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Milan Shrestha, Gih-Keong Lau
This Letter presents a tunable window device based on microscopic wrinkling of a transparent elastomeric surface. "Crack-free" microscopic wrinkling of a 50-nm ZnO thin film is possible on a highly adhesive acrylic elastomer membrane (VHB 4910) upon partial release from a large radial pre-stretch of membrane. This ZnO-based tunable window device demonstrates reversible tunability between transparent and translucent states. At zero compression with a flat surface, the device is transparent with a 93% in-line transmittance at 550-nm wavelength...
October 1, 2016: Optics Letters
Alvaro R Lara, Karim E Jaén, Juan Carlos Sigala, Martina Mühlmann, Lars Regestein, Jochen Büchs
Oxygen limitation can be used as a simple environmental inducer for the expression of target genes. However, there is scarce information on the characteristics of microaerobic promoters potentially useful for cell engineering and synthetic biology applications. Here, we characterized the Vitreoscilla hemoglobin promoter (Pvgb) and a set of microaerobic endogenous promoters in Escherichia coli. Oxygen-limited cultures at different maximum oxygen transfer rates were carried out. The FMN-binding fluorescent protein (FbFP), which is a non-oxygen dependent marker protein, was used as a reporter...
October 7, 2016: ACS Synthetic Biology
Xiangchao Feng, Zhuo Ma, Jonathan V MacArthur, Christopher J Giuffre, Ashraf F Bastawros, Wei Hong
Inspired by the toughening mechanism of double-network (DN) hydrogels, a soft composite consisting of a fabric mesh and VHB tape layers was fabricated. The composite was as stiff as the fabric mesh, and as stretchable as the VHB tape. At certain compositions, the composite was significantly stronger and tougher than the base materials. The extensibility and toughness of the composite can be attributed to a damage delocalization mechanism similar to that of the DN gels. In the partially damaged regions, the fabric mesh fragmented into small islands, surrounded by the highly stretched VHB tapes...
October 3, 2016: Soft Matter
Zewang Guo, Xihua Zhao, Yuanzhi He, Tianxing Yang, Huifang Gao, Ganxi Li, Feixue Chen, Meijing Sun, Jung-Kul Lee, Liaoyuan Zhang
Acetoin (AC) is a volatile platform compound with various potential industrial applications. AC contains two stereoisomeric forms: (3S)-AC and (3R)-AC. Optically pure AC is important potential intermediate and widely used as a precursor to synthesize novel optically materials. In this study, chiral (3R)-AC production from meso-2,3-butanediol (meso-2,3-BD) was obtained using recombinant Escherichia coli cells co-expressing meso-2,3-butanediol dehydrogenase (meso-2,3-BDH), NADH oxidase (NOX) and hemoglobin protein (VHB) from Serratia sp...
October 6, 2016: Journal of Microbiology and Biotechnology
Taner Sar, Benjamin C Stark, Meltem Yesilcimen Akbas
Ethanol production from whey powder was investigated by using free as well as alginate immobilized E. coli and E. coli expressing Vitreoscilla hemoglobin (VHb) in both shake flask and fermenter cultures. Media with varying levels of whey (lactose contents of 3%, 5%, 8% or 15%) and yeast extract (0.3% or 0.5%) were evaluated with fermentation times of 48-96 h. Immobilization and VHb expression resulted in higher ethanol production with all media; the increases ranged from 2% to 89% for immobilization and from 2% to 182% for VHb expression...
August 31, 2016: Bioengineered
Tong-Xin Zhao, Mei Li, Xiang Zheng, Cheng-Hua Wang, Hong-Xin Zhao, Chong Zhang, Xin-Hui Xing
trans-4-Hydroxy-l-proline (Hyp) is a chiral amino acid conventionally produced by acid hydrolysis of animal collagen, a process which involves the bottleneck problems of low efficiency and heavy environmental pollution. Biotransformation of l-proline into Hyp using recombinant whole-cell biocatalysis with proline-4-hydroxylase (P4H) is an environmentally-friendly alternative method. Since biohydroxylation of proline by whole cells is a high-oxygen-demand process, oxygen transfer needs to be improved. To solve this problem, the Vitreoscilla hemoglobin gene (vgb) was integrated into the chromosome of recombinant Escherichia coli expressing the P4H gene originally from Dactylosporangium sp...
August 24, 2016: Journal of Bioscience and Bioengineering
Di Liu, Ni Wan, Fuzhong Zhang, Yinjie J Tang, Stephen G Wu
Our recent (13) C-metabolic flux analysis ((13) C-MFA) study indicates that energy metabolism becomes a rate-limiting factor for fatty acid overproduction in E. coli strains (after "Push-Pull-Block" based genetic modifications). To resolve this bottleneck, Vitreoscilla Hemoglobin (VHb, a membrane protein facilitating O2 transport) was introduced into a fatty-acid-producing strain to promote oxygen supply and energy metabolism. The resulting strain, FAV50, achieved 70% percent higher fatty acid titer than the parent strain in shake tube cultures...
August 6, 2016: Biotechnology and Bioengineering
Hyunwoo Yuk, Teng Zhang, German Alberto Parada, Xinyue Liu, Xuanhe Zhao
Inspired by mammalian skins, soft hybrids integrating the merits of elastomers and hydrogels have potential applications in diverse areas including stretchable and bio-integrated electronics, microfluidics, tissue engineering, soft robotics and biomedical devices. However, existing hydrogel-elastomer hybrids have limitations such as weak interfacial bonding, low robustness and difficulties in patterning microstructures. Here, we report a simple yet versatile method to assemble hydrogels and elastomers into hybrids with extremely robust interfaces (interfacial toughness over 1,000 Jm(-2)) and functional microstructures such as microfluidic channels and electrical circuits...
2016: Nature Communications
Rénovat Ntagirabiri, Belyse Munezero, Caritas Nahimana, Evariste Ndabaneze
INTRODUCTION: Hepatitis B virus infection (VHB) is a serious condition which can lead to serious complications, such as cirrhosis and hepato-cellular carcinoma (HCC). HBV genotypes greatly influence its evolution and the effectiveness of treatment. The aim was to evaluate the HBV genotypes and the evolutionary pathways of chronic HBsAG patients. METHODS: A cross-sectional study was conducted at the University Hospital of Kamenge and at the Digestive and liver diseases Center "CEMADIF" between June 2013 and Mai 2014...
2016: Pan African Medical Journal
Q Mo, H Zhang, Q Liu, X Tang, L Zhao, X Zan, Y Song
UNLABELLED: Oxygen deficiency is a critical limiting factor for nosiheptide production in Streptomyces actuosus during fermentation. To alleviate oxygen limitation and enhance the yield of nosiheptide, haemoprotein from Sinorhizobium meliloti (SmHb) was overexpressed in S. actuosus with overexpression of haemoglobin from Vitreoscilla (VHb) as a positive control. The expression of SmHb and VHb in S. actuosus was confirmed by SDS-PAGE and CO-difference spectra analysis. The results showed that S...
June 2016: Letters in Applied Microbiology
Huan-Jun Li, Yi-Long He, De-Huai Zhang, Tong-Hui Yue, Lu-Xi Jiang, Na Li, Jun-Wei Xu
The Vitreoscilla hemoglobin (VHb) gene was expressed in Ganoderma lucidum to enhance antitumor ganoderic acid (GA) production. The effects of VHb expression on the accumulation of GAs and lanosterol (intermediate) and the transcription of GA biosynthesis genes were also investigated. In VHb-expressing G. lucidum, the maximum concentrations of four individual GAs (GA-S, GA-T, GA-Mk and GA-Me) were 19.1±1.8, 34.6±2.1, 191.5±13.1 and 45.2±2.8μg/100mg dry weight, respectively, which were 1.4-, 2.2, 1.9- and 2...
June 10, 2016: Journal of Biotechnology
Jianrong Wang, Yangyuan Li, Danni Liu
A series of strategies were applied to improve expression level of recombinant endo-β-1,4-xylanase from Aspergillus usamii (A. usamii) in Pichia pastoris (P. pastoris). Firstly, the endo-β-1,4-xylanase (xynB) gene from A. usamii was optimized for P. pastoris and expressed in P. pastoris. The maximum xylanase activity of optimized (xynB-opt) gene was 33500 U/mL after methanol induction for 144 h in 50 L bioreactor, which was 59% higher than that by wild-type (xynB) gene. To further increase the expression of xynB-opt, the Vitreoscilla hemoglobin (VHb) gene was transformed to the recombinant strain containing xynB-opt...
2016: BioMed Research International
Wenwen Zhang, Zhaohui Chen, Mengmeng Wu, Zhong Shi, Feng Zhu, Guoqiang Li, Ting Ma
OBJECTIVE: To improve the production of welan gum and obtain a carotenoid-free strain while reducing the fermentation and post-treatment costs. RESULTS: The vitreoscilla globin (vgb) gene combined with the β-galactosidase (lacZ) promoter was inserted into the phytoene synthase (crtB) gene region of the chromosome in Alcaligenes sp. ATCC31555. When the recombinant strain was grown in a 5 l fermentor, welan gum was produced at 24 ± 0.4 g l(-1) compared to 21 g ± 0...
June 2016: Biotechnology Letters
A Batisse, M Grégoire, M Marillier, M Fortias, S Djezzar
BACKGROUND: The pattern of recreational drug use has changed over the last decade and now includes a multitude of substances sold as "research chemicals" or new psychoactive substances, "NPS". In France, synthetic cathinones emerged in 2008 (while first mentioned by the French police force in 2007 first alerts among users appeared in 2008) and have grown to be popular drugs of abuse. Under the Official Journal dated 11th June 2010, only mephedrone has been listed as narcotics but "designer drugs" have synthesized new substitute cathinones in order to avoid anti-drug laws...
August 2016: L'Encéphale
Hewei Du, Xiaomeng Shen, Yiqin Huang, Min Huang, Zuxin Zhang
BACKGROUND: Vitreoscilla hemoglobin (VHb) is a type of hemoglobin found in the Gram-negative aerobic bacterium Vitreoscilla that has been shown to contribute to the tolerance of anaerobic stress in multiple plant species. Maize (Zea mays L.) is susceptible to waterlogging, causing significant yield loss. In this study, we approached this problem with the introduction of an exogenous VHb gene. RESULTS: We overexpressed the VHb gene in Arabidopsis and maize under the control of the CaMV35S promoter...
2016: BMC Plant Biology
J F Lu, Y Zhu, H L Sun, S Liang, F F Leng, H Y Li
UNLABELLED: During Streptococcus zooepidemicus fermentation, most carbon sources are used to synthesize lactic acid, which can inhibit strain growth and hyaluronic acid production. Here, we expressed bacterial haemoglobin (Vhb) in Strep. zooepidemicus. Due to highly efficient oxygen use, only 15·26 g l(-1) lactic acid was produced, which is 0·73 times the quantity produced by the control strain. Compared with the control strain (1·61 g l(-1) ), hyaluronic acid (HA) production in this strain did not substantially increase, only to 2·16 g l(-1) ...
April 2016: Letters in Applied Microbiology
Yujiao Wang, Yingxin Zhang, Tianyi Jiang, Jingjing Meng, Binbin Sheng, Chunyu Yang, Chao Gao, Ping Xu, Cuiqing Ma
BACKGROUND: The surplus of glycerol has increased remarkably as a main byproduct during the biofuel's production. Exploiting an alternative route for glycerol utilization is significantly important for sustainability of biofuels. RESULTS: A novel biocatalyst that could be prepared from glycerol for producing 2-oxo-carboxylates was developed. First, Pseudomonas putida KT2440 was reconstructed by deleting lldR to develop a mutant expressing the NAD-independent lactate dehydrogenases (iLDHs) constitutively...
2015: Biotechnology for Biofuels
Huan-Jun Li, De-Huai Zhang, Tong-Hui Yue, Lu-Xi Jiang, Xuya Yu, Peng Zhao, Tao Li, Jun-Wei Xu
Expression of Vitreoscilla hemoglobin (VHb) gene was used to improve polysaccharide production in Ganoderma lucidum. The VHb gene, vgb, under the control of the constitutive glyceraldehyde-3-phosphate dehydrogenase gene promoter was introduced into G. lucidum. The activity of expressed VHb was confirmed by the observation of VHb specific CO-difference spectrum with a maximal absorption at 419 nm for the transformant. The effects of VHb expression on intracellular polysaccharide (IPS) content, extracellular polysaccharide (EPS) production and transcription levels of three genes encoding the enzymes involved in polysaccharide biosynthesis, including phosphoglucomutase (PGM), uridine diphosphate glucose pyrophosphorylase (UGP), and β-1,3-glucan synthase (GLS), were investigated...
January 10, 2016: Journal of Biotechnology
Aneta M Białkowska, Marzena Jędrzejczak-Krzepkowska, Ewa Gromek, Joanna Krysiak, Barbara Sikora, Halina Kalinowska, Celina Kubik, Fokko Schütt, Marianna Turkiewicz
Two recombinants of alkaliphilic Bacillus subtilis LOCK 1086, constructed via different strategies such as cloning the gene encoding bacterial hemoglobin from Vitreoscilla stercoraria (vhb) and overexpression of the gene encoding acetoin reductase/2,3-butanediol dehydrogenase (bdhA) from B. subtilis LOCK 1086, did not produce more 2,3-butanediol (2,3-BD) than the parental strain. In batch fermentations, this strain synthesized 9.46 g/L in 24 h and 12.80 g/L 2,3-BD in 46 h from sugar beet molasses and an apple pomace hydrolysate, respectively...
March 2016: Applied Microbiology and Biotechnology
Jose A Patricio, Patricia F Lopes, Thalia Medeiros, Guilherme F Mendes, Andrea A Silva, Eliane B Esberard, Jocemir R Lugon, Jorge R Almeida
INTRODUCTION: Viral hepatitis B (VHB) represents a major public health problem. Studies from HIV multidrug patients have associated the use of tenofovir disoproxil fumarate (TDF) with renal dysfunction and phosphate wasting. OBJECTIVE: The aim of this study was to examine the effect of year-long TDF monotherapy on renal function in VHB patients. PATIENTS AND METHODS: We evaluated adult patients diagnosed with VHB before treatment initiation (T0), and after 3 and 12 months (T3 and T12) of TDF initiation...
January 2016: European Journal of Gastroenterology & Hepatology
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