrolyzed at a high temperature, applied at a moderate rate and to soil with a high-silt content, a moderate pH, and coarse texture, could simultaneously reduce soil N2O and NO emissions. Biochar amendment, thus, has the potential to lower the environmental impact of crop production. Furthermore, the influence of soil properties, biochar characteristics, and field management should be considered in the future to enhance the efficacy of biochar

Analysis of clinical features and prognostic factors in Chinese patients with rheumatic diseases in an intensive care unit

Aim of the work: To describe the clinical features and prognostic factors in patients with rheumatic diseases (RDs) admitted to the intensive care unit (ICU). Patients and methods: Clinical data of 33 RD patients admitted to the ICU of Shenzhen Baoan Hospital were retrospectively analyzed regarding the causes for admission, medications received, duration of stay and the management required. Disease severity of the patients was assessed using the acute physiology and chronic health evaluation (APACHE-II) score. Results: The diagnoses of the patients included 16 (48.5%) systemic lupus erythematosus (SLE), 7 (21.2%) systemic vasculitis, 4 (12.1%) rheumatoid arthritis; 3 (9.1%) polymyositis/dermatomyositis; 2 (6.1%) Sjögren’s syndrome and 1 (3%) with systemic sclerosis. The mean APACHE-II score was mean 16.1 ± 7.3. The main cause for ICU admission was infection in 12 (36.4%) patients, primary disease worsening in 8 (24.2%), infection associated with disease activity in 9 (27.3%) and 4 (12.1%) cases were hospitalized for other disease processes (including 1 case of subarachnoid hemorrhage, 1 case of acute myocardial infarction and 2 with hypovolemic shock). 31 (93.9%) had more than one organ involved. Mortality was 51.5% (17 cases); including 9 (27.3%) deaths from infection, 5 (15.2%) from primary diseases, and 3 (9.1%) from other causes. Primary disease worsening and APACHE-II score were significantly increased in the mortality cases (33.3% and 20 ± 7.1) compared to survivors (13.3% and 10 ± 1.2) (p = 0.017 and 0.0001 respectively). Conclusion: SLE was the most frequent cause of ICU admission; infections are the leading causes prompting admission. RDs patients often had multi-organ involvement with a high mortality rate

In-plane and out-of-plane free vibrations of functionally graded composite arches with graphene reinforcements

This article presents in-plane and out-of-plane free vibration analyses of functionally graded graphene nanoplatelets reinforced composite (FG-GPLRC) arches. The arch is composed of multiple layers reinforced with graphene nanoplatelets (GPLs) that are evenly distributed in each layer but its weight fraction varies layer-by-layer in the thickness direction. The effective material properties are calculated by Halpin-Tsai micromechanics model for Young’s modulus and the rule of mixture for both mass density and Poisson’s ratio of each GPLRC layer. Analytical solutions are obtained for the fundamental frequencies of the in-plane anti-symmetric vibration and out-of-plane vibration of both fixed and pinned FG-GPLRC arches by using Hamilton’s principle. A comprehensive parametric study is carried out to investigate the influences of distribution pattern, concentration and dimensions of GPLs as well as the geometrical parameters of the arch on the fundamental frequency of the FG-GPLRC arch. It is found that the fundamental frequency of the arch can be considerably improved by adding a lower quantity of GPLs as reinforcing nanofillers

Structural and Biochemical Properties of Duckweed Surface Cuticle

The plant cuticle, which consists of cutin and waxes, forms a hydrophobic coating covering the aerial surfaces of all plants. It acts as an interface between plants and their surrounding environment whilst also protecting them against biotic and abiotic stresses. In this research, we have investigated the biodiversity and cuticle properties of aquatic plant duckweed, using samples isolated from four different locations around Hongze lake in Jiangsu province, China. The samples were genotyped using two chloroplast markers and nuclear ribosomal DNA markers, which revealed them as ecotypes of the larger duckweed, Spirodela polyrhiza. Duckweed cuticle properties were investigated by compositional analysis using Gas Chromatography coupled with Mass Spectroscopy (GC-MS) Flame Ionization Detector (GC-FID), and ultrastructural observation by cryo-Scanning Electron Microscopy (cryo-SEM). Cuticle compositional analysis indicated that fatty acids and primary alcohols, the two typical constituents found in many land plant cuticle, are the major duckweed wax components. A large portion of the duckweed wax fraction is composed of phytosterols, represented by campesterol, stigmasterol, sitosterol and their common precursor squalene. The cryo-SEM observation uncovered significant differences between the surface structures of the top air-facing and bottom water-facing sides of the plant fronds. The top side of the fronds, containing multiple stomata complexes, appeared to be represented by a rather flat waxy film sporadically covered with wax crystals. Underneath the waxy film was detected a barely distinguished nanoridge net, which became distinctly noticeable after chloroform treatment. On the bottom side of the fronds, the large epidermal cells were covered by the well-structured net, whose sections became narrower and sharper under cryo-SEM following chloroform treatment. These structural differences between the abaxial and adaxial sides of the fronds evidently relate to their distinct physiological roles in interacting with the contrasting environments of sunlight/air and nutrients/water. The unique structural and biochemical features of Spirodela frond surfaces with their rapid reproductive cycle and readily availability genome sequence, make duckweed an attractive monocot model for studying the fundamental processes related to plant protection against ultraviolet irradiation, pathogens and other environmental stresses

Enhanced recyclability of waste plastics for waterproof cementitious composites with polymer-nanosilica hybrids

Waste plastics may be an environmentally friendly alternative to natural aggregates for concrete manufacture. However, the inferior bond strength between waste plastic aggregates and cement matrix greatly limits the uses of waste plastics for engineering designs and applications. Herein, ethylene–vinyl acetate (EVA) and nanosilica (nS) were jointly employed to enhance the matrix-aggregate interactions in cementitious composites with recycled waste plastics (RWPs). Waterproof properties of the cementitious composites with EVA and nS hybrids were measured. A non-destructive test using micro-focus X-ray computed tomography (µ-XCT) with contrast enhancing technique followed by microstructural tests (SEM/BSE and EDS) were conducted to in-situ trace liquid migration in the composite specimens. The single addition of EVA into the cementitious composites increased the porosity and depressed the compressive strength, but greatly decreased the water sorptivity by nearly 50 %. The organic–inorganic (EVA-nS) hybrids enhanced the recycling potential of the waste plastics in terms of the mitigated strength reduction and improved waterproofing performance. The coupled polymerization of EVA and nanofilling of nS effects were resolved to account for the recyclability improvement. The findings would shed light on design and fabrication of cementitious materials towards large scale recycling methods and technologies of waste plastics.ISSN:0264-1275ISSN:1873-419