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Sample records for bacterial microcrystalline cellulose

  1. Comparison of microcrystalline characterization results from oil palm midrib alpha cellulose using different delignization method

    NASA Astrophysics Data System (ADS)

    Yuliasmi, S.; Pardede, T. R.; Nerdy; Syahputra, H.

    2017-03-01

    Oil palm midrib is one of the waste generated by palm plants containing 34.89% cellulose. Cellulose has the potential to produce microcrystalline cellulose can be used as an excipient in tablet formulations by direct compression. Microcrystalline cellulose is the result of a controlled hydrolysis of alpha cellulose, so the alpha cellulose extraction process of oil palm midrib greatly affect the quality of the resulting microcrystalline cellulose. The purpose of this study was to compare the microcrystalline cellulose produced from alpha cellulose extracted from oil palm midrib by two different methods. Fisrt delignization method uses sodium hydroxide. Second method uses a mixture of nitric acid and sodium nitrite, and continued with sodium hydroxide and sodium sulfite. Microcrystalline cellulose obtained by both method was characterized separately, including organoleptic test, color reagents test, dissolution test, pH test and determination of functional groups by FTIR. The results was compared with microcrystalline cellulose which has been available on the market. The characterization results showed that microcrystalline cellulose obtained by first method has the most similar characteristics to the microcrystalline cellulose available in the market.

  2. Enzymatic preparation of nanocrystalline and microcrystalline cellulose

    Treesearch

    Sarah R. Anderson; Dominic Esposito; William Gillette; J.Y. Zhu; Ulrich Baxa; Scott E. Mcneil

    2014-01-01

    Traditional cellulose nanocrystal (CNC) production methods use harsh chemicals, are energetically expensive, and result in a hydrophilic sulfate surface chemistry with limited utility. Enzymatic production of CNCs is a less expensive alternative production method that eliminates the need for harsh chemicals and requires much less energy for mechanical fibrillation and...

  3. Dielectric barrier discharge plasma pretreatment on hydrolysis of microcrystalline cellulose

    NASA Astrophysics Data System (ADS)

    Huang, Fangmin; Long, Zhouyang; Liu, Sa; Qin, Zhenglong

    2017-04-01

    Dielectric barrier discharge (DBD) plasma was used as a pretreatment method for downstream hydrolysis of microcrystalline cellulose (MCC). The degree of polymerization (DP) of MCC decreased after it was pretreated by DBD plasma under a carrier gas of air/argon. The effectiveness of depolymerization was found to be influenced by the crystallinity of MCC when under the pretreatment of DBD plasma. With the addition of tert-butyl alcohol in the treated MCC water suspension solution, depolymerization effectiveness of MCC was inhibited. When MCC was pretreated by DBD plasma for 30 min, the total reducing sugar concentration (TRSC) and liquefaction yield (LY) of pretreated-MCC (PMCC) increased by 82.98% and 34.18% respectively compared with those for raw MCC.

  4. Functionality and nutritional aspects of microcrystalline cellulose in food.

    PubMed

    Nsor-Atindana, John; Chen, Maoshen; Goff, H Douglas; Zhong, Fang; Sharif, Hafiz Rizwan; Li, Yue

    2017-09-15

    Microcrystalline cellulose (MCC) is among the most commonly used cellulose derivatives in the food industry. In order assess the recent advances of MCC in food product development and its associated nutraceutical implications, google scholar and database of journals subscribed by Jiangnan university, China were used to source literature. Recently published research articles that reported physicochemical properties of MCC for food application or potential application in food and nutraceutical functions were reviewed and major findings outlined. The selected literature reviewed demonstrated that the material has been extensively explored as a functional ingredient in food including meat products, emulsions, beverages, dairy products, bakery, confectionary and filling. The carbohydrate polymer also has many promising applications in functional and nutraceutical food industries. Though widely used as control for many dietary fiber investigations, MCC has been shown to provide positive effects on gastrointestinal physiology, and hypolipidemic effects, influencing the expression of enzymes involved in lipid metabolism. These techno-functional and nutraceutical properties of MCC are influenced by the physicochemical of the material, which are defined by the raw material source and processing conditions. Apart from these functional properties, this review also highlighted limitations and gaps regarding the application of material in food and nutritional realms. Functional, Nutritional and health claims of MCC. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Physical and structural properties of polyaniline/microcrystalline cellulose nanocomposite

    NASA Astrophysics Data System (ADS)

    Abdi, Mahnaz M.; Liyana, Rawaida; Tahir, Paridah Md; Heng, Lee Yook; Sulaiman, Yusran; Waheeda, Nur Farhana; Hassan, Nabihah Abu

    2017-12-01

    A composite of Polyaniline/Microcrystalline Cellulose (PAni/MCC) was prepared via a chemical polymerization method in the presence of ammonium persulfate (NH4)2S2O8 as oxidant and cetyltrimethylammonium bromide (CTAB) as a cationic surfactant. The results of FESEM showed that the morphology of nanocomposite depends on the monomer concentration. Wire-like and porous nanostructure was observed for PAni/MCC/CTAB composite that could be suitable for enzyme immobilization and sensor applications. The electrochemical properties of the composites were studied using Cyclic Voltammetry (CV) and it was shown that PAni/MCC/CTAB composite generated a higher current response compared to the pure PAni. The synergy effect of MCC and CTAB on the physical and electrochemical properties of composite resulted in higher electron transferring in PAni/MCC/CTAB. The presence of significant peaks of PAni and MCC in FT-IR spectrum of nanocomposite indicating polymerization of aniline on the surface of MCC. Characteristic peaks of crystalline cellulose were observed at 22.8 and 14.7 2theta in XRD pattern.

  6. Isolation and characterization of microcrystalline cellulose from roselle fibers.

    PubMed

    Kian, Lau Kia; Jawaid, Mohammad; Ariffin, Hidayah; Alothman, Othman Y

    2017-10-01

    In this study, microcrystalline cellulose (MCC) was extracted from roselle fiber through acid hydrolysis treatment and its properties were compared with those of commercially available MCC. The physicochemical and morphological characteristics, elemental composition, size distribution, crystallinity and thermal properties of the obtained MCC were analyzed in this work. Fourier transform infrared spectroscopy (FTIR) analysis provided clear evidence that the characteristic peak of lignin was absent in the spectrum of the MCC prepared from roselle fiber. Rough surface and slight aggregation of MCC were observed by scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) analysis showed that pure MCC with small quantities of residues and impurities was obtained, with a similar elemental composition to that of commercial MCC. A mean diameter of approximately 44.28μm was measured for MCC by using a particle size analyzer (PSA). X-ray diffraction (XRD) showed the crystallinity increased from 63% in roselle pulp to 78% in roselle MCC, the latter having a slightly higher crystallinity than that of commercial MCC (74%). TGA and DSC results indicated that the roselle MCC had better thermal stability than the roselle pulp, whereas it had poorer thermal stability in comparison with commercial MCC. Thus, the isolated MCC from roselle fibers will be going to use as reinforcing element in green composites and may be a precursor for future roselle derived nanocellulose, and thus a promising subject in nanocomposite research. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Three-dimensional printed polycaprolactone-microcrystalline cellulose scaffolds.

    PubMed

    Alemán-Domínguez, Maria Elena; Giusto, Elena; Ortega, Zaida; Tamaddon, Maryam; Benítez, Antonio Nizardo; Liu, Chaozong

    2018-05-02

    Microcrystalline cellulose (MCC) is proposed in this study as an additive in polycaprolactone (PCL) matrices to obtain three-dimensional (3D) printed scaffolds with improved mechanical and biological properties. Improving the mechanical behavior and the biological performance of polycaprolactone-based scaffolds allows to increase the potential of these structures for bone tissue engineering. Different groups of samples were evaluated in order to analyze the effect of the additive in the properties of the PCL matrix. The concentrations of MCC in the groups of samples were 0, 2, 5, and 10% (w/w). These combinations were subjected to a thermogravimetric analysis in order to evaluate the influence of the additive in the thermal properties of the composites. 3D printed scaffolds were manufactured with a commercial 3D printer based on fused deposition modelling. The operation conditions have been established in order to obtain scaffolds with a 0/90° pattern with pore sizes between 450 and 500 µm and porosity values between 50 and 60%. The mechanical properties of these structures were measured in the compression and flexural modes. The scaffolds containing 2 and 5% MCC have higher flexural and compression elastic modulus, although those containing 10% do not show this reinforcement effect. On the other hand, the proliferation of sheep bone marrow cells on the proposed scaffolds was evaluated over 8 days. The results show that the proliferation is significantly better (p < 0.05) on the group of samples containing 2% MCC. Therefore, these scaffolds (PCL:MCC 98:2) have suitable properties to be further evaluated for bone tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc.

  8. Spherical composite particles of rice starch and microcrystalline cellulose: a new coprocessed excipient for direct compression.

    PubMed

    Limwong, Vasinee; Sutanthavibul, Narueporn; Kulvanich, Poj

    2004-03-12

    Composite particles of rice starch (RS) and microcrystalline cellulose were fabricated by spray-drying technique to be used as a directly compressible excipient. Two size fractions of microcrystalline cellulose, sieved (MCS) and jet milled (MCJ), having volumetric mean diameter (D50) of 13.61 and 40.51 microm, respectively, were used to form composite particles with RS in various mixing ratios. The composite particles produced were evaluated for their powder and compression properties. Although an increase in the microcrystalline cellulose proportion imparted greater compressibility of the composite particles, the shape of the particles was typically less spherical with rougher surface resulting in a decrease in the degree of flowability. Compressibility of composite particles made from different size fractions of microcrystalline cellulose was not different; however, using MCJ, which had a particle size range close to the size of RS (D50 = 13.57 microm), provided more spherical particles than using MCS. Spherical composite particles between RS and MCJ in the ratio of 7:3 (RS-MCJ-73) were then evaluated for powder properties and compressibility in comparison with some marketed directly compressible diluents. Compressibility of RS-MCJ-73 was greater than commercial spray-dried RS (Eratab), coprocessed lactose and microcrystalline cellulose (Cellactose), and agglomerated lactose (Tablettose), but, as expected, lower than microcrystalline cellulose (Vivapur 101). Flowability index of RS-MCJ-73 appeared to be slightly lower than Eratab but higher than Vivapur 101, Cellactose, and Tablettose. Tablets of RS-MCJ-73 exhibited low friability and good self-disintegrating property. It was concluded that these developed composite particles could be introduced as a new coprocessed direct compression excipient.

  9. Impact of carboxymethyl cellulose (CMC) and microcrystalline cellulose (MCC) on functional characteristics of emulsified sausages.

    PubMed

    Schuh, Valerie; Allard, Karin; Herrmann, Kurt; Gibis, Monika; Kohlus, Reinhard; Weiss, Jochen

    2013-02-01

    Inclusion of fibers, such as carboxymethyl cellulose (CMC) and microcrystalline cellulose (MCC), at the expense of fat or protein in meat batters could be used to produce healthier sausages while lowering production costs. To study the impact of CMC/MCC on structural/functional characteristics of emulsified sausages, standard-fat Lyoner-style sausages were formulated with CMC/MCC at concentrations of 0.3-2.0%. Methods of analysis included rheology, water binding capacity (WBC), texture measurements, and Confocal Laser Scanning Microscopy (CLSM). WBC, texture measurements, and rheology all indicated that addition of CMC (>0.7%) led to destabilization of the batter, which upon heating could no longer be converted into a coherent protein network, a fact that was also revealed in CLSM images. In contrast, MCC was highly compatible with the matrix and improved firmness (1405-1651N/100g) with increasing concentration compared to control (1381N/100g) while keeping WBC (4.6-5.9%) with <2% MCC at the level of the control (4.8%). Results were discussed in terms of molecular interactions of meat proteins with celluloses. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Isolation and characterization of nanocrystalline cellulose from roselle-derived microcrystalline cellulose.

    PubMed

    Kian, Lau Kia; Jawaid, Mohammad; Ariffin, Hidayah; Karim, Zoheb

    2018-07-15

    Roselle fiber is a renewable and sustainable agricultural waste enriched with cellulose polysaccharides. The isolation of Nanocrystalline cellulose (NCC) from roselle-derived microcrystalline cellulose (MCC) is an alternative approach to recover the agricultural roselle plant residue. In the present study, acid hydrolysis with different reaction time was carried out to degrade the roselle-derived MCC to form NCC. The characterizations of isolated NCC were conducted through Fourier Transform Infrared Ray (FTIR), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). As evaluated from the performed morphological investigations, the needle-like shape NCC nanostructures were observed under TEM and AFM microscopy studies, while irregular rod-like shape of NCC was observed under FESEM analysis. With 60min hydrolysis time, XRD analysis demonstrated the highest NCC crystallinity degree with 79.5%. In thermal analysis by TGA and DSC, the shorter hydrolysis time tended to produce NCC with higher thermal stability. Thus, the isolated NCC from roselle-derived MCC has high potential to be used in application of pharmaceutical and biomedical fields for nanocomposite fabrication. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Visible light activated TiO2/microcrystalline cellulose nanocatalyst to destroy organic contaminants in water.

    EPA Science Inventory

    Hybrid TiO2/microcrystalline cellulose (MC) nanophotocatalyst was prepared in situ by a facile and simple synthesis utilizing benign precursors such as MC and TiCl4. The as-prepared nanocomposite was characterized by XRD, XPS, BET surface area analyzer, UV–vis DRS and TGA. Surfac...

  12. Preparation and Characterization of Cellulose Microcrystalline (MCC) from Fiber of Empty Fruit Bunch Palm Oil

    NASA Astrophysics Data System (ADS)

    Nasution, H.; Yurnaliza; Veronicha; Irmadani; Sitompul, S.

    2017-03-01

    Alpha cellulose which was isolated from cellulose of fiber empty fruit bunch palm oil was hidrolized with hydrochloric acid (2,5N) at 80°C to produce microcrystalline cellulose (MCC). Microcrystalline cellulose is an important additional ingredient in the pharmaceutical, food, cosmetics, and structural composites. In this study, MCC, alpha cellulose, and cellulose were characterized and thereafter were compared. Characterizations were made using some equipment such as x-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and thermogravimetry analyzer (TGA). X-ray diffraction and infrared spectroscopy were studied to determine crystallinity and molecular structure of MCC, where scanning electron microscopy images were conducted for information about morfology of MCC. Meanwhile, thermal resistance of MCC was determined using thermogravimetry analyzer (TGA). From XRD and FTIR, the obtained results showed that the crystalline part was traced on MCC, where the -OH and C-O groups tended to reduced as alpha cellulose has changed to MCC. From SEM the image showed the reduction of particle size of MCC, while the thermal resistance of MCC was found lower as compared with cellulose and alpha cellulose as well, which was attributed to the lower molecular weight of MCC.

  13. Application of ethyl cellulose, microcrystalline cellulose and octadecanol for wax based floating solid dispersion pellets.

    PubMed

    Yan, Hong-Xiang; Zhang, Shuang-Shuang; He, Jian-Hua; Liu, Jian-Ping

    2016-09-05

    The present study aimed to develop and optimize the wax based floating sustained-release dispersion pellets for a weakly acidic hydrophilic drug protocatechuic acid to achieve prolonged gastric residence time and improved bioavailability. This low-density drug delivery system consisted of octadecanol/microcrystalline cellulose mixture matrix pellet cores prepared by extrusion-spheronization technique, coated with drug/ethyl cellulose 100cp solid dispersion using single-step fluid-bed coating method. The formulation-optimized pellets could maintain excellent floating state without lag time and sustain the drug release efficiently for 12h based on non-Fickian transport mechanism. Observed by SEM, the optimized pellet was the dispersion-layered spherical structure containing a compact inner core. DSC, XRD and FTIR analysis revealed drug was uniformly dispersed in the amorphous molecule form and had no significant physicochemical interactions with the polymer dispersion carrier. The stability study of the resultant pellets further proved the rationality and integrity of the developed formulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Extraction of cellulose microcrystalline from galam wood for biopolymer

    NASA Astrophysics Data System (ADS)

    Ismail, Ika; Sa'adiyah, Devy; Rahajeng, Putri; Suprayitno, Abdi; Andiana, Rocky

    2018-04-01

    Consumption of plastic raw materials tends to increase, but until now the meet of the consumption of plastic raw are still low, even some are still imported. Nowadays, Indonesia's plastic needs are supported by petrochemicals where raw materials are still dependent abroad and petropolymer raw materials are derived from petroleum which will soon be depleted due to rising petroleum needs. Therefore, various studies have been conducted to develop natural fiber-based polymers that are biodegradable and abundant in nature. It is because the natural polymer production process is very efficient and very environmentally friendly. There have been many studies of biopolymers especially natural fiber-based polymers from plants, due to plants containing cellulose, hemicellulose and lignin. However, cellulose is the only one who has crystalline structures. Cellulose has a high crystality compared to amorphous lignin and hemicellulose. In this study, extracted cellulose as biopolymer and amplifier on composite. The cellulose is extracted from galam wood from East Kalimantan. Cellulose extraction will be obtained in nano / micro form through chemical and mechanical treatment processes. The chemical treatment of cellulose extraction is alkalinization process using NaOH solution, bleaching using NaClO2 and acid hydrolysis using sulfuric acid. After chemical treatment, ultrasonic mechanical treatment is made to make cellulose fibers into micro or nano size. Besides, cellulose results will be characterized. Characterization was performed to analyze molecules of cellulose compounds extracted from plants using Fourier Transformation Infra Red (FTIR) testing. XRD testing to analyze cellulose crystallinity. Scanning Electron Microscope (SEM) test to analyze morphology and fiber size.

  15. The Solubility of Microcrystalline Cellulose in Sodium Hydroxide Solution Is Inconsistent with International Specifications.

    PubMed

    Kodama, Hanayo; Tamura, Yoshinaga; Kamei, Ichiro; Sato, Kyoko; Akiyama, Hiroshi

    2017-01-01

    Microcrystalline cellulose (MCC) is used globally as an inactive ingredient in food and nutraceutical products and is commonly used as a food additive. To confirm the conformity of MCC to the solubility requirements stipulated in international specifications, the solubilities of commercially available MCC products were tested in sodium hydroxide (NaOH) solution. All of the samples were insoluble in NaOH solution, which is inconsistent with the descriptions provided in international specifications. We also prepared celluloses with different degree of polymerization (DP) values by acid hydrolysis. Celluloses with lower DP were prepared using a three-step process, and their solubilities were tested in NaOH solution. These celluloses were found to be insoluble, which is inconsistent with the descriptions provided in international specifications. The present study suggests that the descriptions of the solubility of the celluloses in NaOH solution found in the current international specifications should be revised.

  16. Surface Photochemistry: 3,3′-Dialkylthia and Selenocarbocyanine Dyes Adsorbed onto Microcrystalline Cellulose

    PubMed Central

    Vieira Ferreira, Luís F.; Ferreira, Diana P.; Duarte, Paulo; Oliveira, A. S.; Torres, E.; Machado, I. Ferreira; Almeida, P.; Reis, Lucinda V.; Santos, Paulo F.

    2012-01-01

    In this work, thia and selenocarbocyanines with n-alkyl chains of different length, namely with methyl, ethyl, propyl, hexyl and decyl substituents, were studied in homogeneous and heterogeneous media for comparison purposes. For both carbocyanine dyes adsorbed onto microcrystalline cellulose, a remarkable increase in the fluorescence quantum yields and lifetimes were detected, when compared with solution. Contrary to the solution behaviour, where the increase in the n-alkyl chains length increases to a certain extent the fluorescence emission ΦF and τF, on powdered solid samples a decrease of ΦF and τF was observed. The use of an integrating sphere enabled us to obtain absolute ΦF’s for all the powdered samples. The main difference for liquid homogeneous samples is that the increase of the alkyl chain strongly decreases the ΦF values, both for thiacarbocyanines and selenocarbocyanines. A lifetime distribution analysis for the fluorescence of these dyes adsorbed onto microcrystalline cellulose, evidenced location on the ordered and crystalline part of the substrate, as well as on the more disordered region where the lifetime is smaller. The increase of the n-alkyl chains length decreases the photoisomer emission for the dyes adsorbed onto microcrystalline cellulose, as detected for high fluences of the laser excitation, for most samples. PMID:22312274

  17. Processing and characterization of polyols plasticized-starch reinforced with microcrystalline cellulose.

    PubMed

    Rico, M; Rodríguez-Llamazares, S; Barral, L; Bouza, R; Montero, B

    2016-09-20

    Biocomposites suitable for short-life applications such as food packaging were prepared by melt processing and investigated. Biocomposites studied are wheat starch plasticized with two different molecular weight polyols (glycerol and sorbitol) and reinforced with various amounts of microcrystalline cellulose. The effect of the plasticizer type and the filler amount on the processing properties, the crystallization behavior and morphology developed for the materials, and the influence on thermal stability, dynamic mechanical properties and water absorption behavior were investigated. Addition of microcrystalline cellulose led to composites with good filler-matrix adhesion where the stiffness and resistance to humidity absorption were improved. The use of sorbitol as a plasticizer of starch also improved the stiffness and water uptake behavior of the material as well as its thermal stability. Biodegradable starch-based materials with a wide variety of properties can be tailored by varying the polyol plasticizer type and/or by adding microcrystalline cellulose filler. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Water-in-oil Pickering emulsions stabilized by stearoylated microcrystalline cellulose.

    PubMed

    Pang, Bo; Liu, Huan; Liu, Peiwen; Peng, Xinwen; Zhang, Kai

    2018-03-01

    Hydrophobic particles with static water contact angles larger than 90° are more like to stabilize W/O Pickering emulsions. In particular, high internal phase Pickering emulsions (HIPEs) are of great interest for diverse applications. However, W/O HIPEs have rarely been realized using sustainable biopolymers. Herein, we used stearoylated microcrystalline cellulose (SMCC) to stabilize W/O Pickering emulsions and especially, W/O HIPEs. Moreover, these W/O HIPEs can be further used as platforms for the preparation of porous materials, such as porous foams. Stearoylated microcrystalline cellulose (SMCC) was prepared by modifying MCC with stearoyl chloride under heterogeneous conditions. Using SMCC as emulsifiers, W/O medium and high internal phase Pickering emulsions (MIPEs and HIPEs) with various organic solvents as continuous phases were prepared using one-step and two-step methods, respectively. Polystyrene (PS) foams were prepared after polymerization of oil phase using HIPEs as templates and their oil/water separation capacity were studied. SMCC could efficiently stabilize W/O Pickering emulsions and HIPEs could only be prepared via the two-step method. The internal phase volume fraction of the SMCC-stabilized HIPEs reached as high as 89%. Diverse internal phase volume fractions led to distinct inner structures of foams with closed or open cells. These macroporous polystyrene (PS) foams demonstrated great potential for the effective absorption of organic solvents from underwater. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Comparative secretomic analysis of lignocellulose degradation by Lentinula edodes grown on microcrystalline cellulose, lignosulfonate and glucose.

    PubMed

    Cai, Yingli; Gong, Yuhua; Liu, Wei; Hu, Yue; Chen, Lianfu; Yan, Lianlian; Zhou, Yan; Bian, Yinbing

    2017-06-23

    Lentinula edodes has the potential to degrade woody and nonwoody lignocellulosic biomass. However, the mechanism of lignocellulose degradation by L. edodes is unclear. The aim of this work is to explore the profiling of soluble secreted proteins involved in lignocellulose degradation in L. edodes. For that, we compared the secretomes of L. edodes grown on microcrystalline cellulose, cellulose with lignosulfonate and glucose. Based on nanoliquid chromatography coupled with tandem mass spectrometry of whole-protein hydrolysate, 230 proteins were identified. Label-free proteomic analysis showed that the most abundant carbohydrate-active enzymes involved in polysaccharide hydrolysis were endo-β-1,4-glucanase, α-galactosidase, polygalacturonase and glucoamylase in both cellulosic secretomes. In contrast, enzymes involved in lignin degradation were most abundant in glucose culture, with laccase 1 being the predominant protein (13.13%). When the cellulose and cellulose with lignosulfonate secretomes were compared, the abundance of cellulases and hemicellulases was higher in cellulose with lignosulfonate cultures, which was confirmed by enzyme activity assays. In addition, qRT-PCR analysis demonstrated that the expression levels of genes encoding cellulases and hemicellulases were significantly increased (by 32.2- to 1166.7-fold) when L. edodes was grown in cellulose with lignosulfonate medium. In this article, the secretomes of L. edodes grown on three different carbon sources were compared. The presented results revealed the profiling of extracellular enzymes involved in lignocellulose degradation, which is helpful to further explore the mechanism of biomass bioconversion by L. edodes. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Preparation of acetylated nanofibrillated cellulose from corn stalk microcrystalline cellulose and its reinforcing effect on starch films.

    PubMed

    Cheng, Li; Zhang, Dongli; Gu, Zhengbiao; Li, Zhaofeng; Hong, Yan; Li, Caiming

    2018-05-01

    Acetylated nanofibrillated cellulose (ANFC) with different degrees of substitution (DS) was prepared from corn-stalk microcrystalline cellulose (MCC) using chemical-mechanical combined processes. The physicochemical properties of nanofibrillated cellulose (NFC) and ANFC were investigated together with the influence of added nanoparticles on the mechanical properties of starch films. The acetylation reaction was monitored by Fourier transform infrared (FT-IR) and titration. Particle size and morphological of NFC and ANFC were studied by atomic force microscope (AFM). The results suggested that NFC had nano-order-unit web-like network with mean diameter of ~24 nm. The thermostability of all samples was found to decrease as the modification extent rose, and mechanical disposal revealed no significant influence on the DS and crystalline structure of cellulose. The ANFC with the DS value of 0.35 demonstrated the best enhancement effect on starch films, with increased tension strength (TS) by 201%. The tensile tests confirmed that the web-like network structure of NFC was more conducive to strength, and proper chemical modification could improve the uniform dispersion of nano-fillers in starch to result in higher strength performances. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Structure-property relationships of Thai silk-microcrystalline cellulose biocomposite materials fabricated from ionic liquid.

    PubMed

    DeFrates, Kelsey; Markiewicz, Theodore; Callaway, Kayla; Xue, Ye; Stanton, John; Salas-de la Cruz, David; Hu, Xiao

    2017-11-01

    Biomaterials made from natural proteins and polysaccharides have become increasingly popular in the biomedical field due to their good biocompatibility and tunable biodegradability. However, the low miscibility of polysaccharides with proteins presents challenges in the creation of protein-polysaccharide composite materials. In this study, neat 1-allyl-3-methylimidazolium chloride (AMIMCl) ionic liquid was used to regenerate Thailand gold Bombyx mori silk and microcrystalline cellulose blended films. This solvent was found to not only effectively dissolve both natural polymers, but also preserve the structure and integrity of the polymers. A single glass transition temperature for each blend was found in DSC curves, indicating good miscibility between the Thai silk and cellulose molecules. The structural composition as well as the morphology and thermal stability of blend films were then determined using FTIR, SEM and TGA. It was found that by varying the ratio of Thai silk to cellulose, the thermal and physical properties of the material could be tuned. Blended films tended to be more thermally stable which could be due to the presence of hydrophobic-hydrophobic or electrostatic interactions between the silk and cellulose. These studies offered a new pathway to understand the tunable properties of protein-polysaccharide composite biomaterials with controllable physical and biological properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Effect of environmental conditions on the mechanical properties and fungal degradation of polycaprolactone/microcrystalline cellulose/wood flour composites

    Treesearch

    Ronald Sabo; Liwei Jin; Nicole Stark; Rebecca E. Ibach

    2013-01-01

    Polycaprolactone (PCL) filled with microcrystalline cellulose (MCC), wood flour (WF), or both were characterized before and after exposure to various environmental conditions for 60 days. PCL/WF composites had the greatest tensile strength and modulus compared to neat PCL or PCL composites containing MCC. Electron microscopy indicated better adhesion between WF...

  3. Facile synthesis of TiO2/microcrystalline cellulose nanocomposites: photocatalytically active material under visible light irradiation

    EPA Science Inventory

    Doped TiO2 nanocomposites were prepared in situ by a facile and simple synthesis utilizing benign and renewable precursors such as microcrystalline cellulose (MC) and TiCl4 through hydrolysis in alkaline medium without the addition of organic solvents. The as-prepared nanocompos...

  4. Production of bacterial cellulose from alternate feedstocks

    SciTech Connect

    D. N. Thompson; M. A. Hamilton

    2000-05-07

    Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents included low- and high-solids potato effluents (LS and HS), cheese whey permeate (CW), and sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did 10821, and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, while LS was unsuitable for production by 10821. However, 23770 produced 17% more cellulose from LS than from glucose, indicating unamended LS could serve as a feedstock for bacterial cellulose.

  5. Production of Bacterial Cellulose from Alternate Feedstocks

    SciTech Connect

    Thompson, David Neil; Hamilton, Melinda Ann

    2000-05-01

    Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents included low- and high-solids potato effluents (LS & HS), cheese whey permeate (CW), and sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did 10821, and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, while LS was unsuitable for production by 10821. However, 23770 produced 17% more cellulose from LS than from glucose, indicating unamended LS could serve as a feedstock for bacterial cellulose.

  6. Sensing the Structural Differences in Cellulose from Apple and Bacterial Cell Wall Materials by Raman and FT-IR Spectroscopy

    PubMed Central

    Szymańska-Chargot, Monika; Cybulska, Justyna; Zdunek, Artur

    2011-01-01

    Raman and Fourier Transform Infrared (FT-IR) spectroscopy was used for assessment of structural differences of celluloses of various origins. Investigated celluloses were: bacterial celluloses cultured in presence of pectin and/or xyloglucan, as well as commercial celluloses and cellulose extracted from apple parenchyma. FT-IR spectra were used to estimate of the Iβ content, whereas Raman spectra were used to evaluate the degree of crystallinity of the cellulose. The crystallinity index (XCRAMAN%) varied from −25% for apple cellulose to 53% for microcrystalline commercial cellulose. Considering bacterial cellulose, addition of xyloglucan has an impact on the percentage content of cellulose Iβ. However, addition of only xyloglucan or only pectins to pure bacterial cellulose both resulted in a slight decrease of crystallinity. However, culturing bacterial cellulose in the presence of mixtures of xyloglucan and pectins results in an increase of crystallinity. The results confirmed that the higher degree of crystallinity, the broader the peak around 913 cm−1. Among all bacterial celluloses the bacterial cellulose cultured in presence of xyloglucan and pectin (BCPX) has the most similar structure to those observed in natural primary cell walls. PMID:22163913

  7. Extraction of microcrystalline cellulose from rice straw and its effect on polyvinyl alcohol biocomposites film

    NASA Astrophysics Data System (ADS)

    Chin, Kwok-Mern; Ting, Sam Sung; Lin, Ong Hui; Owi, Wei Tieng

    2017-07-01

    The poor management and underutilization of agricultural wastes had proliferated interest of researchers around the world to find alternatives to utilize them as potential value-added products. One of the green alternatives is by extracting cellulose from these waste materials and incorporating them in polymer as reinforcement fillers. The surging amount of plastic waste also posed major issues to the environment due to its recalcitrance to degrade. Microcrystalline cellulose (MCC-RS) was extracted from rice straw through cyclic alkaline and bleaching treatment to remove hemicellulose and lignin respectively. Polyvinyl alcohol (PVOH) was chosen as the matrix and different ratios of PVOH / MCC-RS films were prepared (2.5, 5.0, 7.5 and 10.0wt% of MCC) through solution casting method and its tensile, thermal and morphological properties were studied. X-ray powder diffraction (XRD) results showed increased crystallinity of MCC-RS after chemical treatment (from 44.5% to 60.8%) due to the successful removal of lignin and hemicellulose, which was then confirmed with Fourier transform infrared spectroscopy (FTIR) results. For the biocomposites, both tensile strength and Young's modulus of the films increased with increasing MCC-RS content up until 7.5wt%, supported with scanning electron microscopy (SEM) results which depicted improvement in the interfacial adhesion between MCC-RS and PVOH. From the overall results, the improvement in properties of biocomposite from cellulose-based microfiller had shown promising future in application of the water soluble plastic packaging industry.

  8. Improved enzymatic hydrolysis of microcrystalline cellulose (Avicel PH101) by polyethylene glycol addition.

    PubMed

    Ouyang, Jia; Dong, Zhenwei; Song, Xiangyang; Lee, Xin; Chen, Mu; Yong, Qiang

    2010-09-01

    The effects of additives on hydrolysis of microcrystalline cellulose (Avicel PH101) were examined using commercial cellulose-degrading enzymes (Celluclast 1.5L and Novozyme 188). Polyethylene glycol 4000 (PEG4000) was the most effective additive tested. When PEG4000 was added at 0.05 g/g glucan, the conversion of Avicel PH101 increased 91% (from 41.1% to 78.9%). The cellulase activity of Celluclast 1.5L increased 27.5% with PEG4000 addition. A positive effect on enzyme stabilities of Celluclast 1.5L and Novozyme 188 also occurred with PEG4000 addition. During hydrolysis process, significant changes in free protein concentration and cellulase activity were observed on Avicel PH101. More than 90% of the original enzyme activity remained in the solution after 48 h hydrolysis. Thus, PEG4000 addition is an efficient method to enhance digestibility of cellulosic materials and make enzyme recovery possible and valuable. This provides an opportunity of decreasing the operational cost of the hydrolysis process. (c) 2010 Elsevier Ltd. All rights reserved.

  9. A diffuse reflectance comparative study of benzil inclusion within microcrystalline cellulose and beta-cyclodextrin.

    PubMed

    Vieira Ferreira, Luis F; Ferreira Machado, Isabel; Da Silva, José P; Oliveira, Anabela S

    2004-02-01

    Diffuse reflectance and laser-induced techniques were used to study photochemical and photophysical processes of benzil adsorbed on two solid powdered supports, microcrystalline cellulose and [small beta]-cyclodextrin. In both substrates, a distribution of ground-state benzil conformers exists, largely dominated by skew conformations where the carbonyl groups are twisted one to the other. Room temperature phosphorescence was observed in air-equilibrated samples in both cases. The decay times vary greatly and the largest lifetime was obtained for benzil/[small beta]-cyclodextrin, showing that this host's cavity accommodates benzil well, enhancing its room temperature phosphorescence. Triplet-triplet absorption of benzil entrapped in cellulose was detected and benzil ketyl radical formation also occurred. With benzil included into [small beta]-cyclodextrin, and following laser excitation, benzoyl radicals were detected on the millisecond timescale. Product analysis and identification of laser-irradiated benzil samples in the two hosts clearly showed that the main degradation photoproducts were benzoic acid and benzaldehyde. The main differences were a larger benzoic acid/benzaldehyde ratio in the case of cellulose and the formation of benzyl alcohol in this support.

  10. Conductivity percolation in loosely compacted microcrystalline cellulose: An in situ study by dielectric spectroscopy during densification.

    PubMed

    Nilsson, Martin; Frenning, Göran; Gråsjö, Johan; Alderborn, Göran; Strømme, Maria

    2006-10-19

    The present study aims at contributing to a complete understanding of the water-induced ionic charge transport in cellulose. The behavior of this transport in loosely compacted microcrystalline cellulose (MCC) powder was investigated as a function of density utilizing a new type of measurement setup, allowing for dielectric spectroscopy measurement in situ during compaction. The ionic conductivity in MCC was found to increase with increasing density until a leveling-out was observed for densities above approximately 0.7 g/cm3. Further, it was shown that the ionic conductivity vs density followed a percolation type behavior signifying the percolation of conductive paths in a 3D conducting network. The density percolation threshold was found to be between approximately 0.2 and 0.4 g/cm3, depending strongly on the cellulose moisture content. The observed percolation behavior was attributed to the forming of interparticulate bonds in the MCC and the percolation threshold dependence on moisture was linked to the moisture dependence of particle rearrangement and plastic deformation in MCC during compaction. The obtained results add to the understanding of the density-dependent water-induced ionic transport in cellulose showing that, at given moisture content, the two major parameters determining the magnitude of the conductivity are the connectedness of the interparticluate bonds and the connectedness of pores with a diameter in the 5-20 nm size range. At densities between approximately 0.7 and 1.2 g/cm3 both the bond and the pore networks have percolated, facilitating charge transport through the MCC compact.

  11. Composite edible films based on hydroxypropyl methyl cellulose reinforced with microcrystalline cellulose nanoparticles

    USDA-ARS?s Scientific Manuscript database

    It has been stated that hydroxypropyl methyl cellulose (HPMC) based films have promising applications in the food industry because of their environmental appeal, low cost, flexibility and transparency. Nevertheless, their mechanical and moisture barrier properties should be improved. The aim of th...

  12. The rheological properties of modified microcrystalline cellulose containing high levels of model drugs.

    PubMed

    Knight, Paul E; Podczeck, Fridrun; Newton, J Michael

    2009-06-01

    The rheological properties of different types of microcrystalline cellulose (MCC) mixed with model drugs and water have been evaluated to identify the influence of sodium carboxymethylcellulose (SCMC) added to the cellulose during preparation. A ram extruder was used as a capillary rheometer. The mixtures consisted of 20% spheronizing agent (standard grade MCC or modified types with 6% or 8% of low viscosity grade SCMC) and 80% of ascorbic acid, ibuprofen or lactose monohydrate. The introduction of SCMC changed all rheological parameters assessed. It produced more rigid systems, requiring more stress to induce and maintain flow. Degree of non-Newtonian flow, angle of convergence, extensional viscosity, yield and die land shear stress at zero velocity, and static wall friction were increased, but recoverable shear and compliance were decreased. The presence of SCMC did not remove the influence of the type of drug. The mixture of ibuprofen and standard MCC had the lowest values for shear stress as a function of the rate of shear, extensional viscosity, and angle of convergence, but the highest values for recoverable shear and compliance. The findings indicate that the system has insufficient rigidity to form pellets. (c) 2008 Wiley-Liss, Inc.

  13. The Disintegration Process in Microcrystalline Cellulose Based Tablets, Part 1: Influence of Temperature, Porosity and Superdisintegrants

    PubMed Central

    Yassin, Samy; Goodwin, Daniel J; Anderson, Andrew; Sibik, Juraj; Wilson, D Ian; Gladden, Lynn F; Zeitler, J Axel

    2015-01-01

    Disintegration performance was measured by analysing both water ingress and tablet swelling of pure microcrystalline cellulose (MCC) and in mixture with croscarmellose sodium using terahertz pulsed imaging (TPI). Tablets made from pure MCC with porosities of 10% and 15% showed similar swelling and transport kinetics: within the first 15 s, tablets had swollen by up to 33% of their original thickness and water had fully penetrated the tablet following Darcy flow kinetics. In contrast, MCC tablets with a porosity of 5% exhibited much slower transport kinetics, with swelling to only 17% of their original thickness and full water penetration reached after 100 s, dominated by case II transport kinetics. The effect of adding superdisintegrant to the formulation and varying the temperature of the dissolution medium between 20°C and 37°C on the swelling and transport process was quantified. We have demonstrated that TPI can be used to non-invasively analyse the complex disintegration kinetics of formulations that take place on timescales of seconds and is a promising tool to better understand the effect of dosage form microstructure on its performance. By relating immediate-release formulations to mathematical models used to describe controlled release formulations, it becomes possible to use this data for formulation design. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3440–3450, 2015 PMID:26073446

  14. Evaluation of several microcrystalline celluloses obtained from agricultural by-products

    PubMed Central

    Rojas, John; Lopez, Alvin; Guisao, Santiago; Ortiz, Carlos

    2011-01-01

    Microcrystalline cellulose (MCCI) has been widely used as an excipient for direct compression due to its good flowability, compressibility, and compactibility. In this study, MCCI was obtained from agricultural by-products, such as corn cob, sugar cane bagasse, rice husk, and cotton by pursuing acid hydrolysis, neutralization, clarification, and drying steps. Further, infrared spectroscopy (IR), X-ray diffraction (XRD), optical microscopy, degree of polymerization (DP), and powder and tableting properties were evaluated and compared to those of Avicel PH101, Avicel PH102, and Avicel PH200. Except for the commercial products, all materials showed a DP from 55 to 97. Particles of commercial products and corn cob had an irregular shape, whereas bagasse particles were elongated and thick. Rice and cotton particles exhibited a flake-like and fiber-like shape, respectively. MCCI as obtained from rice husk and cotton was the most densified material, while that produced from corn cob and bagasse was bulky, porous, and more compressible. All products had a moisture content of less than 10% and yields from 7.4% to 60.4%. MCCI as obtained from bagasse was the most porous and compressible material among all materials. This product also showed the best tableting properties along with Avicel products. Likewise, all MCCI products obtained from the above-mentioned sources showed a more rapid disintegration time than that of Avicel products. These materials can be used as a potential source of MCCI in the production of solid dosage forms. PMID:22171310

  15. A study of the properties of compacts from silicified microcrystalline celluloses.

    PubMed

    Muzíková, Jitka; Nováková, Petra

    2007-07-01

    The paper deals with a study of tensile strength and disintegration time of compacts made from silicified microcrystalline celluloses, Prosolv SMCC 90, and Prosolv HD 90, in dependence on compression force, addition of two types of lubricants, and two active ingredients. The lubricants were magnesium stearate and sodium stearyl fumarate in a concentration of 0.5%, the active ingredients being ascorbic acid and acetylsalicylic acid in a concentration of 50%. Prosolv SMCC 90 proved to be better compatible than Prosolv HD 90; the compacts were of higher strength, which was markedly increased with increasing compression force. Prosolv HD 90 was more sensitive to additions of lubricants, and a greater decrease in strength was recorded due to the influence of sodium stearyl fumarate. The effect of lubricants on the strength of compacts in the presence of active ingredients was not identical. The disintegration time of compacts from Prosolv HD 90 without as well as with lubricants was shorter than from Prosolv SMCC 90 and was increasing with increasing compression force. Disintegration time was increased with added lubricants, and it was markedly shortened by addition of active ingredients. Compacts containing ascorbic acid possessed a shorter disintegration time than those containing acetylsalicylic acid, and it was not markedly influenced by the presence of lubricants.

  16. Compression parameters of hexagonal boron nitride on direct compression mixture of microcrystalline cellulose and modified starch.

    PubMed

    Halaçoğlu, Mekin Doğa; Uğurlu, Timuçin

    2015-01-01

    The objective of this study was to investigate the effects of conventional lubricants including a new candidate lubricant "hexagonal boron nitride (HBN)" on direct compression powders. Lubricants such as magnesium stearate (MGST), glyceryl behenate, stearic acid, talc and polyethylene glycol6000 were studied and tablets were manufactured on a single station instrumented tablet press. This study comprised the continuation of our previous one, so mixture of microcrystalline cellulose and modified starch was used as a master formula to evaluate effects of lubricants on pharmaceutical excipients that undergo complete plastic deformation without any fragmentation under compression pressure. Bulk and tapped densities, and Carr's index parameters were calculated for powders. Tensile strength, cohesion index, lower punch ejection force and lubricant effectiveness values were investigated for tablets. The deformation mechanisms of tablets were studied during compression from the Heckel plots with or without lubricant. MGST was found to be the most effective lubricant and HBN was found very close to it. HBN did not show a significant negative effect on the crushing strength and disintegration time of the tablets when we compared with MGST. Based on the Heckel plots at the level of 1%, formulation prepared with HBN showed the most pronounced plastic character.

  17. A study of a co-processed dry binder composed of microcrystalline cellulose and glycerol monostearate.

    PubMed

    Mužíková, Jitka; Muchová, Sandra

    2012-10-01

    The paper studies the co-processed dry binder LubriToseTM MCC from the viewpoint of energy evaluation of the compression process, strength and disintegration time of tablets. The results were compared with the identical evaluation of physical mixtures of microcrystalline cellulose with several types of lubricants. LubriTose MCC showed the lowest value of energy for friction, the highest value of energy accumulated by the tablet, and the highest plasticity of all tableting materials under study. There were no marked differences in the values of the energy of decompression. The tensile strength of tablets from LubriTose MCC was lower than in those from the mixture of Vivapur® 12 and glycerol monostearate, in the compression forces of 4 and 5 kN it was comparable with the tensile strength of tablets from Vivapur 12 with Poloxamer 407. Disintegration time of tablets from LubriTose MCC was shorter than that of those from Vivapur 12 with glycerol monostearate at the compression force of 3 kN, in the case of the compression forces of 4 and 5 kN no statistically significant difference was found between the values of these tableting materials.

  18. EFFECT OF SIMULTANEOUSLY SILICIFIED MICROCRYSTALLINE CELLULOSE AND PREGELATINIZED STARCH ON THE THEOPHYLLINE TABLETS STABILITY.

    PubMed

    Mazurek-Wadołkowska, Edyta; Winnicka, Katarzyna; Czyzewska, Urszula; Miltyk, Wojciech

    2016-07-01

    High profitability and simplicity of direct compression, encourages pharmaceutical industry to create universal excipients to improve technology process. Prosolv® SMCC - silicified microcrystalline cellulose and Starch 1500® - pregelatinized starch, are the example of multifunctional excipients. The aim of the present study was to evaluate the stability of theophylline (API) in the mixtures with excipients with various physico-chemical properties (Prosolv® SMCC 90, Prosolv® SMCC HD 90, Prosolv* SMCC 50®, Starch 1500® and magnesium stearate). The study presents results of thermal analysis of the mixtures with theophylline before and after 6 months storage of the tablets at various temperatures and relative humidity conditions (25 ± 2°C/40 ± 5% RH, 40 ± 2°C/75 ± 5% RH). It was shown that high concentration of Starch 1500® (49%) affects the stability of the theophylline tablets with Prosolv® SMCC. Prosolv® SMCC had no effect on API stability as confirmed by the differential scanning calorimetry (DSC). Changes in peak placements were observed just after tabletting process, which might indicate that compression accelerated the incompatibilities between theophylline and Starch 1500. TGA analysis showed loss in tablets mass equal to water content in starch. GC-MS study established no chemical decomposition of theophylline. We demonstrated that high content of Starch 1500® (49%) in the tablet mass, affects stability on tablets containing theophylline and Prosolv® SMCC.

  19. The Disintegration Process in Microcrystalline Cellulose Based Tablets, Part 1: Influence of Temperature, Porosity and Superdisintegrants.

    PubMed

    Yassin, Samy; Goodwin, Daniel J; Anderson, Andrew; Sibik, Juraj; Wilson, D Ian; Gladden, Lynn F; Zeitler, J Axel

    2015-10-01

    Disintegration performance was measured by analysing both water ingress and tablet swelling of pure microcrystalline cellulose (MCC) and in mixture with croscarmellose sodium using terahertz pulsed imaging (TPI). Tablets made from pure MCC with porosities of 10% and 15% showed similar swelling and transport kinetics: within the first 15 s, tablets had swollen by up to 33% of their original thickness and water had fully penetrated the tablet following Darcy flow kinetics. In contrast, MCC tablets with a porosity of 5% exhibited much slower transport kinetics, with swelling to only 17% of their original thickness and full water penetration reached after 100 s, dominated by case II transport kinetics. The effect of adding superdisintegrant to the formulation and varying the temperature of the dissolution medium between 20°C and 37°C on the swelling and transport process was quantified. We have demonstrated that TPI can be used to non-invasively analyse the complex disintegration kinetics of formulations that take place on timescales of seconds and is a promising tool to better understand the effect of dosage form microstructure on its performance. By relating immediate-release formulations to mathematical models used to describe controlled release formulations, it becomes possible to use this data for formulation design. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3440-3450, 2015. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association.

  20. Simulation of roller compaction with subsequent tableting and characterization of lactose and microcrystalline cellulose.

    PubMed

    Hein, Stephanie; Picker-Freyer, Katharina M; Langridge, John

    2008-01-01

    Tablets are by far the most common solid oral dosage forms, and many drugs need to be granulated before they can be tableted. Increasingly roller compaction is being used as a dry granulation technique; however it is a very time and material intensive method. Thus some mini roller compactors and simulations of the roller compaction process have been developed as a means of studying the technique at small scale. An important factor in the selection of materials for roller compaction is their ability to be recompressed into tablets after the initial roller compaction and milling steps. In this paper the roller compaction process was simulated on the basis of some models by Gereg and Cappola (2002) and Zinchuk et al. (2004). An eccentric tableting machine was used to make compacts from alpha-lactose monohydrate, anhydrous beta-lactose, spray-dried lactose and microcrystalline cellulose at different maximum relative densities (rho rel,max 0.6-0.9). These compacts were milled immediately to granules with a rotary granulator. The properties of the granules were analyzed and compared to the properties of the original powders. These granules and powders were then tableted at different maximum relative densities (rho rel,max 0.75-0.95) and their properties including elastic recovery, crushing force and 3D-model were analyzed. The properties of the tablets made from the granules were compared to the properties of the tablets made from the powders to determine which excipients are most suitable for the roller compaction process. The study showed that anhydrous beta-lactose is the preferred form of lactose for use in roller compaction since compaction did not affect tablet crushing force to a large extent. With the simulation of roller compaction process one is able to find qualified materials for use in roller compaction without the necessity of a great deal of material and time.

  1. Synthesis, characterization and adsorption properties of microcrystalline cellulose based nanogel for dyes and heavy metals removal.

    PubMed

    El-Naggar, Mehrez E; Radwan, Emad K; El-Wakeel, Shaimaa T; Kafafy, Hany; Gad-Allah, Tarek A; El-Kalliny, Amer S; Shaheen, Tharwat I

    2018-07-01

    Recently, naturally occurring biopolymers have attracted the attention as potential adsorbents for the removal of water contaminants. In this work, we present the development of microcrystalline cellulose (MCC)-based nanogel grafted with acrylamide and acrylic acid in the presence of methylene bisacrylamide and potassium persulphate as a crosslinking agent and initiator, respectively. World-class facilities such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), surface analysis, field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and zeta sizer were used to characterize the synthesized MCC based nanogel. The prepared nanogel was applied to remove reactive red 195 (RR195) dye and Cd (II) from aqueous medium at different operational conditions. The adsorption experiments showed that the feed concentration of monomers has a significant effect on the removal of RR195 which peaked (93% removal) after 10min of contact time at pH2 and a dose of 1.5g/L. On contrary, the feed concentration has insignificant effect on the removal of Cd (II) which peaked (97% removal) after 30min of contact time at pH6 and a dose of 0.5g/L. The adsorption equilibrium data of RR195 and Cd (II) was best described by Freundlich and Langmuir, respectively. Conclusively, the prepared MCC based nanogels were proved as promising adsorbents for the removal of organic pollutants as well as heavy metals. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Influence of alkaline hydrogen peroxide pre-hydrolysis on the isolation of microcrystalline cellulose from oil palm fronds.

    PubMed

    Owolabi, Abdulwahab F; Haafiz, M K Mohamad; Hossain, Md Sohrab; Hussin, M Hazwan; Fazita, M R Nurul

    2017-02-01

    In the present study, microcrystalline cellulose (MCC) was isolated from oil palm fronds (OPF) using chemo-mechanical process. Wherein, alkaline hydrogen peroxide (AHP) was utilized to extract OPF fibre at different AHP concentrations. The OPF pulp fibre was then bleached with acidified sodium chlorite solution followed by the acid hydrolysis using hydrochloric acid. Several analytical methods were conducted to determine the influence of AHP concentration on thermal properties, morphological properties, microscopic and crystalline behaviour of isolated MCC. Results showed that the MCC extracted from OPF fibres had fibre diameters of 7.55-9.11nm. X-ray diffraction (XRD) analyses revealed that the obtained microcrystalline fibre had both celluloses I and cellulose II polymorphs structure, depending on the AHP concentrations. The Fourier transmission infrared (FTIR) analyses showed that the AHP pre-hydrolysis was successfully removed hemicelluloses and lignin from the OPF fibre. The crystallinity of the MCC was increased with the AHP concentrations. The degradation temperature of MCC was about 300°C. The finding of the present study showed that pre-treatment process potentially influenced the quality of the isolation of MCC from oil palm fronds. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. The effect of pulping concentration treatment on the properties of microcrystalline cellulose powder obtained from waste paper.

    PubMed

    Okwonna, Okumneme O

    2013-10-15

    Microcrystalline cellulose (MCC) powder was isolated from three grades of waste paper: book, Groundwood/Newsprint and paperboard, through the processes of pulping and hydrolysis. Pulping treatment on these grades of waste paper was done using varying concentrations of caustic soda. Effects of the concentration of the pulping medium on the thermal and kinetic properties were investigated. Also determined were the effects of this on the physico-chemical properties. The chemical structure was characterized using an infrared spectroscopy (FTIR). Results showed these properties to be affected by the concentration of the pulping medium. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. A study of a novel coprocessed dry binder composed of α-lactose monohydrate, microcrystalline cellulose and corn starch.

    PubMed

    Mužíková, Jitka; Srbová, Alena; Svačinová, Petra

    2017-12-01

    This paper deals with a study of the novel coprocessed dry binder Combilac®, which contains 70% of α-lactose monohydrate, 20% of microcrystalline cellulose and 10% of native corn starch. These tests include flow properties, compressibility, lubricant sensitivity, tensile strength and disintegration time of tablets. Compressibility is evaluated by means of the energy profile of compression process, test of stress relaxation and tablet strength. The above-mentioned parameters are also evaluated in the physical mixture of α-lactose monohydrate, microcrystalline cellulose and native corn starch and compared with Combilac. Combilac shows much better flowability than the physical mixture of the used dry binders. Its compressibility is better, tablets possess a higher tensile strength. Neither Combilac, nor the physical mixture can be compressed without lubricants due to high friction and sticking to the matrix. Combilac has a higher lubricant sensitivity than the physical mixture of the dry binders. Disintegration time of Combilac tablets is comparable with the disintegration time of tablets made from the physical mixture.

  5. Joint action of ultrasonic and Fe³⁺ to improve selectivity of acid hydrolysis for microcrystalline cellulose.

    PubMed

    Li, Jinbao; Qiang, Dandan; Zhang, Meiyun; Xiu, Huijuan; Zhang, Xiangrong

    2015-09-20

    In this study, the combination of Fe(3+)/HCl and ultrasonic treatment was applied to selectively hydrolyze cellulose for the preparation of microcrystalline cellulose (MCC). It was found that the crystallinity and specific surface area of hydrocellulose samples were higher (78.92% and 2.23581 m(2)g(-1), respectively), compared with the method that only used Fe(3+)/HCl catalyst without ultrasonic treatment. Meanwhile, the hydrolysate can be extracted and reused for cellulose hydrolysis for three runs, which was effective in saving the dosage of chemicals and reducing the pollution of the environment without affecting the properties of hydrocellulose. Moreover, the increased concentration of total reducing sugar (TRS) after three runs may be used as a valuable source in biofuels production. The technology of cellulose hydrolysis, by retaining the crystalline region for MCC products while promoting hydrolysis of amorphous region for further utilization is of great novelty, which may prove valuable in converting biomass into chemicals and biofuels, environmentally and economically. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. A novel process for synthesis of spherical nanocellulose by controlled hydrolysis of microcrystalline cellulose using anaerobic microbial consortium.

    PubMed

    Satyamurthy, P; Vigneshwaran, N

    2013-01-10

    Degradation of cellulose by anaerobic microbial consortium is brought about either by an exocellular process or by secretion of extracellular enzymes. In this work, a novel route for synthesis of nanocellulose is described where in an anaerobic microbial consortium enriched for cellulase producers is used for hydrolysis. Microcrystalline cellulose derived from cotton fibers was subjected to controlled hydrolysis by the anaerobic microbial consortium and the resultant nanocellulose was purified by differential centrifugation technique. The nanocellulose had a bimodal size distribution (43±13 and 119±9 nm) as revealed by atomic force microscopy. A maximum nanocellulose yield of 12.3% was achieved in a span of 7 days. While the conventional process of nanocellulose preparation using 63.5% (w/w) sulfuric acid resulted in the formation of whisker shaped nanocellulose with surface modified by sulfation, controlled hydrolysis by anaerobic microbial consortium yielded spherical nanocellulose also referred to as nano crystalline cellulose (NCC) without any surface modification as evidenced from Fourier transform infrared spectroscopy. Also, it scores over chemo-mechanical production of nanofibrillated cellulose by consuming less energy due to enzyme (cellulase) assisted catalysis. This implies the scope for use of microbial prepared nanocellulose in drug delivery and bio-medical applications requiring bio-compatibility. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Bacterial cellulose membrane as separation medium

    SciTech Connect

    Shibazaki, Hideki; Kuga, Shigenori; Onabe, Fumihiko

    1993-11-10

    A thin membrane of bacterial cellulose (BC) obtained from Acetobacter culture was tested for its performance as a dialysis membrane in aqueous systems. The BC membrane showed superior mechanical strength to that of a dialysis-grade regenerated cellulose membrane, allowing the use of a thinner membrane than the latter. As a result, the BC membrane gave higher permeation rates for poly(ethylene glycols) as probe solutes. The cutoff molecular weight of the original BC membrane, significantly greater than that of regenerated cellulose, could be modified by concentrated alkali treatments of the membrane. The nature of the change at the ultrastructural level causedmore » by the alkali treatments was studied by X-ray diffraction and scanning electron microscopy.« less

  8. Permeation study through bacterial cellulose membrane.

    PubMed

    Wu, Chengdong; Murtaza, Ghulam; Yameen, Muhammad Arfat; Aamir, Muhammad Naeem; Akhtar, Muhammad; Zhao, Yuhao

    2014-01-01

    Abstract: The objective of this study was to fabricate topical formulations of diclofenac diethylamine (DD) using isopropyl myristate (IPM) and isopropyl palmitate (IPP) as permeation enhancers. Franz cell and bacterial cellulose were used as analytical instrument and diffusion membrane, respectively. Permeation enhancers exhibited significant effect on the permeation characteristics of DD. It was concluded from the results that improved permeation of DD was observed when IPP was used as enhancer.

  9. The effect of deuteration on the structure of bacterial cellulose

    SciTech Connect

    Bali, Garima; Foston, Marcus; O'Neill, Hugh Michael

    2013-01-01

    ABSTRACT In vivo generated deuterated bacterial cellulose, cultivated from 100% deuterated glycerol in D2O medium, was analyzed for deuterium incorporation by ionic liquid dissolution and 2H and 1H nuclear magnetic resonance (NMR). A solution NMR method of the dissolved cellulose was used to determine that this bacterial cellulose had 85 % deuterium incorporation. Acetylation and 1H and 2H NMR of deuterated bacterial cellulose indicated near equal deuteration at all sites of the glucopyranosyl ring except C-6 which was partly deuterated. Despite the high level of deuterium incorporation there were no significant differences in the molecular and morphological properties were observedmore » for the deuterated and protio bacterial cellulose samples. The highly deuterated bacterial cellulose presented here can be used as a model substrate for studying cellulose biopolymer properties via future small angle neutron scattering (SANS) studies.« less

  10. Metallization of bacterial cellulose for electrical and electronic device manufacture

    DOEpatents

    Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Jansen, Valerie Malyvanh [Memphis, TN; Woodward, Jonathan [Knoxville, TN

    2011-06-07

    A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

  11. Metallization of bacterial cellulose for electrical and electronic device manufacture

    DOEpatents

    Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Jansen, Valerie Malyvanh [Memphis, TN; Woodward, Jonathan [Knoxville, TN

    2010-09-28

    A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

  12. Enzymatic properties of Thermoanaerobacterium thermosaccharolyticum β-glucosidase fused to Clostridium cellulovorans cellulose binding domain and its application in hydrolysis of microcrystalline cellulose.

    PubMed

    Zhao, Linguo; Pang, Qian; Xie, Jingcong; Pei, Jianjun; Wang, Fei; Fan, Song

    2013-11-14

    The complete degradation of the cellulose requires the synergistic action of endo-β-glucanase, exo-β-glucanase, and β-glucosidase. But endo-β-glucanase and exo-β-glucanase can be recovered by solid-liquid separation in cellulose hydrolysis by their cellulose binding domain (CBD), however, the β-glucosidases cannot be recovered because of most β-glucosidases without the CBD, so additional β-glucosidases are necessary for the next cellulose degradation. This will increase the cost of cellulose degradation. The glucose-tolerant β-glucosidase (BGL) from Thermoanaerobacterium thermosaccharolyticum DSM 571 was fused with cellulose binding domain (CBD) of Clostridium cellulovorans cellulosome anchoring protein by a peptide linker. The fusion enzyme (BGL-CBD) gene was overexpressed in Escherichia coli with the maximum β-glucosidase activity of 17 U/mL. Recombinant BGL-CBD was purified by heat treatment and following by Ni-NTA affinity. The enzymatic characteristics of the BGL-CBD showed optimal activities at pH 6.0 and 65°C. The fusion of CBD structure enhanced the hydrolytic efficiency of the BGL-CBD against cellobiose, which displayed a 6-fold increase in Vmax/Km in comparison with the BGL. A gram of cellulose was found to absorb 643 U of the fusion enzyme (BGL-CBD) in pH 6.0 at 50°C for 25 min with a high immobilization efficiency of 90%. Using the BGL-CBD as the catalyst, the yield of glucose reached a maximum of 90% from 100 g/L cellobiose and the BGL-CBD could retain over 85% activity after five batches with the yield of glucose all above 70%. The performance of the BGL-CBD on microcrystalline cellulose was also studied. The yield of the glucose was increased from 47% to 58% by adding the BGL-CBD to the cellulase, instead of adding the Novozyme 188. The hydrolytic activity of BGL-CBD is greater than that of the Novozyme 188 in cellulose degradation. The article provides a prospect to decrease significantly the operational cost of the hydrolysis process.

  13. Enzymatic properties of Thermoanaerobacterium thermosaccharolyticum β-glucosidase fused to Clostridium cellulovorans cellulose binding domain and its application in hydrolysis of microcrystalline cellulose

    PubMed Central

    2013-01-01

    Background The complete degradation of the cellulose requires the synergistic action of endo-β-glucanase, exo-β-glucanase, and β-glucosidase. But endo-β-glucanase and exo-β-glucanase can be recovered by solid–liquid separation in cellulose hydrolysis by their cellulose binding domain (CBD), however, the β-glucosidases cannot be recovered because of most β-glucosidases without the CBD, so additional β-glucosidases are necessary for the next cellulose degradation. This will increase the cost of cellulose degradation. Results The glucose-tolerant β-glucosidase (BGL) from Thermoanaerobacterium thermosaccharolyticum DSM 571 was fused with cellulose binding domain (CBD) of Clostridium cellulovorans cellulosome anchoring protein by a peptide linker. The fusion enzyme (BGL-CBD) gene was overexpressed in Escherichia coli with the maximum β-glucosidase activity of 17 U/mL. Recombinant BGL-CBD was purified by heat treatment and following by Ni-NTA affinity. The enzymatic characteristics of the BGL-CBD showed optimal activities at pH 6.0 and 65°C. The fusion of CBD structure enhanced the hydrolytic efficiency of the BGL-CBD against cellobiose, which displayed a 6-fold increase in V max /K m in comparison with the BGL. A gram of cellulose was found to absorb 643 U of the fusion enzyme (BGL-CBD) in pH 6.0 at 50°C for 25 min with a high immobilization efficiency of 90%. Using the BGL-CBD as the catalyst, the yield of glucose reached a maximum of 90% from 100 g/L cellobiose and the BGL-CBD could retain over 85% activity after five batches with the yield of glucose all above 70%. The performance of the BGL-CBD on microcrystalline cellulose was also studied. The yield of the glucose was increased from 47% to 58% by adding the BGL-CBD to the cellulase, instead of adding the Novozyme 188. Conclusions The hydrolytic activity of BGL-CBD is greater than that of the Novozyme 188 in cellulose degradation. The article provides a prospect to decrease significantly the

  14. Isolation and characterisation of microcrystalline cellulose and cellulose nanocrystals from coffee husk and comparative study with rice husk.

    PubMed

    Collazo-Bigliardi, Sofía; Ortega-Toro, Rodrigo; Chiralt Boix, Amparo

    2018-07-01

    Cellulosic material from coffee husk has not been previously studied despite being a potential source of reinforcing agents for different applications. This material has been extracted and characterised from coffee husk, in parallel with previously studied rice husk. Samples have been analysed as to their ability to obtain cellulosic fibres and cellulose nanocrystals (CNC) by applying alkali and bleaching treatments and final sulphuric acid hydrolysis. Microstructural changes were analysed after treatments, and the size and aspect ratio of CNCs were determined. Crystallinity and thermal stability of both materials progressed in line with the enrichment in cellulosic compounds. The CNC aspect ratio was higher than 10, which confers good reinforcing properties. These were tested in thermoplastic starch films, whose elastic modulus increased by 186 and 121% when 1 wt% of CNCs from rice and coffee husks, respectively, was incorporated into the matrix. Coffee husk represents an interesting source of cellulosic reinforcing materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Metallization of bacterial cellulose for electrical and electronic device manufacture

    DOEpatents

    Evans, Barbara R.; O'Neill, Hugh M.; Jansen, Valerie Malyvanh; Woodward, Jonathan

    2006-01-17

    The employment of metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The fuel cell includes an electrolyte membrane comprising a membrane support structure comprising bacterial cellulose, an anode disposed on one side of the electrolyte membrane, and a cathode disposed on an opposite side of the electrolyte membrane. At least one of the anode and the cathode comprises an electrode support structure comprising bacterial cellulose, and a catalyst disposed in or on the electrode support structure.

  16. Microcrystalline-cellulose and polypropylene based composite: A simple, selective and effective material for microwavable packaging.

    PubMed

    Ummartyotin, S; Pechyen, C

    2016-05-20

    Cellulose based composite was successfully designed as active packaging with additional feature of microwavable properties. Small amount of cellulose with 10 μm in diameter was integrated into polypropylene matrix. The use of maleic anhydride was employed as coupling agent. Thermal and mechanical properties of cellulose based composite were superior depending on polypropylene matrix. Crystallization temperature and compressive strength were estimated to be 130 °C and 5.5 MPa. The crystal formation and its percentage were therefore estimated to be 50% and it can be predicted on the feasibility of microwavable packaging. Morphological properties of cellulose based composite presented the good distribution and excellent uniformity. It was remarkable to note that cellulose derived from cotton can be prepared as composite with polypropylene matrix. It can be used as packaging for microwave application. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

    PubMed

    Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

    2018-06-15

    The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Characterization of Bacterial Cellulose by Gluconacetobacter hansenii CGMCC 3917.

    PubMed

    Feng, Xianchao; Ullah, Niamat; Wang, Xuejiao; Sun, Xuchun; Li, Chenyi; Bai, Yun; Chen, Lin; Li, Zhixi

    2015-10-01

    In this study, comprehensive characterization and drying methods on properties of bacterial cellulose were analyzed. Bacterial cellulose was prepared by Gluconacetobacter hansenii CGMCC 3917, which was mutated by high hydrostatic pressure (HHP) treatment. Bacterial cellulose is mainly comprised of cellulose Iα with high crystallinity and purity. High-water holding and absorption capacity were examined by reticulated structure. Thermogravimetric analysis showed high thermal stability. High tensile strength and Young's modulus indicated its mechanical properties. The rheological analysis showed that bacterial cellulose had good consistency and viscosity. These results indicated that bacterial cellulose is a potential food additive and also could be used for a food packaging material. The high textural stability during freeze-thaw cycles makes bacterial cellulose an effective additive for frozen food products. In addition, the properties of bacterial cellulose can be affected by drying methods. Our results suggest that the bacterial cellulose produced from HHP-mutant strain has an effective characterization, which can be used for a wide range of applications in food industry. © 2015 Institute of Food Technologists®

  19. Effects of electron beam radiation dose on the compatibilization behaviour in recycled polypropylene/microcrystalline cellulose composites

    NASA Astrophysics Data System (ADS)

    Samat, N.; Motsidi, S. N. R.; Lazim, N. H. M.

    2018-01-01

    The purpose of this research was to evaluate the influence of dose level of electron beam on the compatibilization behavior of recycled polypropylene (rPP) in rPP/microcrystalline cellulose (MCC) composites. Initially, the rPP was irradiated with various dose of electron beam (5 kGy up to 250 kGy) which then mixed with unirradiated rPP (u-rPP) at a ratio of 30:70 respectively. The composites were prepared by incorporating a series wt% of MCC fibers into rPP (u-rPP : i-rPP) using extruder and finally moulded with an injection moulding machine. The compatibility behavior of irradiated rPP (i-rPP) were analysed with mechanical tensile and thermal methods. The results of mechanical analysis showed great improvement in tensile modulus but an increase in radiation dosage gradually decreased this property. Nevertheless, the tensile strength exhibited a minor effect. The thermal stability of composites is lowered with increase in the absorbed dose, more significantly at higher content of MCC. Fracture surface observations reveal adhesion between the cellulose and rPP matrix.

  20. Biosynthesis of highly porous bacterial cellulose nanofibers

    NASA Astrophysics Data System (ADS)

    Hosseini, Hadi; Kokabi, Mehrdad; Mousavi, Seyyed Mohammad

    2018-01-01

    Bacterial cellulose nanofibers (BCNFs) as a sustainable and biodegradable polymer has drawn tremendous research attention in tissue engineering, bacterial sensors and drug delivery due to its extraordinary properties such as high purity, high crystallinity, high water absorption capacity and excellent mechanical strength in the wet state. This awesome properties, is attributed to BCNFs structure, therefore its characterization is important. In this work, the bacterial strain, Gluconacetobacter xylinus (PTCC 1734, obtained from Iranian Research Organization for Science and Technology (IROST)), was used to produce BCNFs hydrogel using bacterial fermentation under static condition at 29 °C for 10 days in the incubator. Then, the biosynthesized BCNFs wet gel, were dried at ambient temperature and pressure and characterized using Brunauer-Emmett-Teller (BET) and Field emission scanning electron microscopy (FE-SEM) analysis. FESEM image displayed highly interconnected and porous structure composed of web-like continuous, nanofibers with an average diameter of 48.5±2.1 nm. BET result analysis depicted BCNFs dried at ambient conditions had IV isotherm type, according to the IUPAC classification, indicating that BCNFs dried at ambient condition is essentially mesoporous. On the other hand, BET results depicted, mesoporous structure is around 85%. In addition, Specific surface area (SBET) obtained 81.45 m2/g. These results are in accordance with the FESEM observation.

  1. Applications of bacterial cellulose and its composites in biomedicine.

    PubMed

    Rajwade, J M; Paknikar, K M; Kumbhar, J V

    2015-03-01

    Bacterial cellulose produced by few but specific microbial genera is an extremely pure natural exopolysaccharide. Besides providing adhesive properties and a competitive advantage to the cellulose over-producer, bacterial cellulose confers UV protection, ensures maintenance of an aerobic environment, retains moisture, protects against heavy metal stress, etc. This unique nanostructured matrix is being widely explored for various medical and nonmedical applications. It can be produced in various shapes and forms because of which it finds varied uses in biomedicine. The attributes of bacterial cellulose such as biocompatibility, haemocompatibility, mechanical strength, microporosity and biodegradability with its unique surface chemistry make it ideally suited for a plethora of biomedical applications. This review highlights these qualities of bacterial cellulose in detail with emphasis on reports that prove its utility in biomedicine. It also gives an in-depth account of various biomedical applications ranging from implants and scaffolds for tissue engineering, carriers for drug delivery, wound-dressing materials, etc. that are reported until date. Besides, perspectives on limitations of commercialisation of bacterial cellulose have been presented. This review is also an update on the variety of low-cost substrates used for production of bacterial cellulose and its nonmedical applications and includes patents and commercial products based on bacterial cellulose.

  2. [A study of the properties of tablets from mixtures of two size degrees of alpha-lactose monohydrate and microcrystalline cellulose].

    PubMed

    Muzíková, J

    2006-03-01

    The paper examines the strength and disintegration time of compacts from the mixtures of two types of Tablettosas. Tablettosa 70 and Tablettosa 100 with microcrystalline cellulose represented by Vivapur 102. The mixtures of dry binders were prepared in the ratios of 3:1, 1:1, and 1:3. The effect of two concentrations of the lubricant magnesium stearate on the strength and disintegration time of compacts was also examined. Tablet strength increased with higher representation of microcrystalline cellulose in the mixture, and decreased with higher stearate concentration. The compacts from the mixtures with Tablettosa 100 showed higher strength. Disintegration time was highest in the compacts with the largest perccintage of microcrystalline cellulose, and longer in the case of the mixtures with Tablettosa 100. Stearate did not exert a negative effect on disintegration time. In the mixtures of Tablettosas with Vivapur 102 in a ratio of 1:1, the effect of the model active ingredient acetylsalicylic acid on the above-mentioned properties of tablets was tested. acetylsalicylic acid produced a further decrease in the strength of compacts and shortened the disintegration time in more instances in the cased of the mixtures with Tahlettosa 100.

  3. Thermogravimetric analysis for the determination of water release rate from microcrystalline cellulose dry powder and wet bead systems.

    PubMed

    Mayville, Francis C; Wigent, Rodney J; Schwartz, Joseph B

    2006-01-01

    The purpose of this work was to determine the total amount of water contained in dry powder and wet bead samples of microcrystalline cellulose, MCC, (Avicel PH-101), taken from various stages of the extrusion/marumerization process used to make beads and to determine the kinetic rates of water release from each sample. These samples were allowed to equilibrate in controlled humidity chambers at 25 degrees C. The total amount of water in each sample, after equilibration, was determined by thermogravimetric analysis (TGA) as a function of temperature. The rates of water release from these samples were determined by using isothermal gravimetric analysis (ITGA) as a function of time. Analysis of the results for these studies suggest that water was released from these systems by several different kinetic mechanisms. The water release mechanisms for these systems include: zero order, second order, and diffusion controlled kinetics. It is believed that all three kinetic mechanisms will occur at the same time, however; only one mechanism will be prominent. The prominent mechanism was based on the amount of water present in the sample.

  4. Preparation and Properties of a Novel Microcrystalline Cellulose-Filled Composites Based on Polyamide 6/High-Density Polyethylene

    PubMed Central

    Xu, Shihua; Yi, Shunmin; He, Jun; Wang, Haigang; Fang, Yiqun; Wang, Qingwen

    2017-01-01

    In the present study, lithium chloride (LiCl) was utilized as a modifier to reduce the melting point of polyamide 6 (PA6), and then 15 wt % microcrystalline cellulose (MCC) was compounded with low melting point PA6/high-density polyethylene (HDPE) by hot pressing. Crystallization analysis revealed that as little as 3 wt % LiCl transformed the crystallographic forms of PA6 from semi-crystalline to an amorphous state (melting point: 220 °C to none), which sharply reduced the processing temperature of the composites. LiCl improved the mechanical properties of the composites, as evidenced by the fact that the impact strength of the composites was increased by 90%. HDPE increased the impact strength of PA6/MCC composites. In addition, morphological analysis revealed that incorporation of LiCl and maleic anhydride grafted high-density polyethylene (MAPE) improved the interfacial adhesion. LiCl increased the glass transition temperature of the composites (the maximum is 72.6 °C). PMID:28773169

  5. Differential heat of adsorption of water vapor on silicified microcrystalline cellulose (SMCC): an investigation using isothermal microcalorimetry.

    PubMed

    Qian, Ken K; Bogner, Robin H

    2011-01-01

    A novel dual-shaft configuration in isothermal microcalorimetry was developed to study the interaction of water vapor with pharmaceutical excipients. An instrument performance test is suggested to validate the experimental data. Reliable experimental results can be collected using a single perfusion shaft; however, there was limitation of the dual-shaft configuration, which resulted deviation in the experimental results. A periodic performance test is recommended. Silicified microcrystalline cellulose (SMCC) was used as a model system to study the interaction using the dual-shaft method. Enthalpy of water vapor adsorption on SMCC was determined and compared to literature data. The data collected using the dual-shaft configuration did not reflect the actual physical system. The deviation was most likely due to the lack of flow control caused by viscous resistance. The enthalpy of adsorption was then calculated using isothermal microcalorimetry coupled with a dynamic vapor sorption apparatus. The results, -55 kJ/mol at low relative humidity (RH) to -22 kJ/mol at high RH, were consistent with the physical phenomenon of water vapor adsorption. Enthalpy of adsorption showed surface heterogeneity of SMCC and suggested multilayer condensation of water at approximately 60% RH. However, at high RH, the results showed the moisture-excipient interaction can be more complex than the proposed mechanism.

  6. Mussel-inspired fabrication of konjac glucomannan/microcrystalline cellulose intelligent hydrogel with pH-responsive sustained release behavior.

    PubMed

    Wang, Lin; Du, Yu; Yuan, Yi; Mu, Ruo-Jun; Gong, Jingni; Ni, Yongsheng; Pang, Jie; Wu, Chunhua

    2018-07-01

    Intelligent hydrogels are attractive biomaterials for various applications, however, fabricating a hydrogel with both adequate self-healing ability and mechanical properties remains a challenge. Herein, a series of novel intelligent konjac glucomannan (KGM)/microcrystalline cellulose (MCC) hydrogels were prepared vis the mussel-inspired chemistry. MCC was firstly functionalized by the oxidative polymerization of dopamine, and the intelligent hydrogels were obtained by mixing aqueous solutions of KGM and functionalized MCC (PDMCC). By introducing PDMCC, a more compact interconnected porous structure formed for the resulting hydrogels. The self-healing ability and mechanical properties of intelligent hydrogels were dependence on the PDMCC content. Compared with KGM hydrogels, KGM/PDMCC hydrogels exhibited a more distinct pH sensitivity and a lower initial burst release, which was attributed to the compact structure and strong intermolecular hydrogen bond interaction between PDMCC and KGM. These results suggest that the KGM/PDMCC intelligent hydrogels may be promising carriers for controlled drug delivery. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Comparative evaluation of the powder and compression properties of various grades and brands of microcrystalline cellulose by multivariate methods.

    PubMed

    Haware, Rahul V; Bauer-Brandl, Annette; Tho, Ingunn

    2010-01-01

    The present work challenges a newly developed approach to tablet formulation development by using chemically identical materials (grades and brands of microcrystalline cellulose). Tablet properties with respect to process and formulation parameters (e.g. compression speed, added lubricant and Emcompress fractions) were evaluated by 2(3)-factorial designs. Tablets of constant true volume were prepared on a compaction simulator at constant pressure (approx. 100 MPa). The highly repeatable and accurate force-displacement data obtained was evaluated by simple 'in-die' Heckel method and work descriptors. Relationships and interactions between formulation, process and tablet parameters were identified and quantified by multivariate analysis techniques; principal component analysis (PCA) and partial least square regressions (PLS). The method proved to be able to distinguish between different grades of MCC and even between two different brands of the same grade (Avicel PH 101 and Vivapur 101). One example of interaction was studied in more detail by mixed level design: The interaction effect of lubricant and Emcompress on elastic recovery of Avicel PH 102 was demonstrated to be complex and non-linear using the development tool under investigation.

  8. Glycerol as an additional carbon source for bacterial cellulose synthesis

    NASA Astrophysics Data System (ADS)

    Agustin, Y. E.; Padmawijaya, K. S.; Rixwari, H. F.; Yuniharto, V. A. S.

    2018-03-01

    Bacterial cellulose, the fermentation result of Acetobacter xylinus can be produced when glycerol was used as an additional carbon source. In this research, bacterial cellulose produced in two different fermentation medium, Hestrin and Scharmm (HS) medium and HS medium with additional MgSO4. Concentration of glycerol that used in this research were 0%; 5%; 10%; and 15% (v/v). The optimum conditions of bacterial cellulose production on each experiment variations determined by characterization of the mechanical properties, including thickness, tensile strength and elongation. Fourier Transform Infra Red Spectroscopy (FTIR) revealed the characterization of bacterial cellulose. Results showed that the growth rate of bacterial cellulose in HS-MgSO4-glycerol medium was faster than in HS-glycerol medium. Increasing concentrations of glycerol will lower the value of tensile strength and elongation. Elongation test showed that the elongation bacterial cellulose (BC) with the addition of 4.95% (v/v) glycerol in the HS-MgSO4 medium is the highest elongation value. The optimum bacterial cellulose production was achieved when 4.95% (v/v) of glycerol added into HS-MgSO4 medium with stress at break of 116.885 MPa and 4.214% elongation.

  9. Palladium-bacterial cellulose membranes for fuel cells.

    PubMed

    Evans, Barbara R; O'Neill, Hugh M; Malyvanh, Valerie P; Lee, Ida; Woodward, Jonathan

    2003-07-01

    Bacterial cellulose is a versatile renewable biomaterial that can be used as a hydrophilic matrix for the incorporation of metals into thin, flexible, thermally stable membranes. In contrast to plant cellulose, we found it catalyzed the deposition of metals within its structure to generate a finely divided homogeneous catalyst layer. Experimental data suggested that bacterial cellulose possessed reducing groups capable of initiating the precipitation of palladium, gold, and silver from aqueous solution. Since the bacterial cellulose contained water equivalent to at least 200 times the dry weight of the cellulose, it was dried to a thin membranous structure suitable for the construction of membrane electrode assemblies (MEAs). Results of our study with palladium-cellulose showed that it was capable of catalyzing the generation of hydrogen when incubated with sodium dithionite and generated an electrical current from hydrogen in an MEA containing native cellulose as the polyelectrolyte membrane (PEM). Advantages of using native and metallized bacterial cellulose membranes in an MEA over other PEMs such as Nafion 117 include its higher thermal stability to 130 degrees C and lower gas crossover.

  10. High performance cellulose nanocomposites: comparing the reinforcing ability of bacterial cellulose and nanofibrillated cellulose.

    PubMed

    Lee, Koon-Yang; Tammelin, Tekla; Schulfter, Kerstin; Kiiskinen, Harri; Samela, Juha; Bismarck, Alexander

    2012-08-01

    This work investigates the surface and bulk properties of nanofibrillated cellulose (NFC) and bacterial cellulose (BC), as well as their reinforcing ability in polymer nanocomposites. BC possesses higher critical surface tension of 57 mN m(-1) compared to NFC (41 mN m(-1)). The thermal degradation temperature in both nitrogen and air atmosphere of BC was also found to be higher than that of NFC. These results are in good agreement with the higher crystallinity of BC as determined by XRD, measured to be 71% for BC as compared to NFC of 41%. Nanocellulose papers were prepared from BC and NFC. Both papers possessed similar tensile moduli and strengths of 12 GPa and 110 MPa, respectively. Nanocomposites were manufactured by impregnating the nanocellulose paper with an epoxy resin using vacuum assisted resin infusion. The cellulose reinforced epoxy nanocomposites had a stiffness and strength of approximately ∼8 GPa and ∼100 MPa at an equivalent fiber volume fraction of 60 vol.-%. In terms of the reinforcing ability of NFC and BC in a polymer matrix, no significant difference between NFC and BC was observed.

  11. Combining experimental design and orthogonal projections to latent structures to study the influence of microcrystalline cellulose properties on roll compaction.

    PubMed

    Dumarey, Melanie; Wikström, Håkan; Fransson, Magnus; Sparén, Anders; Tajarobi, Pirjo; Josefson, Mats; Trygg, Johan

    2011-09-15

    Roll compaction is gaining importance in pharmaceutical industry for the dry granulation of heat or moisture sensitive powder blends with poor flowing properties prior to tabletting. We studied the influence of microcrystalline cellulose (MCC) properties on the roll compaction process and the consecutive steps in tablet manufacturing. Four dissimilar MCC grades, selected by subjecting their physical characteristics to principal components analysis, and three speed ratios, i.e. the ratio of the feed screw speed and the roll speed of the roll compactor, were included in a full factorial design. Orthogonal projection to latent structures was then used to model the properties of the resulting roll compacted products (ribbons, granules and tablets) as a function of the physical MCC properties and the speed ratio. This modified version of partial least squares regression separates variation in the design correlated to the considered response from the variation orthogonal to that response. The contributions of the MCC properties and the speed ratio to the predictive and orthogonal components of the models were used to evaluate the effect of the design variation. The models indicated that several MCC properties, e.g. bulk density and compressibility, affected all granule and tablet properties, but only one studied ribbon property: porosity. After roll compaction, Ceolus KG 1000 resulted in tablets with obvious higher tensile strength and lower disintegration time compared to the other MCC grades. This study confirmed that the particle size increase caused by roll compaction is highly responsible for the tensile strength decrease of the tablets. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Influence of granulating method on physical and mechanical properties, compression behavior, and compactibility of lactose and microcrystalline cellulose granules.

    PubMed

    Horisawa, E; Danjo, K; Sunada, H

    2000-06-01

    The physical and mechanical properties of lactose (LC) and microcrystalline cellulose (MCC) granules prepared by various granulating methods were determined, and their effects on the compression and strength of the tablets were examined. From the force-displacement curve obtained in a crushing test on a single granule, all LC granules appeared brittle, and MCC granules were somewhat plastically deformable. Inter-granular porosity epsilon inter clearly decreased with greater spherical granule shape for both materials. Decrease in intragranular porosity epsilon intra enhanced the crushing force of a single granule Fg. Agitating granulation brought about the most compactness and hardness of granules. In granule compression tests, the initial slope of Heckel plots K1 appeared closely related to ease of filling voids in a granule bed by the slippage or rolling of granules. The reciprocal of the slope in the succeeding step 1/K2 in compression of MCC granules indicated positive correlation to Fg, while in LC granules, no such obvious relation was evident. 1/K2 differed only slightly among granulating methods. Tensile strength of tablets Tt obtained by compression of various LC granules was low as a whole and was little influenced by granulating method. For MCC granules, which are plastically deformable, tablet strength greatly depended on granulation. Granules prepared by extruding or dry granulation gave strong tablets. Tablets prepared from granules made by the agitating method showed particularly low Tt. From stereomicroscopic observation, the contact area between granule particles in a tablet appeared smaller; this would explain the decrease in inter-granular bond formation.

  13. Effect of moderate electric fields in the properties of starch and chitosan films reinforced with microcrystalline cellulose.

    PubMed

    Coelho, Caroline C S; Cerqueira, Miguel A; Pereira, Ricardo N; Pastrana, Lorenzo M; Freitas-Silva, Otniel; Vicente, António A; Cabral, Lourdes M C; Teixeira, José A

    2017-10-15

    Microcrystalline cellulose (MCC) can provide improved properties when the aim is the development of biodegradable packaging materials. In this work the physicochemical properties of polysaccharide-based films (chitosan and starch) with the incorporation of MCC and the application of moderate electric field (MEF) and ultrasonic bath (UB) as treatments, were evaluated. For each treatment, the thickness, moisture content, solubility, water vapor permeability, contact angle, mechanical properties, along with its color and opacity were determined. The surface morphologies of the films were assessed by scanning electron microscopy (SEM). X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) were also performed. It was observed that the addition of different concentrations of MCC as well as the application of MEF are responsible for changes in the properties of the films, being this effect dependent on the polysaccharide used. Chitosan-based films were slightly yellow, transparent and presented a more homogeneous structure. The use of MEF was efficient in decreasing the permeability to water vapor in chitosan based films without MCC, as well as in production of films with a more hydrophobic surface. The addition of MCC promoted more opaque, rigid, less flexible and less hydrophobic films. Starch-based films were whitish, with a more heterogeneous structure and the application of MEF generated more hydrophilic films with lower tensile strength and Young's modulus. The films with MCC were more opaque, less flexible and less hydrophilic than the films without MCC. The composites presented good thermal properties, which increases their applicability as packaging materials. Therefore, the incorporation of MCC into polysaccharide-based films as well as the application of MEF can be an approach to change the properties of films. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Bacterial cellulose biosynthesis: diversity of operons, subunits, products, and functions.

    PubMed

    Römling, Ute; Galperin, Michael Y

    2015-09-01

    Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits - which differ among various taxa - affect the enzymatic activity and product yield in vivo by modulating (i) the expression of the biosynthesis apparatus, (ii) the export of the nascent β-D-glucan polymer to the cell surface, and (iii) the organization of cellulose fibers into a higher-order structure. These auxiliary subunits play key roles in determining the quantity and structure of resulting biofilms, which is particularly important for the interactions of bacteria with higher organisms - leading to rhizosphere colonization and modulating the virulence of cellulose-producing bacterial pathogens inside and outside of host cells. We review the organization of four principal types of cellulose synthase operon found in various bacterial genomes, identify additional bcs genes that encode components of the cellulose biosynthesis and secretion machinery, and propose a unified nomenclature for these genes and subunits. We also discuss the role of cellulose as a key component of biofilms and in the choice between acute infection and persistence in the host. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Bacterial cellulose biosynthesis: diversity of operons, subunits, products and functions

    PubMed Central

    Römling, Ute; Galperin, Michael Y.

    2015-01-01

    Summary Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits – which differ among various taxa – affect the enzymatic activity and product yield in vivo by modulating expression of biosynthesis apparatus, export of the nascent β-D-glucan polymer to the cell surface, and the organization of cellulose fibers into a higher-order structure. These auxiliary subunits play key roles in determining the quantity and structure of the resulting biofilm, which is particularly important for interactions of bacteria with higher organisms that lead to rhizosphere colonization and modulate virulence of cellulose-producing bacterial pathogens inside and outside of host cells. Here we review the organization of four principal types of cellulose synthase operons found in various bacterial genomes, identify additional bcs genes that encode likely components of the cellulose biosynthesis and secretion machinery, and propose a unified nomenclature for these genes and subunits. We also discuss the role of cellulose as a key component of biofilms formed by a variety of free-living and pathogenic bacteria and, for the latter, in the choice between acute infection and persistence in the host. PMID:26077867

  16. Increased Antibiotic Release from a Bone Cement Containing Bacterial Cellulose

    PubMed Central

    Nakai, Takahisa; Enomoto, Koichi; Uchio, Yuji; Yoshino, Katsumi

    2010-01-01

    Background Major disadvantages of antibiotic bone cements include limited drug release and reduced strength resulting from the addition of high doses of antibiotics. Bacterial cellulose, a three-dimensional hydrophilic mesh, may retain antibiotics and release them gradually. We hypothesized that the addition of cellulose to antibiotic bone cement would improve mechanical strength and antibiotic release. Questions/purposes We therefore examined the mechanical strength and antibiotic release of cellulose antibiotic cement. Methods A high dose of antibiotics (5 g per 40 g cement powder) was incorporated into bacterial cellulose and then mixed with bone cement. We compared the compression strength, fracture toughness, fatigue life, and elution kinetics of this formulation with those of plain cement and a traditional antibiotic cement. Results The average values for compression strength, fracture toughness, and fatigue life of the cellulose antibiotic cement were 97%, 97%, and 78% of the values obtained for plain cement, respectively. The corresponding values for the traditional antibiotic cement were 79%, 82%, and 17%, respectively. The cumulative elution over 35 days was 129% greater from the cellulose antibiotic cement than from the traditional antibiotic cement. Conclusions With a high dose of antibiotics, incorporating cellulose into the bone cement prevented compression and fracture fragility, improved fatigue life, and increased antibiotic elution. Clinical Relevance Antibiotic cements containing cellulose may have applications in clinical situations that require high levels of antibiotic release and preservation of the mechanical properties of the cement. PMID:20945120

  17. Material and Compression Properties of Cedrela odorata Gum Co-Processed with Plantain Starch and Microcrystalline Cellulose.

    PubMed

    Adetunji, Oladapo Adewale; Odeniyi, Michael Ayodele

    2016-01-01

    Many excipients used in tableting exhibit some undesirable properties such as poor flow, cohesion and lubricating characteristics, thus necessitating some modification to achieve the desired product. The objective of this study was to enhance the material, flow and compressional properties of Cedrela odorata gum (COG) (Family: Meliaceae) by co-processing with plantain starch (PS) and microcrystalline cellulose (MCC). The COG was co-processed with PS (or MCC) by physical co-grinding at ratio 1 : 1, 1 : 2 and 1 : 4, and characterized using morphological analysis, swelling index viscosity measurements, particle size analysis and FTIR spectra. The material, flow and compressional properties of the co-processed excipients were also evaluated. Results were analyzed using mean and standard deviation of data. There was a decrease in the degree of agglomeration of COG and a reduction in the size of the powdered gum. The co-processed excipients were more spherical than the native excipients. The COG had the highest viscosity, while MCC and COG : PS (1 : 2) showed the highest and lowest degrees of swelling at 27.0 ± 0.05°C respectively. Water absorption capacity of the component excipients improved with co-processing COG : MCC increasing from 171.8 ± 1.54 (1 : 1) to 214.8 ± 1.07 (1 : 2), while COG : PS increased from 95.2 ± 0.08 (1 : 1) to 206.2 ± 0.13. There was a decrease in the percentage solubility of the co-processed excipients with the highest and lowest solubility observed in COG (54.1 ± 0.07%) and PS (3.7 ± 0.16%), respectively. The FTIR spectra indicate no significant interaction between the excipients. The poor flow of the component excipients did not improve with co-processing; however, there was a significant increase in compressibility. Generally, COG co-processed with MCC showed better compression properties when compared with COG co-processed with PS. Co-processing of COD with MC or PS enhanced the characters of the component excipients, thus making the

  18. Effects of guar gum, ispaghula and microcrystalline cellulose on abdominal symptoms, gastric emptying, orocaecal transit time and gas production in healthy volunteers.

    PubMed

    Bianchi, M; Capurso, L

    2002-09-01

    Dietary fibres are carbohydrates that resist hydrolysis by human intestinal enzymes but are fermented by colonic microflora. Soluble dietary fibres are fermented by anaerobic bacteria with production of gases, short chain fatty acids and other metabolic products believed to cause symptoms such as bloating, abdominal distension, flatulence. Insoluble fibres are only partially fermented, serving almost exclusively as bulking agents that result in shorter transit time and increased faecal mass. To evaluate effect of a supplementation of a single 5 g dose of dietary fibre to a solid meal on gastric emptying, orocaecal transit time, gas production and symptom genesis, in healthy volunteers. Three different dietary fibres were tested, two soluble (guar gum and ispaghula] and one insoluble (microcrystalline cellulose). After a 24-hour low fibre diet, 10 healthy subjects had a standard meal consisting of white bread and one 70 g egg the yolk of which was mixed with 100 mg of 13C octanoic acid and fried. Breath samples were collected for 13CO2 measurements with a mass spectrophotometer and excretion curve (Tlag, T1/2) evaluation. Further breath samples were collected and analysed with a gas chromatograph for the evaluation of H2 and CH4 production and orocaecal transit time. Each evaluation was repeated adding to standard meal, diluted in 300 ml tap water, respectively: a single 5 g dose of microcrystalline cellulose, guar gum or ispaghula. Subjects were asked to report all symptoms experienced from time of meal ingestion over 24 hours, evaluating the intensity. Dietary fibres did not significantly change gastric emptying (Tlag, T1/2) and orocaecal transit time of standard meal. Subjects experienced more symptoms when meals were supplemented with guar gum (p=0.009 vs standard meal) and ispaghula (p=0.048 vs standard meal). There was a poor, but significant, correlation between gas production and symptoms (r=0. 38, p=0. 01). Addition of different dietary fibres to a solid

  19. Bacterial cellulose as an example product for sustainable production and consumption.

    PubMed

    Jang, Woo Dae; Hwang, Ji Hyeon; Kim, Hyun Uk; Ryu, Jae Yong; Lee, Sang Yup

    2017-09-01

    Life cycle of bacterial cellulose. Sustainable production and consumption of bio-based products are showcased using bacterial cellulose as an example. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  20. The preparation by extrusion/spheronization and the properties of pellets containing drugs, microcrystalline cellulose and glyceryl monostearate.

    PubMed

    Chatchawalsaisin, Jittima; Podczeck, Fridrun; Newton, J Michael

    2005-01-01

    Pellets have been prepared by extrusion and spheronization containing microcrystalline cellulose (MCC) and four model drugs with decreasing order of solubility, paracetamol (P), diclofenac sodium (D), ibuprofen (IB) and indomethacin (IN) at a 10% level with and without the addition of a range of levels of glyceryl monostearate (GMS). The drugs differed in their response to extrusion in that all formulations containing the drug D had a 'steady state' extrusion profile whereas the other three drugs exhibited 'forced flow' indicating the possibility of water migration during the process of ram extrusion. The presence of GMS did not influence this effect. The drug D also required consistently less water to function than the other three drugs. In spite of these differences in extrusion performance, it was possible to prepare satisfactory pellets from formulations of all the drugs with 0, 30 and 60% GMS combined with 90, 60 or 30% of MCC at a range of water levels. It was also possible to prepare pellets containing the drug D with 70, 80 and 90% GMS, with corresponding quantities of 20, 10 and 0% of MCC. It was also possible to prepare the pellet formulations by dispersing the drugs in molten GMS, grinding and processing this with MCC and water. Such systems retained the processing characteristics of the composition made by the blending of the powder. The presence of GMS in all cases reduced the quantity of water required for the process to function. The steady state or the mean of the range of the forces observed during forced flow, were dependent on the composition and the quantity of water added. The surface of the extrudate appeared smooth and measurements of surface roughness established that the value of the rugosity R(a) for any of the extrudates did not exceed 6 microm. The extrudate diameter was found to increase with the quantity of GMS in the formulation. The pellets produced were all within a relatively narrow size range (three sieve fractions of a root two

  1. Bacterial cellulose-kaolin nanocomposites for application as biomedical wound healing materials

    NASA Astrophysics Data System (ADS)

    Wanna, Dwi; Alam, Catharina; Toivola, Diana M.; Alam, Parvez

    2013-12-01

    This short communication provides preliminary experimental details on the structure-property relationships of novel biomedical kaolin-bacterial cellulose nanocomposites. Bacterial cellulose is an effective binding agent for kaolin particles forming reticulated structures at kaolin-cellulose interfaces and entanglements when the cellulose fraction is sufficiently high. The mechanical performance of these materials hence improves with an increased fraction of bacterial cellulose, though this also causes the rate of blood clotting to decrease. These composites have combined potential as both short-term (kaolin) and long-term (bacterial cellulose) wound healing materials.

  2. Chromosphores in cellulosics, XI: isoloation and identification of residual chromophores from bacterial cellulose

    USDA-ARS?s Scientific Manuscript database

    In the present work, bacterial cellulose (BC) was analyzed for its chromophore content with the chromophore release and identification (CRI) method. In aged BC, seven chromophores were unambiguously identified, despite their very low (ppb) presence. The compounds contain 2-hydroxy-[1,4]benzoquinone,...

  3. Simulations of cellulose translocation in the bacterial cellulose synthase suggest a regulatory mechanism for the dimeric structure of cellulose

    DOE PAGES

    Knott, Brandon C.; Crowley, Michael F.; Himmel, Michael E.; ...

    2016-01-29

    The processive cycle of the bacterial cellulose synthase (Bcs) includes the addition of a single glucose moiety to the end of a growing cellulose chain followed by the translocation of the nascent chain across the plasma membrane. The mechanism of this translocation and its precise location within the processive cycle are not well understood. In particular, the molecular details of how a polymer (cellulose) whose basic structural unit is a dimer (cellobiose) can be constructed by adding one monomer (glucose) at a time are yet to be elucidated. Here, we have utilized molecular dynamics simulations and free energy calculations tomore » the shed light on these questions. We find that translocation forward by one glucose unit is quite favorable energetically, giving a free energy stabilization of greater than 10 kcal mol-1. In addition, there is only a small barrier to translocation, implying that translocation is not rate limiting within the Bcs processive cycle (given experimental rates for cellulose synthesis in vitro). Perhaps most significantly, our results also indicate that steric constraints at the transmembrane tunnel entrance regulate the dimeric structure of cellulose. Namely, when a glucose molecule is added to the cellulose chain in the same orientation as the acceptor glucose, the terminal glucose freely rotates upon forward motion, thus suggesting a regulatory mechanism for the dimeric structure of cellulose. We characterize both the conserved and non-conserved enzyme-polysaccharide interactions that drive translocation, and find that 20 of the 25 residues that strongly interact with the translocating cellulose chain in the simulations are well conserved, mostly with polar or aromatic side chains. Our results also allow for a dynamical analysis of the role of the so-called 'finger helix' in cellulose translocation that has been observed structurally. Taken together, these findings aid in the elucidation of the translocation steps of the Bcs processive

  4. Simulations of cellulose translocation in the bacterial cellulose synthase suggest a regulatory mechanism for the dimeric structure of cellulose.

    PubMed

    Knott, Brandon C; Crowley, Michael F; Himmel, Michael E; Zimmer, Jochen; Beckham, Gregg T

    2016-05-01

    The processive cycle of the bacterial cellulose synthase (Bcs) includes the addition of a single glucose moiety to the end of a growing cellulose chain followed by the translocation of the nascent chain across the plasma membrane. The mechanism of this translocation and its precise location within the processive cycle are not well understood. In particular, the molecular details of how a polymer (cellulose) whose basic structural unit is a dimer (cellobiose) can be constructed by adding one monomer (glucose) at a time are yet to be elucidated. Here, we have utilized molecular dynamics simulations and free energy calculations to the shed light on these questions. We find that translocation forward by one glucose unit is quite favorable energetically, giving a free energy stabilization of greater than 10 kcal/mol. In addition, there is only a small barrier to translocation, implying that translocation is not rate limiting within the Bcs processive cycle (given experimental rates for cellulose synthesis in vitro ). Perhaps most significantly, our results also indicate that steric constraints at the transmembrane tunnel entrance regulate the dimeric structure of cellulose. Namely, when a glucose molecule is added to the cellulose chain in the same orientation as the acceptor glucose, the terminal glucose freely rotates upon forward motion, thus suggesting a regulatory mechanism for the dimeric structure of cellulose. We characterize both the conserved and non-conserved enzyme-polysaccharide interactions that drive translocation, and find that 20 of the 25 residues that strongly interact with the translocating cellulose chain in the simulations are well conserved, mostly with polar or aromatic side chains. Our results also allow for a dynamical analysis of the role of the so-called `finger helix' in cellulose translocation that has been observed structurally. Taken together, these findings aid in the elucidation of the translocation steps of the Bcs processive cycle and

  5. Preparation of nanocellulose from micro-crystalline cellulose: The effect on the performance and properties of agar-based composite films.

    PubMed

    Shankar, Shiv; Rhim, Jong-Whan

    2016-01-01

    A facile approach has been performed to prepare nanocellulose (NC) from micro-crystalline cellulose (MCC) and test their effect on the performance properties of agar-based composite films. The NC was characterized by STEM, XRD, FTIR, and TGA. The NC was well dispersed in distilled water after sonication and their size was in the range of 100-500nm. The XRD results revealed the crystallinity of NC. The crystallinity index of NC (0.71) was decreased compared to the MCC (0.81). The effect of NC or MCC content (1, 3, 5 and 10wt% based on agar) on the mechanical, water vapor permeability (WVP), and thermal properties of the composites were studied. The NC obtained from MCC can be used as a reinforcing agent for the preparation of biodegradable composites films for their potential use in the development of biodegradable food packaging materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Production and Status of Bacterial Cellulose in Biomedical Engineering

    PubMed Central

    Moniri, Mona; Boroumand Moghaddam, Amin; Abdul Rahim, Raha; Bin Ariff, Arbakariya; Zuhainis Saad, Wan; Navaderi, Mohammad; Mohamad, Rosfarizan

    2017-01-01

    Bacterial cellulose (BC) is a highly pure and crystalline material generated by aerobic bacteria, which has received significant interest due to its unique physiochemical characteristics in comparison with plant cellulose. BC, alone or in combination with different components (e.g., biopolymers and nanoparticles), can be used for a wide range of applications, such as medical products, electrical instruments, and food ingredients. In recent years, biomedical devices have gained important attention due to the increase in medical engineering products for wound care, regeneration of organs, diagnosis of diseases, and drug transportation. Bacterial cellulose has potential applications across several medical sectors and permits the development of innovative materials. This paper reviews the progress of related research, including overall information about bacterial cellulose, production by microorganisms, mechanisms as well as BC cultivation and its nanocomposites. The latest use of BC in the biomedical field is thoroughly discussed with its applications in both a pure and composite form. This paper concludes the further investigations of BC in the future that are required to make it marketable in vital biomaterials.

  7. Nanostructural reorganization of bacterial cellulose by ultrasonic treatment.

    PubMed

    Tischer, Paula C S Faria; Sierakowski, Maria Rita; Westfahl, Harry; Tischer, Cesar Augusto

    2010-05-10

    In this work, bacterial cellulose was subjected to a high-power ultrasonic treatment for different time intervals. The morphological analysis, scanning electron microscopy, and atomic force microscopy revealed that this treatment changed the width and height of the microfibrillar ribbons and roughness of their surface, originating films with new nanostructures. Differential thermal analysis showed a higher thermal stability for ultrasonicated samples with a pyrolysis onset temperature of 208 degrees C for native bacterial cellulose and 250 and 268 degrees C for the modified samples. The small-angle X-ray scattering experiments demonstrated that the treatment with ultrasound increased the thickness of the ribbons, while wide-angle X-ray scattering experiments demonstrated that the average crystallite dimension and the degree of crystallinity also increased. A model is proposed where the thicker ribbons and crystallites result from the fusion of neighboring ribbons due to cavitation effects.

  8. Thin Layer Drying Model of Bacterial Cellulose Film

    NASA Astrophysics Data System (ADS)

    Hadi Jatmiko, Tri; Taufika Rosyida, Vita; Wheni Indrianingsih, Anastasia; Apriyana, Wuri

    2017-12-01

    The bacterial cellulose film produced by Acetobacter xylinum using coconut water as a carbon source was dried at a temperature of 60 to 100 C. The drying process of bacterial cellulose film occur at falling rate drying period. Increasing drying temperature will shorten the drying time. The drying data fitted with thin layer drying models that widely used, Newton, Page and Henderson and Pabis models. All thin layer drying models describe the experimental data well, but Page model is better than the other models on all various temperature with coefficients of determination (R2) range from 0.9908 to 0.9979, chi square range from 0.000212 to 0.000851 and RMSE range from 0.014307 to 0.0289458.

  9. Bacterial Cellulose (BC) as a Functional Nanocomposite Biomaterial

    NASA Astrophysics Data System (ADS)

    Nandgaonkar, Avinav Ghanashyam

    Cellulosic is the most abundant biopolymer in the landscape and can be found in many different organisms. It has been already seen use in the medical field, for example cotton for wound dressings and sutures. Although cellulose is naturally occurring and has found a number of applications inside and outside of the medical field, it is not typically produced in its pure state. A lengthy process is required to separate the lignin, hemicelluloses and other molecules from the cellulose in most renewables (wood, agricultural fibers such as cotton, monocots, grasses, etc.). Although bacterial cellulose has a similar chemical structure to plant cellulose, it is easier to process because of the absence of lignin and hemicelluloses which require a lot of energy and chemicals for removal. Bacterial cellulose (BC) is produced from various species of bacteria such as Gluconacetobacter xylinus. Due to its high water uptake, it has the tendency to form gels. It displays high tensile strength, biocompatibility, and purity compared to wood cellulose. It has found applications in fields such as paper, paper products, audio components (e.g., speaker diaphragms), flexible electronics, supercapacitors, electronics, and soft tissue engineering. In my dissertation, we have functionalized and studied BC-based materials for three specific applications: cartilage tissue engineering, bioelectronics, and dye degradation. In our first study, we prepared a highly organized porous material based on BC by unidirectional freezing followed by a freeze-drying process. Chitosan was added to impart additional properties to the resulting BC-based scaffolds that were evaluated in terms of their morphological, chemical, and physical properties for cartilage tissue engineering. The properties of the resulting scaffold were tailored by adjusting the concentration of chitosan over 1, 1.5, and 2 % (by wt-%). The scaffolds containing chitosan showed excellent shape recovery and structural stability after

  10. Kombucha-synthesized bacterial cellulose: preparation, characterization, and biocompatibility evaluation.

    PubMed

    Zhu, Changlai; Li, Feng; Zhou, Xinyang; Lin, Lin; Zhang, Tianyi

    2014-05-01

    Bacterial cellulose (BC) is a natural biomaterial with unique properties suitable for tissue engineering applications, but it has not yet been used for preparing nerve conduits to repair peripheral nerve injuries. The objectives of this study were to prepare and characterize the Kampuchea-synthesized bacterial cellulose (KBC) and further evaluate the biocompatibility of KBC with peripheral nerve cells and tissues in vitro and in vivo. KBC membranes were composed of interwoven ribbons of about 20-100 nm in width, and had a high purity and the same crystallinity as that of cellulose Iα. The results from light and scanning electron microscopy, MTT assay, flow cytometry, and RT-PCR indicated that no significant differences in the morphology and cell function were observed between Schwann cells (SCs) cultured on KBC membranes and glass slips. We also fabricated a nerve conduit using KBC, which was implanted into the spatium intermusculare of rats. At 1, 3, and 6 weeks post-implantation, clinical chemistry and histochemistry showed that there were no significant differences in blood counts, serum biochemical parameters, and tissue reactions between implanted rats and sham-operated rats. Collectively, our data indicated that KBC possessed good biocompatibility with primary cultured SCs and KBC did not exert hematological and histological toxic effects on nerve tissues in vivo. Copyright © 2013 Wiley Periodicals, Inc.

  11. Nanocellulose patents trends: a comprehensive review on patents on cellulose nanocrystals, microfibrillated and bacterial cellulose.

    PubMed

    Charreau, Hernan; Foresti, Maria L; Vazquez, Analia

    2013-01-01

    Cellulose nanoparticles (i.e. cellulose elements having at least one dimension in the 1-100 nm range) have received increasing attention during the last decade. This is not only evident in academic articles, but it is also manifested by the increasing number of nanocellulose patents that are published every year. In the current review, nanocellulose patents are reviewed using specific software which provides valuable information on the annual number of patents that have been published throughout the years, main patent owners, most prolific inventors, and patents on the field that have received more citations. Patent statistics on rod-like cellulose nanoparticles extracted from plants by acid hydrolysis (nanocrystals), mechanical treatment leading to microfibrillated cellulose (MFC), and microbially produced nanofibrils (bacterial cellulose, BC) are analyzed in detail. The aim of the current review is to provide researchers with patent information which may help them in visualizing the evolution of nanocellulose technology, both as a whole and also divided among the different nanosized particles that are currently the subject of outstanding scientific attention. Then, patents are not only analyzed by their content, but also by global statistics which will reveal the moment at which different cellulose nanoparticles technologies achieved a breakthrough, the relative interest received by different nanocellulose particles throughout the years, the companies that have been most interested in this technology, the most prolific inventors, and the patents that have had more influence in further developments. It is expected that the results showing the explosion that nanocellulose technology is experiencing in current days will still bring more research on the topic and contribute to the expansion of nanocellulosics applications.

  12. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain

    PubMed Central

    Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Micklem, Chris N.; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S.; Kitney, Richard; Reeve, Benjamin; Ellis, Tom

    2016-01-01

    Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae. Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology. PMID:27247386

  13. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain.

    PubMed

    Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Abbott, James; Micklem, Chris N; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S; Kitney, Richard; Reeve, Benjamin; Ellis, Tom

    2016-06-14

    Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology.

  14. Bacterial cellulose production by Gluconacetobacter sp. PKY5 in a rotary biofilm contactor.

    PubMed

    Kim, Yong-Jun; Kim, Jin-Nam; Wee, Young-Jung; Park, Don-Hee; Ryu, Hwa-Won

    2007-04-01

    A rotary biofilm contactor (RBC) inoculated with Gluconacetobacter sp. RKY5 was used as a bioreactor for improved bacterial cellulose production. The optimal number of disk for bacterial cellulose production was found to be eight, at which bacterial cellulose and cell concentrations were 5.52 and 4.98 g/L. When the aeration rate was maintained at 1.25 vvm, bacterial cellulose and cell concentrations were maximized (5.67 and 5.25 g/L, respectively). The optimal rotation speed of impeller in RBC was 15 rpm. When the culture pH in RBC was not controlled during fermentation, the maximal amount of bacterial cellulose (5.53 g/L) and cells (4.91 g/L) was obtained. Under the optimized culture conditions, bacterial cellulose and cell concentrations in RBC reached to 6.17 and 5.58 g/L, respectively.

  15. Bacterial Cellulose Production by Gluconacetobacter sp. RKY5 in a Rotary Biofilm Contactor

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Jun; Kim, Jin-Nam; Wee, Young-Jung; Park, Don-Hee; Ryu, Hwa-Won

    A rotary biofilm contactor (RBC) inoculated with Gluconacetobacter sp. RKY5 was used as a bioreactor for improved bacterial cellulose production. The optimal number of disk for bacterial cellulose production was found to be eight, at which bacterial cellulose and cell concentrations were 5.52 and 4.98 g/L. When the aeration rate was maintained at 1.25 vvm, bacterial cellulose and cell concentrations were maximized (5.67 and 5.25 g/L, respectively). The optimal rotation speed of impeller in RBC was 15 rpm. When the culture pH in RBC was not controlled during fermentation, the maximal amount of bacterial cellulose (5.53 g/L) and cells (4.91 g/L) was obtained. Under the optimized culture conditions, bacterial cellulose and cell concentrations in RBC reached to 6.17 and 5.58 g/L, respectively.

  16. Processing of micro-nano bacterial cellulose with hydrolysis method as a reinforcing bioplastic

    NASA Astrophysics Data System (ADS)

    Maryam, Maryam; Dedy, Rahmad; Yunizurwan, Yunizurwan

    2017-01-01

    Nanotechnology is the ability to create and manipulate atoms and molecules on the smallest of scales. Their size allows them to exhibit novel and significantly improved physical, chemical, biological properties, phenomena, and processes because of their size. The purpose of this research is obtaining micro-nano bacterial cellulose as reinforcing bioplastics. Bacterial cellulose (BC) was made from coconut water for two weeks. BC was dried and grinded. Bacterial cellulose was given purification process with NaOH 5% for 6 hours. Making the micro-nano bacterial cellulose with hydrolysis method. Hydrolysis process with hydrochloric acid (HCl) at the conditions 3,5M, 55°C, 6 hours. Drying process used spray dryer. The hydrolysis process was obtained bacterial cellulose with ±7 μm. The addition 2% micro-nano bacterial cellulose as reinforcing in bioplastics composite can improve the physical characteristics.

  17. To Evaluate the Effect of Solvents and Different Relative Humidity Conditions on Thermal and Rheological Properties of Microcrystalline Cellulose 101 Using METHOCEL™ E15LV as a Binder.

    PubMed

    Jagia, Moksh; Trivedi, Maitri; Dave, Rutesh H

    2016-08-01

    The solvent used for preparing the binder solution in wet granulation can affect the granulation end point and also impact the thermal, rheological, and flow properties of the granules. The present study investigates the effect of solvents and percentage relative humidity (RH) on the granules of microcrystalline cellulose (MCC) with hydroxypropyl methyl cellulose (HPMC) as the binder. MCC was granulated using 2.5% w/w binder solution in water and ethanol/water mixture (80:20 v/v). Prepared granules were dried until constant percentage loss on drying, sieved, and further analyzed. Dried granules were exposed to different percentage RH for 48 h at room temperature. Powder rheometer was used for the rheological and flow characterization, while thermal effusivity and differential scanning calorimeter were used for thermal analysis. The thermal effusivity values for the wet granules showed a sharp increase beginning 50% w/w binder solution in both cases, which reflected the over-wetting of granules. Ethanol/water solvent batches showed greater resistance to flow as compared to the water solvent batches in the wet granule stage, while the reverse was true for the dried granule stage, as evident from the basic flowability energy values. Although the solvents used affected the equilibration kinetics of moisture content, the RH-exposed granules remained unaffected in their flow properties in both cases. This study indicates that the solvents play a vital role on the rheology and flow properties of MCC granules, while the different RH conditions have little or no effect on them for the above combination of solvent and binder.

  18. Influence of wet granulation and lubrication on the powder and tableting properties of codried product of microcrystalline cellulose with beta-cyclodextrin.

    PubMed

    Wu, J; Ho, H; Sheu, M

    2001-01-01

    The individual influence of wet granulation and lubrication on the powder and tableting properties of codried product of microcrystalline cellulose (MCC) with beta-cyclodextrin (beta-CD) was examined in this study. Avicel PH 101 and 301 were included for comparison. The codried product, Avicel PH 101 and 301 were granulated with water, and the granules were milled to retain three different size fractions: 37-60 microm, 60-150 microm, and 150-420 microm. The original Avicels and codried product were lubricated with magnesium stearate in three different percentages (0.2, 0.5, and 1.0%). The results showed that the powder flowability and disintegration of codried product and Avicels were significantly improved after wet granulation. However, the compactibility of codried product and Avicels decreased with increasing particle size. Nevertheless, the compactibility of the codried excipient after granulation was still better than the non-granulated Avicel PH 101 and 301. On the other hand, codried product and Avicels were sensitive to lubrication and resulted in decreasing compactibility and increasing disintegration. Because of the rounder shape of particles, the codried excipient was more sensitive to magnesium stearate and produced weaker tablets than did Avicels.

  19. Cecal and colonic responses in rats fed 5 or 30% corn oil diets containing either 7.5% broccoli dietary fiber or microcrystalline cellulose.

    PubMed

    Paturi, Gunaranjan; Butts, Christine; Monro, John; Nones, Katia; Martell, Sheridan; Butler, Ruth; Sutherland, Juliet

    2010-05-26

    Growing evidence suggests that microbiota in the human gastrointestinal tract play a crucial role in mediating the effects of foods on colonic health and host metabolism. The large bowel ecosystem is known to be perturbed in humans and animals fed high-fat diets and conversely to be protected by fermentable oligosaccharides. We examined the ability of largely fermentable dietary fiber from broccoli ( Brassica oleracea L. var. italica ) and minimally fermented microcrystalline cellulose to buffer against the effects of high-fat intakes. The results showed that high fat lowered food intakes and therefore fiber intake by 27%. The addition of fermentable oligosaccharide to the diet was shown to be beneficial to some microbiota in cecum, altered cecal short-chain fatty acids, and increased the colon crypt depth and the number of goblet cells per crypt in high- and low-fat diets. Although, the fat level was the predominant factor in changes to the large bowel ecosystem, we have shown that broccoli fiber conferred some protection to consumption of a high-fat diet and particularly in terms of colon morphology.

  20. Ultrasound-assisted ionic liquid-based micellar extraction combined with microcrystalline cellulose as sorbent in dispersive microextraction for the determination of phenolic compounds in propolis.

    PubMed

    Cao, Jun; Peng, Li-Qing; Du, Li-Jing; Zhang, Qi-Dong; Xu, Jing-Jing

    2017-04-22

    An ionic liquid-(IL) based micellar extraction combined with microcrystalline cellulose- (MCC) assisted dispersive micro solid-phase extraction method was developed to extract phenolic compounds from propolis. A total of 20 target compounds were identified by ultra-high- performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. The main extraction parameters were optimized and included the ultrasonic power, ultrasonic time, sample pH, type of IL, the concentration of [C12mim]Br, extraction time, concentration of MCC, type of sorbent and type of elution solvents. Under the optimum conditions, the proposed method exhibited good linearities (r 2  ≥ 0.999) for all plant phenolic compounds with the lower limits of detection in the range of 0.21-0.41 ng/mL. The recoveries ranged from 82.74% to 97.88% for pinocembrin, chrysin and galangin. Compared with conventional solvent extraction, the present method was simpler and more efficient and required less organic solvent and a shorter extraction time. Finally, the methodology was successfully used for the extraction and enrichment of phenolic compounds in propolis. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Production of bioplastic from jackfruit seed starch (Artocarpus heterophyllus) reinforced with microcrystalline cellulose from cocoa pod husk (Theobroma cacao L.) using glycerol as plasticizer

    NASA Astrophysics Data System (ADS)

    Lubis, M.; Gana, A.; Maysarah, S.; Ginting, M. H. S.; Harahap, M. B.

    2018-02-01

    The production of bioplastic from jackfruit seed starch reinforced with microcrystalline cellulose (MCC) cocoa pod husk using glycerol as plasticizer was investigated to determine the most optimum mass and volume of MCC and glycerol in producing bioplastics. To produce MCC, Cocoa pod husk was subjected to alkali treatment, bleaching, and hydrochloric acid hydrolysis. The degree of crystallinity of MCC, were determined by XRD, functional group by FT-IR and morphologycal analysis by SEM. Analysis of bioplastic mechanical properties includes tensile strength and elongation at break based on ASTM D882 standard. Bioplastics were produced by casting method from jackfruit seed starch and reinforced with MCC from cocoa pod husk at starch mass to MCC ratio of 6:4, 7:3, 8:2, and 9:1, using glycerol as plasticizer at 20%, 25%, 30% (wt/v of glycerol to starch). From the result, the isolated MCC from cocoa pod husk were in a form of rod-like shape of length 5-10 µm with diameter 11.635 nm and 74% crystallinity. The highest tensile strength of bioplastics was obtained at starch to MCC mass ratio of 8:2, addition of 20% glycerol with measured tensile strength of 0.637 MPa and elongation at break of 7.04%. Transform infrared spectroscopy showed the functional groups of bioplastics, which the majority of O-H groups were found at the bioplastics with reinforcing filler MCC that represented substantial hydrogen bonds.

  2. Provision of micro-nano bacterial cellulose as bio plastic filler by sonication method

    NASA Astrophysics Data System (ADS)

    Maryam; Rahmad, D.; Yunizurwan; Kasim, A.; Novelina; Emriadi

    2017-07-01

    Research and development of bioplastic has increased recently as a solution for substitution of conventional plastic which have many negative impacts to environment. However, physical properties and mechanical properties of its still lower than conventional plastic. An alternative solution for that problem is by using fillers that can increase the strength. Bacterial cellulose is considered as potential source for filler, but still need to be explored more. The privileges of bacterial cellulose are easy to get and does not have lignin, pectin, and hemicelluloses which are impurities in other celluloses. This research focused on gaining bacterial cellulose in micro-nano particle form and its impact on increasing the strength of bio plastic. Ultrasonication has been used as method to form micro-nano particle from bacterial cellulose. The result showed this method may form the particle size of bacterial cellulose approximately ± 3μm. Next step, after getting ± 3μm particle of bacterial cellulose, is making bio plastic with casting method by adding 1% of bacterial cellulose, from the total material in making bio plastic. Physical characteristic of the bio plastic which are tensile strength 11.85 MPa, modulus young 3.13 MPa, elongation 4.11% and density 0.42 g/cm3. The numbers of physical properties showwthat, by adding 1% of bacterial cellulose, the strength of bio plastic was significantly increase, even value of tensile strength has complied the international standard for bio plastic.

  3. Reinforcement of bacterial cellulose aerogels with biocompatible polymers.

    PubMed

    Pircher, N; Veigel, S; Aigner, N; Nedelec, J M; Rosenau, T; Liebner, F

    2014-10-13

    Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  4. Physical and mechanical properties of modified bacterial cellulose composite films

    NASA Astrophysics Data System (ADS)

    Indrarti, Lucia; Indriyati, Syampurwadi, Anung; Pujiastuti, Sri

    2016-02-01

    To open wide range application opportunities of Bacterial Cellulose (BC) such as for agricultural purposes and edible film, BC slurries were blended with Glycerol (Gly), Sorbitol (Sor) and Carboxymethyl Cellulose (CMC). The physical and mechanical properties of BC composites were investigated to gain a better understanding of the relationship between BC and the additive types. Addition of glycerol, sorbitol and CMC influenced the water solubility of BC composite films. FTIR analysis showed the characteristic bands of cellulose. Addition of CMC, glycerol, and sorbitol slightly changed the FTIR spectrum of the composites. Tensile test showed that CMC not only acted as cross-linking agent where the tensile strength doubled up to 180 MPa, but also acted as plasticizer with the elongation at break increased more than 100% compared to that of BC film. On the other hand, glycerol and sorbitol acted as plasticizers that decreased the tensile strength and increased the elongation. Addition of CMC can improve film transparency, which is quite important in consumer acceptance of edible films in food industry.

  5. Reinforcement of bacterial cellulose aerogels with biocompatible polymers

    PubMed Central

    Pircher, N.; Veigel, S.; Aigner, N.; Nedelec, J.M.; Rosenau, T.; Liebner, F.

    2014-01-01

    Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77 K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels. PMID:25037381

  6. Production of bacterial cellulose and enzyme from waste fiber sludge

    PubMed Central

    2013-01-01

    Background Bacterial cellulose (BC) is a highly crystalline and mechanically stable nanopolymer, which has excellent potential as a material in many novel applications, especially if it can be produced in large amounts from an inexpensive feedstock. Waste fiber sludge, a residue with little or no value, originates from pulp mills and lignocellulosic biorefineries. A high cellulose and low lignin content contributes to making the fiber sludge suitable for bioconversion, even without a thermochemical pretreatment step. In this study, the possibility to combine production of BC and hydrolytic enzymes from fiber sludge was investigated. The BC was characterized using field-emission scanning electron microscopy and X-ray diffraction analysis, and its mechanical properties were investigated. Results Bacterial cellulose and enzymes were produced through sequential fermentations with the bacterium Gluconacetobacter xylinus and the filamentous fungus Trichoderma reesei. Fiber sludges from sulfate (SAFS) and sulfite (SIFS) processes were hydrolyzed enzymatically without prior thermochemical pretreatment and the resulting hydrolysates were used for BC production. The highest volumetric yields of BC from SAFS and SIFS were 11 and 10 g/L (DW), respectively. The BC yield on initial sugar in hydrolysate-based medium reached 0.3 g/g after seven days of cultivation. The tensile strength of wet BC from hydrolysate medium was about 0.04 MPa compared to about 0.03 MPa for BC from a glucose-based reference medium, while the crystallinity was slightly lower for BC from hydrolysate cultures. The spent hydrolysates were used for production of cellulase with T. reesei. The cellulase activity (CMCase activity) in spent SAFS and SIFS hydrolysates reached 5.2 U/mL (87 nkat/mL), which was similar to the activity level obtained in a reference medium containing equal amounts of reducing sugar. Conclusions It was shown that waste fiber sludge is a suitable raw material for production of

  7. Preparation and characterization of reinforced papers using nano bacterial cellulose.

    PubMed

    Tabarsa, Taghi; Sheykhnazari, Somayeh; Ashori, Alireza; Mashkour, Mahdi; Khazaeian, Abolghasem

    2017-08-01

    The main goal of this work was to reinforce softwood pulp (SP) with bacterial cellulose (BC) to generate a sustainable biocomposite. BC is a nanocellulose, which was anticipated to increase interfacial adhesion between the cellulosic fibers and BC. The organism used was Gluconacetobacter xylinus, which was incubated in a static Hestrin-Schramm culture at 28°C for 14days. The specimens of BC, SP and the reinforced SP with BC were characterized using X-ray diffraction (XRD), FT-IR, FESEM, and physico-mechanical testing. The crystallinity index was found to be 83 and 54% for BC and SP, respectively. FT-IR spectra showed that the composition of BC was fully different from that of SP fibers. Based on FESEM images, one can conclude that BC and softwood fibers do form a good combination with a nonporous structure. BC fibers fill in among the softwood fibers in the sheet. The physical and mechanical properties showed that as the dosage of BC increased, the properties of tensile index, tear index, and burst index greatly improved, while the porosity and the elongation decreased. The reason for the improved mechanical properties can be attributed to the increase of interfibrillar bonding which reduced porosity. This would be due to the high aspect ratio of BC that is capable of connecting between the cellulosic fibers and BC nanofibers, enhancing a large contact surface and therefore producing excellent coherence. This study suggests that BC could be a promising material for reinforcing composites at low loading. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Genome sequence and plasmid transformation of the model high-yield bacterial cellulose producer Gluconacetobacter hansenii ATCC 53582

    NASA Astrophysics Data System (ADS)

    Florea, Michael; Reeve, Benjamin; Abbott, James; Freemont, Paul S.; Ellis, Tom

    2016-03-01

    Bacterial cellulose is a strong, highly pure form of cellulose that is used in a range of applications in industry, consumer goods and medicine. Gluconacetobacter hansenii ATCC 53582 is one of the highest reported bacterial cellulose producing strains and has been used as a model organism in numerous studies of bacterial cellulose production and studies aiming to increased cellulose productivity. Here we present a high-quality draft genome sequence for G. hansenii ATCC 53582 and find that in addition to the previously described cellulose synthase operon, ATCC 53582 contains two additional cellulose synthase operons and several previously undescribed genes associated with cellulose production. In parallel, we also develop optimized protocols and identify plasmid backbones suitable for transformation of ATCC 53582, albeit with low efficiencies. Together, these results provide important information for further studies into cellulose synthesis and for future studies aiming to genetically engineer G. hansenii ATCC 53582 for increased cellulose productivity.

  9. Bacterial Cellulose Production from Industrial Waste and by-Product Streams

    PubMed Central

    Tsouko, Erminda; Kourmentza, Constantina; Ladakis, Dimitrios; Kopsahelis, Nikolaos; Mandala, Ioanna; Papanikolaou, Seraphim; Paloukis, Fotis; Alves, Vitor; Koutinas, Apostolis

    2015-01-01

    The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102–138 g·water/g·dry bacterial cellulose, viscosities of 4.7–9.3 dL/g, degree of polymerization of 1889.1–2672.8, stress at break of 72.3–139.5 MPa and Young’s modulus of 0.97–1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients. PMID:26140376

  10. Bacterial Cellulose Production from Industrial Waste and by-Product Streams.

    PubMed

    Tsouko, Erminda; Kourmentza, Constantina; Ladakis, Dimitrios; Kopsahelis, Nikolaos; Mandala, Ioanna; Papanikolaou, Seraphim; Paloukis, Fotis; Alves, Vitor; Koutinas, Apostolis

    2015-07-01

    The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102-138 g · water/g · dry bacterial cellulose, viscosities of 4.7-9.3 dL/g, degree of polymerization of 1889.1-2672.8, stress at break of 72.3-139.5 MPa and Young's modulus of 0.97-1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.

  11. Progress in bacterial cellulose matrices for biotechnological applications.

    PubMed

    Cacicedo, Maximiliano L; Castro, M Cristina; Servetas, Ioannis; Bosnea, Loulouda; Boura, Konstantina; Tsafrakidou, Panagiota; Dima, Agapi; Terpou, Antonia; Koutinas, Athanasios; Castro, Guillermo R

    2016-08-01

    Bacterial cellulose (BC) is an extracellular polymer produced by many microorganisms. The Komagataeibacter genus is the best producer using semi-synthetic media and agricultural wastes. The main advantages of BC are the nanoporous structure, high water content and free hydroxyl groups. Modification of BC can be made by two strategies: in-situ, during the BC production, and ex-situ after BC purification. In bioprocesses, multilayer BC nanocomposites can contain biocatalysts designed to be suitable for outside to inside cell activities. These nanocomposites biocatalysts can (i) increase productivity in bioreactors and bioprocessing, (ii) provide cell activities does not possess without DNA cloning and (iii) provide novel nano-carriers for cell inside activity and bioprocessing. In nanomedicine, BC matrices containing therapeutic molecules can be used for pathologies like skin burns, and implantable therapeutic devices. In nanoelectronics, semiconductors BC-based using salts and synthetic polymers brings novel films showing excellent optical and photochemical properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Bacterial cellulose skin masks-Properties and sensory tests.

    PubMed

    Pacheco, Guilherme; de Mello, Carolina Véspoli; Chiari-Andréo, Bruna Galdorfini; Isaac, Vera Lucia Borges; Ribeiro, Sidney José Lima; Pecoraro, Édison; Trovatti, Eliane

    2017-09-29

    Bacterial cellulose (BC) is a versatile material produced by microorganisms in the form of a membranous hydrogel, totally biocompatible, and endowed with high mechanical strength. Its high water-holding capacity based on its highly porous nanofibrillar structure allows BC to incorporate and to release substances very fast, thus being suitable for the preparation of skincare masks. The preparation and characterization of cosmetic masks based on BC membranes and active cosmetics. The masks were prepared by the simple incorporation of the cosmetic actives into BC membranes, used as a swelling matrix. The masks were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), sensory tests, and skin moisture tests on volunteers. The results of sensory tests revealed the good performance of BC, being considered effective by the panel of volunteers, specially for adhesion to the skin (7.7 at the score scale), and improvement of the skin moisture (the hydration effect increased 76% in 75% of the volunteers that used vegetable extract mask formulation [VEM]), or a decrease in skin hydration (80% of the volunteers showed 32.6% decrease on skin hydration using propolis extract formulation [PEM] treatment), indicating the BC nanofiber membranes can be used to skincare applications. The results demonstrate the BC can be used as an alternative support for cosmetic actives for skin treatment. © 2017 Wiley Periodicals, Inc.

  13. Modification of Bacterial Cellulose Biofilms with Xylan Polyelectrolytes.

    PubMed

    Santos, Sara M; Carbajo, José M; Gómez, Nuria; Ladero, Miguel; Villar, Juan C

    2017-11-28

    The effect of the addition of two [4-butyltrimethylammonium]-xylan chloride polyelectrolytes (BTMAXs) on bacterial cellulose (BC) was evaluated. The first strategy was to add the polyelectrolytes to the culture medium together with a cell suspension of the bacterium. After one week of cultivation, the films were collected and purified. The second approach consisted of obtaining a purified and homogenized BC, to which the polyelectrolytes were added subsequently. The films were characterized in terms of tear and burst indexes, optical properties, surface free energy, static contact angle, Gurley porosity, SEM, X-ray diffraction and AFM. Although there are small differences in mechanical and optical properties between the nanocomposites and control films, the films obtained by BC synthesis in the presence of BTMAXs were remarkably less opaque, rougher, and had a much lower specular gloss. The surface free energy depends on the BTMAXs addition method. The crystallinity of the composites is lower than that of the control material, with a higher reduction of this parameter in the composites obtained by adding the BTMAXs to the culture medium. In view of these results, it can be concluded that BC-BTMAX composites are a promising new material, for example, for paper restoration.

  14. Role of water-soluble polysaccharides in bacterial cellulose production.

    PubMed

    Ishida, Takehiko; Mitarai, Makoto; Sugano, Yasushi; Shoda, Makoto

    2003-08-20

    Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC) and a water-soluble polysaccharide called acetan in corn steep liquor-fructose medium. Acetobacter xylinum EP1, which is incapable of acetan production was derived by disrupting the aceA gene of BPR2001. The BC production by EP1 (2.88 g/L) was lower than that by BPR2001 (4.6 g/L) in baffled-flask culture. When purified acetan or agar was added to the medium from the start of cultivation, the BC production by EP1 was enhanced and the final BC yield of EP1 was almost the same as that of BPR2001. A similar improvement of BC production by EP1 by the addition of agar was also confirmed by cultivation in a 50-L airlift reactor. From these results, the role of acetan in BC production is associated with the increase in the viscosity of the culture medium which may hinder coagulation of BC and cells in the culture, thereby accelerating the growth of BPR2001 and BC production by BPR2001. Copyright 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 474-478, 2003.

  15. Electrically conductive nano graphite-filled bacterial cellulose composites.

    PubMed

    Erbas Kiziltas, Esra; Kiziltas, Alper; Rhodes, Kevin; Emanetoglu, Nuri W; Blumentritt, Melanie; Gardner, Douglas J

    2016-01-20

    A unique three dimensional (3D) porous structured bacterial cellulose (BC) can act as a supporting material to deposit the nanofillers in order to create advanced BC-based functional nanomaterials for various technological applications. In this study, novel nanocomposites comprised of BC with exfoliated graphite nanoplatelets (xGnP) incorporated into the BC matrix were prepared using a simple particle impregnation strategy to enhance the thermal properties and electrical conductivity of the BC. The flake-shaped xGnP particles were well dispersed and formed a continuous network throughout the BC matrix. The temperature at 10% weight loss, thermal stability and residual ash content of the nanocomposites increased at higher xGnP loadings. The electrical conductivity of the composites increased with increasing xGnP loading (attaining values 0.75 S/cm with the addition of 2 wt.% of xGnP). The enhanced conductive and thermal properties of the BC-xGnP nanocomposites will broaden applications (biosensors, tissue engineering, etc.) of BC and xGnP. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. The effect of bacterial cellulose on the shape memory behavior of polyvinyl alcohol nanocomposite hydrogel

    NASA Astrophysics Data System (ADS)

    Pirahmadi, Pegah; Kokabi, Mehrdad

    2018-01-01

    Most research on shape memory polymers has been confined to neat polymers in their dry state, while, some hydrogel networks are known for their shape memory properties. Hydrogels have low glass transition temperatures which are below 100°C depend on the content of water. But they are usually weak and brittle, and not suitable for structural applications due to their low mechanical strengths because of these materials have large amount of water (>50%), so they could not remember original shape perfectly. Bacterial cellulose nanofibers with perfect properties such as high water holding capacity, high crystallinity, high tensile strength and good biocompatibility can dismiss all the drawbacks. In the present study, polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel prepared by repetitive freezing-thawing method. The bacterial cellulose was used as reinforcement to improve the mechanical properties and stimuli response. Differential scanning calorimetry was employed to obtain the glass transition temperature. Nanocomposite morphology was characterized by field-emission scanning electron microscopy and mechanical properties were investigated by standard tensile test. Finally, the effect of bacterial cellulose nanofiber on shape memory behavior of polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel was investigated. It is found that switching temperature of this system is the glass transition temperature of the nano domains formed within the system. The results also show increase of shape recovery, and shape recovery speed due to presence of bacterial cellulose.

  17. Design and characterization of synthetic fungal-bacterial consortia for direct production of isobutanol from cellulosic biomass

    PubMed Central

    Minty, Jeremy J.; Singer, Marc E.; Scholz, Scott A.; Bae, Chang-Hoon; Ahn, Jung-Ho; Foster, Clifton E.; Liao, James C.; Lin, Xiaoxia Nina

    2013-01-01

    Synergistic microbial communities are ubiquitous in nature and exhibit appealing features, such as sophisticated metabolic capabilities and robustness. This has inspired fast-growing interest in engineering synthetic microbial consortia for biotechnology development. However, there are relatively few reports of their use in real-world applications, and achieving population stability and regulation has proven to be challenging. In this work, we bridge ecology theory with engineering principles to develop robust synthetic fungal-bacterial consortia for efficient biosynthesis of valuable products from lignocellulosic feedstocks. The required biological functions are divided between two specialists: the fungus Trichoderma reesei, which secretes cellulase enzymes to hydrolyze lignocellulosic biomass into soluble saccharides, and the bacterium Escherichia coli, which metabolizes soluble saccharides into desired products. We developed and experimentally validated a comprehensive mathematical model for T. reesei/E. coli consortia, providing insights on key determinants of the system’s performance. To illustrate the bioprocessing potential of this consortium, we demonstrate direct conversion of microcrystalline cellulose and pretreated corn stover to isobutanol. Without costly nutrient supplementation, we achieved titers up to 1.88 g/L and yields up to 62% of theoretical maximum. In addition, we show that cooperator–cheater dynamics within T. reesei/E. coli consortia lead to stable population equilibria and provide a mechanism for tuning composition. Although we offer isobutanol production as a proof-of-concept application, our modular system could be readily adapted for production of many other valuable biochemicals. PMID:23959872

  18. Design and characterization of synthetic fungal-bacterial consortia for direct production of isobutanol from cellulosic biomass.

    PubMed

    Minty, Jeremy J; Singer, Marc E; Scholz, Scott A; Bae, Chang-Hoon; Ahn, Jung-Ho; Foster, Clifton E; Liao, James C; Lin, Xiaoxia Nina

    2013-09-03

    Synergistic microbial communities are ubiquitous in nature and exhibit appealing features, such as sophisticated metabolic capabilities and robustness. This has inspired fast-growing interest in engineering synthetic microbial consortia for biotechnology development. However, there are relatively few reports of their use in real-world applications, and achieving population stability and regulation has proven to be challenging. In this work, we bridge ecology theory with engineering principles to develop robust synthetic fungal-bacterial consortia for efficient biosynthesis of valuable products from lignocellulosic feedstocks. The required biological functions are divided between two specialists: the fungus Trichoderma reesei, which secretes cellulase enzymes to hydrolyze lignocellulosic biomass into soluble saccharides, and the bacterium Escherichia coli, which metabolizes soluble saccharides into desired products. We developed and experimentally validated a comprehensive mathematical model for T. reesei/E. coli consortia, providing insights on key determinants of the system's performance. To illustrate the bioprocessing potential of this consortium, we demonstrate direct conversion of microcrystalline cellulose and pretreated corn stover to isobutanol. Without costly nutrient supplementation, we achieved titers up to 1.88 g/L and yields up to 62% of theoretical maximum. In addition, we show that cooperator-cheater dynamics within T. reesei/E. coli consortia lead to stable population equilibria and provide a mechanism for tuning composition. Although we offer isobutanol production as a proof-of-concept application, our modular system could be readily adapted for production of many other valuable biochemicals.

  19. Cellulose utilization in forest litter and soil: identification of bacterial and fungal decomposers.

    PubMed

    Stursová, Martina; Zifčáková, Lucia; Leigh, Mary Beth; Burgess, Robert; Baldrian, Petr

    2012-06-01

    Organic matter decomposition in the globally widespread coniferous forests has an important role in the carbon cycle, and cellulose decomposition is especially important in this respect because cellulose is the most abundant polysaccharide in plant litter. Cellulose decomposition was 10 times faster in the fungi-dominated litter of Picea abies forest than in the bacteria-dominated soil. In the soil, the added (13)C-labelled cellulose was the main source of microbial respiration and was preferentially accumulated in the fungal biomass and cellulose induced fungal proliferation. In contrast, in the litter, bacterial biomass showed higher labelling after (13)C-cellulose addition and bacterial biomass increased. While 80% of the total community was represented by 104-106 bacterial and 33-59 fungal operational taxonomic units (OTUs), 80% of the cellulolytic communities of bacteria and fungi were only composed of 8-18 highly abundant OTUs. Both the total and (13)C-labelled communities differed substantially between the litter and soil. Cellulolytic bacteria in the acidic topsoil included Betaproteobacteria, Bacteroidetes and Acidobacteria, whereas these typically found in neutral soils were absent. Most fungal cellulose decomposers belonged to Ascomycota; cellulolytic Basidiomycota were mainly represented by the yeasts Trichosporon and Cryptococcus. Several bacteria and fungi demonstrated here to derive their carbon from cellulose were previously not recognized as cellulolytic. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  20. Simultaneous influence of pectin and xyloglucan on structure and mechanical properties of bacterial cellulose composites.

    PubMed

    Szymańska-Chargot, Monika; Chylińska, Monika; Cybulska, Justyna; Kozioł, Arkadiusz; Pieczywek, Piotr M; Zdunek, Artur

    2017-10-15

    The impact of the matrix polysaccharides on the cellulose microfibrils structure as well as on the mechanical properties of cell walls still remains an open question. Therefore, the aim of investigations was to determine the simultaneous influence of (i) different concentrations of pectins with constant concentration of xyloglucan, and (ii) different concentrations of xyloglucan with constant concentration of pectins on cellulose structure. Composites of bacterial cellulose (BC) produced by Komagataeibacter xylinus are considered to mimic natural plant cell walls. This investigation showed that the lower the ratio of xyloglucan to pectin was, the higher Young's modulus of BC composite was and also obtained cellulose microfibrils were thinner. The increasing concentration of xyloglucan to pectin also caused the drop down in microfibrils crystallinity degree with predominant structure of cellulose I β . In that case, also the length of cellulose chains was growing and reaching the highest value among all BC composites. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Cellulose-ethylenediaminetetraacetic acid conjugates protect mammalian cells from bacterial cells.

    PubMed

    Luo, Jie; Lv, Wei; Deng, Ying; Sun, Yuyu

    2013-04-08

    Cellulose-ethylenediaminetetraacetic acid (EDTA) conjugates were synthesized by the esterification of cellulose with ethylenediaminetetraacetic dianhydride (EDTAD). The new materials provided potent antimicrobial activities against Staphylococcus aureus (S. aureus, Gram-positive bacteria) and Pseudomonas aeruginosa (P. aeruginosa, Gram-negative bacteria), and inhibited the formation of bacterial biofilms. The biocompatibility of the new cellulose-EDTA conjugates was evaluated with mouse skin fibroblasts for up to 14 days. SEM observation and DNA content analysis suggested that the new materials sustained the viability of fibroblast cells. Moreover, in mouse skin fibroblast-bacteria co-culture systems, the new cellulose-EDTA conjugates prevented bacterial biofilm formation and protected the mammalian cells from the bacterial cells for at least one day.

  2. Structure of a cellulose degrading bacterial community during anaerobic digestion.

    PubMed

    O'Sullivan, Cathryn A; Burrell, Paul C; Clarke, William P; Blackall, Linda L

    2005-12-30

    It is widely accepted that cellulose is the rate-limiting substrate in the anaerobic digestion of organic solid wastes and that cellulose solubilisation is largely mediated by surface attached bacteria. However, little is known about the identity or the ecophysiology of cellulolytic microorganisms from landfills and anaerobic digesters. The aim of this study was to investigate an enriched cellulolytic microbial community from an anaerobic batch reactor. Chemical oxygen demand balancing was used to calculate the cellulose solubilisation rate and the degree of cellulose solubilisation. Fluorescence in situ hybridisation (FISH) was used to assess the relative abundance and physical location of three groups of bacteria belonging to the Clostridium lineage of the Firmicutes that have been implicated as the dominant cellulose degraders in this system. Quantitation of the relative abundance using FISH showed that there were changes in the microbial community structure throughout the digestion. However, comparison of these results to the process data reveals that these changes had no impact on the cellulose solubilisation in the reactor. The rate of cellulose solubilisation was approximately stable for much of the digestion despite changes in the cellulolytic population. The solubilisation rate appears to be most strongly affected by the rate of surface area colonisation and the biofilm architecture with the accepted model of first order kinetics due to surface area limitation applying only when the cellulose particles are fully covered with a thin layer of cells. Copyright 2005 Wiley Periodicals, Inc

  3. [Microcrystalline cellulose and their flow -- morphological properties modifications as an effective excpients in tablet formulation technology containing lattice established API and also dry plant extract].

    PubMed

    Zgoda, Marian Mikołaj; Nachajski, Michał Jakub; Kołodziejczyk, Michał Krzysztof

    2009-01-01

    The production technology of powder cellulose (Arbocel) and microcrystaline cellulose (Vivapur) and their application in the composition of direct compression tablet mass was provided. The function of silicified microcrystaline cellulose type Prosolv in the direct compression process of dry plant extract was discussed. An analysis of the chemical structure of cellulose fiber (Vitacel) enabled determining its properties and applications in the manufacture of diet supplement, pharmaceutical and food products.

  4. Progressive structural changes of Avicel, bleached softwood, and bacterial cellulose during enzymatic hydrolysis

    DOE PAGES

    Kafle, Kabindra; Shin, Heenae; Lee, Christopher M.; ...

    2015-10-14

    A comprehensive picture of structural changes of cellulosic biomass during enzymatic hydrolysis is essential for a better understanding of enzymatic actions and development of more efficient enzymes. In this study, a suite of analytical techniques including sum frequency generation (SFG) spectroscopy, infrared (IR) spectroscopy, x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) were employed for lignin-free model biomass samples—Avicel, bleached softwood, and bacterial cellulose—to find correlations between the decrease in hydrolysis rate over time and the structural or chemical changes of biomass during the hydrolysis reaction. The results showed that the decrease in hydrolysis rate over time appears to correlatemore » with the irreversible deposition of non-cellulosic species (either reaction side products or denatured enzymes, or both) on the cellulosic substrate surface. The crystallinity, degree of polymerization, and meso-scale packing of cellulose do not seem to positively correlate with the decrease in hydrolysis rate observed for all three substrates tested in this study. Moreover, it was also found that the cellulose Iα component of the bacterial cellulose is preferentially hydrolyzed by the enzyme than the cellulose Iβ component.« less

  5. Progressive structural changes of Avicel, bleached softwood, and bacterial cellulose during enzymatic hydrolysis

    SciTech Connect

    Kafle, Kabindra; Shin, Heenae; Lee, Christopher M.

    A comprehensive picture of structural changes of cellulosic biomass during enzymatic hydrolysis is essential for a better understanding of enzymatic actions and development of more efficient enzymes. In this study, a suite of analytical techniques including sum frequency generation (SFG) spectroscopy, infrared (IR) spectroscopy, x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) were employed for lignin-free model biomass samples—Avicel, bleached softwood, and bacterial cellulose—to find correlations between the decrease in hydrolysis rate over time and the structural or chemical changes of biomass during the hydrolysis reaction. The results showed that the decrease in hydrolysis rate over time appears to correlatemore » with the irreversible deposition of non-cellulosic species (either reaction side products or denatured enzymes, or both) on the cellulosic substrate surface. The crystallinity, degree of polymerization, and meso-scale packing of cellulose do not seem to positively correlate with the decrease in hydrolysis rate observed for all three substrates tested in this study. It was also found that the cellulose Iα component of the bacterial cellulose is preferentially hydrolyzed by the enzyme than the cellulose Iβ component.« less

  6. Progressive structural changes of Avicel, bleached softwood, and bacterial cellulose during enzymatic hydrolysis

    SciTech Connect

    Kafle, Kabindra; Shin, Heenae; Lee, Christopher M.

    A comprehensive picture of structural changes of cellulosic biomass during enzymatic hydrolysis is essential for a better understanding of enzymatic actions and development of more efficient enzymes. In this study, a suite of analytical techniques including sum frequency generation (SFG) spectroscopy, infrared (IR) spectroscopy, x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) were employed for lignin-free model biomass samples—Avicel, bleached softwood, and bacterial cellulose—to find correlations between the decrease in hydrolysis rate over time and the structural or chemical changes of biomass during the hydrolysis reaction. The results showed that the decrease in hydrolysis rate over time appears to correlatemore » with the irreversible deposition of non-cellulosic species (either reaction side products or denatured enzymes, or both) on the cellulosic substrate surface. The crystallinity, degree of polymerization, and meso-scale packing of cellulose do not seem to positively correlate with the decrease in hydrolysis rate observed for all three substrates tested in this study. Moreover, it was also found that the cellulose Iα component of the bacterial cellulose is preferentially hydrolyzed by the enzyme than the cellulose Iβ component.« less

  7. Progressive structural changes of Avicel, bleached softwood, and bacterial cellulose during enzymatic hydrolysis

    PubMed Central

    Kafle, Kabindra; Shin, Heenae; Lee, Christopher M.; Park, Sunkyu; Kim, Seong H.

    2015-01-01

    A comprehensive picture of structural changes of cellulosic biomass during enzymatic hydrolysis is essential for a better understanding of enzymatic actions and development of more efficient enzymes. In this study, a suite of analytical techniques including sum frequency generation (SFG) spectroscopy, infrared (IR) spectroscopy, x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) were employed for lignin-free model biomass samples—Avicel, bleached softwood, and bacterial cellulose—to find correlations between the decrease in hydrolysis rate over time and the structural or chemical changes of biomass during the hydrolysis reaction. The results showed that the decrease in hydrolysis rate over time appears to correlate with the irreversible deposition of non-cellulosic species (either reaction side products or denatured enzymes, or both) on the cellulosic substrate surface. The crystallinity, degree of polymerization, and meso-scale packing of cellulose do not seem to positively correlate with the decrease in hydrolysis rate observed for all three substrates tested in this study. It was also found that the cellulose Iα component of the bacterial cellulose is preferentially hydrolyzed by the enzyme than the cellulose Iβ component. PMID:26463274

  8. Comparison of pharyngocutaneous fistula closure with and without bacterial cellulose in a rat model.

    PubMed

    Demir, Berat; Sarı, Murat; Binnetoglu, Adem; Yumusakhuylu, Ali Cemal; Filinte, Deniz; Tekin, İshak Özel; Bağlam, Tekin; Batman, Abdullah Çağlar

    2018-04-01

    The present study aimed to compare the effects of bacterial cellulose used for closure of pharyngocutaneous fistulae, a complication of total laryngectomy, with those of primary sutures in a rat model. Thirty female Sprague-Dawley underwent experimental pharyngoesophagotomy and were grouped depending on the material used for pharyngocutaneous fistula closure: group I, which received primary sutures alone, group II, which received bacterial cellulose alone; and group III, which received both. After 7 days, the rats were sacrificed. Pharyngocutaneous fistula development was assessed, the gross wound was inspected, and histological examination was conducted. Pharyngocutaneous fistulae developed in 12 rats (41%) in all: 6 from group I (21%), 4 from group II (14%) and 2 from group III (7%). Fibroblast density and inflammatory cell infiltration were significantly greater in group III than group I. We concluded that bacterial cellulose may be useful for pharyngocutaneous fistula closure. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Isolation of bacterial cellulose nanocrystalline from pineapple peel waste: Optimization of acid concentration in the hydrolysis method

    NASA Astrophysics Data System (ADS)

    Anwar, Budiman; Rosyid, Nurul Huda; Effendi, Devi Bentia; Nandiyanto, Asep Bayu Dani; Mudzakir, Ahmad; Hidayat, Topik

    2016-02-01

    Isolation of needle-shaped bacterial cellulose nanocrystalline with a diameter of 16-64 nm, a fiber length of 258-806 nm, and a degree of crystallinity of 64% from pineapple peel waste using an acid hydrolysis process was investigated. Experimental showed that selective concentration of acid played important roles in isolating the bacterial cellulose nanocrystalline from the cellulose source. To achieve the successful isolation of bacterial cellulose nanocrystalline, various acid concentrations were tested. To confirm the effect of acid concentration on the successful isolation process, the reaction conditions were fixed at a temperature of 50°C, a hydrolysis time of 30 minutes, and a bacterial cellulose-to-acid ratio of 1:50. Pineapple peel waste was used as a model for a cellulose source because to the best of our knowledge, there is no report on the use of this raw material for producing bacterial cellulose nanocrystalline. In fact, this material can be used as an alternative for ecofriendly and cost-free cellulose sources. Therefore, understanding in how to isolate bacterial cellulose nanocrystalline from pineapple peel waste has the potential for large-scale production of inexpensive cellulose nanocrystalline.

  10. Surface-structured bacterial cellulose with guided assembly-based biolithography (GAB).

    PubMed

    Bottan, Simone; Robotti, Francesco; Jayathissa, Prageeth; Hegglin, Alicia; Bahamonde, Nicolas; Heredia-Guerrero, José A; Bayer, Ilker S; Scarpellini, Alice; Merker, Hannes; Lindenblatt, Nicole; Poulikakos, Dimos; Ferrari, Aldo

    2015-01-27

    A powerful replica molding methodology to transfer on-demand functional topographies to the surface of bacterial cellulose nanofiber textures is presented. With this method, termed guided assembly-based biolithography (GAB), a surface-structured polydimethylsiloxane (PDMS) mold is introduced at the gas-liquid interface of an Acetobacter xylinum culture. Upon bacterial fermentation, the generated bacterial cellulose nanofibers are assembled in a three-dimensional network reproducing the geometric shape imposed by the mold. Additionally, GAB yields directional alignment of individual nanofibers and memory of the transferred geometrical features upon dehydration and rehydration of the substrates. Scanning electron and atomic force microscopy are used to establish the good fidelity of this facile and affordable method. Interaction of surface-structured bacterial cellulose substrates with human fibroblasts and keratinocytes illustrates the efficient control of cellular activities which are fundamental in skin wound healing and tissue regeneration. The deployment of surface-structured bacterial cellulose substrates in model animals as skin wound dressing or body implant further proves the high durability and low inflammatory response to the material over a period of 21 days, demonstrating beneficial effects of surface structure on skin regeneration.

  11. Fibrillar assembly of bacterial cellulose in the presence of wood-based hemicelluloses.

    PubMed

    Penttilä, Paavo A; Imai, Tomoya; Sugiyama, Junji

    2017-09-01

    Composite materials mimicking the plant cell wall structure were made by culturing cellulose-producing bacteria together with secondary-wall hemicelluloses from wood. The effects of spruce galactoglucomannan (GGM) and beech xylan on the nanoscale morphology of bacterial cellulose were studied in the original, hydrated state with small-angle X-ray scattering (SAXS). The SAXS intensities were fitted with a model covering multiple levels of the hierarchical structure. Additional information on the structure of dried samples was obtained using scanning and transmission electron microscopy and infra-red spectroscopy. Both hemicelluloses induced a partial conversion of the cellulose crystal structure from I α to I β and a reduction of the cross-sectional dimensions of the cellulose microfibrils, thereby affecting also their packing into bundles. The differences were more pronounced in samples with xylan instead of GGM, and they became more significant with higher hemicellulose concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Chromophores in cellulosics, XI: isolation and identification of residual chromophores from bacterial cellulose

    USDA-ARS?s Scientific Manuscript database

    Cotton or linen fabrics and paper, as well as other items composed chiefly of cellulose, tend to change to a yellow or brown color as they age. The change in color is usually accompanied by increased brittleness and loss of strength, as well. A cause of these phenomena is thought to be the formation...

  13. Bacterial production of free fatty acids from freshwater macroalgal cellulose

    PubMed Central

    Hoovers, Spencer W.; Marner, Wesley D.; Brownson, Amy K.; Lennen, Rebecca M.; Wittkopp, Tyler M.; Yoshitani, Jun; Zulkifly, Shahrizim; Graham, Linda E.; Chaston, Sheena D.; McMahon, Katherine D.

    2013-01-01

    The predominant strategy for using algae to produce biofuels relies on the overproduction of lipids in microalgae with subsequent conversion to biodiesel (methyl-esters) or green diesel (alkanes). Conditions that both optimize algal growth and lipid accumulation rarely overlap, and differences in growth rates can lead to wild species outcompeting the desired lipid-rich strains. Here, we demonstrate an alternative strategy in which cellulose contained in the cell walls of multicellular algae is used as a feedstock for cultivating biofuel-producing micro-organisms. Cellulose was extracted from an environmental sample of Cladophora glomerata-dominated periphyton that was collected from Lake Mendota, WI, USA. The resulting cellulose cake was hydrolyzed by commercial enzymes to release fermentable glucose. The hydrolysis mixture was used to formulate an undefined medium that was able to support the growth, without supplementation, of a free fatty acid (FFA)-overproducing strain of Escherichia coli (Lennen et. al 2010). To maximize free fatty acid production from glucose, an isopropyl β-D-1-thiogalactopyranoside (IPTG)-inducible vector was constructed to express the Umbellularia californica acyl–acyl carrier protein (ACP) thioesterase. Thioesterase expression was optimized by inducing cultures with 50 μM IPTG. Cell density and FFA titers from cultures grown on algae-based media reached 50% of those (~90 μg/mL FFA) cultures grown on rich Luria–Bertani broth supplemented with 0.2% glucose. In comparison, cultures grown in two media based on AFEX-pretreated corn stover generated tenfold less FFA than cultures grown in algae-based media. This study demonstrates that macroalgal cellulose is a potential carbon source for the production of biofuels or other microbially synthesized compounds. PMID:21643704

  14. Bacterial cellulose based hydrogel (BC-g-AA) and preliminary result of swelling behavior

    SciTech Connect

    Hakam, Adil; Lazim, Azwan Mat; Abdul Rahman, I. Irman

    2013-11-27

    In this study, hydrogel based on Bacterial cellulose (BC) or local known as Nata de Coco, which grafted with monomer: Acrylic acid (AA) is synthesis by using gamma radiation technique. These hydrogel (BC-g-AA) has unique characteristic whereby responsive to pH buffer solution.

  15. Cost-effective production of bacterial cellulose using acidic food industry by-products.

    PubMed

    Revin, Victor; Liyaskina, Elena; Nazarkina, Maria; Bogatyreva, Alena; Shchankin, Mikhail

    2018-03-13

    To reduce the cost of obtaining bacterial cellulose, acidic by-products of the alcohol and dairy industries were used without any pretreatment or addition of other nitrogen sources. Studies have shown that the greatest accumulation of bacterial cellulose (6.19g/L) occurs on wheat thin stillage for 3 days of cultivation under dynamic conditions, which is almost 3 times higher than on standard Hestrin and Schramm medium (2.14g/L). The use of whey as a nutrient medium makes it possible to obtain 5.45g/L bacterial cellulose under similar conditions of cultivation. It is established that the pH of the medium during the growth of Gluconacetobacter sucrofermentans B-11267 depends on the feedstock used and its initial value. By culturing the bacterium on thin stillage and whey, there is a decrease in the acidity of the waste. It is shown that the infrared spectra of bacterial cellulose obtained in a variety of environments have a similar character, but we found differences in the micromorphology and crystallinity of the resulting biopolymer. Copyright © 2018 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  16. BcsA and BcsB form the catalytically active core of bacterial cellulose synthase sufficient for in vitro cellulose synthesis

    PubMed Central

    Omadjela, Okako; Narahari, Adishesh; Strumillo, Joanna; Mélida, Hugo; Mazur, Olga; Bulone, Vincent; Zimmer, Jochen

    2013-01-01

    Cellulose is a linear extracellular polysaccharide. It is synthesized by membrane-embedded glycosyltransferases that processively polymerize UDP-activated glucose. Polymer synthesis is coupled to membrane translocation through a channel formed by the cellulose synthase. Although eukaryotic cellulose synthases function in macromolecular complexes containing several different enzyme isoforms, prokaryotic synthases associate with additional subunits to bridge the periplasm and the outer membrane. In bacteria, cellulose synthesis and translocation is catalyzed by the inner membrane-associated bacterial cellulose synthase (Bcs)A and BcsB subunits. Similar to alginate and poly-β-1,6 N-acetylglucosamine, bacterial cellulose is implicated in the formation of sessile bacterial communities, termed biofilms, and its synthesis is likewise stimulated by cyclic-di-GMP. Biochemical studies of exopolysaccharide synthesis are hampered by difficulties in purifying and reconstituting functional enzymes. We demonstrate robust in vitro cellulose synthesis reconstituted from purified BcsA and BcsB proteins from Rhodobacter sphaeroides. Although BcsA is the catalytically active subunit, the membrane-anchored BcsB subunit is essential for catalysis. The purified BcsA-B complex produces cellulose chains of a degree of polymerization in the range 200–300. Catalytic activity critically depends on the presence of the allosteric activator cyclic-di-GMP, but is independent of lipid-linked reactants. Our data reveal feedback inhibition of cellulose synthase by UDP but not by the accumulating cellulose polymer and highlight the strict substrate specificity of cellulose synthase for UDP-glucose. A truncation analysis of BcsB localizes the region required for activity of BcsA within its C-terminal membrane-associated domain. The reconstituted reaction provides a foundation for the synthesis of biofilm exopolysaccharides, as well as its activation by cyclic-di-GMP. PMID:24127606

  17. BcsA and BcsB form the catalytically active core of bacterial cellulose synthase sufficient for in vitro cellulose synthesis.

    PubMed

    Omadjela, Okako; Narahari, Adishesh; Strumillo, Joanna; Mélida, Hugo; Mazur, Olga; Bulone, Vincent; Zimmer, Jochen

    2013-10-29

    Cellulose is a linear extracellular polysaccharide. It is synthesized by membrane-embedded glycosyltransferases that processively polymerize UDP-activated glucose. Polymer synthesis is coupled to membrane translocation through a channel formed by the cellulose synthase. Although eukaryotic cellulose synthases function in macromolecular complexes containing several different enzyme isoforms, prokaryotic synthases associate with additional subunits to bridge the periplasm and the outer membrane. In bacteria, cellulose synthesis and translocation is catalyzed by the inner membrane-associated bacterial cellulose synthase (Bcs)A and BcsB subunits. Similar to alginate and poly-β-1,6 N-acetylglucosamine, bacterial cellulose is implicated in the formation of sessile bacterial communities, termed biofilms, and its synthesis is likewise stimulated by cyclic-di-GMP. Biochemical studies of exopolysaccharide synthesis are hampered by difficulties in purifying and reconstituting functional enzymes. We demonstrate robust in vitro cellulose synthesis reconstituted from purified BcsA and BcsB proteins from Rhodobacter sphaeroides. Although BcsA is the catalytically active subunit, the membrane-anchored BcsB subunit is essential for catalysis. The purified BcsA-B complex produces cellulose chains of a degree of polymerization in the range 200-300. Catalytic activity critically depends on the presence of the allosteric activator cyclic-di-GMP, but is independent of lipid-linked reactants. Our data reveal feedback inhibition of cellulose synthase by UDP but not by the accumulating cellulose polymer and highlight the strict substrate specificity of cellulose synthase for UDP-glucose. A truncation analysis of BcsB localizes the region required for activity of BcsA within its C-terminal membrane-associated domain. The reconstituted reaction provides a foundation for the synthesis of biofilm exopolysaccharides, as well as its activation by cyclic-di-GMP.

  18. Physicochemical characterization of novel Schiff bases derived from developed bacterial cellulose 2,3-dialdehyde.

    PubMed

    Keshk, Sherif M A S; Ramadan, Ahmed M; Bondock, Samir

    2015-08-20

    The synthesis of two novel Schiff's bases (cellulose-2,3-bis-[(4-methylene-amino)-benzene-sulfonamide] (5) & cellulose-2,3-bis-[(4-methylene-amino)-N-(thiazol-2-yl)-benzenesulfonamide] (6) via condensation reactions of periodate oxidized developed bacterial cellulose ODBC (2) with sulfa drugs [sulfanilamide (3) & sulfathiazole (4)] was reported. The physicochemical characterization of the condensation products was performed using FTIR, (1)H NMR, (13)C NMR spectral analyses, X-ray diffraction and DTA. The ODBC exhibited the highest degree of oxidation based on the aldehyde group number percentage (82.9%), which confirms the highest reactivity of developed bacterial cellulose [DBC (1)]. The X-ray diffractograms indicated an increase in the interplanar distance of the cellulose Schiff base (6) compared to ODBC (2) due to sulfathiazole (4) inclusion between ODBC (2) sheets corresponding to the 1 1 0 plane. In addition, the aldehyde content of Schiff base (6) was (20.8%) much lower than that of Schiff base (5) (41.5%). These results confirmed the high affinity of sulfathiazole (4) to the ODBC (2) chain, and the substantial changes in the original properties of ODBC were due to these chemical modifications rather than the sulfanilamide (3). Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. A Novel Platform for Evaluating the Environmental Impacts on Bacterial Cellulose Production.

    PubMed

    Basu, Anindya; Vadanan, Sundaravadanam Vishnu; Lim, Sierin

    2018-04-10

    Bacterial cellulose (BC) is a biocompatible material with versatile applications. However, its large-scale production is challenged by the limited biological knowledge of the bacteria. The advent of synthetic biology has lead the way to the development of BC producing microbes as a novel chassis. Hence, investigation on optimal growth conditions for BC production and understanding of the fundamental biological processes are imperative. In this study, we report a novel analytical platform that can be used for studying the biology and optimizing growth conditions of cellulose producing bacteria. The platform is based on surface growth pattern of the organism and allows us to confirm that cellulose fibrils produced by the bacteria play a pivotal role towards their chemotaxis. The platform efficiently determines the impacts of different growth conditions on cellulose production and is translatable to static culture conditions. The analytical platform provides a means for fundamental biological studies of bacteria chemotaxis as well as systematic approach towards rational design and development of scalable bioprocessing strategies for industrial production of bacterial cellulose.

  20. Identification of Cellulose-Responsive Bacterial and Fungal Communities in Geographically and Edaphically Different Soils by Using Stable Isotope Probing

    PubMed Central

    Eichorst, Stephanie A.

    2012-01-01

    Many bacteria and fungi are known to degrade cellulose in culture, but their combined response to cellulose in different soils is unknown. Replicate soil microcosms amended with [13C]cellulose were used to identify bacterial and fungal communities responsive to cellulose in five geographically and edaphically different soils. The diversity and composition of the cellulose-responsive communities were assessed by DNA-stable isotope probing combined with Sanger sequencing of small-subunit and large-subunit rRNA genes for the bacterial and fungal communities, respectively. In each soil, the 13C-enriched, cellulose-responsive communities were of distinct composition compared to the original soil community or 12C-nonenriched communities. The composition of cellulose-responsive taxa, as identified by sequence operational taxonomic unit (OTU) similarity, differed in each soil. When OTUs were grouped at the bacterial order level, we found that members of the Burkholderiales, Caulobacteriales, Rhizobiales, Sphingobacteriales, Xanthomonadales, and the subdivision 1 Acidobacteria were prevalent in the 13C-enriched DNA in at least three of the soils. The cellulose-responsive fungi were identified as members of the Trichocladium, Chaetomium, Dactylaria, and Arthrobotrys genera, along with two novel Ascomycota clusters, unique to one soil. Although similarities were identified in higher-level taxa among some soils, the composition of cellulose-responsive bacteria and fungi was generally unique to a certain soil type, suggesting a strong potential influence of multiple edaphic factors in shaping the community. PMID:22287013

  1. Cellulosic hydrogen production with a sequencing bacterial hydrolysis and dark fermentation strategy.

    PubMed

    Lo, Yung-Chung; Bai, Ming-Der; Chen, Wen-Ming; Chang, Jo-Shu

    2008-11-01

    In this study, cellulose hydrolysis activity of two mixed bacterial consortia (NS and QS) was investigated. Combination of NS culture and BHM medium exhibited better hydrolytic activity under the optimal condition of 35 degrees C, initial pH 7.0, and 100rpm agitation. The NS culture could hydrolyze carboxymethyl cellulose (CMC), rice husk, bagasse and filter paper, among which CMC gave the best hydrolysis performance. The CMC hydrolysis efficiency increased with increasing CMC concentration from 5 to 50g/l. With a CMC concentration of 10g/l, the total reducing sugar (RS) production and the RS producing rate reached 5531.0mg/l and 92.9mg/l/h, respectively. Furthermore, seven H2-producing bacterial isolates (mainly Clostridium species) were used to convert the cellulose hydrolysate into H2 energy. With an initial RS concentration of 0.8g/l, the H2 production and yield was approximately 23.8ml/l and 1.21mmol H2/g RS (0.097mmol H2/g cellulose), respectively.

  2. Influence of ambient moisture on the compaction behavior of microcrystalline cellulose powder undergoing uni-axial compression and roller-compaction: a comparative study using near-infrared spectroscopy.

    PubMed

    Gupta, Abhay; Peck, Garnet E; Miller, Ronald W; Morris, Kenneth R

    2005-10-01

    This study evaluates the effect of variation in the ambient moisture on the compaction behavior of microcrystalline cellulose (MCC) powder. The study was conducted by comparing the physico-mechanical properties of, and the near infrared (NIR) spectra collected on, compacts prepared by roller compaction with those collected on simulated ribbons, that is, compacts prepared under uni-axial compression. Relative density, moisture content, tensile strength (TS), and Young modulus were used as key sample attributes for comparison. Samples prepared at constant roller compactor settings and feed mass showed constant density and a decrease in TS with increasing moisture content. Compacts prepared under uni-axial compression at constant pressure and compact mass showed the opposite effect, that is, density increased while TS remained almost constant with increasing moisture content. This suggests difference in the influence of moisture on the material under roller compaction, in which the roll gap (i.e., thickness and therefore density) remains almost constant, vs. under uni-axial compression, in which the thickness is free to change in response to the applied pressure. Key sample attributes were also related to the NIR spectra using multivariate data analysis by the partial least squares projection to latent structures (PLS). Good agreement was observed between the measured and the NIR-PLS predicted values for all key attributes for both, the roller compacted samples as well as the simulated ribbons. Copyright (c) 2005 Wiley-Liss, Inc. and the American Pharmacists Association

  3. Simple green approach to reinforce natural rubber with bacterial cellulose nanofibers.

    PubMed

    Trovatti, Eliane; Carvalho, Antonio J F; Ribeiro, Sidney J L; Gandini, Alessandro

    2013-08-12

    Natural rubber (NR) is a renewable polymer with a wide range of applications, which is constantly tailored, further increasing its utilizations. The tensile strength is one of its most important properties susceptible of being enhanced by the simple incorporation of nanofibers. The preparation and characterization of natural-rubber based nanocomposites reinforced with bacterial cellulose (BC) and bacterial cellulose coated with polystyrene (BCPS), yielded high performance materials. The nanocomposites were prepared by a simple and green process, and characterized by tensile tests, dynamical mechanical analysis (DMA), scanning electron microscopy (SEM), and swelling experiments. The effect of the nanofiber content on morphology, static, and dynamic mechanical properties was also investigated. The results showed an increase in the mechanical properties, such as Young's modulus and tensile strength, even with modest nanofiber loadings.

  4. Dispersions of attractive semiflexible fiberlike colloidal particles from bacterial cellulose microfibrils.

    PubMed

    Kuijk, Anke; Koppert, Remco; Versluis, Peter; van Dalen, Gerard; Remijn, Caroline; Hazekamp, Johan; Nijsse, Jaap; Velikov, Krassimir P

    2013-11-26

    We prepared dispersions from bacterial cellulose microfibrils (CMF) of a commercial Nata de Coco source. We used an ultra-high-energy mechanical deagglomeration process that is able to disperse the CMFs from the pellicle in which they are organized in an irregular network. Because of the strong attractions between the CMFs, the dispersion remained highly heterogeneous, consisting of fiber bundles, flocs, and voids spanning tens to hundreds of micrometers depending on concentration. The size of these flocs increased with CMF concentration, the size of the bundles stayed constant, and the size of the voids decreased. The observed percolation threshold in MFC dispersions is lower than the theoretical prediction, which is accounted for by the attractive interactions in the system. Because bacterial cellulose is chemically very pure, it can be used to study the interaction of attractive and highly shape-anisotropic, semiflexible fiberlike colloidal particles.

  5. Effect of γ irradiation on poly(vinyl alcohol) and bacterial cellulose composites used as packaging materials

    NASA Astrophysics Data System (ADS)

    Stoica-Guzun, Anicuta; Stroescu, Marta; Jipa, Iuliana; Dobre, Loredana; Zaharescu, Traian

    2013-03-01

    The aim of this paper is to present the influence of bacterial cellulose microfibrils and γ-radiation dose on poly(vinyl alcohol) (PVA)-bacterial cellulose (BC) composites. Two composite materials were obtained: the first one from PVA aqueous solution 4% and 5% wet bacterial cellulose and the second from the same PVA solution and 10% wet bacterial cellulose. In terms of PVA/dry BC ratios (w/w) for these films the ratios are 1/0.025 and 1/0.050. The obtained composite materials were characterized by infrared spectroscopy with Fourier transform (FT-IR) and UV-vis spectroscopy in order to evaluate the irradiation effect on their stability. The swelling behavior of the polymeric composites was also studied. The composite materials were compared with a film of pure PVA and a dry BC membrane.

  6. Cellulose Nanofibrils and Mechanism of their Mineralization in Biomimetic Synthesis of Hydroxyapatite/Native Bacterial Cellulose Nanocomposites: Molecular Dynamics Simulations.

    PubMed

    Lukasheva, N V; Tolmachev, D A

    2016-01-12

    Molecular dynamics (MD) simulation of a nanofibril of native bacterial cellulose (BC) in solutions of mineral ions is presented. The supersaturated calcium-phosphate (CP) solution with the ionic composition of hydroxyapatite and CaCl2 solutions with the concentrations below, equal to, and above the solubility limits are simulated. The influence of solvation models (TIP3P and TIP4P-ew water models) on structural characteristics of the simulated nanofibril and on the crystal nucleation process is assessed. The structural characteristics of cellulose nanofibrils (in particular, of the surface layer) are found to be nearly independent of the solvation models used in the simulation and on the presence of ions in the solutions. It is shown that ionic clusters are formed in the solution rather than on the fibril surface. The cluster sizes are slightly different for the two water models. The effect of the ion-ion interaction parameters on the results is discussed. The main conclusion is that the activity of hydroxyl groups on the BC fibril surface is not high enough to cause adsorption of Ca(2+) ions from the solution. Therefore, the nucleation of CP crystals takes place initially in solution, and then the crystallites formed can be adsorbed on BC nanofibril surfaces.

  7. Nanomaterials from bacterial cellulose for antimicrobial wound dressing

    NASA Astrophysics Data System (ADS)

    Liyaskina, E.; Revin, V.; Paramonova, E.; Nazarkina, M.; Pestov, N.; Revina, N.; Kolesnikova, S.

    2017-01-01

    Bacterial nanocellulose (BNC) is widely used in biomedical applications. BNC has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity. To get over this problem in the present study the BNC was saturated with antibiotic fusidic acid (FA). The subject of the experiment was BNC, produced by bacteria Gluconacetobacter sucrofermentans B-11267. The resulting biocomposites have high antibiotic activity against Staphylococcus aureus and can be used in medicine as a wound dressing. The structure of BNC was analyzed by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR).

  8. Effect of electron beam irradiation on bacterial cellulose membranes used as transdermal drug delivery systems

    NASA Astrophysics Data System (ADS)

    Stoica-Guzun, Anicuta; Stroescu, Marta; Tache, Florin; Zaharescu, Traian; Grosu, Elena

    2007-12-01

    Ionizing radiation is an effective energetic source for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. In this work, gamma rays have been applied to induce changes in bacterial cellulose membranes. Permeation of drug (tetracycline) was theoretically and experimentally investigated starting from the effect of γ-irradiation on membranes permeability. Release and permeation of drug from irradiated and non-irradiated membranes have been performed using a diffusion cell.

  9. Performance of improved bacterial cellulose application in the production of functional paper.

    PubMed

    Basta, A H; El-Saied, H

    2009-12-01

    The purpose of this work was to study the feasibility of producing economic flame retardant bacterial cellulose (BC) and evaluating its behaviour in paper production. This type of BC was prepared by Gluconacetobacter subsp. xylinus and substituting the glucose in the cultivation medium by glucose phosphate as a carbon source; as well as using corn steep liquor as a nitrogen source. The investigated processing technique did not dispose any toxic chemicals that pollute the surroundings or cause unacceptable effluents, making the process environmentally safe. The fire retardant behaviour of the investigated BC has been studied by non-isothermal thermogravimetric analysis (TGA & DTGA). The activation energy of each degradation stage and the order of degradation were estimated using the Coats-Redfern equation and the least square method. Strength, optical properties, and thermogravimetric analysis of BC-phosphate added paper sheets were also tested. The study confirmed that the use of glucose phosphate along with glucose was significant in the high yield production of phosphate containing bacterial cellulose (PCBC1); more so than the use of glucose phosphate alone (PCBC2). Incorporating 5% of the PCBC with wood pulp during paper sheet formation was found to significantly improve kaolin retention, strength, and fire resistance properties as compared to paper sheets produced from incorporating bacterial cellulose (BC). This modified BC is a valuable product for the preparation of specialized paper, in addition to its function as a fillers aid.

  10. Bacterial populations and environmental factors controlling cellulose degradation in an acidic Sphagnum peat.

    PubMed

    Pankratov, Timofey A; Ivanova, Anastasia O; Dedysh, Svetlana N; Liesack, Werner

    2011-07-01

    Northern peatlands represent a major global carbon store harbouring approximately one-third of the global reserves of soil organic carbon. A large proportion of these peatlands consists of acidic Sphagnum-dominated ombrotrophic bogs, which are characterized by extremely low rates of plant debris decomposition. The degradation of cellulose, the major component of Sphagnum-derived litter, was monitored in long-term incubation experiments with acidic (pH 4.0) peat extracts. This process was almost undetectable at 10°C and occurred at low rates at 20°C, while it was significantly accelerated at both temperature regimes by the addition of available nitrogen. Cellulose breakdown was only partially inhibited in the presence of cycloheximide, suggesting that bacteria participated in this process. We aimed to identify these bacteria by a combination of molecular and cultivation approaches and to determine the factors that limit their activity in situ. The indigenous bacterial community in peat was dominated by Alphaproteobacteria and Acidobacteria. The addition of cellulose induced a clear shift in the community structure towards an increase in the relative abundance of the Bacteroidetes. Increasing temperature and nitrogen availability resulted in a selective development of bacteria phylogenetically related to Cytophaga hutchinsonii (94-95% 16S rRNA gene sequence similarity), which densely colonized microfibrils of cellulose. Among isolates obtained from this community only some subdivision 1 Acidobacteria were capable of degrading cellulose, albeit at a very slow rate. These Acidobacteria represent indigenous cellulolytic members of the microbial community in acidic peat and are easily out-competed by Cytophaga-like bacteria under conditions of increased nitrogen availability. Members of the phylum Firmicutes, known to be key players in cellulose degradation in neutral habitats, were not detected in the cellulolytic community enriched at low pH. © 2011 Society for

  11. Effective Young's modulus of bacterial and microfibrillated cellulose fibrils in fibrous networks.

    PubMed

    Tanpichai, Supachok; Quero, Franck; Nogi, Masaya; Yano, Hiroyuki; Young, Robert J; Lindström, Tom; Sampson, William W; Eichhorn, Stephen J

    2012-05-14

    The deformation micromechanics of bacterial cellulose (BC) and microfibrillated cellulose (MFC) networks have been investigated using Raman spectroscopy. The Raman spectra of both BC and MFC networks exhibit a band initially located at ≈ 1095 cm(-1). We have used the intensity of this band as a function of rotation angle of the specimens to study the cellulose fibril orientation in BC and MFC networks. We have also used the change in this peak's wavenumber position with applied tensile deformation to probe the stress-transfer behavior of these cellulosic materials. The intensity of this Raman band did not change significantly with rotation angle, indicating an in-plane 2D network of fibrils with uniform random orientation; conversely, a highly oriented flax fiber exhibited a marked change in intensity with rotation angle. Experimental data and theoretical analysis shows that the Raman band shift rate arising from deformation of networks under tension is dependent on the angles between the axis of fibrils, the strain axis, the incident laser polarization direction, and the back scattered polarization configurations. From this analysis, the effective moduli of single fibrils of BC and MFC in the networks were estimated to be in the ranges of 79-88 and 29-36 GPa, respectively. It is shown also that for the model to fit the data it is necessary to use a negative Poisson's ratio for MFC networks and BC networks. Discussion of this in-plane "auxetic" behavior is given.

  12. Super-Strong, Super-Stiff Macrofibers with Aligned, Long Bacterial Cellulose Nanofibers.

    PubMed

    Wang, Sha; Jiang, Feng; Xu, Xu; Kuang, Yudi; Fu, Kun; Hitz, Emily; Hu, Liangbing

    2017-09-01

    With their impressive properties such as remarkable unit tensile strength, modulus, and resistance to heat, flame, and chemical agents that normally degrade conventional macrofibers, high-performance macrofibers are now widely used in various fields including aerospace, biomedical, civil engineering, construction, protective apparel, geotextile, and electronic areas. Those macrofibers with a diameter of tens to hundreds of micrometers are typically derived from polymers, gel spun fibers, modified carbon fibers, carbon-nanotube fibers, ceramic fibers, and synthetic vitreous fibers. Cellulose nanofibers are promising building blocks for future high-performance biomaterials and textiles due to their high ultimate strength and stiffness resulting from a highly ordered orientation along the fiber axis. For the first time, an effective fabrication method is successfully applied for high-performance macrofibers involving a wet-drawing and wet-twisting process of ultralong bacterial cellulose nanofibers. The resulting bacterial cellulose macrofibers yield record high tensile strength (826 MPa) and Young's modulus (65.7 GPa) owing to the large length and the alignment of nanofibers along fiber axis. When normalized by weight, the specific tensile strength of the macrofiber is as high as 598 MPa g -1 cm 3 , which is even substantially stronger than the novel lightweight steel (227 MPa g -1 cm 3 ). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Production and characterization of bacterial cellulose membranes with hyaluronic acid from chicken comb.

    PubMed

    de Oliveira, Sabrina Alves; da Silva, Bruno Campos; Riegel-Vidotti, Izabel Cristina; Urbano, Alexandre; de Sousa Faria-Tischer, Paula Cristina; Tischer, Cesar Augusto

    2017-04-01

    The bacterial cellulose (BC), from Gluconacetobacter hansenii, is a biofilm with a high degree of crystallinity that can be used for therapeutic purposes and as a candidate for healing wounds. Hyaluronic acid (HA) is a constitutive polysaccharide found in the extracellular matrix and is a material used in tissue engineering and scaffolding for tissue regeneration. In this study, polymeric composites were produced in presence of hyaluronic acid isolated from chicken comb on different days of fermentation, specifically on the first (BCHA-SABT0) and third day (BCHA-SABT3) of fermentation. The structural characteristics, thermal stability and molar mass of hyaluronic acid from chicken comb were evaluated. Native membrane and polymeric composites were characterized with respect to their morphology and crystallinity. The optimized process of extraction and purification of hyaluronic acid resulted in low molar mass hyaluronic acid with structural characteristics similar to the standard commercial hyaluronic acid. The results demonstrate that the polymeric composites (BC/HA-SAB) can be produced in situ. The membranes produced on the third day presented better incorporation of HA-SAB between cellulose microfiber, resulting in membranes with higher thermal stability, higher roughness and lower crystallinity. The biocompatiblily of bacterial cellulose and the importance of hyaluronic acid as a component of extracellular matrix qualify the polymeric composites as promising biomaterials for tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Stable coexistence of five bacterial strains as a cellulose-degrading community.

    PubMed

    Kato, Souichiro; Haruta, Shin; Cui, Zong Jun; Ishii, Masaharu; Igarashi, Yasuo

    2005-11-01

    A cellulose-degrading defined mixed culture (designated SF356) consisting of five bacterial strains (Clostridium straminisolvens CSK1, Clostridium sp. strain FG4, Pseudoxanthomonas sp. strain M1-3, Brevibacillus sp. strain M1-5, and Bordetella sp. strain M1-6) exhibited both functional and structural stability; namely, no change in cellulose-degrading efficiency was observed, and all members stably coexisted through 20 subcultures. In order to investigate the mechanisms responsible for the observed stability, "knockout communities" in which one of the members was eliminated from SF356 were constructed. The dynamics of the community structure and the cellulose degradation profiles of these mixed cultures were determined in order to evaluate the roles played by each eliminated member in situ and its impact on the other members of the community. Integration of each result gave the following estimates of the bacterial relationships. Synergistic relationships between an anaerobic cellulolytic bacterium (C. straminisolvens CSK1) and two strains of aerobic bacteria (Pseudoxanthomonas sp. strain M1-3 and Brevibacillus sp. strain M1-5) were observed; the aerobes introduced anaerobic conditions, and C. straminisolvens CSK1 supplied metabolites (acetate and glucose). In addition, there were negative relationships, such as the inhibition of cellulose degradation by producing excess amounts of acetic acid by Clostridium sp. strain FG4, and growth suppression of Bordetella sp. strain M1-6 by Brevibacillus sp. strain M1-5. The balance of the various types of relationships (both positive and negative) is thus considered to be essential for the stable coexistence of the members of this mixed culture.

  15. Antimicrobial bacterial cellulose nanocomposites prepared by in situ polymerization of 2-aminoethyl methacrylate.

    PubMed

    Figueiredo, Ana R P; Figueiredo, Andrea G P R; Silva, Nuno H C S; Barros-Timmons, Ana; Almeida, Adelaide; Silvestre, Armando J D; Freire, Carmen S R

    2015-06-05

    Antimicrobial bacterial cellulose/poly(2-aminoethyl methacrylate) (BC/PAEM) nanocomposites were prepared by in situ radical polymerization of 2-aminoethyl methacrylate, using variable amounts of N,N-methylenebis(acrylamide) (MBA) as cross-linker. The obtained nanocomposites were characterized in terms of their structure, morphology, thermal stability, mechanical properties and antibacterial activity. The ensuing composite membranes were significantly more transparent than those of pure BC and showed improved thermal and mechanical properties. The antibacterial activity of the obtained nanocomposites was assessed towards a recombinant bioluminescent Escherichia coli and only the non-crosslinked nanocomposite (BC/PAEM) proved to have antibacterial activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Applicability of bacterial cellulose as an alternative to paper points in endodontic treatment.

    PubMed

    Yoshino, Aya; Tabuchi, Mari; Uo, Motohiro; Tatsumi, Hiroto; Hideshima, Katsumi; Kondo, Seiji; Sekine, Joji

    2013-04-01

    Dental root canal treatment is required when dental caries progress to infection of the dental pulp. A major goal of this treatment is to provide complete decontamination of the dental root canal system. However, the morphology of dental root canal systems is complex, and many human dental roots have inaccessible areas. In addition, dental reinfection is fairly common. In conventional treatment, a cotton pellet and paper point made from plant cellulose is used to dry and sterilize the dental root canal. Such sterilization requires a treatment material with high absorbency to remove any residue, the ability to improve the efficacy of intracanal medication and high biocompatibility. Bacterial cellulose (BC) is produced by certain strains of bacteria. In this study, we developed BC in a pointed form and evaluated its applicability as a novel material for dental canal treatment with regard to solution absorption, expansion, tensile strength, drug release and biocompatibility. We found that BC has excellent material and biological characteristics compared with conventional materials, such as paper points (plant cellulose). BC showed noticeably higher absorption and expansion than paper points, and maintained a high tensile strength even when wet. The cumulative release of a model drug was significantly greater from BC than from paper points, and BC showed greater compatibility than paper points. Taken together, BC has great potential for use in dental root canal treatment. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Property evaluations of dry-cast reconstituted bacterial cellulose/tamarind xyloglucan biocomposites.

    PubMed

    de Souza, Clayton F; Lucyszyn, Neoli; Woehl, Marco A; Riegel-Vidotti, Izabel C; Borsali, Redouane; Sierakowski, Maria Rita

    2013-03-01

    We describe the mechanical defibrillation of bacterial cellulose (BC) followed by the dry-cast generation of reconstituted BC films (RBC). Xyloglucan (XGT), extracted from tamarind seeds, was incorporated into the defibrillated cellulose at various compositions, and new films were created using the same process. Microscopy and contact angle analyses of films revealed an increase in the microfibre adhesion, a reduced polydispersity in the diameters of the microfibrils and increased hydrophobic behaviour as a function of %XGT. X-ray diffraction analysis revealed changes to the crystallographic planes of the RBC and the biocomposite films with preferential orientation along the (110) plane. Compared with BC, RBC/XGT biocomposite with 10% XGT exhibited improvement in its thermal properties and in Young's modulus. These results indicated a reorganisation of the microfibres with mechanical treatment, which when combined with hydrocolloids, can create cellulose-based materials that could be applied as scaffolding for tissue engineering and drug release. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Production of nano bacterial cellulose from waste water of candied jujube-processing industry using Acetobacter xylinum.

    PubMed

    Li, Zheng; Wang, Lifen; Hua, Jiachuan; Jia, Shiru; Zhang, Jianfei; Liu, Hao

    2015-04-20

    The work is aimed to investigate the suitability of waste water of candied jujube-processing industry for the production of bacterial cellulose (BC) by Gluconacetobacter xylinum CGMCC No.2955 and to study the structure properties of bacterial cellulose membranes. After acid pretreatment, the glucose of hydrolysate was higher than that of waste water of candied jujube. The volumetric yield of bacterial cellulose in hydrolysate was 2.25 g/L, which was 1.5-folds of that in waste water of candied jujube. The structures indicated that the fiber size distribution was 3-14 nm in those media with an average diameter being around 5.9 nm. The crystallinity index of BC from pretreatment medium was lower than that of without pretreatment medium and BCs from various media had similar chemical binding. Ammonium citrate was a key factor for improving production yield and the crystallinity index of BC. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. NMR relaxometric probing of ionic liquid dynamics and diffusion under mesoscopic confinement within bacterial cellulose ionogels

    NASA Astrophysics Data System (ADS)

    Smith, Chip J.; Gehrke, Sascha; Hollóczki, Oldamur; Wagle, Durgesh V.; Heitz, Mark P.; Baker, Gary A.

    2018-05-01

    Bacterial cellulose ionogels (BCIGs) represent a new class of material comprising a significant content of entrapped ionic liquid (IL) within a porous network formed from crystalline cellulose microfibrils. BCIGs suggest unique opportunities in separations, optically active materials, solid electrolytes, and drug delivery due to the fact that they can contain as much as 99% of an IL phase by weight, coupled with an inherent flexibility, high optical transparency, and the ability to control ionogel cross-sectional shape and size. To allow for the tailoring of BCIGs for a multitude of applications, it is necessary to better understand the underlying principles of the mesoscopic confinement within these ionogels. Toward this, we present a study of the structural, relaxation, and diffusional properties of the ILs, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmpy][Tf2N]), using 1H and 19F NMR T1 relaxation times, rotational correlation times, and diffusion ordered spectroscopy (DOSY) diffusion coefficients, accompanied by molecular dynamics (MD) simulations. We observed that the cation methyl groups in both ILs were primary points of interaction with the cellulose chains and, while the pore size in cellulose is rather large, [emim]+ diffusion was slowed by ˜2-fold, whereas [Tf2N]- diffusion was unencumbered by incorporation in the ionogel. While MD simulations of [bmpy][Tf2N] confinement at the interface showed a diffusion coefficient decrease roughly 3-fold compared to the bulk liquid, DOSY measurements did not reveal any significant changes in diffusion. This suggests that the [bmpy][Tf2N] alkyl chains dominate diffusion through formation of apolar domains. This is in contrast to [emim][Tf2N] where delocalized charge appears to preclude apolar domain formation, allowing interfacial effects to be manifested at a longer range in [emim][Tf2N].

  20. Plackett-Burman experimental design for bacterial cellulose-silica composites synthesis.

    PubMed

    Guzun, Anicuta Stoica; Stroescu, Marta; Jinga, Sorin Ion; Voicu, Georgeta; Grumezescu, Alexandru Mihai; Holban, Alina Maria

    2014-09-01

    Bacterial cellulose-silica hybrid composites were prepared starting from wet bacterial cellulose (BC) membranes using Stöber reaction. The structure and surface morphology of hybrid composites were examined by FTIR and SEM. The SEM pictures revealed that the silica particles are attached to BC fibrils and are well dispersed in the BC matrix. The influence of silica particles upon BC crystallinity was studied using XRD analysis. Thermogravimetric (TG) analysis showed that the composites are stable up to 300°C. A Plackett-Burman design was applied in order to investigate the influence of process parameters upon silica particle sizes and silica content of BC-silica composites. The statistical model predicted that it is possible for silica particles size to vary the synthesis parameters in order to obtain silica particles deposed on BC membranes in the range from 34.5 to 500 nm, the significant parameters being ammonia concentration, reaction time and temperature. The silica content also varies depending on process parameters, the statistical model predicting that the most influential parameters are water-tetraethoxysilane (TEOS) ratio and reaction temperature. The antimicrobial behavior on Staphylococcus aureus of BC-silica composites functionalized with usnic acid (UA) was also studied, in order to create improved surfaces with antiadherence and anti-biofilm properties. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Interparticle interactions mediated superspin glass to superferromagnetic transition in Ni-bacterial cellulose aerogel nanocomposites

    NASA Astrophysics Data System (ADS)

    Thiruvengadam, V.; Vitta, Satish

    2016-06-01

    The interparticle interactions in the magnetic nanocomposites play a dominant role in controlling phase transitions: superparamagnetic to superspin glass and to superferromagnetic. These interactions can be tuned by controlling the size and number density of nanoparticles. The aerogel composites, 0.3Ni-BC and 0.7Ni-BC, consisting of Ni nanoparticles distributed in the bacterial cellulose have been used as a model system to study these interactions. Contrary to conventional approach, size of Ni-nanoparticles is not controlled and allowed to form naturally in bacterial cellulose template. The uncontrolled growth of Ni results in the formation of nanoparticles with 3 different size distributions - <10 nm particles along the length of fibrils, 50 nm particles in the intermediate spaces between the fibrils, and >100 nm particles in voids formed by reticulate structure. At room temperature, the composites exhibit a weakly ferromagnetic behaviour with a coercivity of 40 Oe, which increases to 160 Oe at 10 K. The transition from weakly ferromagnetic state to superferromagnetic state at low temperatures is mediated by the superspin glass state at intermediate temperatures via the interparticle interactions aided by nanoparticles present along the length of fibres. A temperature dependent microstructural model has been developed to understand the magnetic behaviour of nanocomposite aerogels.

  2. Luffa sponge offsets the negative effects of aeration on bacterial cellulose production.

    PubMed

    Krusong, W; Kerdpiboon, S; Pornpukdeewattana, S; Jindaprasert, A

    2016-12-01

    To offset the negative effects of aeration on bacterial cellulose (BC) production by acetic acid bacteria using enmeshed cellulose microfibrils (CM) on luffa sponge matrices (LSM). The CM were enmeshed on LSM (LSM-CM). The optimal amount of LSM-CM was determined for BC production under aerated conditions. Without LSM-CM, no BC was produced in seven out of nine production cycles at the highest aeration rate (9 l min -1 ). However, with 0·5% LSM-CM and an aeration rate of 3 l min -1 , a satisfactory oxygen transfer coefficient was achieved, and also a good yield of BC (5·24 g l -1 ). Moreover, the LSM-CM was able to be recycled through nine consecutive BC production cycles. The highest BC yields (from 5·8 ± 0·4 to 6·6 ± 0·4 g l -1 ) were associated with high bacterial biomass and this was confirmed by scanning electron microscopy. We confirm that LSM-CM works well as a starter. Microenvironments low in dissolved oxygen within the matrices of LSM-CM are important for BC production under aeration conditions. The LSM-CM provides a microenvironment which offsets the negative effects of aeration on BC production. A sustainable, economic process for mass BC production is described using recycled LSM-CM with aeration. © 2016 The Society for Applied Microbiology.

  3. Bacterial Cellulose Membranes Used as Artificial Substitutes for Dural Defection in Rabbits

    PubMed Central

    Xu, Chen; Ma, Xia; Chen, Shiwen; Tao, Meifeng; Yuan, Lutao; Jing, Yao

    2014-01-01

    To improve the efficacy and safety of dural repair in neurosurgical procedures, a new dural material derived from bacterial cellulose (BC) was evaluated in a rabbit model with dural defects. We prepared artificial dura mater using bacterial cellulose which was incubated and fermented from Acetobacter xylinum. The dural defects of the rabbit model were repaired with BC membranes. All surgeries were performed under sodium pentobarbital anesthesia, and all efforts were made to minimize suffering. All animals were humanely euthanized by intravenous injection of phenobarbitone, at each time point, after the operation. Then, the histocompatibility and inflammatory effects of BC were examined by histological examination, real-time fluorescent quantitative polymerase chain reaction (PCR) and Western Blot. BC membranes evenly covered the surface of brain without adhesion. There were seldom inflammatory cells surrounding the membrane during the early postoperative period. The expression of inflammatory cytokines IL-1β, IL-6 and TNF-α as well as iNOS and COX-2 were lower in the BC group compared to the control group at 7, 14 and 21 days after implantation. BC can repair dural defects in rabbit and has a decreased inflammatory response compared to traditional materials. However, the long-term effects need to be validated in larger animals. PMID:24937688

  4. Towards an Integrated QR Code Biosensor: Light-Driven Sample Acquisition and Bacterial Cellulose Paper Substrate.

    PubMed

    Yuan, Mingquan; Jiang, Qisheng; Liu, Keng-Ku; Singamaneni, Srikanth; Chakrabartty, Shantanu

    2018-06-01

    This paper addresses two key challenges toward an integrated forward error-correcting biosensor based on our previously reported self-assembled quick-response (QR) code. The first challenge involves the choice of the paper substrate for printing and self-assembling the QR code. We have compared four different substrates that includes regular printing paper, Whatman filter paper, nitrocellulose membrane and lab synthesized bacterial cellulose. We report that out of the four substrates bacterial cellulose outperforms the others in terms of probe (gold nanorods) and ink retention capability. The second challenge involves remote activation of the analyte sampling and the QR code self-assembly process. In this paper, we use light as a trigger signal and a graphite layer as a light-absorbing material. The resulting change in temperature due to infrared absorption leads to a temperature gradient that then exerts a diffusive force driving the analyte toward the regions of self-assembly. The working principle has been verified in this paper using assembled biosensor prototypes where we demonstrate higher sample flow rate due to light induced thermal gradients.

  5. Metagenomic Characterization and Biochemical Analysis of Cellulose-Degrading Bacterial Communities from Sheep Rumen, Termite Hindgut, Decaying Plant Materials, and Soil

    DTIC Science & Technology

    2016-01-04

    Biochemical Analysis of Cellulose-DegradingBacterial Communities from Sheep Rumen, Termite Hindgut, Decaying Plant Materials,and Soil In an effort to...degrading bacteria from various samples, including termite gut, sheep rumen, soil, and decaying plant materials. Using selective media culture with...Metagenomic Characterization and Biochemical Analysis of Cellulose-DegradingBacterial Communities from Sheep Rumen, Termite Hindgut, Decaying Plant

  6. The productive cellulase binding capacity of cellulosic substrates.

    PubMed

    Karuna, Nardrapee; Jeoh, Tina

    2017-03-01

    Cellulosic biomass is the most promising feedstock for renewable biofuel production; however, the mechanisms of the heterogeneous cellulose saccharification reaction are still unsolved. As cellulases need to bind isolated molecules of cellulose at the surface of insoluble cellulose fibrils or larger aggregated cellulose structures in order to hydrolyze glycosidic bonds, the "accessibility of cellulose to cellulases" is considered to be a reaction limiting property of cellulose. We have defined the accessibility of cellulose to cellulases as the productive binding capacity of cellulose, that is, the concentration of productive binding sites on cellulose that are accessible for binding and hydrolysis by cellulases. Productive cellulase binding to cellulose results in hydrolysis and can be quantified by measuring hydrolysis rates. In this study, we measured the productive Trichoderma reesei Cel7A (TrCel7A) binding capacity of five cellulosic substrates from different sources and processing histories. Swollen filter paper and bacterial cellulose had higher productive binding capacities of ∼6 µmol/g while filter paper, microcrystalline cellulose, and algal cellulose had lower productive binding capacities of ∼3 µmol/g. Swelling and regenerating filter paper using phosphoric acid increased the initial accessibility of the reducing ends to TrCel7A from 4 to 6 µmol/g. Moreover, this increase in initial productive binding capacity accounted in large part for the difference in the overall digestibility between filter paper and swollen filter paper. We further demonstrated that an understanding of how the productive binding capacity declines over the course of the hydrolysis reaction has the potential to predict overall saccharification time courses. Biotechnol. Bioeng. 2017;114: 533-542. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. ZnO nanostructures directly grown on paper and bacterial cellulose substrates without any surface modification layer.

    PubMed

    Costa, Saionara V; Gonçalves, Agnaldo S; Zaguete, Maria A; Mazon, Talita; Nogueira, Ana F

    2013-09-21

    In this report, hierarchical ZnO nano- and microstructures were directly grown for the first time on a bacterial cellulose substrate and on two additional different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures.

  8. Bacterial cellulose may provide the microbial-life biosignature in the rock records

    NASA Astrophysics Data System (ADS)

    Zaets, I.; Podolich, O.; Kukharenko, O.; Reshetnyak, G.; Shpylova, S.; Sosnin, M.; Khirunenko, L.; Kozyrovska, N.; de Vera, J.-P.

    2014-03-01

    Bacterial cellulose (BC) is a matrix for a biofilm formation, which is critical for survival and persistence of microbes in harsh environments. BC could play a significant role in the formation of microbial mats in pristine ecosystems on Earth. The prime objective of this study was to measure to what extent spectral and other characteristics of BC were changed under the performance of BC interaction with the earthly rock - anorthosite - via microorganisms. The spectral analyses (Fourier Transform Infrared FT-IR, spectroscopy, and atomic absorption spectroscopy) showed unprecedented accumulation of chemical elements in the BC-based biofilm. The absorption capacity of IR by BC was shielded a little by mineral crust formed by microorganisms on the BC-based biofilm surface, especially clearly seen in the range of 1200-900 cm-1 in FT-IR spectra. Confocal scanning laser microscopy analysis revealed that elements bioleached from anorthosite created surface coats on the BC nanofibril web. At the same time, the vibrational spectra bands showed the presence of the characteristic region of anomeric carbons (960-730 cm-1), wherein a band at 897 cm-1 confirmed the presence of β-1, 4-linkages, which may serve as the cellulose fingerprint region. Results show that BC may be a biosignature for search signs of living organisms in rock records.

  9. In situ and ex situ modifications of bacterial cellulose for applications in tissue engineering.

    PubMed

    Stumpf, Taisa Regina; Yang, Xiuying; Zhang, Jingchang; Cao, Xudong

    2018-01-01

    Bacterial cellulose (BC) is secreted by a few strains of bacteria and consists of a cellulose nanofiber network with unique characteristics. Because of its excellent mechanical properties, outstanding biocompatibilities, and abilities to form porous structures, BC has been studied for a variety of applications in different fields, including the use as a biomaterial for scaffolds in tissue engineering. To extend its applications in tissue engineering, native BC is normally modified to enhance its properties. Generally, BC modifications can be made by either in situ modification during cell culture or ex situ modification of existing BC microfibers. In this review we will first provide a brief introduction of BC and its attributes; this will set the stage for in-depth and up-to-date discussions on modified BC. Finally, the review will focus on in situ and ex situ modifications of BC and its applications in tissue engineering, particularly in bone regeneration and wound dressing. Copyright © 2016. Published by Elsevier B.V.

  10. Strategies for cost-effective and enhanced production of bacterial cellulose.

    PubMed

    Islam, Mazhar Ul; Ullah, Muhammad Wajid; Khan, Shaukat; Shah, Nasrullah; Park, Joong Kon

    2017-09-01

    Bacterial cellulose (BC) has received substantial attention because of its high purity, mechanical strength, crystallinity, liquid-absorbing capabilities, biocompatibility, and biodegradability etc. These properties allow BC to be used in various fields, especially in industries producing medical, electronic, and food products etc. A major discrepancy associated with BC is its high production cost, usually much higher than the plant cellulose. To address this limitations, researchers have developed several strategies for enhanced production of BC including the designing of advanced reactors and utilization of various carbon sources. Another promising approach is the production of BC from waste materials such as food, industrial, agricultural, and brewery wastes etc. which not only reduces the overall BC production cost but is also environment-friendly. Besides, exploration of novel and efficient BC producing microbial strains provides impressive boost to the BC production processes. To this end, development of genetically engineered microbial strains has proven useful for enhanced BC production. In this review, we have summarized major efforts to enhance BC production in order to make it a cost-effective biopolymer. This review can be of interest to researchers investigating strategies for enhanced BC production, as well as companies exploring pilot projects to scale up BC production for industrial applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Hydrothermal synthesis of bacterial cellulose-copper oxide nanocomposites and evaluation of their antimicrobial activity.

    PubMed

    Araújo, Inês M S; Silva, Robson R; Pacheco, Guilherme; Lustri, Wilton R; Tercjak, Agnieszka; Gutierrez, Junkal; Júnior, José R S; Azevedo, Francisco H C; Figuêredo, Girlene S; Vega, Maria L; Ribeiro, Sidney J L; Barud, Hernane S

    2018-01-01

    In this work, for the first time bacterial cellulose (BC) hydrogel membranes were used for the fabrication of antimicrobial cellulosic nanocomposites by hydrothermal deposition of Cu derivative nanoparticles (i.e.Cu(0) and CuxOy species). BC-Cu nanocomposites were characterized by FTIR, SEM, AFM, XRD and TGA, to study the effect of hydrothermal processing time on the final physicochemical properties of final products. XRD result show that depending on heating time (3-48h), different CuxOy phases were achieved. SEM and AFM analyses unveil the presence of the Cu(0) and copper CuxOy nanoparticles over BC fibrils while the surface of 3D network became more compact and smother for longer heating times. Furthermore, the increase of heating time placed deleterious effect on the structure of BC network leading to decrease of BC crystallinity as well as of the on-set degradation temperature. Notwithstanding, BC-Cu nanocomposites showed excellent antimicrobial activity against E. coli, S. aureus and Salmonella bacteria suggesting potential applications as bactericidal films. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Bacterial cellulose production from cotton-based waste textiles: enzymatic saccharification enhanced by ionic liquid pretreatment.

    PubMed

    Hong, Feng; Guo, Xiang; Zhang, Shuo; Han, Shi-fen; Yang, Guang; Jönsson, Leif J

    2012-01-01

    Cotton-based waste textiles were explored as alternative feedstock for production of bacterial cellulose (BC) by Gluconacetobacter xylinus. The cellulosic fabrics were treated with the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). [AMIM]Cl caused 25% inactivation of cellulase activity at a concentration as low as of 0.02 g/mL and decreased BC production during fermentation when present in concentrations higher than 0.0005 g/mL. Therefore, removal of residual IL by washing with hot water was highly beneficial to enzymatic saccharification as well as BC production. IL-treated fabrics exhibited a 5-7-fold higher enzymatic hydrolysis rate and gave a seven times larger yield of fermentable sugars than untreated fabrics. BC from cotton cloth hydrolysate was obtained at an yield of 10.8 g/L which was 83% higher than that from the culture grown on glucose-based medium. The BC from G. xylinus grown on IL-treated fabric hydrolysate had a 79% higher tensile strength than BC from glucose-based culture medium which suggests that waste cotton pretreated with [AMIM]Cl has potential to serve as a high-quality carbon source for BC production. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Thin stillage supplementation greatly enhances bacterial cellulose production by Gluconacetobacter xylinus.

    PubMed

    Wu, Jyh-Ming; Liu, Ren-Han

    2012-09-01

    Thin stillage (TS), a wastewater from rice wine distillery can well sustain the growth of Gluconacetobacter xylinus for production of bacterial cellulose (BC). When used as a supplement to the traditional BC production medium (Hestrin and Schramm medium), the enhancement of BC production increased with the amount of TS supplemented in a static culture of G. xylinus. When TS was employed to replace distilled water for preparing HS medium (100%TS-HS medium), the BC production in this 100%TS-HS medium was enhanced 2.5-fold to a concentration of 10.38 g/l with sugar to BC conversion yield of 57% after 7 days cultivation. The cost-free TS as a supplement in BC production medium not only can greatly enhance the BC production, but also can effectively dispose the nuisance wastewater of rice wine distillery. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Characterization of purified bacterial cellulose focused on its use on paper restoration.

    PubMed

    Santos, Sara M; Carbajo, José M; Quintana, Ester; Ibarra, David; Gomez, Nuria; Ladero, Miguel; Eugenio, M Eugenia; Villar, Juan C

    2015-02-13

    Bacterial cellulose (BC) synthesized by Gluconacetobacter sucrofermentans CECT 7291 seems to be a good option for the restoration of degraded paper. In this work BC layers are cultivated and purified by two different methods: an alkaline treatment when the culture media contains ethanol and a thermal treatment if the media is free from ethanol. The main goal of these tests was the characterization of BC layers measured in terms of tear and burst indexes, optical properties, SEM, X-ray diffraction, FTIR, degree of polymerization, static and dynamic contact angles, and mercury intrusion porosimetry. The BC layers were also evaluated in the same terms after an aging treatment. Results showed that BC has got high crystallinity index, low internal porosity, good mechanical properties and high stability over time, especially when purified by the alkaline treatment. These features make BC an adequate candidate for degraded paper reinforcement. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Simple preparation of Fenton catalyst@bacterial cellulose for waste water treatment

    NASA Astrophysics Data System (ADS)

    Wibowo, Arie; Febi Indrawan, Radian; Triadhi, Untung; Hasdi Aimon, Akfiny; Iskandar, Ferry; Ardy, Husaini

    2018-02-01

    Heterogeneous fenton catalyst is one of the attractive technologies for destruction of persistent and non-biodegradable pollutant in wastewater, because it can be used in wide range of pH and recyclable. Herein, commercial bacterial celluloses (BCs) were used as an alternative support of fenton catalyst to improve their catalytic activity. Scanning Electron Microscope (SEM) observations indicated that the presence of BCs and decreasing precursor concentration might promote formation of smaller particle sizes of catalyst from 3.5 μm of bare catalyst to 0.7 μm of catalyst@BC. UV-vis measurement showed that fast degradation of dyes with half-time degradation at around 25 min was observed in sample using catalyst@BCs with precursor concentration of 0.01 M. Successful preparation of heterogeneous fenton catalyst with smaller particle size and better catalytic activity is important for their application in wastewater treatment.

  16. Flexible polypyrrole/copper sulfide/bacterial cellulose nanofibrous composite membranes as supercapacitor electrodes.

    PubMed

    Peng, Shuo; Fan, Lingling; Wei, Chengzhuo; Liu, Xiaohong; Zhang, Hongwei; Xu, Weilin; Xu, Jie

    2017-02-10

    Polypyrrole (PPy) and copper sulfide (CuS) have been successfully deposited on bacterial cellulose (BC) membranes to prepare nanofibrous composite electrodes of PPy/CuS/BC for flexible supercapacitor applications. The introduction of CuS remarkably improves the specific capacitance and cycling stability of BC-based electrodes. The specific capacitance of the supercapacitors based on the PPy/CuS/BC electrodes can reach to about 580Fg -1 at a current density of 0.8mAcm -2 and can retain about 73% of their initial value after 300 cycles, while the PPy/BC-based device could retain only 21.7% after 300 cycles. This work provides a promising approach to fabricate cost-effective and flexible nanofibrous composite membranes for high-performance supercapacitor electrodes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Drug release from nanoparticles embedded in four different nanofibrillar cellulose aerogels.

    PubMed

    Valo, Hanna; Arola, Suvi; Laaksonen, Päivi; Torkkeli, Mika; Peltonen, Leena; Linder, Markus B; Serimaa, Ritva; Kuga, Shigenori; Hirvonen, Jouni; Laaksonen, Timo

    2013-09-27

    Highly porous nanocellulose aerogels prepared by freeze-drying from various nanofibrillar cellulose (NFC) hydrogels are introduced as nanoparticle reservoirs for oral drug delivery systems. Here we show that beclomethasone dipropionate (BDP) nanoparticles coated with amphiphilic hydrophobin proteins can be well integrated into the NFC aerogels. NFCs from four different origins are introduced and compared to microcrystalline cellulose (MCC). The nanocellulose aerogel scaffolds made from red pepper (RC) and MCC release the drug immediately, while bacterial cellulose (BC), quince seed (QC) and TEMPO-oxidized birch cellulose-based (TC) aerogels show sustained drug release. Since the release of the drug is controlled by the structure and interactions between the nanoparticles and the cellulose matrix, modulation of the matrix formers enable a control of the drug release rate. These nanocomposite structures can be very useful in many pharmaceutical nanoparticle applications and open up new possibilities as carriers for controlled drug delivery. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Effects of different fermentation methods on bacterial cellulose and acid production by Gluconacetobacter xylinus in Cantonese-style rice vinegar.

    PubMed

    Fu, Liang; Chen, Siqian; Yi, Jiulong; Hou, Zongxia

    2014-07-01

    A strain of acidogenic bacterium was isolated from the fermentation liquid of Cantonese-style rice vinegar produced by traditional surface fermentation. 16S rDNA identification confirmed the bacterium as Gluconacetobacter xylinus, which synthesizes bacterial cellulose, and the acid productivity of the strain was investigated. In the study, the effects of the membrane integrity and the comparison of the air-liquid interface membrane with immerged membrane on total acidity, cellulose production, alcohol dehydrogenase (ADH) activity and number of bacteria were investigated. The cellulose membrane and the bacteria were observed under SEM for discussing their relationship. The correlations between oxygen consumption and total acid production rate were compared in surface and shake flask fermentation. The results showed the average acid productivity of the strain was 0.02g/(100mL/h), and the integrity of cellulose membrane in surface fermentation had an important effect on total acidity and cellulose production. With a higher membrane integrity, the total acidity after 144 h of fermentation was 3.75 g/100 mL, and the cellulose production was 1.71 g/100 mL after 360 h of fermentation. However, when the membrane was crushed by mechanical force, the total acidity and the cellulose production were as low as 0.36 g/100 mL and 0.14 g/100 mL, respectively. When the cellulose membrane was forced under the surface of fermentation liquid, the total acid production rate was extremely low, but the activity of ADH in the cellulose membrane was basically the same with the one above the liquid surface. The bacteria were mainly distributed in the cellulose membrane during the fermentation. The bacterial counts in surface fermentation were more than in the shake flask fermentation and G. xylinus consumed the substrate faster, in surface fermentation than in shake flask fermentation. The oxygen consumption rate and total acid production rate of surface fermentation were respectively 26

  19. Production of Bacterial Cellulose by Gluconacetobacter hansenii Using Corn Steep Liquor As Nutrient Sources

    PubMed Central

    Costa, Andrea F. S.; Almeida, Fabíola C. G.; Vinhas, Glória M.; Sarubbo, Leonie A.

    2017-01-01

    Cellulose is mainly produced by plants, although many bacteria, especially those belonging to the genus Gluconacetobacter, produce a very peculiar form of cellulose with mechanical and structural properties that can be exploited in numerous applications. However, the production cost of bacterial cellulose (BC) is very high to the use of expensive culture media, poor yields, downstream processing, and operating costs. Thus, the purpose of this work was to evaluate the use of industrial residues as nutrients for the production of BC by Gluconacetobacter hansenii UCP1619. BC pellicles were synthesized using the Hestrin–Schramm (HS) medium and alternative media formulated with different carbon (sugarcane molasses and acetylated glucose) and nitrogen sources [yeast extract, peptone, and corn steep liquor (CSL)]. A jeans laundry was also tested. None of the tested sources (beside CSL) worked as carbon and nutrient substitute. The alternative medium formulated with 1.5% glucose and 2.5% CSL led to the highest yield in terms of dry and hydrated mass. The BC mass produced in the alternative culture medium corresponded to 73% of that achieved with the HS culture medium. The BC pellicles demonstrated a high concentration of microfibrils and nanofibrils forming a homogenous, compact, and three-dimensional structure. The biopolymer produced in the alternative medium had greater thermal stability, as degradation began at 240°C, while degradation of the biopolymer produced in the HS medium began at 195°C. Both biopolymers exhibited high crystallinity. The mechanical tensile test revealed the maximum breaking strength and the elongation of the break of hydrated and dry pellicles. The dry BC film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The dry film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The values

  20. Enhanced production of bacterial cellulose by using a biofilm reactor and its material property analysis

    PubMed Central

    Cheng, Kuan-Chen; Catchmark, Jeff M; Demirci, Ali

    2009-01-01

    Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS) were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC) production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L) that was 2.5-fold greater than the control (2.82 g/L). The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93%) and similar crystal size (5.2 nm) to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher Tmax compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC. The

  1. Acetylation of bacterial cellulose catalyzed by citric acid: Use of reaction conditions for tailoring the esterification extent.

    PubMed

    Ávila Ramírez, Jhon Alejandro; Gómez Hoyos, Catalina; Arroyo, Silvana; Cerrutti, Patricia; Foresti, María Laura

    2016-11-20

    Bacterial cellulose (BC) nanoribbons were partially acetylated by a simple direct solvent-free route catalyzed by citric acid. The assay of reaction conditions within chosen intervals (i.e. esterification time (0.5-7h), catalyst content (0.08-1.01mmol/mmol AGU), and temperature (90-140°C)), illustrated the flexibility of the methodology proposed, with reaction variables which can be conveniently manipulated to acetylate BC to the required degree of substitution (DS) within the 0.20-0.73 interval. Within this DS interval, characterization results indicated a surface-only process in which acetylated bacterial cellulose with tunable DS, preserved fibrous structure and increased hydrophobicity could be easily obtained. The feasibility of reusing the catalyst/excess acylant in view of potential scale-up was also illustrated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Biotemplated preparation of CdS nanoparticles/bacterial cellulose hybrid nanofibers for photocatalysis application.

    PubMed

    Yang, Jiazhi; Yu, Junwei; Fan, Jun; Sun, Dongping; Tang, Weihua; Yang, Xuejie

    2011-05-15

    In this work, we describe a novel facile and effective strategy to prepare micrometer-long hybrid nanofibers by deposition of CdS nanoparticles onto the substrate of hydrated bacterial cellulose nanofibers (BCF). Hexagonal phase CdS nanocrystals were achieved via a simple hydrothermal reaction between CdCl(2) and thiourea at relatively low temperature. The prepared pristine BCF and the CdS/BCF hybrid nanofibers were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The results reveal that the CdS nanoparticles were homogeneously deposited on the BCF surface and stabilized via coordination effect. The CdS/BCF hybrid nanofibers demonstrated high-efficiency photocatalysis with 82% methyl orange (MO) degradation after 90 min irradiation and good recyclability. The results indicate that the CdS/BCF hybrid nanofibers are promising candidate as robust visible light responsive photocatalysts. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Production of bacterial cellulose using different carbon sources and culture media.

    PubMed

    Mohammadkazemi, Faranak; Azin, Mehrdad; Ashori, Alireza

    2015-03-06

    In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) have been studied. BC nanofibers were synthesized using Gluconacetobacter xylinus strain PTCC 1734. Media used were Hestrin-Schramm (H), Yamanaka (Y), and Zhou (Z). Five different carbon sources, namely date syrup, glucose, mannitol, sucrose, and food-grade sucrose were used in these media. All the produced BC pellicles were characterized in terms of dry weight production, biomass yield, thermal stability, crystallinity and morphology by thermogravimetric analysis (TGA), x-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The obtained results showed that mannitol lead to the highest yield, followed by sucrose. The highest production efficiency of mannitol might be due to the nitrogen source, which plays an important role. The maximum improvement on the thermal stability of the composites was achieved when mannitol was used in H medium. In addition, the crystallinity was higher in BC formed in H medium compared to other media. FE-SEM micrographs illustrated that the BC pellicles, synthesized in the culture media H and Z, were stable, unlike those in medium Y that were unstable. The micrographs of BC produced in media containing mannitol and sucrose provided evidence of the strong interfacial adhesion between the BC fibers without noticeable aggregates. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Bacterial cellulose production by Gluconacetobacter xylinus by employing alternative culture media.

    PubMed

    Jozala, Angela Faustino; Pértile, Renata Aparecida Nedel; dos Santos, Carolina Alves; de Carvalho Santos-Ebinuma, Valéria; Seckler, Marcelo Martins; Gama, Francisco Miguel; Pessoa, Adalberto

    2015-02-01

    Bacterial cellulose (BC) is used in different fields as a biological material due to its unique properties. Despite there being many BC applications, there still remain many problems associated with bioprocess technology, such as increasing productivity and decreasing production cost. New technologies that use waste from the food industry as raw materials for culture media promote economic advantages because they reduce environmental pollution and stimulate new research for science sustainability. For this reason, BC production requires optimized conditions to increase its application. The main objective of this study was to evaluate BC production by Gluconacetobacter xylinus using industry waste, namely, rotten fruits and milk whey, as culture media. Furthermore, the structure of BC produced at different conditions was also determined. The culture media employed in this study were composed of rotten fruit collected from the disposal of free markets, milk whey from a local industrial disposal, and their combination, and Hestrin and Schramm media was used as standard culture media. Although all culture media studied produced BC, the highest BC yield-60 mg/mL-was achieved with the rotten fruit culture. Thus, the results showed that rotten fruit can be used for BC production. This culture media can be considered as a profitable alternative to generate high-value products. In addition, it combines environmental concern with sustainable processes that can promote also the reduction of production cost.

  5. Biosynthesis of Bacterial Cellulose/Carboxylic Multi-Walled Carbon Nanotubes for Enzymatic Biofuel Cell Application

    PubMed Central

    Lv, Pengfei; Feng, Quan; Wang, Qingqing; Li, Guohui; Li, Dawei; Wei, Qufu

    2016-01-01

    Novel nanocomposites comprised of bacterial cellulose (BC) with carboxylic multi-walled carbon nanotubes (c-MWCNTs) incorporated into the BC matrix were prepared through a simple method of biosynthesis. The biocathode and bioanode for the enzyme biological fuel cell (EBFC) were prepared using BC/c-MWCNTs composite injected by laccase (Lac) and glucose oxidase (GOD) with the aid of glutaraldehyde (GA) crosslinking. Biosynthesis of BC/c-MWCNTs composite was characterized by digital photos, scanning electron microscope (SEM), and Fourier Transform Infrared (FTIR). The experimental results indicated the successful incorporation of c-MWCNTs into the BC. The electrochemical and biofuel performance were evaluated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The power density and current density of EBFCs were recorded at 32.98 µW/cm3 and 0.29 mA/cm3, respectively. Additionally, the EBFCs also showed acceptable stability. Preliminary tests on double cells indicated that renewable BC have great potential in the application field of EBFCs. PMID:28773310

  6. Using wastewater after lipid fermentation as substrate for bacterial cellulose production by Gluconacetobacter xylinus.

    PubMed

    Huang, Chao; Guo, Hai-Jun; Xiong, Lian; Wang, Bo; Shi, Si-Lan; Chen, Xue-Fang; Lin, Xiao-Qing; Wang, Can; Luo, Jun; Chen, Xin-De

    2016-01-20

    In this study, lipid fermentation wastewater (fermentation broth after separation with yeast biomass) with high Chemical Oxygen Demand (COD) value of 25,591 mg/L was used as substrate for bacterial cellulose (BC) production by Gluconacetobacter xylinus for the first time. After 5 days of fermentation, the highest BC yield (0.659 g/L) was obtained. Both monosaccharide and polysaccharides present in lipid fermentation wastewater could be utilized by G. xylinus simultaneously during fermentation. By this bioconversion, 30.0% of COD could be removed after 10 days of fermentation and the remaining wastewater could be used for further BC fermentation. The crystallinity of BC samples in lipid fermentation wastewater increased gradually during fermentation but overall the environment of lipid fermentation wastewater showed small influence on BC structure by comparison with that in traditional HS medium by using FE-SEM, FTIR, and XRD. By this work, the possibility of using lipid fermentation wastewater containing low value carbohydrate polymer (extracellular polysaccharides) for high value carbohydrate polymer (BC) production was proven. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Novel keratin modified bacterial cellulose nanocomposite production and characterization for skin tissue engineering.

    PubMed

    Keskin, Zalike; Sendemir Urkmez, Aylin; Hames, E Esin

    2017-06-01

    As it is known that bacterial cellulose (BC) is a biocompatible and natural biopolymer due to which it has a large set of biomedical applications. But still it lacks some desired properties, which limits its uses in many other applications. Therefore, the properties of BC need to be boosted up to an acceptable level. Here in this study for the first time, a new natural nanocomposite was produced by the incorporating keratin (isolated from human hair) to the BC (produced by Acetobacter xylinum) to enhance dermal fibroblast cells' attachment. Two different approaches were used in BC based nanocomposite production: in situ and post modifications. BC/keratin nanocomposites were characterized using SEM, FTIR, EDX, XRD, DSC and XPS analyses. Both production methods have yielded successful results for production of BC based nanocomposite-containing keratin. In vitro cell culture experiments performed with human skin keratinocytes and human skin fibroblast cells indicate the potential of the novel BC/keratin nanocomposites for use in skin tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Effects of alternative energy sources on bacterial cellulose characteristics produced by Komagataeibacter medellinensis.

    PubMed

    Molina-Ramírez, Carlos; Enciso, Carla; Torres-Taborda, Mabel; Zuluaga, Robin; Gañán, Piedad; Rojas, Orlando J; Castro, Cristina

    2018-05-27

    Bacterial cellulose (BC) was produced by Komagataeibacter medellinensis using Hestrin and Schramm modified medium in the presence of alternative energy sources (AES), such as ethanol and acetic acid, to explore the effect of AES on the characteristics and properties of the resulting BC. In this study, the physicochemical and structural characteristics of the obtained BC were determined using Fourier-transform infrared spectroscopy, X-ray diffraction spectrometry, thermogravimetric analysis, and mechanical testing analysis. Ethanol and acetic acid (at 0.1 wt%) were proven to improve the BC yield by K. medellinensis by 279% and 222%, respectively. However, the crystallinity index (%), the degree of polymerization, and maximum rate of degradation temperatures decreased by 9.2%, 36%, and 4.96%, respectively, by the addition of ethanol and by 7.2%, 27%, and 4.21%, respectively, by the addition of acetic acid. The significance of this work, lies on the fact that there is not any report about how BC properties change when substances like ethanol or acetic acid are added to culture medium, and which is the mechanism that provokes those changes, that in our case we could demonstrate the relationship of a higher BC production rate (provoked by ethanol and acetic acid adding) and changes in BC properties. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Bacterial cellulose synthesis mechanism of facultative anaerobe Enterobacter sp. FY-07.

    PubMed

    Ji, Kaihua; Wang, Wei; Zeng, Bing; Chen, Sibin; Zhao, Qianqian; Chen, Yueqing; Li, Guoqiang; Ma, Ting

    2016-02-25

    Enterobacter sp. FY-07 can produce bacterial cellulose (BC) under aerobic and anaerobic conditions. Three potential BC synthesis gene clusters (bcsI, bcsII and bcsIII) of Enterobacter sp. FY-07 have been predicted using genome sequencing and comparative genome analysis, in which bcsIII was confirmed as the main contributor to BC synthesis by gene knockout and functional reconstitution methods. Protein homology, gene arrangement and gene constitution analysis indicated that bcsIII had high identity to the bcsI operon of Enterobacter sp. 638; however, its arrangement and composition were same as those of BC synthesizing operon of G. xylinum ATCC53582 except for the flanking sequences. According to the BC biosynthesizing process, oxygen is not directly involved in the reactions of BC synthesis, however, energy is required to activate intermediate metabolites and synthesize the activator, c-di-GMP. Comparative transcriptome and metabolite quantitative analysis demonstrated that under anaerobic conditions genes involved in the TCA cycle were downregulated, however, genes in the nitrate reduction and gluconeogenesis pathways were upregulated, especially, genes in three pyruvate metabolism pathways. These results suggested that Enterobacter sp. FY-07 could produce energy efficiently under anaerobic conditions to meet the requirement of BC biosynthesis.

  10. Bacterial cellulose synthesis mechanism of facultative anaerobe Enterobacter sp. FY-07

    PubMed Central

    Ji, Kaihua; Wang, Wei; Zeng, Bing; Chen, Sibin; Zhao, Qianqian; Chen, Yueqing; Li, Guoqiang; Ma, Ting

    2016-01-01

    Enterobacter sp. FY-07 can produce bacterial cellulose (BC) under aerobic and anaerobic conditions. Three potential BC synthesis gene clusters (bcsI, bcsII and bcsIII) of Enterobacter sp. FY-07 have been predicted using genome sequencing and comparative genome analysis, in which bcsIII was confirmed as the main contributor to BC synthesis by gene knockout and functional reconstitution methods. Protein homology, gene arrangement and gene constitution analysis indicated that bcsIII had high identity to the bcsI operon of Enterobacter sp. 638; however, its arrangement and composition were same as those of BC synthesizing operon of G. xylinum ATCC53582 except for the flanking sequences. According to the BC biosynthesizing process, oxygen is not directly involved in the reactions of BC synthesis, however, energy is required to activate intermediate metabolites and synthesize the activator, c-di-GMP. Comparative transcriptome and metabolite quantitative analysis demonstrated that under anaerobic conditions genes involved in the TCA cycle were downregulated, however, genes in the nitrate reduction and gluconeogenesis pathways were upregulated, especially, genes in three pyruvate metabolism pathways. These results suggested that Enterobacter sp. FY-07 could produce energy efficiently under anaerobic conditions to meet the requirement of BC biosynthesis. PMID:26911736

  11. Medium Chain-Length Polyhydroxyalkanoate Copolymer Modified by Bacterial Cellulose for Medical Devices.

    PubMed

    Panaitescu, Denis Mihaela; Lupescu, Irina; Frone, Adriana Nicoleta; Chiulan, Ioana; Nicolae, Cristian Andi; Tofan, Vlad; Stefaniu, Amalia; Somoghi, Raluca; Trusca, Roxana

    2017-10-09

    Medium chain-length polyhydroxyalkanoates (mPHAs) are flexible elastomeric biopolymers with valuable properties for biomedical applications like artificial arteries and other medical implants. However, an environmentally friendly and high productivity process together with the tuning of the mechanical and biological properties of mPHAs are mandatory for this purpose. Here, for the first time, a melt processing technique was applied for the preparation of bionanocomposites starting from poly(3-hydroxyoctanoate) (PHO) and bacterial cellulose nanofibers (BC). The incorporation of only 3 wt % BC in PHO improved its thermal stability with 25 °C and reinforced it, increasing the Young's modulus with 76% and the tensile strength with 44%. The percolation threshold calculated with the aspect ratio of the fibers after melt processing was very low and close to 3 wt %. We showed that this bionanocomposite is able to preserve the ductile behavior during storage, no important aging being noted between 3 h and one month after compression-molding. Moreover, this study is the first to investigate the melt processability of PHO nanocomposite for tube extrusion. In addition, biocompatibility study showed no proinflammatory immune response and better cell adhesion for PHO/BC nanocomposite with 3 wt % BC and demonstrated the high feasibility of this bionanocomposite for in vivo application of tissue-engineered blood vessels.

  12. Surface functional group dependent apatite formation on bacterial cellulose microfibrils network in a simulated body fluid.

    PubMed

    Nge, Thi Thi; Sugiyama, Junji

    2007-04-01

    The apatite forming ability of biopolymer bacterial cellulose (BC) has been investigated by soaking different BC specimens in a simulated body fluid (1.5 SBF) under physiological conditions, at 37 degrees C and pH 7.4, mimicking the natural process of apatite formation. From ATR-FTIR spectra and ICP-AES analysis, the crystalline phase nucleated on the BC microfibrils surface was calcium deficient carbonated apatite through initial formation of octacalcium phosphate (OCP) or OCP like calcium phosphate phase regardless of the substrates. Morphology of the deposits from SEM, FE-SEM, and TEM observations revealed the fine structure of thin film plates uniting together to form apatite globules of various size (from <1 mum to 3 mum) with respect to the substrates. Surface modification by TEMPO (2,2,6,6-tetramethylpyperidine-1-oxyl)-mediated oxidation, which can readily form active carboxyl functional groups upon selective oxidation of primary hydroxyl groups on the surface of BC microfibrils, enhanced the rate of apatite nucleation. Ion exchanged treatment with calcium chloride solution after TEMPO-mediated oxidation was found to be remarkably different from other BC substrates with the highest deposit weight and the smallest apatite globules size. The role of BC substrates to induce mineralization rate differs according to the nature of the BC substrates, which strongly influences the growth behavior of the apatite crystals. (c) 2006 Wiley Periodicals, Inc.

  13. Esophageal replacement by hydroxylated bacterial cellulose patch in a rabbit model.

    PubMed

    Zhu, Changlai; Liu, Fang; Qian, Wenbo; Wang, Yingjie; You, Qingsheng; Zhang, Tianyi; Li, Feng

    2015-01-01

    To repair esophageal defects by hydroxylated and kombucha-synthesized bacterial cellulose (HKBC) patch in a rabbit model. Semicircular esophageal defects 1 cm in length of the cervical esophagus were initially created in 18 Japanese big-ear rabbits and then repaired with HKBC patch grafts. The clinical outcomes including survival rate, weight change, food intake, and hematological and radiologic evaluation were observed. After X-ray evaluation, the rabbits were sacrificed sequentially at 1, 3, and 6 months for histopathologic analysis with light microscopy and scanning electron microscopy. Survival rate during the first month was 88.9% (n = 16). Two rabbits died from anastomotic leakage during the entire follow-up. Postoperatively, feeding function and body weight were gradually restored in the surviving animals. No hematological abnormalities were found, and no obvious anastomotic leakage, stenosis, or obstruction was observed under X-ray examination. The histopathologic results showed a progressive regeneration of the esophagus in the graft area, where the neo-esophagus tissue had characteristics similar to native esophageal tissue after 3 months of surgery. HKBC is beneficial for esophageal tissue regeneration and may be a promising material for esophageal reconstruction.

  14. Bacterial cellulose of Gluconoacetobacter hansenii as a potential bioadsorption agent for its green environment applications.

    PubMed

    Mohite, Bhavna V; Patil, Satish V

    2014-01-01

    Bacterial cellulose (BC) is an interesting biopolymer produced by bacteria having superior properties. BC produced by Gluconoacetobacter hansenii (strain NCIM 2529) under shaking condition and explored for its applications in dye removal and bioadsorption of protein and heavy metals. Purity of BC was confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) analysis. BC removed azo dye and Aniline blue (400 mg/L) with 80% efficiency within 60 min. The adsorption and elution of Bovine serum albumin (BSA) and heavy metals like lead, cadmium and nickel (Pb(2+), Cd(2+) and Ni(2+)) was achieved with BC which confirms the exclusion ability with reusability. The BSA adsorption quantity was increased with increase in protein concentration with more than 90% adsorption and elution ratio. The effect of pH and temperature on BSA adsorption has been investigated. Bioadsorption (82%) and elution ratio (92%) of BC for Pb(2+) was more when compared with Cd(2+) (41 and 67%) and Ni(2+) (33 and 85%), respectively. BC was also explored as soil conditioner to increase the water-holding capacity and porosity of soil. The results elucidated the significance of BC as renewable effective ecofriendly bioadsorption agent.

  15. Statistical optimization of culture conditions for bacterial cellulose production using Box-Behnken design.

    PubMed

    Bae, Sangok; Shoda, Makoto

    2005-04-05

    Culture conditions in a jar fermentor for bacterial cellulose (BC) production from A. xylinum BPR2001 were optimized by statistical analysis using Box-Behnken design. Response surface methodology was used to predict the levels of the factors, fructose (X1), corn steep liquor (CSL) (X2), dissolved oxygen (DO) (X3), and agar concentration (X4). Total 27 experimental runs by combination of each factor were carried out in a 10-L jar fermentor, and a three-dimensional response surface was generated to determine the effect of the factors and to find out the optimum concentration of each factor for maximum BC production and BC yield. The fructose and agar concentration highly influenced the BC production and BC yield. However, the optimum conditions according to changes in CSL and DO concentrations were predicted at almost central values of tested ranges. The predicted results showed that BC production was 14.3 g/L under the condition of 4.99% fructose, 2.85% CSL, 28.33% DO, and 0.38% agar concentration. On the other hand, BC yield was predicted in 0.34 g/g under the condition of 3.63% fructose, 2.90% CSL, 31.14% DO, and 0.42% agar concentration. Under optimized culture conditions, improvement of BC production and BC yield were experimentally confirmed, which increased 76% and 57%, respectively, compared to BC production and BC yield before optimizing the culture conditions. Copyright (c) 2005 Wiley Periodicals, Inc.

  16. Flexible magnetic membranes based on bacterial cellulose and its evaluation as electromagnetic interference shielding material.

    PubMed

    Marins, Jéssica A; Soares, Bluma G; Barud, Hernane S; Ribeiro, Sidney J L

    2013-10-01

    Flexible magnetic membranes with high proportion of magnetite were successfully prepared by previous impregnation of the never dried bacterial cellulose pellicles with ferric chloride followed by reduction with sodium bisulfite and alkaline treatment for magnetite precipitation. Membranes were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating magnetometer, field emission scanning electron microscopy (FEG-SEM) and impedance spectroscopy. Microwave properties of these membranes were investigated in the X-band (8.2 to 12.4 GHz). FEG-SEM micrographs show an effective coverage of the BC nanofibers by Fe3O4 nanoparticles. Membranes with up to 75% in weight of particles have been prepared after 60 min of reaction. Magnetite nanoparticles in the form of aggregates well adhered to the BC fibers were observed by SEM. The average crystal sizes of the magnetic particles were in the range of 10±1 to 13±1 nm (estimated by XRD). The magnetic particles in the BC pellicles presented superparamagnetic behavior with a saturation magnetization in the range of 60 emu g(-1) and coercive force around 15 Oe. These magnetic pellicles also displayed high electrical permittivity and a potential application as microwave absorber materials. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Mechanical and thermal properties of bacterial-cellulose-fibre-reinforced Mater-Bi(®) bionanocomposite.

    PubMed

    Nainggolan, Hamonangan; Gea, Saharman; Bilotti, Emiliano; Peijs, Ton; Hutagalung, Sabar D

    2013-01-01

    The effects of the addition of fibres of bacterial cellulose (FBC) to commercial starch of Mater-Bi(®) have been investigated. FBC produced by cultivating Acetobacter xylinum for 21 days in glucose-based medium were purified by sodium hydroxide 2.5 wt % and sodium hypochlorite 2.5 wt % overnight, consecutively. To obtain water-free BC nanofibres, the pellicles were freeze dried at a pressure of 130 mbar at a cooling rate of 10 °C min(-1). Both Mater-Bi and FBC were blended by using a mini twin-screw extruder at 160 °C for 10 min at a rotor speed of 50 rpm. Tensile tests were performed according to ASTM D638 to measure the Young's modulus, tensile strength and elongation at break. A field emission scanning electron microscope was used to observe the morphology at an accelerating voltage of 10 kV. The crystallinity (T c) and melting temperature (T m) were measured by DSC. Results showed a significant improvement in mechanical and thermal properties in accordance with the addition of FBC into Mater-Bi. FBC is easily incorporated in Mater-Bi matrix and produces homogeneous Mater-Bi/FBC composite. The crystallinity of the Mater-Bi/FBC composites decrease in relation to the increase in the volume fraction of FBC.

  18. Double network bacterial cellulose hydrogel to build a biology-device interface.

    PubMed

    Shi, Zhijun; Li, Ying; Chen, Xiuli; Han, Hongwei; Yang, Guang

    2014-01-21

    Establishing a biology-device interface might enable the interaction between microelectronics and biotechnology. In this study, electroactive hydrogels have been produced using bacterial cellulose (BC) and conducting polymer (CP) deposited on the BC hydrogel surface to cover the BC fibers. The structures of these composites thus have double networks, one of which is a layer of electroactive hydrogels combined with BC and CP. The electroconductivity provides the composites with capabilities for voltage and current response, and the BC hydrogel layer provides good biocompatibility, biodegradability, bioadhesion and mass transport properties. Such a system might allow selective biological functions such as molecular recognition and specific catalysis and also for probing the detailed genetic and molecular mechanisms of life. A BC-CP composite hydrogel could then lead to a biology-device interface. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) are used here to study the composite hydrogels' electroactive property. BC-PAni and BC-PPy respond to voltage changes. This provides a mechanism to amplify electrochemical signals for analysis or detection. BC hydrogels were found to be able to support the growth, spreading and migration of human normal skin fibroblasts without causing any cytotoxic effect on the cells in the cell culture. These double network BC-CP hydrogels are biphasic Janus hydrogels which integrate electroactivity with biocompatibility, and might provide a biology-device interface to produce implantable devices for personalized and regenerative medicine.

  19. Double network bacterial cellulose hydrogel to build a biology-device interface

    NASA Astrophysics Data System (ADS)

    Shi, Zhijun; Li, Ying; Chen, Xiuli; Han, Hongwei; Yang, Guang

    2013-12-01

    Establishing a biology-device interface might enable the interaction between microelectronics and biotechnology. In this study, electroactive hydrogels have been produced using bacterial cellulose (BC) and conducting polymer (CP) deposited on the BC hydrogel surface to cover the BC fibers. The structures of these composites thus have double networks, one of which is a layer of electroactive hydrogels combined with BC and CP. The electroconductivity provides the composites with capabilities for voltage and current response, and the BC hydrogel layer provides good biocompatibility, biodegradability, bioadhesion and mass transport properties. Such a system might allow selective biological functions such as molecular recognition and specific catalysis and also for probing the detailed genetic and molecular mechanisms of life. A BC-CP composite hydrogel could then lead to a biology-device interface. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) are used here to study the composite hydrogels' electroactive property. BC-PAni and BC-PPy respond to voltage changes. This provides a mechanism to amplify electrochemical signals for analysis or detection. BC hydrogels were found to be able to support the growth, spreading and migration of human normal skin fibroblasts without causing any cytotoxic effect on the cells in the cell culture. These double network BC-CP hydrogels are biphasic Janus hydrogels which integrate electroactivity with biocompatibility, and might provide a biology-device interface to produce implantable devices for personalized and regenerative medicine.

  20. Box-Behnken experimental design for chromium(VI) ions removal by bacterial cellulose-magnetite composites.

    PubMed

    Stoica-Guzun, Anicuta; Stroescu, Marta; Jinga, Sorin Ion; Mihalache, Nicoleta; Botez, Adriana; Matei, Cristian; Berger, Daniela; Damian, Celina Maria; Ionita, Valentin

    2016-10-01

    In this study bacterial cellulose-magnetite composites were synthesised for the removal of chromium(VI) from aqueous solutions. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the bacterial cellulose-magnetite composites and to reveal the uniform dispersion of nanomagnetite in the BC matrix. Magnetic properties were also measured to confirm the magnetite immobilization on bacterial cellulose membrane. The effects of initial Cr(VI) concentration, solution pH and solid/liquid ratio upon chromium removal were examined using the statistical Box-Behnken Design. Because of the possibility of magnetite dissolution during chromium(VI) adsorption, the degree of iron leaching was also analysed in the same conditions as Cr(VI) adsorption. From the factors affecting chromium(VI) adsorption the most important was solution pH. The highest Cr(VI) removal efficiency was observed at pH 4, accompanied by the lowest iron leaching in the solution. The adsorption experiments also indicated that the adsorption process of chromium(VI) is well described by Freundlich adsorption model. Our results proved that the BC-magnetite composites could be used for an efficient removal of chromium(VI) from diluted solutions with a minimum magnetite dissolution during operation. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Enhanced cellulose degradation using cellulase-nanosphere complexes.

    PubMed

    Blanchette, Craig; Lacayo, Catherine I; Fischer, Nicholas O; Hwang, Mona; Thelen, Michael P

    2012-01-01

    Enzyme catalyzed conversion of plant biomass to sugars is an inherently inefficient process, and one of the major factors limiting economical biofuel production. This is due to the physical barrier presented by polymers in plant cell walls, including semi-crystalline cellulose, to soluble enzyme accessibility. In contrast to the enzymes currently used in industry, bacterial cellulosomes organize cellulases and other proteins in a scaffold structure, and are highly efficient in degrading cellulose. To mimic this clustered assembly of enzymes, we conjugated cellulase obtained from Trichoderma viride to polystyrene nanospheres (cellulase:NS) and tested the hydrolytic activity of this complex on cellulose substrates from purified and natural sources. Cellulase:NS and free cellulase were equally active on soluble carboxymethyl cellulose (CMC); however, the complexed enzyme displayed a higher affinity in its action on microcrystalline cellulose. Similarly, we found that the cellulase:NS complex was more efficient in degrading natural cellulose structures in the thickened walls of cultured wood cells. These results suggest that nanoparticle-bound enzymes can improve catalytic efficiency on physically intractable substrates. We discuss the potential for further enhancement of cellulose degradation by physically clustering combinations of different glycosyl hydrolase enzymes, and applications for using cellulase:NS complexes in biofuel production.

  2. Enhanced Cellulose Degradation Using Cellulase-Nanosphere Complexes

    PubMed Central

    Blanchette, Craig; Lacayo, Catherine I.; Fischer, Nicholas O.; Hwang, Mona; Thelen, Michael P.

    2012-01-01

    Enzyme catalyzed conversion of plant biomass to sugars is an inherently inefficient process, and one of the major factors limiting economical biofuel production. This is due to the physical barrier presented by polymers in plant cell walls, including semi-crystalline cellulose, to soluble enzyme accessibility. In contrast to the enzymes currently used in industry, bacterial cellulosomes organize cellulases and other proteins in a scaffold structure, and are highly efficient in degrading cellulose. To mimic this clustered assembly of enzymes, we conjugated cellulase obtained from Trichoderma viride to polystyrene nanospheres (cellulase:NS) and tested the hydrolytic activity of this complex on cellulose substrates from purified and natural sources. Cellulase:NS and free cellulase were equally active on soluble carboxymethyl cellulose (CMC); however, the complexed enzyme displayed a higher affinity in its action on microcrystalline cellulose. Similarly, we found that the cellulase:NS complex was more efficient in degrading natural cellulose structures in the thickened walls of cultured wood cells. These results suggest that nanoparticle-bound enzymes can improve catalytic efficiency on physically intractable substrates. We discuss the potential for further enhancement of cellulose degradation by physically clustering combinations of different glycosyl hydrolase enzymes, and applications for using cellulase:NS complexes in biofuel production. PMID:22870287

  3. Bacterial Cellulose: A Robust Platform for Design of Three Dimensional Carbon-Based Functional Nanomaterials.

    PubMed

    Wu, Zhen-Yu; Liang, Hai-Wei; Chen, Li-Feng; Hu, Bi-Cheng; Yu, Shu-Hong

    2016-01-19

    Three dimensional (3D) carbon nanomaterials exhibit great application potential in environmental protection, electrochemical energy storage and conversion, catalysis, polymer science, and advanced sensors fields. Current methods for preparing 3D carbon nanomaterials, for example, carbonization of organogels, chemical vapor deposition, and self-assembly of nanocarbon building blocks, inevitably involve some drawbacks, such as expensive and toxic precursors, complex equipment and technological requirements, and low production ability. From the viewpoint of practical application, it is highly desirable to develop a simple, cheap, and environmentally friendly way for fabricating 3D carbon nanomaterials in large scale. On the other hand, in order to extend the application scope and improve the performance of 3D carbon nanomaterials, we should explore efficient strategies to prepare diverse functional nanomaterials based on their 3D carbon structure. Recently, many researchers tend to fabricate high-performance 3D carbon-based nanomaterials from biomass, which is low cost, easy to obtain, and nontoxic to humans. Bacterial cellulose (BC), a typical biomass material, has long been used as the raw material of nata-de-coco (an indigenous dessert food of the Philippines). It consists of a polysaccharide with a β-1,4-glycosidic linkage and has a interconnected 3D porous network structure. Interestingly, the network is made up of a random assembly of cellulose nanofibers, which have a high aspect ratio with a diameter of 20-100 nm. As a result, BC has a high specific surface area. Additionally, BC hydrogels can be produced on an industrial scale via a microbial fermentation process at a very low price. Thus, it can be an ideal platform for design of 3D carbon-based functional nanomaterials. Before our work, no systematic work and summary on this topic had been reported. This Account presents the concepts and strategies of our studies on BC in the past few years, that is

  4. Identification of Uncultured Bacterial Species from Firmicutes, Bacteroidetes and CANDIDATUS Saccharibacteria as Candidate Cellulose Utilizers from the Rumen of Beef Cows

    PubMed Central

    Opdahl, Lee James; Gonda, Michael G.

    2018-01-01

    The ability of ruminants to utilize cellulosic biomass is a result of the metabolic activities of symbiotic microbial communities that reside in the rumen. To gain further insight into this complex microbial ecosystem, a selection-based batch culturing approach was used to identify candidate cellulose-utilizing bacterial consortia. Prior to culturing with cellulose, rumen contents sampled from three beef cows maintained on a forage diet shared 252 Operational Taxonomic Units (OTUs), accounting for 41.6–50.0% of bacterial 16S rRNA gene sequences in their respective samples. Despite this high level of overlap, only one OTU was enriched in cellulose-supplemented cultures from all rumen samples. Otherwise, each set of replicate cellulose supplemented cultures originating from a sampled rumen environment was found to have a distinct bacterial composition. Two of the seven most enriched OTUs were closely matched to well-established rumen cellulose utilizers (Ruminococcus flavefaciens and Fibrobacter succinogenes), while the others did not show high nucleotide sequence identity to currently defined bacterial species. The latter were affiliated to Prevotella (1 OTU), Ruminococcaceae (3 OTUs), and the candidate phylum Saccharibacteria (1 OTU), respectively. While further investigations will be necessary to elucidate the metabolic function(s) of each enriched OTU, these results together further support cellulose utilization as a ruminal metabolic trait shared across vast phylogenetic distances, and that the rumen is an environment conducive to the selection of a broad range of microbial adaptations for the digestion of plant structural polysaccharides. PMID:29495256

  5. Identification of Uncultured Bacterial Species from Firmicutes, Bacteroidetes and CANDIDATUS Saccharibacteria as Candidate Cellulose Utilizers from the Rumen of Beef Cows.

    PubMed

    Opdahl, Lee James; Gonda, Michael G; St-Pierre, Benoit

    2018-02-24

    The ability of ruminants to utilize cellulosic biomass is a result of the metabolic activities of symbiotic microbial communities that reside in the rumen. To gain further insight into this complex microbial ecosystem, a selection-based batch culturing approach was used to identify candidate cellulose-utilizing bacterial consortia. Prior to culturing with cellulose, rumen contents sampled from three beef cows maintained on a forage diet shared 252 Operational Taxonomic Units (OTUs), accounting for 41.6-50.0% of bacterial 16S rRNA gene sequences in their respective samples. Despite this high level of overlap, only one OTU was enriched in cellulose-supplemented cultures from all rumen samples. Otherwise, each set of replicate cellulose supplemented cultures originating from a sampled rumen environment was found to have a distinct bacterial composition. Two of the seven most enriched OTUs were closely matched to well-established rumen cellulose utilizers ( Ruminococcus flavefaciens and Fibrobacter succinogenes ), while the others did not show high nucleotide sequence identity to currently defined bacterial species. The latter were affiliated to Prevotella (1 OTU), Ruminococcaceae (3 OTUs), and the candidate phylum Saccharibacteria (1 OTU), respectively. While further investigations will be necessary to elucidate the metabolic function(s) of each enriched OTU, these results together further support cellulose utilization as a ruminal metabolic trait shared across vast phylogenetic distances, and that the rumen is an environment conducive to the selection of a broad range of microbial adaptations for the digestion of plant structural polysaccharides.

  6. Grafting of bacterial polyhydroxybutyrate (PHB) onto cellulose via in situ reactive extrusion with dicumyl peroxide.

    PubMed

    Wei, Liqing; McDonald, Armando G; Stark, Nicole M

    2015-03-09

    Polyhydroxybutyrate (PHB) was grafted onto cellulose fiber by dicumyl peroxide (DCP) radical initiation via in situ reactive extrusion. The yield of the grafted (cellulose-g-PHB) copolymer was recorded and grafting efficiency was found to be dependent on the reaction time and DCP concentration. The grafting mechanism was investigated by electron spin resonance (ESR) analysis and showed the presence of radicals produced by DCP radical initiation. The grafted copolymer structure was determined by nuclear magnetic resonance (NMR) spectroscopy. Scanning electronic microscopy (SEM) showed that the cellulose-g-PHB copolymer formed a continuous phase between the surfaces of cellulose and PHB as compared to cellulose-PHB blends. The relative crystallinity of cellulose and PHB were quantified from Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) results, while the absolute degree of crystallinity was evaluated by differential scanning calorimetry (DSC). The reduction of crystallinity indicated the grafting reaction occurred not just in the amorphous region but also slightly in crystalline regions of both cellulose and PHB. The smaller crystal sizes suggested the brittleness of PHB was decreased. Thermogravimetric analysis (TGA) showed that the grafted copolymer was stabilized relative to PHB. By varying the reaction parameters the compositions (%PHB and %cellulose) of resultant cellulose-g-PHB copolymer are expected to be manipulated to obtain tunable properties.

  7. Investigation into the structural, morphological, mechanical and thermal behaviour of bacterial cellulose after a two-step purification process.

    PubMed

    Gea, Saharman; Reynolds, Christopher T; Roohpour, Nima; Wirjosentono, Basuki; Soykeabkaew, Nattakan; Bilotti, Emiliano; Peijs, Ton

    2011-10-01

    Bacterial cellulose (BC) is a natural hydrogel, which is produced by Acetobacter xylinum (recently renamed Gluconacetobacter xylinum) in culture and constitutes of a three-dimensional network of ribbon-shaped bundles of cellulose microfibrils. Here, a two-step purification process is presented that significantly improves the structural, mechanical, thermal and morphological behaviour of BC sheet processed from these hydrogels produced in static culture. Alkalisation of BC using a single-step treatment of 2.5 wt.% NaOH solution produced a twofold increase in Young's modulus of processed BC sheet over untreated BC sheet. Further enhancements are achieved after a second treatment with 2.5 wt.% NaOCl (bleaching). These treatments were carefully designed in order to prevent any polymorphic crystal transformation from cellulose I to cellulose II, which can be detrimental for the mechanical properties. Scanning electron microscopy and thermogravimetric analysis reveals that with increasing chemical treatment, morphological and thermal stability of the processed films are also improved. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Grafting of Bacterial Polyhydroxybutyrate (PHB) onto Cellulose via In Situ Reactive Extrusion with Dicumyl Peroxide

    Treesearch

    Liqing Wei; Armando G. McDonald; Nicole M. Stark

    2015-01-01

    Polyhydroxybutyrate (PHB) was grafted onto cellulose fiber by dicumyl peroxide (DCP) radical initiation via in situ reactive extrusion. The yield of the grafted (cellulose-g-PHB) copolymer was recorded and grafting efficiency was found to be dependent on the reaction time and DCP concentration. The grafting mechanism was investigated by electron spin...

  9. Green in-situ synthesized silver nanoparticles embedded in bacterial cellulose nanopaper as a bionanocomposite plasmonic sensor.

    PubMed

    Pourreza, Nahid; Golmohammadi, Hamed; Naghdi, Tina; Yousefi, Hossein

    2015-12-15

    Herein, we introduce a new strategy for green, in-situ generation of silver nanoparticles using flexible and transparent bacterial cellulose nanopapers. In this method, adsorbed silver ions on bacterial cellulose nanopaper are reduced by the hydroxyl groups of cellulose nanofibers, acting as the reducing agent producing a bionanocomposite "embedded silver nanoparticles in transparent nanopaper" (ESNPs). The fabricated ESNPs were investigated and characterized by field emission scanning electron microscopy (FE-SEM), UV-visible spectroscopy (UV-vis), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and energy-dispersive X-ray spectroscopy (EDX). The important parameters affecting the ESNPs were optimized during the fabrication of specimens. The resulting ESNPs were used as a novel and sensitive probe for the optical sensing of cyanide ion (CN(-)) and 2-mercaptobenzothiazole (MBT) in water samples with satisfactory results. The change in surface plasmon resonance absorption intensity of ESNPs was linearly proportional to the concentration in the range of 0.2-2.5 µg mL(-1) and 2-110 µg mL(-1) with a detection limit of 0.012 µg mL(-1) and 1.37 µg mL(-1) for CN(-) and MBT, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Probing crystal structure and mesoscale assembly of cellulose microfibrils in plant cell walls, tunicate tests, and bacterial films using vibrational sum frequency generation (SFG) spectroscopy.

    PubMed

    Lee, Christopher M; Kafle, Kabindra; Park, Yong Bum; Kim, Seong H

    2014-06-14

    This study reports that the noncentrosymmetry and phase synchronization requirements of the sum frequency generation (SFG) process can be used to distinguish the three-dimensional organization of crystalline cellulose distributed in amorphous matrices. Crystalline cellulose is produced as microfibrils with a few nanometer diameters by plants, tunicates, and bacteria. Crystalline cellulose microfibrils are embedded in wall matrix polymers and assembled into hierarchical structures that are precisely designed for specific biological and mechanical functions. The cellulose microfibril assemblies inside cell walls are extremely difficult to probe. The comparison of vibrational SFG spectra of uniaxially-aligned and disordered films of cellulose Iβ nanocrystals revealed that the spectral features cannot be fully explained with the crystallographic unit structure of cellulose. The overall SFG intensity, the alkyl peak shape, and the alkyl/hydroxyl intensity ratio are sensitive to the lateral packing and net directionality of the cellulose microfibrils within the SFG coherence length scale. It was also found that the OH SFG stretch peaks could be deconvoluted to find the polymorphic crystal structures of cellulose (Iα and Iβ). These findings were used to investigate the cellulose crystal structure and mesoscale cellulose microfibril packing in intact plant cell walls, tunicate tests, and bacterial films.

  11. Piezoelectric immunochip coated with thin films of bacterial cellulose nanocrystals for dengue detection.

    PubMed

    Pirich, Cleverton Luiz; de Freitas, Rilton Alves; Torresi, Roberto Manuel; Picheth, Guilherme Fadel; Sierakowski, Maria Rita

    2017-06-15

    Low-cost piezoelectric devices, such as simple frequency monitoring quartz crystal microbalance (QCM) devices, have good clinical utility as fast diagnostic tools for the detection of several diseases. However, unspecific antigen recognition, poor molecular probe adsorption and the need for sample dilution are still common drawbacks that hinder their use in routine diagnosis. In this work, piezoelectric sensors were previously coated with thin films of bacterial cellulose nanocrystals (CN) to provide a more sensitive and adapted interface for the attachment of monoclonal immunoglobulin G (IgGNS1) and to favor specific detection of non-structural protein 1 (NS1) of dengue fever. The assembly of the immunochip surface was analyzed by atomic force microscopy (AFM) and the NS1 detection was followed by quartz crystal microbalance with (QCM-D) and without energy dissipation monitoring (QCM). The CN surface was able to immobilize 2.30±0.5mgm -2 of IgGNS1, as confirmed by AFM topography and phase images along with QCM-D. The system was able to detect the NS1 protein in serum with only 10-fold dilution in the range of 0.01-10µgmL -1 by both QCM and QCM-D. The limits of detection of the two devices were 0.1μgmL -1 for QCM-D and 0.32μgmL -1 for QCM. As a result, QCM-D and QCM apparatuses can be used to follow NS1 recognition and have good potential for more sensitive, fast and/or less expensive diagnostic assays for dengue. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Rheological performance of bacterial cellulose based nonmineralized and mineralized hydrogel scaffolds

    NASA Astrophysics Data System (ADS)

    Basu, Probal; Saha, Nabanita; Bandyopadhyay, Smarak; Saha, Petr

    2017-05-01

    Bacterial cellulose (BC) based hydrogels (BC-PVP and BC-CMC) are modified with β-tri-calcium phosphate (β-TCP) and hydroxyapatite (HA) to improve the structural and functional properties of the existing hydrogel scaffolds. The modified hydrogels are then biomineralized with CaCO3 following liquid diffusion technique, where salt solutions of Na2CO3 (5.25 g/100 mL) and CaCl2 (7.35 g/100 mL) were involved. The BC-PVP and BC-CMC are being compared with the non-mineralized (BC-PVP-β-TCP/HA and BC-CMC-β-TCP/HA) and biomineralized (BC-PVP-β-TCP/HA-CaCO3 and BC-CMC-β-TCP/HA-CaCO3) hydrogels on the basis of their structural and rheological properties. The Fourier Transform Infrared (FTIR) spectral analysis demonstrated the presence of BC, CMC, PVP, β-TCP, HA in the non-mineralized and BC, CMC, PVP, β-TCP, HA and CaCO3 in the biomineralized samples. Interestingly, the morphological property of non-mineralized and biomineralized, hydrogels are different than that of BC-PVP and BC-CMC based novel biomaterials. The Scanning Electron Microscopic (SEM) images of the before mentioned samples reveal the denser structures than BC-PVP and BC-CMC, which exhibits the changes in their pore sizes. Concerning rheological analysis point of view, all the non-mineralized and biomineralized hydrogel scaffolds have shown significant elastic property. Additionally, the complex viscosity (η*) values have also found in decreasing order with the increase of angular frequency (ω) 0.1 rad.sec-1 to 100 rad.sec-1. All these BC based hydrogel scaffolds are elastic in nature, can be recommended for their application as an implant for bone tissue engineering.

  13. Behavior and biocompatibility of rabbit bone marrow mesenchymal stem cells with bacterial cellulose membrane

    PubMed Central

    Leite, Yulla Klinger de Carvalho; de Carvalho, Camila Ernanda Sousa; Feitosa, Matheus Levi Tajra; Alves, Michel Muálem de Moraes; Carvalho, Fernando Aécio de Amorim; Neto, Bartolomeu Cruz Viana; Miglino, Maria Angélica

    2018-01-01

    Background Tissue engineering has been shown to exhibit great potential for the creation of biomaterials capable of developing into functional tissues. Cellular expansion and integration depends on the quality and surface-determinant factors of the scaffold, which are required for successful biological implants. The objective of this research was to characterize and evaluate the in vitro characteristics of rabbit bone marrow mesenchymal stem cells (BM-MSCs) associated with a bacterial cellulose membrane (BCM). We assessed the adhesion, expansion, and integration of the biomaterial as well as its ability to induce macrophage activation. Finally, we evaluated the cytotoxicity and toxicity of the BCM. Methods Samples of rabbit bone marrow were collected. Mesenchymal stem cells were isolated from medullary aspirates to establish fibroblast colony-forming unit assay. Osteogenic, chondrogenic, and adipogenic differentiation was performed. Integration with the BCM was assessed by scanning electron microscopy at 1, 7, and 14 days. Cytotoxicity was assessed via the production of nitric oxide, and BCM toxicity was assessed with the MTT assay; phagocytic activity was also determined. Results The fibroblastoid colony-forming unit (CFU-F) assay showed cells with a fibroblastoid morphology organized into colonies, and distributed across the culture area surface. In the growth curve, two distinct phases, lag and log phase, were observed at 15 days. Multipotentiality of the cells was evident after induction of osteogenic, chondrogenic, and adipogenic lineages. Regarding the BM-MSCs’ bioelectrical integration with the BCM, BM-MSCs were anchored in the BCM in the first 24 h. On day 7 of culture, the cytoplasm was scattered, and on day 14, the cells were fully integrated with the biomaterial. We also observed significant macrophage activation; analysis of the MTT assay and the concentration of nitric oxide revealed no cytotoxicity of the biomaterial. Conclusion The BCM allowed the

  14. Oxidoreductive Cellulose Depolymerization by the Enzymes Cellobiose Dehydrogenase and Glycoside Hydrolase 61▿†

    PubMed Central

    Langston, James A.; Shaghasi, Tarana; Abbate, Eric; Xu, Feng; Vlasenko, Elena; Sweeney, Matt D.

    2011-01-01

    Several members of the glycoside hydrolase 61 (GH61) family of proteins have recently been shown to dramatically increase the breakdown of lignocellulosic biomass by microbial hydrolytic cellulases. However, purified GH61 proteins have neither demonstrable direct hydrolase activity on various polysaccharide or lignacious components of biomass nor an apparent hydrolase active site. Cellobiose dehydrogenase (CDH) is a secreted flavocytochrome produced by many cellulose-degrading fungi with no well-understood biological function. Here we demonstrate that the binary combination of Thermoascus aurantiacus GH61A (TaGH61A) and Humicola insolens CDH (HiCDH) cleaves cellulose into soluble, oxidized oligosaccharides. TaGH61A-HiCDH activity on cellulose is shown to be nonredundant with the activities of canonical endocellulase and exocellulase enzymes in microcrystalline cellulose cleavage, and while the combination of TaGH61A and HiCDH cleaves highly crystalline bacterial cellulose, it does not cleave soluble cellodextrins. GH61 and CDH proteins are coexpressed and secreted by the thermophilic ascomycete Thielavia terrestris in response to environmental cellulose, and the combined activities of T. terrestris GH61 and T. terrestris CDH are shown to synergize with T. terrestris cellulose hydrolases in the breakdown of cellulose. The action of GH61 and CDH on cellulose may constitute an important, but overlooked, biological oxidoreductive system that functions in microbial lignocellulose degradation and has applications in industrial biomass utilization. PMID:21821740

  15. Diethylaminoethyl-cellulose-bacterial cell immunoadsorbent columns: preparation of serotype-specific globulin and immunofluorescent conjugates for Streptococcus mutans serotypes a and d.

    PubMed

    McKinney, R M; Thacker, L

    1976-04-01

    Diethylaminoethyl (DEAE)-cellulose was used as a support material for preparing bacterial cell columns. Pretreatment of the bacterial cells with formalin was essential in obtaining satisfactory adherence of the cells to DEAE-cellulose. Cross-reacting antibodies were removed from antibody preparations against strains of Streptococcus mutans serotypes a and d by adsorption on appropriate bacterial cell columns. S. mutans serotype d was further divided into two subtypes on the basis of immunofluorescent staining with conjugates of immunospecifically adsorbed immunoglobulin G. The DEAE-cellulose-bacterial cell columns were regenerated after use by desorbing the cross-reacting antibodies with low-pH buffer and were used repeatedly over and 18-month period with no detectable loss in effectiveness.

  16. Assessing the impact of lyophilization process in production of implants based on the bacterial cellulose using Raman spectroscopy method

    NASA Astrophysics Data System (ADS)

    Timchenko, E. V.; Timchenko, P. E.; Pisareva, E. V.; Vlasov, M. Yu; Revin, V. V.; Klenova, N. A.; Asadova, A. A.

    2017-01-01

    In this article we present the research results of lyophilization process influence on the composition of hybrid materials based on the bacterial cellulose (BC) using Raman spectroscopy method. As an object of research was used BC, as well as hybrids based on it, comprising the various combinations of hydroxyapatite (HAP) and collagen. Our studies showed that during the lyophilization process changes the ratio of the individual components. It was found that for samples hybrid based on BC with addition of HAP occurs increase of PO4 3- peak intensity in the region 956 cm-1 with decreasing width, which indicates a change in the degree of HAP crystallinity.

  17. Cellulose- and xylan-degrading thermophilic anaerobic bacteria from biocompost.

    PubMed

    Sizova, M V; Izquierdo, J A; Panikov, N S; Lynd, L R

    2011-04-01

    Nine thermophilic cellulolytic clostridial isolates and four other noncellulolytic bacterial isolates were isolated from self-heated biocompost via preliminary enrichment culture on microcrystalline cellulose. All cellulolytic isolates grew vigorously on cellulose, with the formation of either ethanol and acetate or acetate and formate as principal fermentation products as well as lactate and glycerol as minor products. In addition, two out of nine cellulolytic strains were able to utilize xylan and pretreated wood with roughly the same efficiency as for cellulose. The major products of xylan fermentation were acetate and formate, with minor contributions of lactate and ethanol. Phylogenetic analyses of 16S rRNA and glycosyl hydrolase family 48 (GH48) gene sequences revealed that two xylan-utilizing isolates were related to a Clostridium clariflavum strain and represent a distinct novel branch within the GH48 family. Both isolates possessed high cellulase and xylanase activity induced independently by either cellulose or xylan. Enzymatic activity decayed after growth cessation, with more-rapid disappearance of cellulase activity than of xylanase activity. A mixture of xylan and cellulose was utilized simultaneously, with a significant synergistic effect observed as a reduction of lag phase in cellulose degradation.

  18. Bacterial cellulose composites loaded with SiO2 nanoparticles: Dynamic-mechanical and thermal properties.

    PubMed

    Sheykhnazari, Somayeh; Tabarsa, Taghi; Ashori, Alireza; Ghanbari, Abbas

    2016-12-01

    The aim of this paper was to prepare composites of bacterial cellulose (BC) filled with silica (SiO 2 ) nanoparticles to evaluate the influence of the SiO 2 contents (3, 5 and 7wt%) on the thermo-mechanical properties of the composites. BC hydro-gel was immersed in an aqueous solution of silanol derived from tetraethoxysilane (TEOS), the silanol was then converted into SiO 2 in the BC matrix by pressing at 120°C and 2MPa. The BC/SiO 2 translucent sheets were examined by dynamic-mechanical analysis (DMA), thermo gravimetric analysis (TGA), and scanning electron microscopy (SEM). The temperature dependence of the storage modulus, loss modulus and tan delta was determined by DMA. In general, the results revealed that the increment of storage modulus and thermal stability increased concomitantly with the augmentation of SiO 2 content. Therefore, it could be concluded that the mechanical properties of the composites were improved by using high amounts of nano silica. This would be a high aspect ratio of BC capable of connecting the BC matrix and SiO 2 , thereby enhancing a large contact surface and resulting in excellent coherence. A decrease of the storage modulus was consistent with increasing temperature, resulting from softening of the composites. The storage modulus of the composites increased in the order: BC/S7>BC/S5>BC/S3, while the loss modulus and tan delta decreased. On the other hand, the thermal stabilities of all BC/SiO 2 composites were remarkably enhanced as compared to the pristine BC. TGA curves showed that the temperature of decomposition of the pure BC gradually shifted from about 260°C to about 370°C as silica content increased. SEM observations illustrated that the nano-scale SiO 2 was embedded between the voids and nano-fibrils of the BC matrix. Overall, the results indicated that the successful synthesis and superior properties of BC/SiO 2 advocate its effectiveness for various applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Sonication reduces the attachment of Salmonella Typhimurium ATCC 14028 cells to bacterial cellulose-based plant cell wall models and cut plant material.

    PubMed

    Tan, Michelle S F; Rahman, Sadequr; Dykes, Gary A

    2017-04-01

    This study investigated the removal of bacterial surface structures, particularly flagella, using sonication, and examined its effect on the attachment of Salmonella Typhimurium ATCC 14028 cells to plant cell walls. S. Typhimurium ATCC 14028 cells were subjected to sonication at 20 kHz to remove surface structures without affecting cell viability. Effective removal of flagella was determined by staining flagella of sonicated cells with Ryu's stain and enumerating the flagella remaining by direct microscopic counting. The attachment of sonicated S. Typhimurium cells to bacterial cellulose-based plant cell wall models and cut plant material (potato, apple, lettuce) was then evaluated. Varying concentrations of pectin and/or xyloglucan were used to produce a range of bacterial cellulose-based plant cell wall models. As compared to the non-sonicated controls, sonicated S. Typhimurium cells attached in significantly lower numbers (between 0.5 and 1.0 log CFU/cm 2 ) to all surfaces except to the bacterial cellulose-only composite without pectin and xyloglucan. Since attachment of S. Typhimurium to the bacterial cellulose-only composite was not affected by sonication, this suggests that bacterial surface structures, particularly flagella, could have specific interactions with pectin and xyloglucan. This study indicates that sonication may have potential applications for reducing Salmonella attachment during the processing of fresh produce. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Production of cellulose II from native cellulose by near- and supercritical water solubilization.

    PubMed

    Sasaki, Mitsuru; Adschiri, Tadafumi; Arai, Kunio

    2003-08-27

    We explored conditions for dissolving microcrystalline cellulose in high-temperature and high-pressure water without catalyst and in order to produce cellulose II in a rapid and selective manner. For understanding reactions of microcrystalline cellulose in subcritical and supercritical water, its solubilization treatment was conducted using a continuous-flow-type microreactor. It was found that cellulose could dissolve in near- and supercritical water at short treatment times of 0.02-0.4 s, resulting in the formation of cellulose II in relatively high yield after the treatment. Next, characteristics of the cellulose II obtained were investigated. As a result, it was confirmed that the relative crystallinity index and the degree of polymerization of the cellulose II were high values ranging from 80 to 60% and from 50 to 30%, respectively. From these findings, it was suggested that this method had high potential as an alternative technique for the conventional cellulose II production method.

  1. In situ synthesis of silver-nanoparticles/bacterial cellulose composites for slow-released antimicrobial wound dressing.

    PubMed

    Wu, Jian; Zheng, Yudong; Song, Wenhui; Luan, Jiabin; Wen, Xiaoxiao; Wu, Zhigu; Chen, Xiaohua; Wang, Qi; Guo, Shaolin

    2014-02-15

    Bacterial cellulose has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity, which is one of critical skin-barrier functions in wound healing. To overcome such deficiency, we developed a novel method to synthesize and impregnate silver nanoparticles on to bacterial cellulose nanofibres (AgNP-BC). Uniform spherical silver nano-particles (10-30 nm) were generated and self-assembled on the surface of BC nano-fibers, forming a stable and evenly distributed Ag nanoparticles coated BC nanofiber. Such hybrid nanostructure prevented Ag nanoparticles from dropping off BC network and thus minimized the toxicity of nanoparticles. Regardless the slow Ag(+) release, AgNP-BC still exhibited significant antibacterial activities with more than 99% reductions in Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, AgNP-BC allowed attachment and growth of epidermal cells with no cytotoxicity emerged. The results demonstrated that AgNP-BC could reduce inflammation and promote wound healing. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Development of enzymatically-active bacterial cellulose membranes through stable immobilization of an engineered β-galactosidase.

    PubMed

    Estevinho, Berta N; Samaniego, Nuria; Talens-Perales, David; Fabra, Maria José; López-Rubio, Amparo; Polaina, Julio; Marín-Navarro, Julia

    2018-08-01

    Enzymatically-active bacterial cellulose (BC) was prepared by non-covalent immobilization of a hybrid enzyme composed by a β-galactosidase from Thermotoga maritima (TmLac) and a carbohydrate binding module (CBM2) from Pyrococcus furiosus. TmLac-CBM2 protein was bound to BC, with higher affinity at pH 6.5 than at pH 8.5 and with high specificity compared to the non-engineered enzyme. Both hydrated (HBC) and freeze-dried (DBC) bacterial cellulose showed equivalent enzyme binding efficiencies. Initial reaction rate of HBC-bound enzyme was higher than DBC-bound and both of them were lower than the free enzyme. However, enzyme performance was similar in all three cases for the hydrolysis of 5% lactose to a high extent. Reuse of the immobilized enzyme was limited by the stability of the β-galactosidase module, whereas the CBM2 module provided stable attachment of the hybrid enzyme to the BC support, after long incubation periods (3 h) at 75 °C. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. A soft biomolecule actuator based on a highly functionalized bacterial cellulose nano-fiber network with carboxylic acid groups.

    PubMed

    Wang, Fan; Jeon, Jin-Han; Park, Sukho; Kee, Chang-Doo; Kim, Seong-Jun; Oh, Il-Kwon

    2016-01-07

    Upcoming human-related applications such as soft wearable electronics, flexible haptic systems, and active bio-medical devices will require bio-friendly actuating materials. Here, we report a soft biomolecule actuator based on carboxylated bacterial cellulose (CBC), ionic liquid (IL), and poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) ( PSS) electrodes. Soft and biocompatible polymer-IL composites were prepared via doping of CBC with ILs. The highly conductive PSS layers were deposited on both sides of the CBC-IL membranes by a dip-coating technique to yield a sandwiched actuator system. Ionic conductivity and ionic exchange capacity of the CBC membrane can be increased up to 22.8 times and 1.5 times compared with pristine bacterial cellulose (BC), respectively, resulting in 8 times large bending deformation than the pure BC actuators with metallic electrodes in an open air environment. The developed CBC-IL actuators show significant progress in the development of biocompatible and soft actuating materials with quick response, low operating voltage and comparatively large bending deformation.

  4. Bacterial cellulose-polyaniline nano-biocomposite: A porous media hydrogel bioanode enhancing the performance of microbial fuel cell

    NASA Astrophysics Data System (ADS)

    Mashkour, Mehrdad; Rahimnejad, Mostafa; Mashkour, Mahdi

    2016-09-01

    Microbial fuel cells (MFCs) are one of the possible renewable energy supplies which microorganisms play an active role in bio-oxidize reactions of a substrate such as glucose. Electrode materials and surface modifications are highly effective tools in enhancing MFCs' Performance. In this study, new composite anodes are fabricated. Bacterial cellulose (BC) is used as continuous phase and polyaniline (PANI) as dispersed one which is synthesized by in situ chemical oxidative polymerization on BC's fibers. With hydrogel nature of BC as a novel feature and polyaniline conductivity there meet the favorable conditions to obtain an active microbial biofilm on anode surface. Maximum power density of 117.76 mW/m2 in current density of 617 mA/m2 is achieved for BC/PANI anode. The amounts demonstrate a considerable enhancement compared with graphite plate (1 mW/m2 and 10 mA/m2).

  5. Establishing a Role for Bacterial Cellulose in Environmental Interactions: Lessons Learned from Diverse Biofilm-Producing Proteobacteria

    PubMed Central

    Augimeri, Richard V.; Varley, Andrew J.; Strap, Janice L.

    2015-01-01

    Bacterial cellulose (BC) serves as a molecular glue to facilitate intra- and inter-domain interactions in nature. Biosynthesis of BC-containing biofilms occurs in a variety of Proteobacteria that inhabit diverse ecological niches. The enzymatic and regulatory systems responsible for the polymerization, exportation, and regulation of BC are equally as diverse. Though the magnitude and environmental consequences of BC production are species-specific, the common role of BC-containing biofilms is to establish close contact with a preferred host to facilitate efficient host–bacteria interactions. Universally, BC aids in attachment, adherence, and subsequent colonization of a substrate. Bi-directional interactions influence host physiology, bacterial physiology, and regulation of BC biosynthesis, primarily through modulation of intracellular bis-(3′→5′)-cyclic diguanylate (c-di-GMP) levels. Depending on the circumstance, BC producers exhibit a pathogenic or symbiotic relationship with plant, animal, or fungal hosts. Rhizobiaceae species colonize plant roots, Pseudomonadaceae inhabit the phyllosphere, Acetobacteriaceae associate with sugar-loving insects and inhabit the carposphere, Enterobacteriaceae use fresh produce as vehicles to infect animal hosts, and Vibrionaceae, particularly Aliivibrio fischeri, colonize the light organ of squid. This review will highlight the diversity of the biosynthesis and regulation of BC in nature by discussing various examples of Proteobacteria that use BC-containing biofilms to facilitate host–bacteria interactions. Through discussion of current data we will establish new directions for the elucidation of BC biosynthesis, its regulation and its ecophysiological roles. PMID:26635751

  6. Application of Molecular Techniques To Elucidate the Influence of Cellulosic Waste on the Bacterial Community Structure at a Simulated Low-Level-Radioactive-Waste Site▿ †

    PubMed Central

    Field, Erin K.; D'Imperio, Seth; Miller, Amber R.; VanEngelen, Michael R.; Gerlach, Robin; Lee, Brady D.; Apel, William A.; Peyton, Brent M.

    2010-01-01

    Low-level-radioactive-waste (low-level-waste) sites, including those at various U.S. Department of Energy sites, frequently contain cellulosic waste in the form of paper towels, cardboard boxes, or wood contaminated with heavy metals and radionuclides such as chromium and uranium. To understand how the soil microbial community is influenced by the presence of cellulosic waste products, multiple soil samples were obtained from a nonradioactive model low-level-waste test pit at the Idaho National Laboratory. Samples were analyzed using 16S rRNA gene clone libraries and 16S rRNA gene microarray (PhyloChip) analyses. Both methods revealed changes in the bacterial community structure with depth. In all samples, the PhyloChip detected significantly more operational taxonomic units, and therefore relative diversity, than the clone libraries. Diversity indices suggest that diversity is lowest in the fill and fill-waste interface (FW) layers and greater in the wood waste and waste-clay interface layers. Principal-coordinate analysis and lineage-specific analysis determined that the Bacteroidetes and Actinobacteria phyla account for most of the significant differences observed between the layers. The decreased diversity in the FW layer and increased members of families containing known cellulose-degrading microorganisms suggest that the FW layer is an enrichment environment for these organisms. These results suggest that the presence of the cellulosic material significantly influences the bacterial community structure in a stratified soil system. PMID:20305022

  7. Cellulose and hemicellulose decomposition by forest soil bacteria proceeds by the action of structurally variable enzymatic systems

    PubMed Central

    López-Mondéjar, Rubén; Zühlke, Daniela; Becher, Dörte; Riedel, Katharina; Baldrian, Petr

    2016-01-01

    Evidence shows that bacteria contribute actively to the decomposition of cellulose and hemicellulose in forest soil; however, their role in this process is still unclear. Here we performed the screening and identification of bacteria showing potential cellulolytic activity from litter and organic soil of a temperate oak forest. The genomes of three cellulolytic isolates previously described as abundant in this ecosystem were sequenced and their proteomes were characterized during the growth on plant biomass and on microcrystalline cellulose. Pedobacter and Mucilaginibacter showed complex enzymatic systems containing highly diverse carbohydrate-active enzymes for the degradation of cellulose and hemicellulose, which were functionally redundant for endoglucanases, β-glucosidases, endoxylanases, β-xylosidases, mannosidases and carbohydrate-binding modules. Luteibacter did not express any glycosyl hydrolases traditionally recognized as cellulases. Instead, cellulose decomposition was likely performed by an expressed GH23 family protein containing a cellulose-binding domain. Interestingly, the presence of plant lignocellulose as well as crystalline cellulose both trigger the production of a wide set of hydrolytic proteins including cellulases, hemicellulases and other glycosyl hydrolases. Our findings highlight the extensive and unexplored structural diversity of enzymatic systems in cellulolytic soil bacteria and indicate the roles of multiple abundant bacterial taxa in the decomposition of cellulose and other plant polysaccharides. PMID:27125755

  8. Bacterial-cellulose-derived carbon nanofiber@MnO₂ and nitrogen-doped carbon nanofiber electrode materials: an asymmetric supercapacitor with high energy and power density.

    PubMed

    Chen, Li-Feng; Huang, Zhi-Hong; Liang, Hai-Wei; Guan, Qing-Fang; Yu, Shu-Hong

    2013-09-14

    A new kind of high-performance asymmetric supercapacitor is designed with pyrolyzed bacterial cellulose (p-BC)-coated MnO₂ as a positive electrode material and nitrogen-doped p-BC as a negative electrode material via an easy, efficient, large-scale, and green fabrication approach. The optimal asymmetric device possesses an excellent supercapacitive behavior with quite high energy and power density. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Bacterial cellulose composites: Synthetic strategies and multiple applications in bio-medical and electro-conductive fields.

    PubMed

    Ul-Islam, Mazhar; Khan, Shaukat; Ullah, Muhammad Wajid; Park, Joong Kon

    2015-12-01

    Bacterial cellulose (BC), owing to its pure nature and impressive physicochemical properties, including high mechanical strength, crystallinity, porous fibrous structure, and liquid absorbing capabilities, has emerged as an advanced biomaterial. To match the market demand and economic values, BC has been produced through a number of synthetic routes, leading to slightly different structural features and physical appearance. Chemical nature, porous geometry, and 3D fibrous structure of BC make it an ideal material for composites synthesis that successfully overcome certain deficiencies of pure BC. In this review, we have focused various strategies developed for synthesizing BC and BC composites. Reinforcement materials including nanoparticles and polymers have enhanced the antimicrobial, conducting, magnetic, biocompatible, and mechanical properties of BC. Both pure BC and its composites have shown impressive applications in medical fields and in the development of optoelectronic devices. Herein, we have given a special attention to discuss its applications in the medical and electronic fields. In conclusion, BC and BC composites have realistic potential to be used in future development of medical devices, artificial organs and electronic and conducting materials. The contents discussed herein will provide an eye-catching theme to the researchers concerned with practical applications of BC and BC composites. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A Highly Flexible Supercapacitor Based on MnO2/RGO Nanosheets and Bacterial Cellulose-Filled Gel Electrolyte

    PubMed Central

    Fei, Haojie; Saha, Nabanita; Kazantseva, Natalia; Moucka, Robert; Cheng, Qilin; Saha, Petr

    2017-01-01

    The flexible supercapacitors (SCs) of the conventional sandwich-type structure have poor flexibility due to the large thickness of the final entire device. Herein, we have fabricated a highly flexible asymmetric SC using manganese dioxide (MnO2) and reduced graphene oxide (RGO) nanosheet-piled hydrogel films and a novel bacterial cellulose (BC)-filled polyacrylic acid sodium salt-Na2SO4 (BC/PAAS-Na2SO4) neutral gel electrolyte. Apart from being environmentally friendly, this BC/PAAS-Na2SO4 gel electrolyte has high viscosity and a sticky property, which enables it to combine two electrodes together. Meanwhile, the intertangling of the filled BC in the gel electrolyte hinders the decrease of the viscosity with temperature, and forms a separator to prevent the two electrodes from short-circuiting. Using these materials, the total thickness of the fabricated device does not exceed 120 μm. This SC device demonstrates high flexibility, where bending and even rolling have no obvious effect on the electrochemical performance. In addition, owing to the asymmetric configuration, the cell voltage of this flexible SC has been extended to 1.8 V, and the energy density can reach up to 11.7 Wh kg−1 at the power density of 441 W kg−1. This SC also exhibits a good cycling stability, with a capacitance retention of 85.5% over 5000 cycles. PMID:29084177

  11. Development and characterization of bacterial cellulose reinforced biocomposite films based on protein from buckwheat distiller's dried grains.

    PubMed

    Wang, Xuejiao; Ullah, Niamat; Sun, Xuchun; Guo, Yan; Chen, Lin; Li, Zhixi; Feng, Xianchao

    2017-03-01

    Biocomposite films were manufactured by combining protein extracted from buckwheat distiller's dried grains with bacterial cellulose (BC). The film microstructures showed that BC is compatible with protein matrix and endows the film with high rigidity. Differential scanning calorimetry (DSC) showed that BC can promote thermal stability of the composite films. BC promoted the transition from a Newtonian to a non-Newtonian fluid and the shear thinning behavior of protein-BC solution. Fourier Transform Infrared (FTIR) spectroscopy showed the main functional groups' absorption peaks shifted to lower wavenumbers. Results of both FTIR and viscosity analysis proved the formation of intermolecular interactions through hydrogen bonds. These bonds affected film characteristics such as moisture content (MC), water solubility (WS), and water vapor permeability (WVP), which decreased with addition of BC. The WVP (6.68±0.78-5.95±0.54×10 -10 gm/Pasm 2 ) of the films were lower than other protein films. Tensile strength (TS) values of films containing 1.8% and 2.0% BC (14.98±0.97 and 15.03±2.04MPa) were significantly higher than that of pure protein films (4.26±0.66MPa). Combination of proteins extracted from a waste product and BC led to composite films with low water vapor permeability and excellent mechanical properties. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Novel Piezoelectric Paper‐Based Flexible Nanogenerators Composed of BaTiO3 Nanoparticles and Bacterial Cellulose

    PubMed Central

    Zhang, Guangjie; Liao, Qingliang; Zhang, Zheng; Liang, Qijie; Zhao, Yingli; Zheng, Xin

    2015-01-01

    A piezoelectric paper based on BaTiO3 (BTO) nanoparticles and bacterial cellulose (BC) with excellent output properties for application of nanogenerators (NGs) is reported. A facile and scalable vacuum filtration method is used to fabricate the piezoelectric paper. The BTO/BC piezoelectric paper based NG shows outstanding output performance with open‐circuit voltage of 14 V and short‐circuit current density of 190 nA cm−2. The maximum power density generated by this unique BTO/BC structure is more than ten times higher than BTO/polydimethylsiloxane structure. In bending conditions, the NG device can generate output voltage of 1.5 V, which is capable of driving a liquid crystal display screen. The improved performance can be ascribed to homogeneous distribution of piezoelectric BTO nanoparticles in the BC matrix as well as the enhanced stress on piezoelectric nanoparticles implemented by the unique percolated networks of BC nanofibers. The flexible BTO/BC piezoelectric paper based NG is lightweight, eco‐friendly, and cost‐effective, which holds great promises for achieving wearable or implantable energy harvesters and self‐powered electronics. PMID:27774389

  13. Superelastic and superhydrophobic bacterial cellulose/silica aerogels with hierarchical cellular structure for oil absorption and recovery.

    PubMed

    He, Jian; Zhao, Hangyuan; Li, Xiaolei; Su, Dong; Zhang, Fengrui; Ji, Huiming; Liu, Rui

    2018-03-15

    Bacterial cellulose aerogels/silica aerogels (BCAs/SAs) are prepared using three-dimensional self-assembled BC skeleton as reinforcement and methyltriethoxysilane derived silica aerogels as filler through vacuum infiltration and freeze drying. The BCAs/SAs possess a hierarchical cellular structure giving them superelasticity and recyclable compressibility. The BCAs/SAs can bear a compressive strain up to 80% and recover their original shapes after the release of the stress. The BCAs/SAs exhibit super-hydrophobicity with a contact angle of 152° and super-oleophilicity resulting from the methyl groups on the surface of silica aerogel filler. This endows the BCAs/SAs outstanding oil absorbing capability with the quality factor Q from 8 to 14 for organic solvents and oils. Moreover, the absorbed oil can be retrieved by mechanically squeezed with a recovery of 88% related to the superelastic ability of the composites. In addition, the oil absorbing of BS/SAs could be well maintained with the quality factor Q about 11 for gasoline after harsh conditional treatment down to -200 °C and up to 300 °C. Such outstanding elastic and oleophilic properties make the BC/SAs tremendous potential for applications of oil absorbing, recovery and oil-water separation. Copyright © 2017. Published by Elsevier B.V.

  14. Ultrafine nano-network structured bacterial cellulose as reductant and bridging ligands to fabricate ultrathin K-birnessite type MnO2 nanosheets for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaojuan; He, Mingqian; He, Ping; Li, Caixia; Liu, Huanhuan; Zhang, Xingquan; Ma, Yongjun

    2018-03-01

    In this work, nanostructured ultrathin K-birnessite type MnO2 nanosheets are successfully prepared by a rapid and environmently friendly hydrothermal method, which involves only a facile redox reaction between KMnO4 and nano-network structured bacterial cellulose with abundant hydroxyl groups. The results show that the unique three-dimensional interwoven structured bacterial cellulose acts as not only reductant but also bridging ligands for assembling nanoscaled building units to control the desired morphology of prepared MnO2. Furthermore, electrochemical performances of prepared MnO2 are investigated as electrode materials for supercapacitors by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum in 1.0 M Na2SO4 electrolyte. The resulting ultrathin K-birnessite type MnO2 nanosheets based electrode exhibits higher capacitance (328.2 F g-1 at 0.2 A g-1), excellent rate capability (328.2 F g-1 and 200.4 F g-1 at 0.2 A g-1 and 2.0 A g-1, respectively) and satisfactory cyclic stability (91.6% of initial capacitance even after 2000 cycles at 3.0 A g-1). This work suggests that bacterial cellulose as reductant is a promising candidate in the development of nanostructures of metal oxides.

  15. Processive endoglucanase active in crystalline cellulose hydrolysis by the brown rot Basidiomycete Gloeophyllum trabeum

    Treesearch

    Roni Cohen; Melissa R. Suzuki; Kenneth E. Hammel

    2005-01-01

    Brown rot basidiomycetes have long been thought to lack the processive cellulases that release soluble sugars from crystalline cellulose. On the other hand, these fungi remove all of the cellulose, both crystalline and amorphous, from wood when they degrade it. To resolve this discrepancy, we grew Gloeophyllum trabeum on microcrystalline cellulose (Avicel) and purified...

  16. Characterization of cellulose II nanoparticles regenerated from ionic liquid, 1-butyl-3-methylimidazolium chloride

    USDA-ARS?s Scientific Manuscript database

    Regenerated cellulose nanoparticles (RCNs) including both elongated fiber and spherical structures were prepared from microcrystalline cellulose (MCC)and cotton using 1-butyl-3-methylimidazolium chloride followed by high-pressure homogenization. The crystalline structure of RCNs was cellulose II in ...

  17. Chromophores in lignin-free cellulosic materials belong to three compound classes. Chromophores in cellulosics, XII

    USDA-ARS?s Scientific Manuscript database

    The CRI (chromophore release and identification) method isolates well-defined chromophoric substances from different cellulosic matrices, such as highly bleached pulps, cotton linters, bacterial cellulose, viscose or lyocell fibers, and cellulose acetates. The chromophores are present only in extrem...

  18. Mechanical Retention and Waterproof Properties of Bacterial Cellulose-Reinforced Thermoplastic Starch Biocomposites Modified with Sodium Hexametaphosphate

    PubMed Central

    Wang, Da-wei; Xu, Ying-juan; Li, Xin; Huang, Chao-ming; Huang, Kuo-shien; Wang, Chuen-kai; Yeh, Jen-taut

    2015-01-01

    The waterproof and strength retention properties of bacterial cellulose (BC)-reinforced thermoplastic starch (TPS) resins were successfully improved by reacting with sodium hexametaphosphate (SHMP). After modification with SHMP, the tensile strength (σf) and impact strength (Is) values of initial and conditioned BC-reinforced TPS, modified with varying amounts of SHMP(TPS100BC0.02SHMPx), and their blends with poly(lactic acid)((TPS100BC0.02SHMPx)75PLA25) specimens improved significantly and reached a maximal value as SHMP content approached 10 parts per hundred parts of TPS resin (phr), while their moisture content and elongation at break (ɛf) was reduced to a minimal value as SHMP contents approached 10 phr. The σf, Is and ɛf retention values of a (TPS100BC0.02SHMP10)75PLA25 specimen conditioned for 56 days are 52%, 50% and 3 times its initial σf, Is and ɛf values, respectively, which are 32.5 times, 8.9 times and 40% of those of a corresponding conditioned TPS100BC0.02 specimen, respectively. As evidenced by FTIR analyses of TPS100BC0.02SHMPx specimens, hydroxyl groups of TPS100BC0.02 resins were successfully reacted with the phosphate groups of SHMP molecules. New melting endotherms and diffraction peaks of VH-type crystals were found on DSC thermograms and WAXD patterns of TPS or TPS100BC0.02 specimens conditioned for 7 days, while no new melting endotherm or diffraction peak was found for TPS100BC0.02SHMPx and/or (TPS100BC0.02SHMPx)75PLA25 specimens conditioned for less than 14 and 28 days, respectively.

  19. Arginine functionalized bacterial cellulose nanofibers containing gel as an effective wound dressing; in vitro and in vivo evaluation.

    PubMed

    Feizabadi, Farideh; Minaiyan, Mohsan; Taheri, Azade

    2018-02-19

    Nanofibers such as bacterial cellulose nanofibers (BC-NFs) have gained increasing attention for use in wound dressings. Topical application of arginine can stimulate wound healing significantly. In order to promote the wound healing process, arginine functionalized BC-NFs containing gel (Arg-BC-NFs gel) was prepared by the electrostatic attachment of arginine on the surface of BC-NFs. The effect of pH was evaluated on the amount of the attached arginine on the BC-NFs surface. The attachment of arginine on BC-NFs surface was investigated by FTIR spectroscopy. The morphology of Arg-BC-NFs was evaluated using FESEM. The viscosity and spreadability of Arg-BC-NFs and the release of arginine from Arg-BC-NFs were evaluated. The effectiveness of Arg-BC-NFs gel was assessed in a full thickness wound model in rats. Re-epithelization, collagen deposition and neovascularization were investigated in the wound tissues using histological and immunohistochemical analysis. FTIR spectra and the zeta potential of BC-NFs confirmed the surface modification of BC-NFs by arginine. FESEM images showed the nanofibrous structure of Arg-BC-NFs. The release of arginine from Arg-BC-NFs gel was in a sustained release manner for 24 h. The appropriate viscosity and spreadability of Arg-BC-NFs gel confirmed its easy topical application. In vivo studies revealed that Arg-BC-NFs gel promoted wound closure at a faster rate than BC-NFs gel and arginine solution. Moreover, faster and more organized re-epithelialization, angiogenesis and collagen deposition were achieved in Arg-BC-NFs gel treated group in comparison to other groups. Arg-BC-NFs gel can be introduced as an effective wound dressing for acute wounds. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  20. Flexible and Freestanding Supercapacitor Electrodes Based on Nitrogen-Doped Carbon Networks/Graphene/Bacterial Cellulose with Ultrahigh Areal Capacitance.

    PubMed

    Ma, Lina; Liu, Rong; Niu, Haijun; Xing, Lixin; Liu, Li; Huang, Yudong

    2016-12-14

    Flexible energy-storage devices based on supercapacitors rely largely on the scrupulous design of flexible electrodes with both good electrochemical performance and high mechanical properties. Here, nitrogen-doped carbon nanofiber networks/reduced graphene oxide/bacterial cellulose (N-CNFs/RGO/BC) freestanding paper is first designed as a high-performance, mechanically tough, and bendable electrode for a supercapacitor. The BC is exploited as both a supporting substrate for a large mass loading of 8 mg cm -2 and a biomass precursor for N-CNFs by pyrolysis. The one-step carbonization treatment not only fabricates the nitrogen-doped three-dimensional (3D) nanostructured carbon composite materials but also forms the reduction of the GO sheets at the same time. The fabricated paper electrode exhibits an ultrahigh areal capacitance of 2106 mF cm -2 (263 F g -1 ) in a KOH electrolyte and 2544 mF cm -2 (318 F g -1 ) in a H 2 SO 4 electrolyte, exceptional cycling stability (∼100% retention after 20000 cycles), and excellent tensile strength (40.7 MPa). The symmetric supercapacitor shows a high areal capacitance (810 mF cm -2 in KOH and 920 mF cm -2 in H 2 SO 4 ) and thus delivers a high energy density (0.11 mWh cm -2 in KOH and 0.29 mWh cm -2 in H 2 SO 4 ) and a maximum power density (27 mW cm -2 in KOH and 37.5 mW cm -2 in H 2 SO 4 ). This work shows that the new procedure is a powerful and promising way to design flexible and freestanding supercapacitor electrodes.

  1. Bacterial cellulose hydrolysis in anaerobic environmental subsystems--Clostridium thermocellum and Clostridium stercorarium, thermophilic plant-fiber degraders.

    PubMed

    Zverlov, Vladimir V; Schwarz, Wolfgang H

    2008-03-01

    Cellulose degradation is a rare trait in bacteria. However, the truly cellulolytic bacteria are extremely efficient hydrolyzers of plant cell wall polysaccharides, especially those in thermophilic anaerobic ecosystems. Clostridium stercorarium, a thermophilic ubiquitous soil dweller, has a simple cellulose hydrolyzing enzyme system of only two cellulases. However, it seems to be better suited for the hydrolysis of a wide range of hemicelluloses. Clostridium thermocellum, an ubiquitous thermophilic gram-type positive bacterium, is one of the most successful cellulose degraders known. Its extracellular enzyme complex, the cellulosome, was prepared from C. thermocellum cultures grown on cellulose, cellobiose, barley beta-1,3-1,4-glucan, or a mixture of xylan and cellulose. The single proteins were identified by peptide chromatography and MALDI-TOF-TOF. Eight cellulosomal proteins could be found in all eight preparations, 32 proteins occur in at least one preparation. A number of enzymatic components had not been identified previously. The proportion of components changes if C. thermocellum is grown on different substrates. Mutants of C. thermocellum, devoid of scaffoldin CipA, that now allow new types of experiments with in vitro cellulosome reassembly and a role in cellulose hydrolysis are described. The characteristics of these mutants provide strong evidence of the positive effect of complex (cellulosome) formation on hydrolysis of crystalline cellulose.

  2. Rational design of a high-strength bone scaffold platform based on in situ hybridization of bacterial cellulose/nano-hydroxyapatite framework and silk fibroin reinforcing phase.

    PubMed

    Jiang, Pei; Ran, Jiabing; Yan, Pan; Zheng, Lingyue; Shen, Xinyu; Tong, Hua

    2018-02-01

    Bacterial cellulose/hydroxyapatite (BC/HAp) composite had favourable bioaffinity but its poor mechanical strength limited its widespread applications in bone tissue engineering (BTE). Silk fibroin, which possesses special crystalline structure, has been widely used as organic reinforcing material, and different SFs have different amino acid sequences, which exhibit different bioaffinity and mechanical properties. In this regard, bacterial cellulose-Antheraea yamamai silk fibroin/hydroxyapatite (BC-AYSF/HAp), bacterial cellulose-Bombyx mori silk fibroin/hydroxyapatite (BC-BMSF/HAp), and BC/HAp nano-composites were synthesized via a novel in situ hybridization method. Compared with BC/HAp and BC-BMSF/HAp, the BC-AYSF/HAp exhibited better interpenetration, which may benefit for the transportation of nutrients and wastes, the adhesion of cells as well. Additionally, the BC-AYSF/HAp also presented superior thermal stability than the other two composites revealed by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). Compression testing indicated that the mechanical strength of BC-BMSF/HAp was greatly reinforced compared with BC/HAp and was even a little higher than that of BC-AYSF/HAp. Tensile testing showed that BC-AYSF/HAp possesses extraordinary mechanical properties with a higher elastic modulus at low strain and higher fracture strength simultaneously than the other two composites. In vitro cell culture exhibited that MC3T3-E1 cells on the BC-AYSF/HAp membrane took on higher proliferative potential than those on the BC-BMSF/HAp membrane. These results suggested that compared with BC-BMSF/HAp, the BC-AYSF/HAp composite was more appropriate as an ideal bone scaffold platform or biomedical membrane to be used in BTE.

  3. Modulation of population density and size of silver nanoparticles embedded in bacterial cellulose via ammonia exposure: visual detection of volatile compounds in a piece of plasmonic nanopaper

    NASA Astrophysics Data System (ADS)

    Heli, B.; Morales-Narváez, E.; Golmohammadi, H.; Ajji, A.; Merkoçi, A.

    2016-04-01

    The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and from amber to a grey or taupe colour upon fish or meat spoilage exposure. These phenomena are proposed as a simple visual detection of volatile compounds in a flexible, transparent, permeable and stable single-use nanoplasmonic membrane, which opens the way to innovative approaches and capabilities in gas sensing and smart packaging.The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and

  4. Nitrogen-doped carbon nanofibers derived from polypyrrole coated bacterial cellulose as high-performance electrode materials for supercapacitors and Li-ion batteries

    DOE PAGES

    Lei, Wen; Han, Lili; Xuan, Cuijuan; ...

    2016-05-24

    Here, nitrogen-doped carbon nanofiber (NDCN) was synthesized via carbonization of polypyrrole (PPy) coated bacterial cellulose (BC) composites, where BC serves as templates as well as precursor, and PPy serves as the nitrogen source. The synthesized NDCN was employed as electrode for both supercapacitors and Li-ion batteries. The large surface area exposed to electrolyte resulting from the 3D carbon networks leads to sufficient electrode/electrolyte interface and creates shorter transport paths of electrolyte ions and Li + ion. Besides, the three types of N dopants in NDCN improve the electronic conductivity, as well as superior electrochemical performance.

  5. Efficacy of bacterial cellulose membrane for the treatment of lower limbs chronic varicose ulcers: a randomized and controlled trial.

    PubMed

    Cavalcanti, Luciana Marins; Pinto, Flávia Cristina Morone; Oliveira, Glícia Maria DE; Lima, Salvador Vilar Correia; Aguiar, José Lamartine DE Andrade; Lins, Esdras Marques

    2017-01-01

    to evaluate the efficacy of Bacterial Cellulose (BC) membrane dressings in the treatment of lower limb venous ulcers. we carried out a prospective, randomized, controlled study of 25 patients with chronic venous ulcer disease in the lower limbs from the Angiology and Vascular Surgery Service of the Federal University of Pernambuco Hospital and from the Salgado Polyclinic of the County Health Department, Caruaru, Pernambuco. We randomly assigned patients to two groups: control group, receiving dressings with triglyceride oil (11 patients) and experimental group, treated with BC membrane (14 patients). We followed the patients for a period of 120 days. There was a reduction in the wound area in both groups. There were no infections or reactions to the product in any of the groups. Patients in the BC group showed decreased pain and earlier discontinuation of analgesic use. BC membrane can be used as a dressing for the treatment of varicose ulcers of the lower limbs. avaliar a eficácia de curativos com membrana de Celulose Bacteriana (CB) no tratamento de úlceras venosas de membros inferiores. estudo prospectivo, randomizado e controlado de 25 pacientes com úlceras decorrentes de doença venosa crônica nos membros inferiores provenientes do Serviço de Angiologia e Cirurgia Vascular do Hospital de Clínicas da Universidade Federal de Pernambuco e da Policlínica do Salgado da Secretaria Municipal de Saúde, Caruaru, Pernambuco. Os pacientes foram distribuídos aleatoriamente em dois grupos: grupo controle, que recebeu curativos com óleo de triglicerídeos (11 pacientes) e grupo experimental, tratado com membrana de CB (14 pacientes). Os pacientes foram acompanhados por um período de 120 dias. houve uma redução na área de ferida em ambos os grupos. Não houve infecção ou reações ao produto em nenhum dos grupos. Pacientes do grupo CB mostraram diminuição da dor e interrupção mais precoce do uso de analgésicos. a membrana de CB pode ser usada como

  6. Statistical optimization of medium composition for bacterial cellulose production by Gluconacetobacter hansenii UAC09 using coffee cherry husk extract--an agro-industry waste.

    PubMed

    Rani, Mahadevaswamy Usha; Rastogi, Navin K; Appaiah, K A Anu

    2011-07-01

    During the production of grape wine, the formation of thick leathery pellicle/bacterial cellulose (BC) at the airliquid interface was due to the bacterium, which was isolated and identified as Gluconacetobacter hansenii UAC09. Cultural conditions for bacterial cellulose production from G. hansenii UAC09 were optimized by central composite rotatable experimental design. To economize the BC production, coffee cherry husk (CCH) extract and corn steep liquor (CSL) were used as less expensive sources of carbon and nitrogen, respectively. CCH and CSL are byproducts from the coffee processing and starch processing industry, respectively. The interactions between pH (4.5- 8.5), CSL (2-10%), alcohol (0.5-2%), acetic acid (0.5- 2%), and water dilution rate to CCH ratio (1:1 to 1:5) were studied using response surface methodology. The optimum conditions for maximum BC production were pH (6.64), CSL (10%), alcohol (0.5%), acetic acid (1.13%), and water to CCH ratio (1:1). After 2 weeks of fermentation, the amount of BC produced was 6.24 g/l. This yield was comparable to the predicted value of 6.09 g/l. This is the first report on the optimization of the fermentation medium by RSM using CCH extract as the carbon source for BC production by G. hansenii UAC09.

  7. Cellular interactions with bacterial cellulose: Polycaprolactone nanofibrous scaffolds produced by a portable electrohydrodynamic gun for point-of-need wound dressing.

    PubMed

    Aydogdu, Mehmet Onur; Altun, Esra; Crabbe-Mann, Maryam; Brako, Francis; Koc, Fatma; Ozen, Gunes; Kuruca, Serap Erdem; Edirisinghe, Ursula; Luo, C J; Gunduz, Oguzhan; Edirisinghe, Mohan

    2018-05-27

    Electrospun nanofibrous scaffolds are promising regenerative wound dressing options but have yet to be widely used in practice. The challenge is that nanofibre productions rely on bench-top apparatuses, and the delicate product integrity is hard to preserve before reaching the point of need. Timing is critically important to wound healing. The purpose of this investigation is to produce novel nanofibrous scaffolds using a portable, hand-held "gun", which enables production at the wound site in a time-dependent fashion, thereby preserving product integrity. We select bacterial cellulose, a natural hydrophilic biopolymer, and polycaprolactone, a synthetic hydrophobic polymer, to generate composite nanofibres that can tune the scaffold hydrophilicity, which strongly affects cell proliferation. Composite scaffolds made of 8 different ratios of bacterial cellulose and polycaprolactone were successfully electrospun. The morphological features and cell-scaffold interactions were analysed using scanning electron microscopy. The biocompatibility was studied using Saos-2 cell viability test. The scaffolds were found to show good biocompatibility and allow different proliferation rates that varied with the composition of the scaffolds. A nanofibrous dressing that can be accurately moulded and standardised via the portable technique is advantageous for wound healing in practicality and in its consistency through mass production. © 2018 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

  8. Prevalence and trends of cellulosics in pharmaceutical dosage forms.

    PubMed

    Mastropietro, David J; Omidian, Hossein

    2013-02-01

    Many studies have shown that cellulose derivatives (cellulosics) can provide various benefits when used in virtually all types of dosage forms. Nevertheless, the popularity of their use in approved drug products is rather unknown. This research reports the current prevalence and trends of use for 15 common cellulosics in prescription drug products. The cellulosics were powdered and microcrystalline cellulose (MCC), ethyl cellulose, hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), hypromellose (HPMC), HPMC phthalate, HPMC acetate succinate, cellulose acetate (CA), CA phthalate, sodium (Na) and calcium (Ca) carboxymethylcellulose (CMC), croscarmellose sodium (XCMCNa), methyl cellulose, and low substituted HPC. The number of brand drug products utilizing each cellulosics was determined using the online drug index Rxlist. A total of 607 brand products were identified having one or more of the cellulosics as an active or inactive ingredient. An array of various dosage forms was identified and revealed HPMC and MCC to be the most utilized cellulosics in all products followed by XCMCNa and HPC. Many products contained two or more cellulosics in the formulation (42% containing two, 23% containing three, and 4% containing 4-5). The largest combination occurrence was HPMC with MCC. The use of certain cellulosics within different dosage form types was found to contain specific trends. All injectables utilized only CMCNa, and the same with all ophthalmic solutions utilizing HPMC, and otic suspensions utilizing HEC. Popularity and trends regarding cellulosics use may occur based on many factors including functionality, safety, availability, stability, and ease of manufacturing.

  9. Two-colour fluorescence fluorimetric analysis for direct quantification of bacteria and its application in monitoring bacterial growth in cellulose degradation systems.

    PubMed

    Duedu, Kwabena O; French, Christopher E

    2017-04-01

    Monitoring bacterial growth is an important technique required for many applications such as testing bacteria against compounds (e.g. drugs), evaluating bacterial composition in the environment (e.g. sewage and wastewater or food suspensions) and testing engineered bacteria for various functions (e.g. cellulose degradation). T?=1,^FigItem(1) ^ReloadFigure=Yesraditionally, rapid estimation of bacterial growth is performed using spectrophotometric measurement at 600nm (OD600) but this estimation does not differentiate live and dead cells or other debris. Colony counting enumerates live cells but the process is laborious and not suitable for large numbers of samples. Enumeration of live bacteria by flow cytometry is a more suitable rapid method with the use of dual staining with SYBR I Green nucleic acid gel stain and Propidium Iodide (SYBR-I/PI). Flow cytometry equipment and maintenance costs however are relatively high and this technique is unavailable in many laboratories that may require a rapid method for evaluating bacteria growth. We therefore sought to adapt and evaluate the SYBR-I/PI technique of enumerating live bacterial cells for a cheaper platform, a fluorimeter. The fluorimetry adapted SYBR-I/PI enumeration of bacteria in turbid growth media had direct correlations with OD600 (p>0.001). To enable comparison of fluorescence results across labs and instruments, a fluorescence intensity standard unit, the equivalent fluorescent DNA (EFD) was proposed, evaluated and found useful. The technique was further evaluated for its usefulness in enumerating bacteria in turbid media containing insoluble particles. Reproducible results were obtained which OD600 could not give. An alternative method based on the assessment of total protein using the Pierce Coomassie Plus (Bradford) Assay was also evaluated and compared. In all, the SYBR-I/PI method was found to be the quickest and most reliable. The protocol is potentially useful for high-throughput applications such as

  10. Syntrophic association of termite gut bacterial symbionts with bifunctional characteristics of cellulose degrading and polyhydroxyalkanoate producing bacteria.

    PubMed

    Cibichakravarthy, Balasubramanian; Abinaya, Subramani; Prabagaran, Solai Ramatchandirane

    2017-10-01

    The guild between higher termites and their partnership with the diverse community of bacteria and archaea in their gut is a marvel evolutionary achievement. Sustained attempts were made worldwide with a quest for identifying viable important biological macromolecule polyhydroxyalkanoate (PHA) accumulating bacteria. Termite gut serve as a novel source for bacteria with dual properties like PHA production as well as cellulose degradation. Among 40 isolates cultivated, 32.5% turned positive for PCR based screening of PhaC gene. The 16S rRNA gene sequencing revealed that elite PHA producer and cellulose degrader which is phylogenetically affiliated to Bacillus cereus. The PHA production was maximized by employing different carbon and nitrogen sources along with altered pH and temperatures. GC-MS, FTIR and 1 HNMR analyses confirmed the presence of PHA and the thermal characterization was performed through TGA and DSC for the termite gut isolate. Our results indicated that the combined integrative approach using isolated strains from termite gut would be preferable choice in producing biomolecules from cellulosic materials. Copyright © 2017. Published by Elsevier B.V.

  11. Spatially Resolved Characterization of Cellulose Nanocrystal-Polypropylene Composite by Confocal Raman Microscopy

    Treesearch

    Umesh P. Agarwal; Ronald Sabo; Richard S. Reiner; Craig M. Clemons; Alan W. Rudie

    2012-01-01

    Raman spectroscopy was used to analyze cellulose nanocrystal (CNC)–polypropylene (PP) composites and to investigate the spatial distribution of CNCs in extruded composite filaments. Three composites were made from two forms of nanocellulose (CNCs from wood pulp and the nanoscale fraction of microcrystalline cellulose) and two of the three composites investigated used...

  12. Negative results of growing titania nanotubes on cellulose nanocrystals - Effect of hydrothermal reaction

    NASA Astrophysics Data System (ADS)

    Chamakh, Mariem Mohamed; Ponnamma, Deepalekshmi; Al-Maadeed, Mariam Al Ali

    Titania nanotubes (TiO2 nanotubes or TNT) are grown hydrothermally on cellulose nanocrystals (CNC) synthesized from microcrystalline cellulose. It is observed that the CNC are lost during synthesis due to its low thermal stability. This negative result of metal growth on CNC and its influence on thermal degradation are reported here.

  13. Moisture sorption by cellulose powders of varying crystallinity.

    PubMed

    Mihranyan, Albert; Llagostera, Assumpcio Piñas; Karmhag, Richard; Strømme, Maria; Ek, Ragnar

    2004-01-28

    Moisture in microcrystalline cellulose may cause stability problems for moisture sensitive drugs. The aim of this study was to investigate the influence of crystallinity and surface area on the uptake of moisture in cellulose powders. Powders of varying crystallinity were manufactured, and the uptake of moisture was investigated at different relative humidities. The structure of the cellulose powders was characterized by X-ray diffraction, BET surface area analysis, and scanning electron microscopy. Moisture uptake was directly related to the cellulose crystallinity and pore volume: Cellulose powders with higher crystallinity showed lower moisture uptake at relative humidities below 75%, while at higher humidities the moisture uptake could be associated with filling of the large pore volume of the cellulose powder of highest crystallinity. In conclusion, the structure of cellulose should be thoroughly considered when manufacturing low moisture grades of MCC.

  14. Electro-mechanical properties of hydrogel composites with micro- and nano-cellulose fillers

    NASA Astrophysics Data System (ADS)

    N, Mohamed Shahid U.; Deshpande, Abhijit P.; Lakshmana Rao, C.

    2015-09-01

    Stimuli responsive cross-linked hydrogels are of great interest for applications in diverse fields such as sensors and biomaterials. In this study, we investigate polymer composites filled with cellulose fillers. The celluloses used in making the composites were a microcrystalline cellulose of commercial grade and cellulose nano-whiskers obtained through acid hydrolysis of microcrystalline cellulose. The filler concentration was varied and corresponding physical, mechanical and electro-mechanical characterization was carried out. The electro-mechanical properties were determined using a quasi-static method. The fillers not only enhance the mechanical properties of the composite by providing better reinforcement but also provide a quantitative electric potential in the composite. The measurements reveal that the polymer composites prepared from two different cellulose fillers possess a quantitative electric potential which can be utilized in biomedical applications. It is argued that the mechanism behind the quantitative electric potential in the composites is due to streaming potentials arising due to electrical double layer formation.

  15. Size- and dose-dependent toxicity of cellulose nanocrystals (CNC) on human fibroblasts and colon adenocarcinoma.

    PubMed

    Hanif, Zahid; Ahmed, Farrukh R; Shin, Seung Won; Kim, Young-Kee; Um, Soong Ho

    2014-07-01

    A controlled preparation of cellulose nanocrystals of different sizes and shapes has been carried out by acid hydrolysis of microcrystalline cellulose. The size- and concentration-dependent toxicity effects of the resulting cellulose nanocrystals were evaluated against two different cell lines, NIH3T3 murine embryo fibroblasts and HCT116 colon adenocarcinoma. It could serve as a therapeutic platform for cancer treatment. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Producing Solar Cells By Surface Preparation For Accelerated Nucleation Of Microcrystalline Silicon On Heterogeneous Substrates.

    DOEpatents

    Yang, Liyou; Chen, Liangfan

    1998-03-24

    Attractive multi-junction solar cells and single junction solar cells with excellent conversion efficiency can be produced with a microcrystalline tunnel junction, microcrystalline recombination junction or one or more microcrystalline doped layers by special plasma deposition processes which includes plasma etching with only hydrogen or other specified etchants to enhance microcrystalline growth followed by microcrystalline. nucleation with a doped hydrogen-diluted feedstock.

  17. Incorporation of citrus essential oils into bacterial cellulose-based edible films and assessment of their physical properties

    NASA Astrophysics Data System (ADS)

    Indrarti, L.; Indriyati

    2017-03-01

    The use of edible films in food protection and preservation has recently gained more interest since they offer several advantages over synthetic packaging materials. Biocellulose (BC) offers great opportunity as edible film due to their unique physical and mechanical properties. In this study, biocellulose films were prepared by solution casting with addition of 30% carboxymethyl cellulose (CMC) and 30% glycerol as the homogenizer and plasticizer, respectively. Furthermore, various citrus essential oils (EOs) including lemon, lime, and sweet orange were added at 50% w/w of BC dried weight. The solutions were then cast on the tray and allowed to dry in the air convection oven at 40°C overnight. The films were characterized for water solubility, tensile strength (TS), elongation at break (EB), water vapour transmission rate (WVTR), and color. Those characteristics may influence consumer acceptability of the packaged products. Results revealed that addition of lemon and sweet orange EOs into BC-based edible film decreased water solubility and TS, but improved EB, as these oils acted as plasticizers in the film. However, different trend was observed for BC-based film incorporated with lime oil, which had higher solubility and TS, but lower EB and WVTR compared with that of control film. Addition of citrus EOs into BC-based films did not have much effect on color properties as stated in L*, a*, and b* values.

  18. An XRPD and EPR spectroscopy study of microcrystalline calcite bioprecipitated by Bacillus subtilis

    NASA Astrophysics Data System (ADS)

    Perito, B.; Romanelli, M.; Buccianti, A.; Passaponti, M.; Montegrossi, G.; Di Benedetto, F.

    2018-05-01

    We report in this study the first XRPD and EPR spectroscopy characterisation of a biogenic calcite, obtained from the activity of the bacterium Bacillus subtilis. Microcrystalline calcite powders obtained from bacterial culture in a suitable precipitation liquid medium were analysed without further manipulation. Both techniques reveal unusual parameters, closely related to the biological source of the mineral, i.e., to the bioprecipitation process and in particular to the organic matrix observed inside calcite. In detail, XRPD analysis revealed that bacterial calcite has slightly higher c/a lattice parameters ratio than abiotic calcite. This correlation was already noticed in microcrystalline calcite samples grown by bio-mineralisation processes, but it had never been previously verified for bacterial biocalcites. EPR spectroscopy evidenced an anomalously large value of W 6, a parameter that can be linked to occupation by different chemical species in the next nearest neighbouring sites. This parameter allows to clearly distinguish bacterial and abiotic calcite. This latter achievement was obtained after having reduced the parameters space into an unbiased Euclidean one, through an isometric log-ratio transformation. We conclude that this approach enables the coupled use of XRPD and EPR for identifying the traces of bacterial activity in fossil carbonate deposits.

  19. Cellulose Microfibril Formation by Surface-Tethered Cellulose Synthase Enzymes.

    PubMed

    Basu, Snehasish; Omadjela, Okako; Gaddes, David; Tadigadapa, Srinivas; Zimmer, Jochen; Catchmark, Jeffrey M

    2016-02-23

    Cellulose microfibrils are pseudocrystalline arrays of cellulose chains that are synthesized by cellulose synthases. The enzymes are organized into large membrane-embedded complexes in which each enzyme likely synthesizes and secretes a β-(1→4) glucan. The relationship between the organization of the enzymes in these complexes and cellulose crystallization has not been explored. To better understand this relationship, we used atomic force microscopy to visualize cellulose microfibril formation from nickel-film-immobilized bacterial cellulose synthase enzymes (BcsA-Bs), which in standard solution only form amorphous cellulose from monomeric BcsA-B complexes. Fourier transform infrared spectroscopy and X-ray diffraction techniques show that surface-tethered BcsA-Bs synthesize highly crystalline cellulose II in the presence of UDP-Glc, the allosteric activator cyclic-di-GMP, as well as magnesium. The cellulose II cross section/diameter and the crystal size and crystallinity depend on the surface density of tethered enzymes as well as the overall concentration of substrates. Our results provide the correlation between cellulose microfibril formation and the spatial organization of cellulose synthases.

  20. A Molecular Description of Cellulose Biosynthesis

    PubMed Central

    McNamara, Joshua T.; Morgan, Jacob L.W.; Zimmer, Jochen

    2016-01-01

    Cellulose is the most abundant biopolymer on Earth, and certain organisms from bacteria to plants and animals synthesize cellulose as an extracellular polymer for various biological functions. Humans have used cellulose for millennia as a material and an energy source, and the advent of a lignocellulosic fuel industry will elevate it to the primary carbon source for the burgeoning renewable energy sector. Despite the biological and societal importance of cellulose, the molecular mechanism by which it is synthesized is now only beginning to emerge. On the basis of recent advances in structural and molecular biology on bacterial cellulose synthases, we review emerging concepts of how the enzymes polymerize glucose molecules, how the nascent polymer is transported across the plasma membrane, and how bacterial cellulose biosynthesis is regulated during biofilm formation. Additionally, we review evolutionary commonalities and differences between cellulose synthases that modulate the nature of the cellulose product formed. PMID:26034894

  1. Plant cellulose synthesis: CESA proteins crossing kingdoms.

    PubMed

    Kumar, Manoj; Turner, Simon

    2015-04-01

    Cellulose is a biopolymer of considerable economic importance. It is synthesised by the cellulose synthase complex (CSC) in species ranging from bacteria to higher plants. Enormous progress in our understanding of bacterial cellulose synthesis has come with the recent publication of both the crystal structure and biochemical characterisation of a purified complex able to synthesis cellulose in vitro. A model structure of a plant CESA protein suggests considerable similarity between the bacterial and plant cellulose synthesis. In this review article we will cover current knowledge of how plant CESA proteins synthesise cellulose. In particular the focus will be on the lessons learned from the recent work on the catalytic mechanism and the implications that new data on cellulose structure has for the assembly of CESA proteins into the large complex that synthesis plant cellulose microfibrils. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Bacterial-cellulose-derived interconnected meso-microporous carbon nanofiber networks as binder-free electrodes for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Hao, Xiaodong; Wang, Jie; Ding, Bing; Wang, Ya; Chang, Zhi; Dou, Hui; Zhang, Xiaogang

    2017-06-01

    Bacterial cellulose (BC), a typical biomass prepared from the microbial fermentation process, has been proved that it can be an ideal platform for design of three-dimensional (3D) multifunctional nanomaterials in energy storage and conversion field. Here we developed a simple and general silica-assisted strategy for fabrication of interconnected 3D meso-microporous carbon nanofiber networks by confine nanospace pyrolysis of sustainable BC, which can be used as binder-free electrodes for high-performance supercapacitors. The synthesized carbon nanofibers exhibited the features of interconnected 3D networks architecture, large surface area (624 m2 g-1), mesopores-dominated hierarchical porosity, and high graphitization degree. The as-prepared electrode (CN-BC) displayed a maximum specific capacitance of 302 F g-1 at a current density of 0.5 A g-1, high-rate capability and good cyclicity in 6 M KOH electrolyte. This work, together with cost-effective preparation strategy to make high-value utilization of cheap biomass, should have significant implications in the green and mass-producible energy storage.

  3. Specific spice modeling of microcrystalline silicon TFTs

    NASA Astrophysics Data System (ADS)

    Moustapha, O.; Bui, V. D.; Bonnassieux, Y.; Parey, J. Y.

    2008-03-01

    In this paper we present a specific spice static and dynamic model of microcrystalline silicon (μc-Si) thin film transistors (TFTs) taking into account the access resistances and the capacitors contributions. The previously existing models of amorphous silicon and polysilicon TFTs were not completely suited, so we combined them to build a new specific model of μc-Si TFTs. The reliability of the model is then checked by the comparison of experimental measurements to simulations and by simulating the characteristics of some electronic devices (OLED pixels, inverters, and so on).

  4. Bacterial cellulose-based sheet-like carbon aerogels for the in situ growth of nickel sulfide as high performance electrode materials for asymmetric supercapacitors.

    PubMed

    Zuo, Lizeng; Fan, Wei; Zhang, Youfang; Huang, Yunpeng; Gao, Wei; Liu, Tianxi

    2017-03-30

    Electroactive materials, such as nickel sulfide (NiS), with high theoretical capacities have attracted broad interest to fabricate highly efficient supercapacitors. Preventing aggregation and increasing the conductivity of NiS particles are key challenging tasks to fully achieve excellent electrochemical properties of NiS. One effective approach to solve these problems is to combine NiS with highly porous and conductive carbon materials such as carbon aerogels. In this study, a green and facile method for the in situ growth of NiS particles on bacterial cellulose (BC)-derived sheet-like carbon aerogels (CAs) has been reported. CA prepared by the dissolution-gelation-carbonization process was used as a framework to construct NiS/CA composite aerogels with NiS uniformly decorated on the pore walls of CA. It was found that the NiS/CA composite aerogel electrodes exhibit excellent capacitive performance with high specific capacitance (1606 F g -1 ), good rate capacitance retention (69% at 10 A g -1 ), and enhanced cycling stability (91.2% retention after 10 000 continuous cyclic voltammetry cycles at 100 mV s -1 ). Furthermore, asymmetric supercapacitors (ASCs) were constructed utilizing NiS/CA composite and CA as the positive and negative electrode materials, respectively. Through the synergistic effect of three-dimensional porous structures and conductive networks derived from CA and the high capacitive performance offered by NiS, the ASC device exhibited an energy density of ∼21.5 Wh kg -1 and a power density of 700 W kg -1 at the working voltage of 1.4 V in 2 M KOH aqueous solution. The ASC device also showed excellent long-term cycle stability with ∼87.1% specific capacitance retention after 10 000 cycles of cyclic voltammetry scans. Therefore, the NiS/CA composite shows great potential as a promising alternative to high-performance electrode materials for supercapacitors.

  5. Influence of laser therapy on the dynamic formation of extracellular matrix in standard second degree burns treated with bacterial cellulose membrane.

    PubMed

    Vasconcellos, Patricia Keler Freitas Machado; Nóia, Manuela Pimentel; De Castro, Isabele Cardoso Vieira; Dos Santos, Jean Nunes; Pinheiro, Antonio Luiz B; Marques, Aparecida Maria Cordeiro; Ramos, Eduardo Antonio Gonçalves; Rocha, Clarissa Gurgel

    2018-05-01

    The present study aims to assess the influence of Aluminum-Gallium-Indium-Phosphide laser (AlGaInP laser, λ = 660 nm), whether or not in association with the application of a membrane of bacterial cellulose (Nexfill™), during recovery from induced second-degree burns at the dorsum of Wistar rats. (Rattus norvegicus, Wistar). Forty-eight animals have been distributed into four groups: Control (burns remained untreated), Group I (laser-treated), Group II (treated with Nexfill), and Group III (laser + Nexfill™). In addition to a morphological analysis, immunohistochemical analysis has been performed for type I collagen, type III collagen, fibronectin, and laminin. The Fisher's Test was used to assess differences among groups (p < 0,05). A larger amount of collagen type III was observed in Control, Group II and Group III when compared with Group I (p < 0,05). Group I and Group III have shown a greater collagen deposition when compared with Group II (p < 0,05), but the amount of collagen was similar in Group I, Group III, and Control. Group III has shown larger fibronectin amounts in comparison with Group II (p < 0,05). As regards laminin, Group I has shown a predominant discontinuity pattern on the basal lamina in comparison with Control, Group II, and Group III (p < 0,05). It is concluded that in this current study the laser when used alone (Group I) hasn't influenced collagen deposition neither has it acted on fiber pattern (fibril and/or reticular). Moreover, laser application hasn't accelerated the repair of wounds caused by inflicted second-degree burns. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. The fixation effect of a silk fibroin-bacterial cellulose composite plate in segmental defects of the zygomatic arch: an experimental study.

    PubMed

    Lee, Jung Min; Kim, Ji Heui; Lee, Ok Joo; Park, Chan Hum

    2013-06-01

    Bioresorbable fixation systems have been popular for the treatment of facial fractures. However, their mechanical properties are uncertain and complications have been reported. To overcome these problems, we developed a bioresorbable fixation plate using a composite of silk fibroin and bacterial cellulose (SF-BC) with biodegradability and increased biocompatibility. To investigate the regenerative effect of the bioresorbable SF-BC fixation plate on zygomatic arch defects in rats. In vivo animal study. The SF-BC composite plate had a tensile strength similar to that of a polylactic acid plate and a tight, pore-free microstructure. Bilateral segmental bone defects (2 mm in length) were created in the zygomatic arches of adult rats. One side was fixed with the SF-BC composite plate, and the other side was left without fixation. Academic research laboratory. Fifteen adult Sprague-Dawley rats. Fixation of the zygomatic arch defect with the SF-BC composite plate. Micro-computed tomography and histological evaluation of bone samples. Gross inspection revealed no specific complication. At 1, 2, 4, and 8 postoperative weeks, the zygomatic arches were explored by micro-computed tomography and histological examination. Control sides did not heal completely and showed bony degeneration and necrosis during the 8-week follow-up. However, we observed new bone formation in sides treated with the SF-BC composite plate, and bony defects were completely healed within 8 weeks. The SF-BC composite plate is a potential candidate for a new bioresorbable fixation system. Our composite material could considerably shorten bone regeneration time. Additional study of the control of biodegradability and mechanical properties of SF-BC composite plates and a comparative study with the resorbable plates currently in use should be undertaken.

  7. Microcrystalline silicon growth for heterojunction solar cells

    NASA Technical Reports Server (NTRS)

    Iles, P. A.; Leung, D. C.; Fang, P. H.

    1983-01-01

    A total of sixteen runs of e-beam vacuum deposition of p type microcrystalline Si (m-Si) films were attempted on n type or p-n junction single crystalline Si (C-Si) substrates. The m-Si film thickness varied from .15 to .7 um and metal contacts were deposited after plasma hydrogenation. The p-m-Si on n-c-Si structure had a Voc of up to 490 m V while no Voc improvements were observed in the p-m-Si on p-n C-Si structure against p-n controls. Both CFF and Jsc were lower than control. Possible problem areas were interfaced between m-Si and C-si and the back contacts due to lack of sintering for fear of dehydrogenation.

  8. Method for depositing high-quality microcrystalline semiconductor materials

    DOEpatents

    Guha, Subhendu [Bloomfield Hills, MI; Yang, Chi C [Troy, MI; Yan, Baojie [Rochester Hills, MI

    2011-03-08

    A process for the plasma deposition of a layer of a microcrystalline semiconductor material is carried out by energizing a process gas which includes a precursor of the semiconductor material and a diluent with electromagnetic energy so as to create a plasma therefrom. The plasma deposits a layer of the microcrystalline semiconductor material onto the substrate. The concentration of the diluent in the process gas is varied as a function of the thickness of the layer of microcrystalline semiconductor material which has been deposited. Also disclosed is the use of the process for the preparation of an N-I-P type photovoltaic device.

  9. Polypeptide composition of bacterial cyclic diguanylic acid-dependent cellulose synthase and the occurrence of immunologically crossreacting proteins in higher plants

    SciTech Connect

    Mayer, R.; Ross, P.; Weinhouse, H.

    1991-06-15

    To comprehend the catalytic and regulatory mechanism of the cyclic diguanylic acid (c-di-GMP)-dependent cellulose synthase of Acetobacter xylinum and its relatedness to similar enzymes in other organisms, the structure of this enzyme was analyzed at the polypeptide level. The enzyme, purified 350-fold by enzyme-product entrapment, contains three major peptides (90, 67, and 54 kDa), which, based on direct photoaffinity and immunochemical labeling and amino acid sequence analysis, are constituents of the native cellulose synthase. Labeling of purified synthase with either ({sup 32}P)c-di-GMP or ({alpha}-{sup 32}P)UDP-glucose indicates that activator- and substrate-specific binding sites are most closely associated with the 67- andmore » 54-kDa peptides, respectively, whereas marginal photolabeling is detected in the 90-k-Da peptide. However, antibodies raised against a protein derived from the cellulose synthase structural gene (bcsB) specifically label all three peptides. The authors suggest that the structurally related 67- and 54-kDa peptides are fragments proteolytically derived from the 90-kDa peptide encoded by bcsB. The anti-cellulose synthase antibodies crossreact with a similar set of peptides derived from other cellulose-producing microorganisms and plants such as Agrobacterium tumefaciens, Rhizobium leguminosarum, mung bean, peas, barley, and cotton. The occurrence of such cellulose synthase-like structures in plant species suggests that a common enzymatic mechanism for cellulose biogenesis is employed throughout nature.« less

  10. Cellulose Synthesis in Agrobacterium tumefaciens

    SciTech Connect

    Alan R. White; Ann G. Matthysse

    2004-07-31

    We have cloned the celC gene and its homologue from E. coli, yhjM, in an expression vector and expressed the both genes in E. coli; we have determined that the YhjM protein is able to complement in vitro cellulose synthesis by extracts of A. tumefaciens celC mutants, we have purified the YhjM protein product and are currently examining its enzymatic activity; we have examined whole cell extracts of CelC and various other cellulose mutants and wild type bacteria for the presence of cellulose oligomers and cellulose; we have examined the ability of extracts of wild type and cellulose mutants includingmore » CelC to incorporate UDP-14C-glucose into cellulose and into water-soluble, ethanol-insoluble oligosaccharides; we have made mutants which synthesize greater amounts of cellulose than the wild type; and we have examined the role of cellulose in the formation of biofilms by A. tumefaciens. In addition we have examined the ability of a putative cellulose synthase gene from the tunicate Ciona savignyi to complement an A. tumefaciens celA mutant. The greatest difference between our knowledge of bacterial cellulose synthesis when we started this project and current knowledge is that in 1999 when we wrote the original grant very few bacteria were known to synthesize cellulose and genes involved in this synthesis were sequenced only from Acetobacter species, A. tumefaciens and Rhizobium leguminosarum. Currently many bacteria are known to synthesize cellulose and genes that may be involved have been sequenced from more than 10 species of bacteria. This additional information has raised the possibility of attempting to use genes from one bacterium to complement mutants in another bacterium. This will enable us to examine the question of which genes are responsible for the three dimensional structure of cellulose (since this differs among bacterial species) and also to examine the interactions between the various proteins required for cellulose synthesis. We have carried

  11. Microcrystalline silicon growth for heterojunction solar cells

    NASA Technical Reports Server (NTRS)

    Leung, D. C.; Iles, P. A.; Fang, P. H.

    1984-01-01

    Microcrystalline Si (m-Si) films with a 1.7eV energy bandgap and crystal size of several hundred A were e-beam evaporated on single crystalline Si (c-Si) to form a heterojunction with the substrate, or a window layer to a single crystalline p-n junction (heteroface structure). The goal was to enhance Voc by such uses of the larger bandgap m-Si, with the intriguing prospect of forming heterostructures with exact lattice match on each layer. The heterojunction structure was affected by interface and shunting problems and the best Voc achieved was only 482mV, well below that of single crystal Si homojunctions. The heteroface structure showed promise for some of the samples with p m-Si/p-n structure (the complementary structure did not show any improvement). Although several runs with different deposition conditions were run, the results were inconsistent. Any Voc enhancement obtained was too small to compensate for the current loss due to the extra absorption and poor carrier transport properties of the m-Si film.

  12. Laser marking on microcrystalline silicon film.

    PubMed

    Park, Min Gyu; Choi, Se-Bum; Ruh, Hyun; Hwang, Hae-Sook; Yu, Hyunung

    2012-07-01

    We present a compact dot marker using a CW laser on a microcrystalline silicon (Si) thin film. A laser annealing shows a continuous crystallization transformation from nano to a large domain (> 200 nm) of Si nanocrystals. This microscale patterning is quite useful since we can manipulate a two-dimentional (2-D) process of Si structural forms for better and efficient thin-film transistor (TFT) devices as well as for photovoltaic application with uniform electron mobility. A Raman scattering microscope is adopted to draw a 2-D mapping of crystal Si film with the intensity of optical-phonon mode at 520 cm(-1). At a 300-nm spatial resolution, the position resolved the Raman scattering spectra measurements carried out to observe distribution of various Si species (e.g., large crystalline, polycrystalline and amorphous phase). The population of polycrystalline (poly-Si) species in the thin film can be analyzed with the frequency shift (delta omega) from the optical-phonon line since poly-Si distribution varies widely with conditions, such as an irradiated-laser power. Solid-phase crystallization with CW laser irradiation improves conductivity of poly-Si with micropatterning to develop the potential of the device application.

  13. Simple citric acid-catalyzed surface esterification of cellulose nanocrystals.

    PubMed

    Ávila Ramírez, Jhon Alejandro; Fortunati, Elena; Kenny, José María; Torre, Luigi; Foresti, María Laura

    2017-02-10

    A simple straightforward route for the surface esterification of cellulose nanocrystals (CNC) is herein proposed. CNC obtained from microcrystalline cellulose were acetylated using as catalyst citric acid, a α-hydroxy acid present in citrus fruits and industrially produced by certain molds in sucrose or glucose-containing medium. No additional solvent was added to the system; instead, the acylant (acetic anhydride) was used in sufficient excess to allow CNC dispersion and proper suspension agitation. By tuning the catalyst load, CNC with two different degree of substitution (i.e. DS=0.18 and 0.34) were obtained. Acetylated cellulose nanocrystals were characterized in terms of chemical structure, crystallinity, morphology, thermal decomposition and dispersion in a non-polar solvent. Results illustrated for the first time the suitability of the protocol proposed for the simple surface acetylation of cellulose nanocrystals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Influence of the crystalline structure of cellulose on the production of ethanol from lignocellulose biomass

    NASA Astrophysics Data System (ADS)

    Smuga-Kogut, Małgorzata; Zgórska, Kazimiera; Szymanowska-Powałowska, Daria

    2016-01-01

    In recent years, much attention has been devoted to the possibility of using lignocellulosic biomass for energy. Bioethanol is a promising substitute for conventional fossil fuels and can be produced from straw and wood biomass. Therefore, the aim of this paper was to investigate the effect of 1-ethyl-3-methylimidazolium pretreatment on the structure of cellulose and the acquisition of reducing sugars and bioethanol from cellulosic materials. Material used in the study was rye straw and microcrystalline cellulose subjected to ionic liquid 1-ethyl-3-methylimidazolium pretreatment. The morphology of cellulose fibres in rye straw and microcrystalline cellulose was imaged prior to and after ionic liquid pretreatment. Solutions of ionic liquid-treated and untreated cellulosic materials were subjected to enzymatic hydrolysis in order to obtain reducing sugars, which constituted a substrate for alcoholic fermentation. An influence of the ionic liquid on the cellulose structure, accumulation of reducing sugars in the process of hydrolysis of this material, and an increase in ethanol amount after fermentation was observed. The ionic liquid did not affect cellulolytic enzymes negatively and did not inhibit yeast activity. The amount of reducing sugars and ethyl alcohol was higher in samples purified with 1-ethyl-3-methy-limidazolium acetate. A change in the supramolecular structure of cellulose induced by the ionic liquid was also observed.

  15. Micromechanics and poroelasticity of hydrated cellulose networks.

    PubMed

    Lopez-Sanchez, P; Rincon, Mauricio; Wang, D; Brulhart, S; Stokes, J R; Gidley, M J

    2014-06-09

    The micromechanics of cellulose hydrogels have been investigated using a new rheological experimental approach, combined with simulation using a poroelastic constitutive model. A series of mechanical compression steps at different strain rates were performed as a function of cellulose hydrogel thickness, combined with small amplitude oscillatory shear after each step to monitor the viscoelasticity of the sample. During compression, bacterial cellulose hydrogels behaved as anisotropic materials with near zero Poisson's ratio. The micromechanics of the hydrogels altered with each compression as water was squeezed out of the structure, and microstructural changes were strain rate-dependent, with increased densification of the cellulose network and increased cellulose fiber aggregation observed for slower compressive strain rates. A transversely isotropic poroelastic model was used to explain the observed micromechanical behavior, showing that the mechanical properties of cellulose networks in aqueous environments are mainly controlled by the rate of water movement within the structure.

  16. Bacterial production of short-chain organic acids and trehalose from levulinic acid: a potential cellulose-derived building block as a feedstock for microbial production.

    PubMed

    Habe, Hiroshi; Sato, Shun; Morita, Tomotake; Fukuoka, Tokuma; Kirimura, Kohtaro; Kitamoto, Dai

    2015-02-01

    Levulinic acid (LA) is a platform chemical derived from cellulosic biomass, and the expansion of LA utilization as a feedstock is important for production of a wide variety of chemicals. To investigate the potential of LA as a substrate for microbial conversion to chemicals, we isolated and identified LA-utilizing bacteria. Among the six isolated strains, Pseudomonas sp. LA18T and Rhodococcus hoagie LA6W degraded up to 70 g/L LA in a high-cell-density system. The maximal accumulation of acetic acid by strain LA18T and propionic acid by strain LA6W was 13.6 g/L and 9.1 g/L, respectively, after a 4-day incubation. Another isolate, Burkholderia stabilis LA20W, produced trehalose extracellularly in the presence of 40 g/L LA to approximately 2 g/L. These abilities to produce useful compounds supported the potential of microbial LA conversion for future development and cellulosic biomass utilization. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Production of Starch Based Bioplastic from Cassava Peel Reinforced with Microcrystalline Celllulose Avicel PH101 Using Sorbitol as Plasticizer

    NASA Astrophysics Data System (ADS)

    Maulida; Siagian, M.; Tarigan, P.

    2016-04-01

    The production of starch based bioplastics from cassava peel reeinforced with microcrystalline cellulose using sorbitol as plasticizer were investigated. Physical properties of bioplastics were determined by density, water uptake, tensile strength and Fourier Transform Infrared Spectroscopy. Bioplastics were prepared from cassava peel starch plasticized using sorbitol with variation of 20; 25; 30% (wt/v of sorbitol to starch) reinforced with microcrystalline celllulose (MCC) Avicel PH101 fillers with range of 0 to 6% (wt/wt of MCC to starch). The results showed improvement in tensile strength with higher MCC content up to 9, 12 mpa compared to non-reinforced bioplastics. This could be mainly attributed to the strong hydrogen bonds between MCC and starch. On the contrary, the addition of MCC decreased the elongation at break, density and water uptake. Fourier Transform Infrared Spectroscopy showed the functional groups of bioplastics, which the majority of O-H groups were found at the bioplastics with reinforcing filler MCC that represented substantial hydrogen bonds. The highest tensile strength value was obtained for bioplastic with MCC content 6% and sorbitol content 20%. With good adhesion between MCC and starch the production of bioplastics could be widely used as a substitute for conventional plastics with more benefits to the environment.

  18. Chemical Pretreatment-Independent Saccharifications of Xylan and Cellulose of Rice Straw by Bacterial Weak Lignin-Binding Xylanolytic and Cellulolytic Enzymes

    PubMed Central

    Teeravivattanakit, Thitiporn; Baramee, Sirilak; Phitsuwan, Paripok; Sornyotha, Somphit; Waeonukul, Rattiya; Pason, Patthra; Tachaapaikoon, Chakrit; Poomputsa, Kanokwan; Kosugi, Akihiko; Sakka, Kazuo

    2017-01-01

    ABSTRACT Complete utilization of carbohydrate fractions is one of the prerequisites for obtaining economically favorable lignocellulosic biomass conversion. This study shows that xylan in untreated rice straw was saccharified to xylose in one step without chemical pretreatment, yielding 58.2% of the theoretically maximum value by Paenibacillus curdlanolyticus B-6 PcAxy43A, a weak lignin-binding trifunctional xylanolytic enzyme, endoxylanase/β-xylosidase/arabinoxylan arabinofuranohydrolase. Moreover, xylose yield from untreated rice straw was enhanced to 78.9% by adding endoxylanases PcXyn10C and PcXyn11A from the same bacterium, resulting in improvement of cellulose accessibility to cellulolytic enzyme. After autoclaving the xylanolytic enzyme-treated rice straw, it was subjected to subsequent saccharification by a combination of the Clostridium thermocellum endoglucanase CtCel9R and Thermoanaerobacter brockii β-glucosidase TbCglT, yielding 88.5% of the maximum glucose yield, which was higher than the glucose yield obtained from ammonia-treated rice straw saccharification (59.6%). Moreover, this work presents a new environment-friendly xylanolytic enzyme pretreatment for beneficial hydrolysis of xylan in various agricultural residues, such as rice straw and corn hull. It not only could improve cellulose saccharification but also produced xylose, leading to an improvement of the overall fermentable sugar yields without chemical pretreatment. IMPORTANCE Ongoing research is focused on improving “green” pretreatment technologies in order to reduce energy demands and environmental impact and to develop an economically feasible biorefinery. The present study showed that PcAxy43A, a weak lignin-binding trifunctional xylanolytic enzyme, endoxylanase/β-xylosidase/arabinoxylan arabinofuranohydrolase from P. curdlanolyticus B-6, was capable of conversion of xylan in lignocellulosic biomass such as untreated rice straw to xylose in one step without chemical pretreatment

  19. Chemical Pretreatment-Independent Saccharifications of Xylan and Cellulose of Rice Straw by Bacterial Weak Lignin-Binding Xylanolytic and Cellulolytic Enzymes.

    PubMed

    Teeravivattanakit, Thitiporn; Baramee, Sirilak; Phitsuwan, Paripok; Sornyotha, Somphit; Waeonukul, Rattiya; Pason, Patthra; Tachaapaikoon, Chakrit; Poomputsa, Kanokwan; Kosugi, Akihiko; Sakka, Kazuo; Ratanakhanokchai, Khanok

    2017-11-15

    Complete utilization of carbohydrate fractions is one of the prerequisites for obtaining economically favorable lignocellulosic biomass conversion. This study shows that xylan in untreated rice straw was saccharified to xylose in one step without chemical pretreatment, yielding 58.2% of the theoretically maximum value by Paenibacillus curdlanolyticus B-6 PcAxy43A, a weak lignin-binding trifunctional xylanolytic enzyme, endoxylanase/β-xylosidase/arabinoxylan arabinofuranohydrolase. Moreover, xylose yield from untreated rice straw was enhanced to 78.9% by adding endoxylanases PcXyn10C and PcXyn11A from the same bacterium, resulting in improvement of cellulose accessibility to cellulolytic enzyme. After autoclaving the xylanolytic enzyme-treated rice straw, it was subjected to subsequent saccharification by a combination of the Clostridium thermocellum endoglucanase CtCel9R and Thermoanaerobacter brockii β-glucosidase TbCglT, yielding 88.5% of the maximum glucose yield, which was higher than the glucose yield obtained from ammonia-treated rice straw saccharification (59.6%). Moreover, this work presents a new environment-friendly xylanolytic enzyme pretreatment for beneficial hydrolysis of xylan in various agricultural residues, such as rice straw and corn hull. It not only could improve cellulose saccharification but also produced xylose, leading to an improvement of the overall fermentable sugar yields without chemical pretreatment. IMPORTANCE Ongoing research is focused on improving "green" pretreatment technologies in order to reduce energy demands and environmental impact and to develop an economically feasible biorefinery. The present study showed that PcAxy43A, a weak lignin-binding trifunctional xylanolytic enzyme, endoxylanase/β-xylosidase/arabinoxylan arabinofuranohydrolase from P. curdlanolyticus B-6, was capable of conversion of xylan in lignocellulosic biomass such as untreated rice straw to xylose in one step without chemical pretreatment. It

  20. Green synthesis of a typical chiral stationary phase of cellulose-tris(3, 5-dimethylphenylcarbamate)

    PubMed Central

    2013-01-01

    Background At present, the study on the homogeneous-phase derivatization of cellulose in ionic liquid is mainly focused on its acetylation. To the best of our knowledge, there has been no such report on the preparation of cellulose-tris(3,5-dimethylphenylcarbamate) (CDMPC) with ionic liquid 1-allyl-3-methyl-imidazolium chloride (AmimCl) so far. Results With ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) as a reaction solvent, cellulose-tris(3,5-dimethylphenylcarbamate) (CDMPC) was synthesized by the reaction of 3,5-dimethylphenyl isocyanate and soluble microcrystalline cellulose in a homogeneous phase. The synthesized CDMPC was then coated onto the surfaces of aminopropyl silica gel to prepare a chiral stationary phase (CSP). The prepared CSP was successfully used in chiral separation of seven racemic pesticides by high performance liquid chromatography (HPLC). Good chiral separation was obtained using n-hexane and different modifiers as the mobile phases under the optimal percentage and column temperature, with the resolution of metalaxyl, diniconazole, flutriafol, paclobutrazol, hexaconazole, myclobutanil and hexythiazox of 1.73, 1.56, 1.26, 1.00, 1.18, 1.14 and 1.51, respectively. The experimental results suggested it was a good choice using a green solvent of AmimCl for cellulose functionalization. Conclusion CDMPC was successfully synthesized as the chiral selector by reacting 3, 5-dimethylphenyl isocyanate with dissolved microcrystalline cellulose in a green ionic liquid of AmimCl. PMID:23890199

  1. Preparation and characterization of directly compactible layer-by-layer nanocoated cellulose.

    PubMed

    Strydom, Schalk J; Otto, Daniel P; Liebenberg, Wilna; Lvov, Yuri M; de Villiers, Melgardt M

    2011-02-14

    Microcrystalline cellulose is a commonly used direct compression tablet diluent and binder. It is derived from purified α-cellulose in an environmentally unfriendly process that involves mineral acid catalysed hydrolysis. In this study Kraft softwood fibers was nanocoated using a layer-by-layer self-assembling process. Powder flow and compactibility results showed that the application of nano-thin polymer layers on the fibers turned non-flowing, non-compacting cellulose into powders that can be used in the direct compression of tablets. The powder flow properties and tableting indices of compacts compressed from these nanocoated microfibers were similar or better than that of directly compactible microcrystalline cellulose powders. Cellulose microfibers coated with four PSS/PVP bilayers had the best compaction properties while still producing tablets that were able to absorb water and disintegrate and did not retard the dissolution of a model drug acetaminophen. The advantages of nanocoating rather than traditional pharmaceutical coating are that it add less than 1% to the weight of the fibers and allows control of the molecular properties of the surface and the thickness of the coat to within a few nanometers. This process is potentially friendlier to the environment because of the type and quantity of materials used. Also, it does not involve acid-catalyzed hydrolysis and neutralization of depolymerized cellulose. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Cellulose amorphization by swelling in ionic liquid/water mixtures: a combined macroscopic and second-harmonic microscopy study.

    PubMed

    Glas, Daan; Paesen, Rik; Depuydt, Daphne; Binnemans, Koen; Ameloot, Marcel; De Vos, Dirk E; Ameloot, Rob

    2015-01-01

    Amorphization of cellulose by swelling in ionic liquid (IL)/water mixtures at room temperature is a suitable alternative to the dissolution-precipitation pretreatment known to facilitate enzymatic digestion. When soaking microcrystalline cellulose in the IL 1-ethyl-3-methylimidazolium acetate containing 20 wt % water, the crystallinity of the cellulose sample is strongly reduced. As less than 4 % of the cellulose dissolves in this mixture, this swelling method makes a precipitation step and subsequent energy-intensive IL purification redundant. Second-harmonic generation (SHG) microscopy is used as a structure-sensitive technique for in situ monitoring of the changes in cellulose crystallinity. Combined optical and SHG observations confirm that in the pure IL complete dissolution takes place, while swelling without dissolution in the optimal IL/water mixture yields a solid cellulose with a significantly reduced crystallinity in a single step. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Phosphoethanolamine cellulose: A naturally produced chemically modified cellulose.

    PubMed

    Thongsomboon, Wiriya; Serra, Diego O; Possling, Alexandra; Hadjineophytou, Chris; Hengge, Regine; Cegelski, Lynette

    2018-01-19

    Cellulose is a major contributor to the chemical and mechanical properties of plants and assumes structural roles in bacterial communities termed biofilms. We find that Escherichia coli produces chemically modified cellulose that is required for extracellular matrix assembly and biofilm architecture. Solid-state nuclear magnetic resonance spectroscopy of the intact and insoluble material elucidates the zwitterionic phosphoethanolamine modification that had evaded detection by conventional methods. Installation of the phosphoethanolamine group requires BcsG, a proposed phosphoethanolamine transferase, with biofilm-promoting cyclic diguanylate monophosphate input through a BcsE-BcsF-BcsG transmembrane signaling pathway. The bcsEFG operon is present in many bacteria, including Salmonella species, that also produce the modified cellulose. The discovery of phosphoethanolamine cellulose and the genetic and molecular basis for its production offers opportunities to modulate its production in bacteria and inspires efforts to biosynthetically engineer alternatively modified cellulosic materials. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  4. Surface structure, crystallographic and ice-nucleating properties of cellulose

    NASA Astrophysics Data System (ADS)

    Hiranuma, Naruki; Möhler, Ottmar; Kiselev, Alexei; Saathoff, Harald; Weidler, Peter; Shutthanandan, Shuttha; Kulkarni, Gourihar; Jantsch, Evelyn; Koop, Thomas

    2015-04-01

    Increasing evidence of the high diversity and efficient freezing ability of biological ice-nucleating particles is driving a reevaluation of their impact upon climate. Despite their potential importance, little is known about their atmospheric abundance and ice nucleation efficiency, especially non-proteinaceous ones, in comparison to non-biological materials (e.g., mineral dust). Recently, microcrystalline cellulose (MCC; non-proteinaceous plant structural polymer) has been identified as a potential biological ice-nucleating particle. However, it is still uncertain if the ice-nucleating activity is specific to the MCC structure or generally relevant to all cellulose materials, such that the results of MCC can be representatively scaled up to the total cellulose content in the atmosphere to address its role in clouds and the climate system. Here we use the helium ion microscopy (HIM) imaging and the X-ray diffraction (XRD) technique to characterize the nanoscale surface structure and crystalline properties of the two different types of cellulose (MCC and fibrous cellulose extracted from natural wood pulp) as model proxies for atmospheric cellulose particles and to assess their potential accessibility for water molecules. To complement these structural characterizations, we also present the results of immersion freezing experiments using the cold stage-based droplet freezing BINARY (Bielefeld Ice Nucleation ARaY) technique. The HIM results suggest that both cellulose types have a complex porous morphology with capillary spaces between the nanoscale fibrils over the microfiber surface. These surface structures may make cellulose accessible to water. The XRD results suggest that the structural properties of both cellulose materials are in agreement (i.e., P21 space group; a=7.96 Å, b=8.35 Å, c=10.28 Å) and comparable to the crystallographic properties of general monoclinic cellulose (i.e., Cellulose Iβ). The results obtained from the BINARY measurements suggest

  5. [Study of mixed dry binders in directly compressible lactoses and microcrystalline cellulose].

    PubMed

    Muzíková, J; Vinklarová, S

    2004-09-01

    The paper evaluated the compressibility of dry binders prepared in the ratios of 3:1, 1:1, and 1:3 from Pharmatosa DCL 15 and DCL 21 and Avicel PH 200, and the sensitivity of the mixtures to an addition of the lubricant magnesium stearate from the standpoint of the effect on the strength of tablets. Mixtures of lactoses with Avicel PH -200 in a ratio of 3:1 proved to be most advantageous. The strengths of tablets made of these mixtures oscillated in the optimal range and they showed the least sensitivity to the added lubricant. An increase in stearate concentration did not result in a marked decrease in the strength of compacts. Pharmatosa DCL 21 in a mixture with Avicel PH 200 yielded stronger compacts at lower compression force than Pharmatosa DCL 15.

  6. A STUDY OF COMPRESSION PROCESS AND PROPERTIES OF TABLETS WITH MICROCRYSTALLINE CELLULOSE AND COLLOIDAL SILICON DIOXIDE.

    PubMed

    Muzikova, Jitka; Louzenska, Marketa; Pekarek, Tomas

    2016-09-01

    This paper compares the compressibility and properties of tablets from Prosolv SMCC 90 and a mixture of Avicel PH-102 and colloidal silicon dioxide with a different specific surface. The effect of an addition of the lubricant magnesium stearate on these parameters under varying conditions of mixing and the homogeneity of the lubricant in the mixtures are also examined. Compressibility is evaluated by means of the energy balance of the compression process; the examined properties of tablets are tensile strength and disintegration time. The total energy of compression was increased with compression force, the highest being in Prosolv SMCC 90. Its values did not differ for differing conditions of mixing with the lubricant. Plasticity was slightly decreased with compression force and in the mixture with magnesium stearate it was not influenced by the conditions of mixing. Tablets made from Prosolv SMCC 90 and Avicel PH-102 were stronger than those from the mixtures from Avicel PH-102 and both types of Aerosil. The addition of magnesium stearate markedly decreased the strength of tablets from Avicel PH-102. An increase in the period and frequency of mixing with the lubricant resulted in a further decrease in strength. Disintegration time was longer in tablets from Avicel PH-102 and Prosolv SMCC 90, and it was further prolonged by an addition of magnesium stearate.

  7. Saccharification of Cellulose by Recombinant Rhodococcus opacus PD630 Strains

    PubMed Central

    Hetzler, Stephan; Bröker, Daniel

    2013-01-01

    The noncellulolytic actinomycete Rhodococcus opacus strain PD630 is the model oleaginous prokaryote with regard to the accumulation and biosynthesis of lipids, which serve as carbon and energy storage compounds and can account for as much as 87% of the dry mass of the cell in this strain. In order to establish cellulose degradation in R. opacus PD630, we engineered strains that episomally expressed six different cellulase genes from Cellulomonas fimi ATCC 484 (cenABC, cex, cbhA) and Thermobifida fusca DSM43792 (cel6A), thereby enabling R. opacus PD630 to degrade cellulosic substrates to cellobiose. Of all the enzymes tested, five exhibited a cellulase activity toward carboxymethyl cellulose (CMC) and/or microcrystalline cellulose (MCC) as high as 0.313 ± 0.01 U · ml−1, but recombinant strains also hydrolyzed cotton, birch cellulose, copy paper, and wheat straw. Cocultivations of recombinant strains expressing different cellulase genes with MCC as the substrate were carried out to identify an appropriate set of cellulases for efficient hydrolysis of cellulose by R. opacus. Based on these experiments, the multicellulase gene expression plasmid pCellulose was constructed, which enabled R. opacus PD630 to hydrolyze as much as 9.3% ± 0.6% (wt/vol) of the cellulose provided. For the direct production of lipids from birch cellulose, a two-step cocultivation experiment was carried out. In the first step, 20% (wt/vol) of the substrate was hydrolyzed by recombinant strains expressing the whole set of cellulase genes. The second step was performed by a recombinant cellobiose-utilizing strain of R. opacus PD630, which accumulated 15.1% (wt/wt) fatty acids from the cellobiose formed in the first step. PMID:23793636

  8. Production by Tobacco Transplastomic Plants of Recombinant Fungal and Bacterial Cell-Wall Degrading Enzymes to Be Used for Cellulosic Biomass Saccharification.

    PubMed

    Longoni, Paolo; Leelavathi, Sadhu; Doria, Enrico; Reddy, Vanga Siva; Cella, Rino

    2015-01-01

    Biofuels from renewable plant biomass are gaining momentum due to climate change related to atmospheric CO2 increase. However, the production cost of enzymes required for cellulosic biomass saccharification is a major limiting step in this process. Low-cost production of large amounts of recombinant enzymes by transgenic plants was proposed as an alternative to the conventional microbial based fermentation. A number of studies have shown that chloroplast-based gene expression offers several advantages over nuclear transformation due to efficient transcription and translation systems and high copy number of the transgene. In this study, we expressed in tobacco chloroplasts microbial genes encoding five cellulases and a polygalacturonase. Leaf extracts containing the recombinant enzymes showed the ability to degrade various cell-wall components under different conditions, singly and in combinations. In addition, our group also tested a previously described thermostable xylanase in combination with a cellulase and a polygalacturonase to study the cumulative effect on the depolymerization of a complex plant substrate. Our results demonstrate the feasibility of using transplastomic tobacco leaf extracts to convert cell-wall polysaccharides into reducing sugars, fulfilling a major prerequisite of large scale availability of a variety of cell-wall degrading enzymes for biofuel industry.

  9. Functional reconstitution of cellulose synthase in Escherichia coli.

    PubMed

    Imai, Tomoya; Sun, Shi-Jing; Horikawa, Yoshiki; Wada, Masahisa; Sugiyama, Junji

    2014-11-10

    Cellulose is a high molecular weight polysaccharide of β1 → 4-d-glucan widely distributed in nature-from plant cell walls to extracellular polysaccharide in bacteria. Cellulose synthase, together with other auxiliary subunit(s) in the cell membrane, facilitates the fibrillar assembly of cellulose polymer chains into a microfibril. The gene encoding the catalytic subunit of cellulose synthase is cesA and has been identified in many cellulose-producing organisms. Very few studies, however, have shown that recombinant CesA protein synthesizes cellulose polymer, but the mechanism by which CesA protein synthesizes cellulose microfibrils is not known. Here we show that cellulose-synthesizing activity is successfully reconstituted in Escherichia coli by expressing the bacterial cellulose synthase complex of Gluconacetobacter xylinus: CesA and CesB (formerly BcsA and BcsB, respectively). Cellulose synthase activity was, however, only detected when CesA and CesB were coexpressed with diguanyl cyclase (DGC), which synthesizes cyclic-di-GMP (c-di-GMP), which in turn activates cellulose-synthesizing activity in bacteria. Direct observation by electron microscopy revealed extremely thin fibrillar structures outside E. coli cells, which were removed by cellulase treatment. This fiber structure is not likely to be the native crystallographic form of cellulose I, given that it was converted to cellulose II by a chemical treatment milder than ever described. We thus putatively conclude that this fine fiber is an unprecedented structure of cellulose. Despite the inability of the recombinant enzyme to synthesize the native structure of cellulose, the system described in this study, named "CESEC (CEllulose-Synthesizing E. Coli)", represents a useful tool for functional analyses of cellulose synthase and for seeding new nanomaterials.

  10. Cellulose Perversions

    PubMed Central

    Canejo, João P.; Godinho, Maria H.

    2013-01-01

    Cellulose micro/nano-fibers can be produced by electrospinning from liquid crystalline solutions. Scanning electron microscopy (SEM), as well as atomic force microscopy (AFM) and polarizing optical microscopy (POM) measurements showed that cellulose-based electrospun fibers can curl and twist, due to the presence of an off-core line defect disclination, which was present when the fibers were prepared. This permits the mimicking of the shapes found in many systems in the living world, e.g., the tendrils of climbing plants, three to four orders of magnitude larger. In this work, we address the mechanism that is behind the spirals’ and helices’ appearance by recording the trajectories of the fibers toward diverse electrospinning targets. The intrinsic curvature of the system occurs via asymmetric contraction of an internal disclination line, which generates different shrinkages of the material along the fiber. The completely different instabilities observed for isotropic and anisotropic electrospun solutions at the exit of the needle seem to corroborate the hypothesis that the intrinsic curvature of the material is acquired during liquid crystalline sample processing inside the needle. The existence of perversions, which joins left and right helices, is also investigated by using suspended, as well as flat, targets. Possible routes of application inspired from the living world are addressed. PMID:28809215

  11. A technique for production of nanocrystalline cellulose with a narrow size distribution

    SciTech Connect

    Bai, Wen; Holbery, James D.; Li, Kaichang

    2009-02-01

    Nanocrystalline cellulose (NCC) was prepared by sulfuric acid hydrolysis of microcrystalline cellulose. A differential centrifugation technique was studied to obtain NCC whiskers with a narrow size distribution. It was shown that the volume of NCC in different fractions had an inverse relationship with relative centrifugal force (RCF). The length of NCC whiskers was also fractionized by differential RCF. The aspect ratio of NCC in different fractions had a relatively narrow range. This technique provides an easy way of producing NCC whiskers with a narrow size distribution.

  12. XRD and solid state 13C-NMR evaluation of the crystallinity enhancement of 13C-labeled bacterial cellulose biosynthesized by Komagataeibacter xylinus under different stimuli: A comparative strategy of analyses.

    PubMed

    Meza-Contreras, Juan C; Manriquez-Gonzalez, Ricardo; Gutiérrez-Ortega, José A; Gonzalez-Garcia, Yolanda

    2018-05-22

    The production and crystallinity of 13 C bacterial cellulose (BC) was examined in static culture of Komagataeibacter xylinus with different chemical and physical stimuli: the addition of NaCl or cloramphenicol as well as exposure to a magnetic field or to UV light. Crystalline BC biosynthesized under each stimulus was studied by XRD and solid state 13 C NMR analyses. All treatments produced BC with enhanced crystallinity over 90% (XRD) and 80% (NMR) compared to the control (83 and 76%, respectively) or to Avicel (77 and 62%, respectively). The XRD data indicated that the crystallite size was 80-85 Å. Furthermore, changes on the allomorphs (I α and I β ) ratio tendency of BC samples addressed to the stimuli were estimated using the C4 signal from 13 C NMR data. These results showed a decrease of the allomorph I α (3%) when BC was biosynthesized with UV light and chloramphenicol compared to control (58.79%). In contrast, the BC obtained with NaCl increased up to 60.31% of the I α allomorph ratio. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Effect of cooking temperature on the crystallinity of acid hydrolysed-oil palm cellulose

    NASA Astrophysics Data System (ADS)

    Kuthi, Fatin Afifah Binti Ahmad; Badri, Khairiah Haji

    2014-09-01

    In this research, we studied the effect of acid hydrolysis temperature on the crystallinity of cellulose produced from empty fruit bunch (EFB). The hydrolysis temperature was studied from 120 to 140 °C at a fixed time and sulfuric acid, H2SO4 concentration which were 1 h and 1% (v/v) respectively. X-ray diffractometry (XRD) was carried out to measure the crystallinity of cellulose produced at varying hydrolysis temperatures. During hydrolysis, the amorphous region of α-cellulose was removed and the crystalline region was obtained. Percentage of crystallinity (CrI) for acid hydrolysed cellulose at 120, 130 and 140 °C were 54.21, 50.59 and 50.55 % respectively. Morphological studies using scanning electron microscope (SEM) showed that acid hydrolysis defibrilised to microfibrils in α-cellulose. The extraction process to produce α-cellulose has also been successfully carried out as the impurities at the outer surface, lignin and hemicellulose were removed. These findings were supported by the disappearance of peaks at 1732, 1512 and 1243 cm-1 on Fourier Transform infrared (FTIR) spectrum of α-cellulose. Similar peaks were identified in both the commercial microcrystalline cellulose (C-MCC) and acid hydrolysed cellulose (H-EFB), indicating the effectiveness of heat-catalysed acid hydrolysis.

  14. Bionanocomposite films based on plasticized PLA-PHB/cellulose nanocrystal blends.

    PubMed

    Arrieta, M P; Fortunati, E; Dominici, F; López, J; Kenny, J M

    2015-05-05

    Optically transparent plasticized poly(lactic acid) (PLA) based bionanocomposite films intended for food packaging were prepared by melt blending. Materials were plasticized with 15wt% of acetyl(tributyl citrate) (ATBC) to improve the material processability and to obtain flexibile films. Poly(hydroxybutyrate) (PHB) was used to increase PLA crystallinity. The thermal stability of the PLA-PHB blends was improved by the addition of 5 wt% of cellulose nanocrystals (CNC) or modified cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose. The combination of ATBC and cellulose nanocrystals, mainly the better dispersed CNCs, improved the interaction between PLA and PHB. Thus, an improvement on the oxygen barrier and stretchability was achieved in PLA-PHB-CNCs-ATBC which also displayed somewhat UV light blocking effect. All bionanocomposite films presented appropriate disintegration in compost suggesting their possible applications as biodegradable packaging materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Three dimensional amorphous silicon/microcrystalline silicon solar cells

    DOEpatents

    Kaschmitter, James L.

    1996-01-01

    Three dimensional deep contact amorphous silicon/microcrystalline silicon (a-Si/.mu.c-Si) solar cells which use deep (high aspect ratio) p and n contacts to create high electric fields within the carrier collection volume material of the cell. The deep contacts are fabricated using repetitive pulsed laser doping so as to create the high aspect p and n contacts. By the provision of the deep contacts which penetrate the electric field deep into the material where the high strength of the field can collect many of the carriers, thereby resulting in a high efficiency solar cell.

  16. Three dimensional amorphous silicon/microcrystalline silicon solar cells

    DOEpatents

    Kaschmitter, J.L.

    1996-07-23

    Three dimensional deep contact amorphous silicon/microcrystalline silicon (a-Si/{micro}c-Si) solar cells are disclosed which use deep (high aspect ratio) p and n contacts to create high electric fields within the carrier collection volume material of the cell. The deep contacts are fabricated using repetitive pulsed laser doping so as to create the high aspect p and n contacts. By the provision of the deep contacts which penetrate the electric field deep into the material where the high strength of the field can collect many of the carriers, thereby resulting in a high efficiency solar cell. 4 figs.

  17. Pretreatment of Cellulose By Electron Beam Irradiation Method

    NASA Astrophysics Data System (ADS)

    Jusri, N. A. A.; Azizan, A.; Ibrahim, N.; Salleh, R. Mohd; Rahman, M. F. Abd

    2018-05-01

    Pretreatment process of lignocellulosic biomass (LCB) to produce biofuel has been conducted by using various methods including physical, chemical, physicochemical as well as biological. The conversion of bioethanol process typically involves several steps which consist of pretreatment, hydrolysis, fermentation and separation. In this project, microcrystalline cellulose (MCC) was used in replacement of LCB since cellulose has the highest content of LCB for the purpose of investigating the effectiveness of new pretreatment method using radiation technology. Irradiation with different doses (100 kGy to 1000 kGy) was conducted by using electron beam accelerator equipment at Agensi Nuklear Malaysia. Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) analyses were studied to further understand the effect of the suggested pretreatment step to the content of MCC. Through this method namely IRR-LCB, an ideal and optimal condition for pretreatment prior to the production of biofuel by using LCB may be introduced.

  18. A cellulosic responsive "living" membrane.

    PubMed

    Qin, Guokui; Panilaitis, Bruce J; Kaplan, Zhongyuan Sun David L

    2014-01-16

    Bacterial cellulose has been demonstrated to be a remarkably versatile biomaterial and widely used in biomedical applications due to its unique physical properties. Here we reported for the first time a "living membrane" system based on recombinant Escherichia coli bacterial strains entrapped in cellulosic membranes produced by Gluconacetobacter xylinus. Biologically driven detection and identification of a range of target molecules presents unique challenges, and requires that detection methods are developed to be rapid, specific and sensitive. The compatibility of G. xylinus and recombinant E. coli strains was first investigated for co-cultivation, and the relationship between the number of entrapped E. coli and the level of inducible signal achieved was further explored by fluorescent signal observation in confocal microscopy. Finally to amplify the response to inducers for maximum fluorescent signal, a positive-feedback genetic amplifier was designed within recombinant E. coli strain entrapped in the living cellulosic membrane system, allowing for the detection mechanism to be extremely sensitive and resulting in a significant fluorescent signal from a single receptor binding event. The living membrane system proposed here will create devices of greater complexity in function for applications in biological and chemical detection. Copyright © 2013. Published by Elsevier Ltd.

  19. Hydrolysis of cellulose catalyzed by quaternary ammonium perrhenates in 1-allyl-3-methylimidazolium chloride.

    PubMed

    Wang, Jingyun; Zhou, Mingdong; Yuan, Yuguo; Zhang, Quan; Fang, Xiangchen; Zang, Shuliang

    2015-12-01

    Quaternary ammonium perrhenates were applied as catalyst to promote the hydrolysis of cellulose in 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The quaternary ammonium perrhenates displayed good catalytic performance for cellulose hydrolysis. Water was also proven to be effective to promote cellulose hydrolysis. Accordingly, 97% of total reduced sugar (TRS) and 42% of glucose yields could be obtained under the condition of using 5mol% of tetramethyl ammonium perrhenate as catalyst, 70μL of water, ca. 0.6mmol of microcrystalline cellulose (MCC) and 2.0g of [Amim]Cl as solvent under microwave irradiation for 30min at 150°C (optimal conditions). The influence of quaternary ammonium cation on the efficiency of cellulose hydrolysis was examined based on different cation structures of perrhenates. The mechanism on perrhenate catalyzed cellulose hydrolysis is also discussed, whereas hydrogen bonding between ReO4 anion and hydroxyl groups of cellulose is assumed to be the key step for depolymerization of cellulose. Copyright © 2015. Published by Elsevier Ltd.

  20. Preliminary study on biosynthesis and characterization of bacteria cellulose films from coconut water

    NASA Astrophysics Data System (ADS)

    Indrianingsih, A. W.; Rosyida, V. T.; Jatmiko, T. H.; Prasetyo, D. J.; Poeloengasih, C. D.; Apriyana, W.; Nisa, K.; Nurhayati, S.; Hernawan; Darsih, C.; Pratiwi, D.; Suwanto, A.; Ratih, D.

    2017-12-01

    Bacterial cellulose produced by Acetobacter xylinum is a unique type of bacterial cellulose. It contains more than 90% of water. A preliminary study had shown that bacterial cellulose films has remarkable mechanical properties. The aim of this study was to investigate the optimum condition such as percentage of carbon source, time of cultivation, and pH to produce bacterial cellulose films from local coconut water, and its characterization on morphology, swelling ability and tensile strength of dried bacterial cellulose. A. xylinum was grown on coconut water culture medium with addition of 3%, 5%, and 7% of sugar, while the cultivation time was vary from 3 days, 5 days and 7 days. pH condition was conducted in pH 3, pH 5 and pH 7. Bacterial cellulose samples were dried using oven with temperature of 100°C until the moisture content reached 4-5%. This study showed that several parameters for optimum condition to produce bacterial cellulose films from local waste of coconut water had been obtained (5% of carbon source; pH 5; and 7 day of incubation period). The electron microscopy also showed that dried bacterial cellulose films had pores covered by fibrils on the surface. Therefore, the present work proposes the optimum formula and condition that can be used based on properties of end product needed.

  1. Cellulose effects on morphology and elasticity of Vibrio fischeri biofilms.

    PubMed

    Ziemba, Christopher; Shabtai, Yael; Piatkovsky, Maria; Herzberg, Moshe

    2016-01-01

    Cellulose effects on Vibrio fischeri biofilm morphology were tested for the wild-type and two of its isogenic mutants that either exhibit increased cellulose production or do not produce cellulose at all. Confocal laser scanning microscopy imaging of each biofilm revealed that total sessile volume increases with cellulose expression, but the size of colonies formed with cellulose was smaller, creating a more diffuse biofilm. These morphological differences were not attributed to variations in bacterial deposition, extracellular polymeric substances affinity to the surface or bacterial growth. A positive correlation was found between cellulose expression, Young's (elastic) modulus of the biofilm analyzed with atomic force microscope and shear modulus of the related extracellular polymeric substances layers analyzed with quartz crystal microbalance with dissipation monitoring. Cellulose production also correlated positively with concentrations of extracellular DNA. A significant negative correlation was observed between cellulose expression and rates of diffusion through the extracellular polymeric substances. The difference observed in biofilm morphology is suggested as a combined result of cellulose and likely extracellular DNA (i) increasing biofilm Young's modulus, making shear removal more difficult, and (ii) decreased diffusion rate of nutrients and wastes into and out of the biofilm, which effectively limits colony size.

  2. Crystallographic snapshot of cellulose synthesis and membrane translocation.

    PubMed

    Morgan, Jacob L W; Strumillo, Joanna; Zimmer, Jochen

    2013-01-10

    Cellulose, the most abundant biological macromolecule, is an extracellular, linear polymer of glucose molecules. It represents an essential component of plant cell walls but is also found in algae and bacteria. In bacteria, cellulose production frequently correlates with the formation of biofilms, a sessile, multicellular growth form. Cellulose synthesis and transport across the inner bacterial membrane is mediated by a complex of the membrane-integrated catalytic BcsA subunit and the membrane-anchored, periplasmic BcsB protein. Here we present the crystal structure of a complex of BcsA and BcsB from Rhodobacter sphaeroides containing a translocating polysaccharide. The structure of the BcsA-BcsB translocation intermediate reveals the architecture of the cellulose synthase, demonstrates how BcsA forms a cellulose-conducting channel, and suggests a model for the coupling of cellulose synthesis and translocation in which the nascent polysaccharide is extended by one glucose molecule at a time.

  3. Cellulose Crystal Dissolution in Imidazolium-Based Ionic Liquids: A Theoretical Study.

    PubMed

    Uto, Takuya; Yamamoto, Kazuya; Kadokawa, Jun-Ichi

    2018-01-11

    The highly crystalline nature of cellulose results in poor processability and solubility, necessitating the search for solvents that can efficiently dissolve this material. Thus, ionic liquids (ILs) have recently been shown to be well suited for this purpose, although the corresponding dissolution mechanism has not been studied in detail. Herein, we adopt a molecular dynamics (MD) approach to study the dissolution of model cellulose crystal structures in imidazolium-based ILs and gain deep mechanistic insights, demonstrating that dissolution involves IL penetration-induced cleavage of hydrogen bonds between cellulose molecular chains. Moreover, we reveal that in ILs with high cellulose dissolving power (powerful solvents, such as 1-allyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium chloride), the above molecular chains are peeled from the crystal phase and subsequently dispersed in the solvent, whereas no significant structural changes are observed in poor-dissolving-power solvents. Finally, we utilize MD trajectory analysis to show that the solubility of microcrystalline cellulose is well correlated with the number of intermolecular hydrogen bonds in cellulose crystals. The obtained results allow us to conclude that both anions and cations of high-dissolving-power ILs contribute to the stepwise breakage of hydrogen bonds between cellulose chains, whereas this breakage does not occur to a sufficient extent in poorly solubilizing ILs.

  4. Acoustic Properties of Cellulose

    NASA Astrophysics Data System (ADS)

    Trematerra, Amelia; Lombardi, Ilaria

    2017-08-01

    Cellulose is the oldest material for thermal insulation in construction field. Thomas Jefferson was the first architect that used the cellulose in his project of the Monticello house (1800). But only after 1945 that the cellulose from newsprint was used across America and northern Europe. In the 70s with the energy crisis it Austria, Czech Republic, Switzerland and Germany began the production of cellulose derived from paper newspapers. It used for both winter and summer thermal insulation, while respecting the environment. In this paper are reported acoustic measurements carried out with the tube of Kundt, with the cellulose melted and with glue with different thicknesses.

  5. Electrically conductive cellulose composite

    DOEpatents

    Evans, Barbara R.; O'Neill, Hugh M.; Woodward, Jonathan

    2010-05-04

    An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

  6. Alteration of in vivo cellulose ribbon assembly by carboxymethylcellulose and other cellulose derivatives.

    PubMed

    Haigler, C H; White, A R; Brown, R M; Cooper, K M

    1982-07-01

    In vivo cellulose ribbon assembly by the Gram-negative bacterium Acetobacter xylinum can be altered by incubation in carboxymethylcellulose (CMC), a negatively charged water-soluble cellulose derivative, and also by incubation in a variety of neutral, water-soluble cellulose derivatives. In the presence of all of these substituted celluloses, normal fasciation of microfibril bundles to form the typical twisting ribbon is prevented. Alteration of ribbon assembly is most extensive in the presence of CMC, which often induces synthesis of separate, intertwining bundles of microfibrils. Freeze-etch preparations of the bacterial outer membrane suggest that particles that are thought to be associated with cellulose synthesis or extrusion may be specifically organized to mediate synthesis of microfibril bundles. These data support the previous hypothesis that the cellulose ribbon of A. xylinum is formed by a hierarchical, cell-directed, self-assembly process. The relationship of these results to the regulation of cellulose microfibril size and wall extensibility in plant cell walls is discussed.

  7. Single Grain Boundary Modeling and Design of Microcrystalline Si Solar Cells.

    PubMed

    Lin, Chu-Hsuan; Hsu, Wen-Tzu; Tai, Cheng-Hung

    2013-01-21

    For photovoltaic applications, microcrystalline silicon has a lot of advantages, such as the ability to absorb the near-infrared part of the solar spectrum. However, there are many dangling bonds at the grain boundary in microcrystalline Si. These dangling bonds would lead to the recombination of photo-generated carriers and decrease the conversion efficiency. Therefore, we included the grain boundary in the numerical study in order to simulate a microcrystalline Si solar cell accurately, designing new three-terminal microcrystalline Si solar cells. The 3-μm-thick three-terminal cell achieved a conversion efficiency of 10.8%, while the efficiency of a typical two-terminal cell is 9.7%. The three-terminal structure increased the J SC but decreased the V OC , and such phenomena are discussed. High-efficiency and low-cost Si-based thin film solar cells can now be designed based on the information provided in this paper.

  8. Single Grain Boundary Modeling and Design of Microcrystalline Si Solar Cells

    PubMed Central

    Lin, Chu-Hsuan; Hsu, Wen-Tzu; Tai, Cheng-Hung

    2013-01-01

    For photovoltaic applications, microcrystalline silicon has a lot of advantages, such as the ability to absorb the near-infrared part of the solar spectrum. However, there are many dangling bonds at the grain boundary in microcrystalline Si. These dangling bonds would lead to the recombination of photo-generated carriers and decrease the conversion efficiency. Therefore, we included the grain boundary in the numerical study in order to simulate a microcrystalline Si solar cell accurately, designing new three-terminal microcrystalline Si solar cells. The 3-μm-thick three-terminal cell achieved a conversion efficiency of 10.8%, while the efficiency of a typical two-terminal cell is 9.7%. The three-terminal structure increased the JSC but decreased the VOC, and such phenomena are discussed. High-efficiency and low-cost Si-based thin film solar cells can now be designed based on the information provided in this paper. PMID:28809309

  9. Measurements of Raman crystallinity profiles in thin-film microcrystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Choong, G.; Vallat-Sauvain, E.; Multone, X.; Fesquet, L.; Kroll, U.; Meier, J.

    2013-06-01

    Wedge-polished thin film microcrystalline silicon solar cells are prepared and used for micro-Raman measurements. Thereby, the variations of the Raman crystallinity with depth are accessed easily. Depth resolution limits of the measurement set-up are established and calculations evidencing the role of optical limits are presented. Due to this new technique, Raman crystallinity profiles of two microcrystalline silicon cells give first hints for the optimization of the profile leading to improved electrical performance of such devices.

  10. The spatial proximity effect of beta-glucosidase and cellulosomes on cellulose degradation.

    PubMed

    Li, Xiaoyi; Xiao, Yan; Feng, Yingang; Li, Bin; Li, Wenli; Cui, Qiu

    2018-08-01

    Low-cost saccharification is one of the key bottlenecks hampering the further application of lignocellulosic biomass. Clostridium thermocellum is a naturally ideal cellulose degrading bacterium armed with cellulosomes, which are multienzyme complexes that are capable of efficiently degrading cellulose. However, under controlled condition, the inhibition effect of hydrolysate cellobiose severely restricts the hydrolytic ability of cellulosomes. Although the addition of beta-glucosidase (Bgl) could effectively relieve this inhibition, the spatial proximity effect of Bgl and cellulosomes on cellulose degradation is still unclear. To address this issue, free Bgl from Caldicellulosiruptor sp. F32 (CaBglA), carbohydrate-binding module (CBM) fused CaBglA (CaBglA-CBM) and cellulosomal type II cohesin module (CohII) fused to CaBglA (CaBglA-CohII) were successfully constructed, and their enzymatic activities, binding abilities and saccharification efficiencies were systematically investigated in vitro and in vivo. In vivo, with the adjacency of CaBglA to cellulosomes, the saccharification efficiency of microcrystalline cellulose increased from 40% to 50%. For the pretreated wheat straw, the degradation rate of the combination of cells and the CaBglA-CohII or the CaBglA-CBM was as efficient as that of the free CaBglA (approximately 60%). This study demonstrated that the proximity of CaBglA to cellulosomes had a positive effect on microcrystalline cellulose but not on pretreated wheat straw, which may result from the nonproductive adsorption of lignin and the decreased thermostability of CaBglA-CBM and CaBglA-CohII compared to that of CaBglA. The above results will contribute to the design of cost-effective Bgls for industrial cellulose degradation. Copyright © 2018. Published by Elsevier Inc.

  11. Ice nucleation by cellulose and its potential impact on clouds and climate

    NASA Astrophysics Data System (ADS)

    Hiranuma, Naruki; Möhler, Ottmar; Yamashita, Katsuya; Tajiri, Takuya; Saito, Atsushi; Kiselev, Alexei; Hoose, Corinna; Murakami, Masataka

    2014-05-01

    Biological aerosol particles have recently been accentuated by their efficient ice nucleating activity as well as potential impact on clouds and global climate. Despite their potential importance, little is known about the abundance of biological particles in the atmosphere and their role compared to non-biological material and, consequently, their potential role in the cloud-hydrology and climate system is also poorly constrained. However, field observations show that the concentration of airborne cellulose, which is one of the most important derivatives of glucose and atmospherically relevant biopolymers, is consistently prevalent (>10 ng per cubic meter) throughout the whole year even at remote- and elevated locations. Here we use a novel cloud simulation chamber in Tsukuba, Japan to demonstrate that airborne cellulose of biological origin can act as efficient ice nucleating particles in super-cooled clouds of the lower and middle troposphere. In specific, we measured the surface-based ice nucleation activity of microcrystalline cellulose particles immersed in cloud droplets, which may add crucial importance to further quantify the role of biological particles as ice nuclei in the troposphere. Our results suggest that the concentration of ice nucleating cellulose to become significant (>0.1 per liter) below about -17 °C and nearly comparable to other known ice nucleating clay mineral particles (e.g., illite rich clay mineral - INUIT comparisons are also presented). An important and unique characteristic of microcrystalline cellulose compared to other particles of biological origin is its high molecular packing density, enhancing resistance to hydrolysis degradation. More in-depth microphysical understandings as well as quantitative observations of ice nucleating cellulose particles in the atmosphere are necessary to allow better estimates of their effects on clouds and the global climate. Acknowledgement: We acknowledge support by German Research Society (Df

  12. Analysis of Enzymatic Degradation of Cellulose Microfibrils using Quantitative Surface Plasmon Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Reiter, Kyle; Raegen, Adam; Allen, Scott; Quirk, Amanda; Clarke, Anthony; Lipkowski, Jacek; Dutcher, John

    2013-03-01

    Cellulose is the largest component of biomass on Earth and, as a result, is a significant potential energy source. The production of cellulosic ethanol as a fuel source requires conversion of cellulose fibers into fermentable sugars. Increasing our understanding of the action of cellulose enzymes (cellulases) on cellulose microfibrils is an important step in developing more efficient industrial processes for the production of cellulosic ethanol. We have used a custom designed Surface Plasmon Resonance imaging (SPRi) device to study the action of cellulases from the Hypocrea jecorinasecretome on bacterial cellulose microfibrils. This has allowed us to determine the rates of action and extent of degradation of cellulose microfibrils on exposure to both individual cellulases and combinations of different classes of cellulases, which has allowed us to investigate synergistic interactions between the cellulases.

  13. Parameter and Process Significance in Mechanistic Modeling of Cellulose Hydrolysis

    NASA Astrophysics Data System (ADS)

    Rotter, B.; Barry, A.; Gerhard, J.; Small, J.; Tahar, B.

    2005-12-01

    The rate of cellulose hydrolysis, and of associated microbial processes, is important in determining the stability of landfills and their potential impact on the environment, as well as associated time scales. To permit further exploration in this field, a process-based model of cellulose hydrolysis was developed. The model, which is relevant to both landfill and anaerobic digesters, includes a novel approach to biomass transfer between a cellulose-bound biofilm and biomass in the surrounding liquid. Model results highlight the significance of the bacterial colonization of cellulose particles by attachment through contact in solution. Simulations revealed that enhanced colonization, and therefore cellulose degradation, was associated with reduced cellulose particle size, higher biomass populations in solution, and increased cellulose-binding ability of the biomass. A sensitivity analysis of the system parameters revealed different sensitivities to model parameters for a typical landfill scenario versus that for an anaerobic digester. The results indicate that relative surface area of cellulose and proximity of hydrolyzing bacteria are key factors determining the cellulose degradation rate.

  14. Microwave-assisted rapid synthesis and characterization of CaF₂ particles-filled cellulose nanocomposites in ionic liquid.

    PubMed

    Deng, Fu; Fu, Lian-Hua; Ma, Ming-Guo

    2015-05-05

    In this article, we try to compound cellulose/alkali earth metal fluorides (MF2, M=Ca, Mg, Sr, Ba) nanocomposites via microwave-assisted ionic liquid method, wherein cellulose/CaF2 and cellulose/MgF2 were successfully synthesized through this method while cellulose/SrF2 and cellulose/BaF2 could not be synthesized. We focused on the synthesis of cellulose/CaF2 and investigated the influences of the different time and different temperature for the synthesis of cellulose/CaF2 nanocomposites. The influence of different heating methods such as oil-bath heating method was also studied. Ionic liquid ([Bmim][BF4]) was used for dissolving microcrystalline cellulose and providing the source of fluoride ionic and the alkali earth metal nitrate (Ca(NO3)2, Mg(NO3)2, Sr(NO3)2, and Ba(NO3)2) was used as the reaction initiator. They were investigated by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TG), derivative thermogravimetric (DTG), and energy-dispersive X-ray spectra (EDS). The different heating modes have influence on the morphology and property. The different temperature and heating time also have a certain influence on the morphology and crystallinity of calcium fluoride. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Green thermal-assisted synthesis and characterization of novel cellulose-Mg(OH)2 nanocomposite in PEG/NaOH solvent.

    PubMed

    Ponomarev, Nikolai; Repo, Eveliina; Srivastava, Varsha; Sillanpää, Mika

    2017-11-15

    Synthesis of nanocomposites was performed using microcrystalline cellulose (MCC), MgCl 2 in PEG/NaOH solvent by a thermal-assisted method at different temperatures by varying time and the amount of MCC. Results of XRD, FTIR, and EDS mapping showed that the materials consisted of only cellulose (CL) and magnesium hydroxide (MH). According to FTIR and XRD, it was found that crystallinity of MH in cellulose nanocomposites is increased with temperature and heating time and decreased with increasing of cellulose amount. The PEG/NaOH solvent has a significant effect on cellulose and Mg(OH) 2 morphology. BET and BJH results demonstrated the effects of temperature and cellulose amount on the pore size corresponding to mesoporous materials. TG and DTG analyses showed the increased thermal stability of cellulose nanocomposites with increasing temperature. TEM and SEM analyses showed an even distribution of MH nanostructures with various morphology in the cellulose matrix. The cellulose presented as the polymer matrix in the nanocomposites. It was supposed the possible interaction between cellulose and Mg(OH) 2 . The novel synthesis method used in this study is feasible, cost-efficient and environmentally friendly. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Determination of the size and phase composition of silver nanoparticles in a gel film of bacterial cellulose by small-angle X-ray scattering, electron diffraction, and electron microscopy

    SciTech Connect

    Volkov, V. V.; Klechkovskaya, V. V., E-mail: klechvv@ns.crys.ras.ru; Shtykova, E. V.

    2009-03-15

    The nanoscale structural features in a composite (gel film of Acetobacter Xylinum cellulose with adsorbed silver nanoparticles, stabilized by N-polyvinylpyrrolidone) have been investigated by small-angle X-ray scattering. The size distributions of inhomogeneities in the porous structure of the cellulose matrix and the size distributions of silver nanoparticles in the composite have been determined. It is shown that the sizes of synthesized nanoparticles correlate with the sizes of inhomogeneities in the gel film. Particles of larger size (with radii up to 100 nm) have also been found. Electron microscopy of thin cross sections of a dried composite layer showed that largemore » particles are located on the cellulose layer surface. Electron diffraction revealed a crystal structure of silver nanoparticles in the composite.« less

  17. Environmentally friendly ultrosound synthesis and antibacterial activity of cellulose/Ag/AgCl hybrids.

    PubMed

    Dong, Yan-Yan; Deng, Fu; Zhao, Jin-Jin; He, Jing; Ma, Ming-Guo; Xu, Feng; Sun, Run-Cang

    2014-01-01

    This study aims to investigate the fabrication and property of cellulose/Ag/AgCl hybrids. In this article, preparation of cellulose/Ag/AgCl hybrids was reported using the cellulose solution, AgNO₃, AlCl₃·6H₂O with ultrasound agitation method. The cellulose solution was synthesized by the dissolution of the microcrystalline cellulose in NaOH/urea aqueous solution. Influences of the experimental parameters of ultrasound treatment time and ultrasonic intermittent on the hybrids were investigated. The phase, microstructure, thermal stability, and morphology of the hybrids were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectrometry, thermogravimetric analysis (TGA), differential thermal analysis (DTA), and scanning electron microscopy (SEM). Results showed the successful synthesis of cellulose/Ag/AgCl hybrids with good thermal stability. Moreover, the hybrids displayed desirable antimicrobial activities. Compared with other conventional methods, the rapid, green, and environmentally friendly ultrasound agitation method opens a new window to the high value-added applications of biomass. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Cellulose biosynthesis by the beta-proteobacterium, Chromobacterium violaceum.

    PubMed

    Recouvreux, Derce O S; Carminatti, Claudimir A; Pitlovanciv, Ana K; Rambo, Carlos R; Porto, Luismar M; Antônio, Regina V

    2008-11-01

    The Chromobacterium violaceum ATCC 12472 genome was sequenced by The Brazilian National Genome Project Consortium. Previous annotation reported the presence of cellulose biosynthesis genes in that genome. Analysis of these genes showed that, as observed in other bacteria, they are organized in two operons. In the present work, experimental evidences of the presence of cellulose in the extracellular matrix of the biofilm produced by C. violaceum in static cultures are shown. Biofilm samples were enzymatically digested by cellulase, releasing glucose units, suggesting the presence of cellulose as an extracellular matrix component. Fluorescence microscopy observations showed that C. violaceum produces a cellulase-sensitive extracellular matrix composed of fibers able to bind calcofluor. C. violaceum grows on medium containing Congo red, forming brown-red colonies. Together, these results suggest that cellulase-susceptible matrix material is cellulose. Scanning electronic microscopy analysis showed that the extracellular matrix exhibited a network of microfibrils, typical of bacterial cellulose. Although cellulose production is widely distributed between several bacterial species, including at least the groups of Gram-negative proteobacteria alpha and gamma, we give for the first time experimental evidence for cellulose production in beta-proteobacteria.

  19. A universal route for the simultaneous extraction and functionalization of cellulose nanocrystals from industrial and agricultural celluloses

    NASA Astrophysics Data System (ADS)

    Chen, Guo-Yin; Yu, Hou-Yong; Zhang, Cai-Hong; Zhou, Ying; Yao, Ju-Ming

    2016-02-01

    A simple route was designed to extract the cellulose nanocrystals (CNCs) with formate groups from industrial and agricultural celluloses like microcrystalline cellulose (MCC), viscose fiber, ginger fiber, and bamboo fiber. The effect of reaction time on the microstructure and properties of the CNCs was investigated in detail, while microstructure and properties of different CNCs were compared. The rod-like CNCs (MCC) with hundreds of nanometers in length and about 10 nm in width, nanofibrillated CNCs (ginger fiber bamboo fiber) with average width of 30 nm and the length of 1 μm, and spherical CNCs (viscose fiber) with the width of 56 nm were obtained by one-step HCOOH/HCl hydrolysis. The CNCs with improved thermal stability showed the maximum degradation temperature ( T max) of 368.9-388.2 °C due to the introduction of formate groups (reducibility) and the increased crystallinity. Such CNCs may be used as an effective template for the synthesis of nanohybrids or reinforcing material for high-performance nanocomposites.

  20. Catalytic hydrolysis of cellulose into furans

    NASA Astrophysics Data System (ADS)

    Shi, Chengmei; Tao, Furong; Cui, Yuezhi

    2016-12-01

    Chromium chloride in 4-(3-methylimidazolium-1-yl)butane-1-sulfonic acid hydrogen sulfate (IL-1) was found to effectively catalyze the hydrolysis of microcrystalline cellulose (MCC) at 150°C for 300 min to achieve 87.8% conversion to a slate of products. With a catalytic amount of CrCl3, the yields of 5-hydroxymethyl furfural (HMF) and furfural were up to 32.4 and 15.2%, respectively, small molecules levulinic acid (LA, 10.8%) and the total reducing sugars (TRS, 10.7%) were also generated. Through LC-MSD analysis and mass spectra, dimer of furan compounds as the main by-products were speculated, and the components of gas products were methane, ethane, CO, CO2, and H2. We suggested that IL-1 and CrCl3 exhibited a coordination interaction; the formation of the intermediate via the hydride shift played a key role in the formation of HMF. The catalyst was recycled and exhibited constant activity for five successive trials.

  1. Cellulose binding domain proteins

    DOEpatents

    Shoseyov, O.; Shpiegl, I.; Goldstein, M.; Doi, R.

    1998-11-17

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 16 figs.

  2. Cellulose binding domain proteins

    DOEpatents

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc; Doi, Roy

    1998-01-01

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  3. Cellulose nanomaterials as green nanoreinforcements for polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Dufresne, Alain

    2017-12-01

    Unexpected and attractive properties can be observed when decreasing the size of a material down to the nanoscale. Cellulose is no exception to the rule. In addition, the highly reactive surface of cellulose resulting from the high density of hydroxyl groups is exacerbated at this scale. Different forms of cellulose nanomaterials, resulting from a top-down deconstruction strategy (cellulose nanocrystals, cellulose nanofibrils) or bottom-up strategy (bacterial cellulose), are potentially useful for a large number of industrial applications. These include the paper and cardboard industry, use as reinforcing filler in polymer nanocomposites, the basis for low-density foams, additives in adhesives and paints, as well as a wide variety of filtration, electronic, food, hygiene, cosmetic and medical products. This paper focuses on the use of cellulose nanomaterials as a filler for the preparation of polymer nanocomposites. Impressive mechanical properties can be obtained for these materials. They obviously depend on the type of nanomaterial used, but the crucial point is the processing technique. The emphasis is on the melt processing of such nanocomposite materials, which has not yet been properly resolved and remains a challenge. This article is part of a discussion meeting issue `New horizons for cellulose nanotechnology'.

  4. Evaluating models of cellulose degradation by Fibrobacter succinogenes S85

    DOE PAGES

    Burnet, Meagan C.; Dohnalkova, Alice C.; Neumann, Anthony P.; ...

    2015-12-02

    Fibrobacter succinogenes S85 is an anaerobic non-cellulosome utilizing cellulolytic bacterium originally isolated from the cow rumen microbial community. Efforts to elucidate its cellulolytic machinery have resulted in the proposal of numerous models which involve a combination of cell-surface attachment via a combination of cellulose-binding fibro-slime proteins and pili, the production of cellulolytic vesicles, and the entry of cellulose fibers into the periplasmic space. Here, we used a combination of RNA-sequencing, proteomics, and transmission electron microscopy (TEM) to further elucidate the cellulolytic mechanism of F. succinogenes. Our RNA-sequence analysis shows that genes encoding Type II and III secretion systems, fibro-slime proteins,more » and pili are differentially expressed on cellulose, relative to glucose. A subcellular fractionation of cells grown on cellulose revealed that carbohydrate active enzymes associated with cellulose deconstruction and fibro-slime proteins were greater in the extracellular media, as compared to the periplasm and outer membrane fractions. TEMs of samples harvested at mid-exponential and stationary phases of growth on cellulose and glucose showed the presence of grooves in the cellulose between the bacterial cells and substrate, suggesting enzymes work extracellularly for cellulose degradation. Membrane vesicles were only observed in stationary phase cultures grown on cellulose. Furthermore, these results provide evidence that F. succinogenes attaches to cellulose fibers using fibro-slime and pili, produces cellulases, such as endoglucanases, that are secreted extracellularly using type II and III secretion systems, and degrades the cellulose into cellodextrins that are then imported back into the periplasm for further digestion by β-glucanases and other cellulases.« less

  5. Evaluating Models of Cellulose Degradation by Fibrobacter succinogenes S85

    PubMed Central

    Burnet, Meagan C.; Dohnalkova, Alice C.; Neumann, Anthony P.; Lipton, Mary S.; Smith, Richard D.; Suen, Garret; Callister, Stephen J.

    2015-01-01

    Fibrobacter succinogenes S85 is an anaerobic non-cellulosome utilizing cellulolytic bacterium originally isolated from the cow rumen microbial community. Efforts to elucidate its cellulolytic machinery have resulted in the proposal of numerous models which involve cell-surface attachment via a combination of cellulose-binding fibro-slime proteins and pili, the production of cellulolytic vesicles, and the entry of cellulose fibers into the periplasmic space. Here, we used a combination of RNA-sequencing, proteomics, and transmission electron microscopy (TEM) to further clarify the cellulolytic mechanism of F. succinogenes. Our RNA-sequence analysis shows that genes encoding type II and III secretion systems, fibro-slime proteins, and pili are differentially expressed on cellulose, relative to glucose. A subcellular fractionation of cells grown on cellulose revealed that carbohydrate active enzymes associated with cellulose deconstruction and fibro-slime proteins were greater in the extracellular medium, as compared to the periplasm and outer membrane fractions. TEMs of samples harvested at mid-exponential and stationary phases of growth on cellulose and glucose showed the presence of grooves in the cellulose between the bacterial cells and substrate, suggesting enzymes work extracellularly for cellulose degradation. Membrane vesicles were only observed in stationary phase cultures grown on cellulose. These results provide evidence that F. succinogenes attaches to cellulose fibers using fibro-slime and pili, produces cellulases, such as endoglucanases, that are secreted extracellularly using type II and III secretion systems, and degrades the cellulose into cellodextrins that are then imported back into the periplasm for further digestion by β-glucanases and other cellulases. PMID:26629814

  6. Chimeric proteins combining phosphatase and cellulose-binding activities: proof-of-concept and application in the hydrolysis of paraoxon.

    PubMed

    Gonçalves, Larissa M; Chaimovich, Hernan; Cuccovia, Iolanda M; Marana, Sandro R

    2014-05-01

    Phosphatases for organophosphate degradation and carbohydrate-binding domains (CBMs) have potential biotechnological applications. As a proof-of-concept, a soluble chimeric protein that combines acid phosphatase (AppA) from Escherichia coli and a CBM from Xanthomonas axonopodis pv. citri (AppA-CBM) was produced in E.coli. AppACBM adsorbed in microcrystalline cellulose Avicel PH101 catalyzed the hydrolysis of p-nitrophenyl phosphate (PNPP). The binding to microcrystalline cellulose displayed saturation behavior with an apparent binding constant (Kb) of 22 ± 5 mg and a maximum binding (Bmax) of 1.500 ± 0.001 enzyme units. Binding was highest at pH 2.5 and decreased above pH 6.5, as previously observed for family 2 CBMs. The Km values for PNPP of AppA-CBM and native AppA were identical (2.7 mM). To demonstrate that this strategy for protein engineering has practical applications and is largely functional, even for phosphatases exhibiting diverse folds, a chimeric protein combining human paraoxonase 1 (hPON1) and the CBM was produced. Both PON1-CBM and hPON1 had identical Km values for paraoxon (1.3 mM). Additionally, hPON1 bound to microcrystalline cellulose with a Kb of 27 ± 3 mg, the same as that observed for AppA-CBM. These data show that the phosphatase domains are as functional in both of the chimeric proteins as they are in the native enzymes and that the CBM domain maintains the same cellulose affinity. Therefore, the engineering of chimeric proteins combining domains of phosphatases and CBMs is fully feasible, resulting in chimeric enzymes that exhibit potential for OP detoxification.

  7. Re-constructing our models of cellulose and primary cell wall assembly

    SciTech Connect

    Cosgrove, Daniel J.

    2014-11-16

    The cellulose microfibril has more subtlety than is commonly recognized. Details of its structure may influence how matrix polysaccharides interact with its distinctive hydrophobic and hydrophilic surfaces to form a strong yet extensible structure. We report that recent advances in this field include the first structures of bacterial and plant cellulose synthases and revised estimates of microfibril structure, reduced from 36 to 18 chains. New results also indicate that cellulose interactions with xyloglucan are more limited than commonly believed, whereas pectin-cellulose interactions are more prevalent. Computational results indicate that xyloglucan binds tightest to the hydrophobic surface of cellulose microfibrils. Finally,more » wall extensibility may be controlled at limited regions (“biomechanical hotspots”) where cellulose-cellulose contacts are made, potentially mediated by trace amounts of xyloglucan.« less

  8. Re-constructing our models of cellulose and primary cell wall assembly

    PubMed Central

    Cosgrove, Daniel J.

    2014-01-01

    The cellulose microfibril has more subtlety than is commonly recognized. Details of its structure may influence how matrix polysaccharides interact with its distinctive hydrophobic and hydrophilic surfaces to form a strong yet extensible structure. Recent advances in this field include the first structures of bacterial and plant cellulose synthases and revised estimates of microfibril structure, reduced from 36 to 18 chains. New results also indicate that cellulose interactions with xyloglucan are more limited than commonly believed, whereas pectin-cellulose interactions are more prevalent. Computational results indicate that xyloglucan binds tightest to the hydrophobic surface of cellulose microfibrils. Wall extensibility may be controlled at limited regions (“biomechanical hotspots”) where cellulose-cellulose contacts are made, potentially mediated by trace amounts of xyloglucan. PMID:25460077

  9. Acetobacter xylinum Mutant with High Cellulose Productivity and an Ordered Structure.

    PubMed

    Watanabe, K; Tabuchi, M; Ishikawa, A; Takemura, H; Tsuchida, T; Morinaga, Y; Yoshinaga, F

    1998-01-01

    Acetobacter xylinum subsp. sucrofermentans BPR2001, a cellulose-producing bacterium, that was newly isolated from a natural source, produced large amounts of the water-soluble polysaccharide, acetan. UDP-glucose is known to be the direct precursor in the synthetic pathways of both cellulose and acetan. We attempted to breed mutant strains and succeeded in obtaining one, BPR3001A, which produced 65% more bacterial cellulose and accumulated 83% less acetan than the parent strain, BPR2001. The cellulose formed was found to be structurally ordered, with higher degrees of polymerization and crystallinity and larger crystallite size than those produced by BPR2001 and other conventional strains. Furthermore, a processed dry sheet of this cellulose exhibited a higher Young's modulus than that of the wild strain. The ordered structure of the cellulose obtained was probably due to the decreased amount of acetan which may reflect the ribbon assembly of cellulose fibrils without prevention of hydrogen bonding between microfibrils.

  10. P and n-type microcrystalline semiconductor alloy material including band gap widening elements, devices utilizing same

    DOEpatents

    Guha, Subhendu; Ovshinsky, Stanford R.

    1988-10-04

    An n-type microcrystalline semiconductor alloy material including a band gap widening element; a method of fabricating p-type microcrystalline semiconductor alloy material including a band gap widening element; and electronic and photovoltaic devices incorporating said n-type and p-type materials.

  11. Hazy Transparent Cellulose Nanopaper

    PubMed Central

    Hsieh, Ming-Chun; Koga, Hirotaka; Suganuma, Katsuaki; Nogi, Masaya

    2017-01-01

    The aim of this study is to clarify light scattering mechanism of hazy transparent cellulose nanopaper. Clear optical transparent nanopaper consists of 3–15 nm wide cellulose nanofibers, which are obtained by the full nanofibrillation of pulp fibers. At the clear transparent nanopaper with 40 μm thickness, their total transmittance are 89.3–91.5% and haze values are 4.9–11.7%. When the pulp fibers are subjected to weak nanofibrillation, hazy transparent nanopapers are obtained. The hazy transparent nanopaper consists of cellulose nanofibers and some microsized cellulose fibers. At the hazy transparent nanopaper with 40 μm thickness, their total transmittance were constant at 88.6–92.1% but their haze value were 27.3–86.7%. Cellulose nanofibers are solid cylinders, whereas the pulp fibers are hollow cylinders. The hollow shape is retained in the microsized cellulose fibers, but they are compressed flat inside the nanopaper. This compressed cavity causes light scattering by the refractive index difference between air and cellulose. As a result, the nanopaper shows a hazy transparent appearance and exhibits a high thermal durability (295–305 °C), and low thermal expansion (8.5–10.6 ppm/K) because of their high density (1.29–1.55 g/cm3) and crystallinity (73–80%). PMID:28128326

  12. Solid residues from Ruminococcus cellulose fermentations as components of wood adhesive formulations

    Treesearch

    P.J. Weimer; A.H. Conner; L.F. Lorenz

    2003-01-01

    Residues from the fermentation of cellulose by the anaerobic bacteria Ruminococcus albus (strain 7) or Ruminococcus flavefaciens (strains FD-1 or B34b) containing residual cellulose, bacterial cells and their associated adhesins, were examined for their ability to serve as components of adhesives for plywood fabrication. The residues contained differing amounts of...

  13. Low melting point pyridinium ionic liquid pretreatment for enhancing enzymatic saccharification of cellulosic biomass.

    PubMed

    Uju; Nakamoto, Aya; Shoda, Yasuhiro; Goto, Masahiro; Tokuhara, Wataru; Noritake, Yoshiyuki; Katahira, Satoshi; Ishida, Nobuhiro; Ogino, Chiaki; Kamiya, Noriho

    2013-05-01

    The potential of 1-hexylpyridinium chloride ([Hpy][Cl]), to pretreat cellulosic feedstocks was investigated using microcrystalline cellulose (Avicel) and Bagasse at 80 °C or 100 °C. Short [Hpy][Cl] pretreatments, <30 min, at lower temperature accelerate subsequent enzymatic saccharification of Avicel. Over 95% conversion of pretreated Avicel to glucose was attained after 24h enzymatic saccharification under optimal conditions, whereas regenerated Bagasse showed 1-3-fold higher conversion than untreated biomass. FT-IR analysis of both Avicel and Bagasse samples pretreated with [Hpy][Cl] or 1-ethyl-3-methyimidazolium acetate ([Emim][OAc]) revealed that these ionic liquids behaved differently during pretreatment. [Hpy][Cl] pretreatment for an extended duration (180 min) released mono- and disaccharides without using cellulase enzymes, suggesting [Hpy][Cl] has capability for direct saccharification of cellulosic feedstocks. On the basis of the results obtained, [Hpy][Cl] pretreatment enhanced initial reaction rates in enzymatic saccharification by either crystalline polymorphic alteration of cellulose or partial degradation of the crystalline cellulosic fraction in biomass. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Evaluation of cellulose-binding domain fused to a lipase for the lipase immobilization.

    PubMed

    Hwang, Sangpill; Ahn, Jungoh; Lee, Sumin; Lee, Tai Gyu; Haam, Seungjoo; Lee, Kangtaek; Ahn, Ik-Sung; Jung, Joon-Ki

    2004-04-01

    A cellulose-binding domain (CBD) fragment of a cellulase gene of Trichoderma hazianum was fused to a lipase gene of Bacillus stearothermophilus L1 to make a gene cluster for CBD-BSL lipase. The specific activity of CBD-BSL lipase for oil hydrolysis increased by 33% after being immobilized on Avicel (microcrystalline cellulose), whereas those of CBD-BSL lipase and BSL lipase decreased by 16% and 54%, respectively, after being immobilized on silica gel. Although the loss of activity of an enzyme immobilized by adsorption has been reported previously, the loss of activity of the CBD-BSL lipase immobilized on Avicel was less than 3% after 12 h due to the irreversible binding of CBD to Avicel.

  15. Binary PVA bio-nanocomposites containing cellulose nanocrystals extracted from different natural sources: part I.

    PubMed

    Fortunati, E; Puglia, D; Luzi, F; Santulli, C; Kenny, J M; Torre, L

    2013-09-12

    PVA bio-nanocomposites reinforced with cellulose nanocrystals (CNC) extracted from commercial microcrystalline cellulose (MCC) and from two types of natural fibres, Phormium tenax and Flax of the Belinka variety, were produced by solvent casting in water. Morphological, thermal, mechanical and transparency properties were studied while the respective efficiency of the extraction process of CNC from the three sources was evaluated. The effect of CNC types and content on PVA properties and water absorption capacity were also evaluated. Natural fibres offered higher levels of extraction efficiency when compared with MCC hydrolysis yield. Thermal analysis proved that CNC promotes the crystallization of the PVA matrix, while improving its plastic response. It was also clarified that all PVA/CNC systems remain transparent due to CNC dispersion at the nanoscale, while being all saturated after the first 18-24h of water absorption. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Genotoxic and immunotoxic effects of cellulose nanocrystals in vitro.

    PubMed

    Catalán, Julia; Ilves, Marit; Järventaus, Hilkka; Hannukainen, Kati-Susanna; Kontturi, Eero; Vanhala, Esa; Alenius, Harri; Savolainen, Kai M; Norppa, Hannu

    2015-03-01

    Nanocellulosics are among the most promising innovations for a wide-variety of applications in materials science. Although nanocellulose is presently produced only on a small scale, its possible toxic effects should be investigated at this early stage. The aim of the present study was to examine the potential genotoxicity and immunotoxicity of two celluloses in vitro - cellulose nanocrystals (CNC; mean fibril length 135 nm, mean width 7.3 nm) and a commercially available microcrystalline (non-nanoscale) cellulose (MCC; particle size ∼50 µm). Both celluloses showed 55% cytotoxicity at approximately 100 µg/ml after 4-h, 24-h, and 48-h treatment of human bronchial epithelial BEAS 2B cells, as determined by luminometric detection of ATP and cell count (dead cells identified by propidium iodide). Neither of the materials was able to induce micronuclei (MN) in binucleate or mononucleate BEAS 2B cells after a 48-h treatment (2.5-100 µg/ml). In human monocyte-derived macrophages, MCC induced a release (measured by enzyme-linked immunosorbent assay; ELISA) of the pro-inflammatory cytokines tumor necrosis factor α (TNF-α) and (after lipopolysaccharide-priming) interleukin 1β (IL-1β) after a 6-h exposure to a dose of 300 µg/ml, but CNC (30-300 µg/ml) did not. In conclusion, our results show that nanosized CNC is neither genotoxic nor immunotoxic under the conditions tested, whereas non-nanosized MCC is able to induce an inflammatory response. More studies are needed, especially in vivo, to further assess if CNC and other nanocelluloses induce secondary genotoxic effects mediated by inflammation. © 2014 Wiley Periodicals, Inc.

  17. Occurrence of Cellulose-Producing Gluconacetobacter spp. in Fruit Samples and Kombucha Tea, and Production of the Biopolymer.

    PubMed

    Neera; Ramana, Karna Venkata; Batra, Harsh Vardhan

    2015-06-01

    Cellulose producing bacteria were isolated from fruit samples and kombucha tea (a fermented beverage) using CuSO4 solution in modified Watanabe and Yamanaka medium to inhibit yeasts and molds. Six bacterial strains showing cellulose production were isolated and identified by 16S rRNA gene sequencing as Gluconacetobacter xylinus strain DFBT, Ga. xylinus strain dfr-1, Gluconobacter oxydans strain dfr-2, G. oxydans strain dfr-3, Acetobacter orientalis strain dfr-4, and Gluconacetobacter intermedius strain dfr-5. All the cellulose-producing bacteria were checked for the cellulose yield. A potent cellulose-producing bacterium, i.e., Ga. xylinus strain DFBT based on yield (cellulose yield 5.6 g/L) was selected for further studies. Cellulose was also produced in non- conventional media such as pineapple juice medium and hydrolysed corn starch medium. A very high yield of 9.1 g/L cellulose was obtained in pineapple juice medium. Fourier transform infrared spectrometer (FT-IR) analysis of the bacterial cellulose showed the characteristic peaks. Soft cellulose with a very high water holding capacity was produced using limited aeration. Scanning electron microscopy (SEM) was used to analyze the surface characteristics of normal bacterial cellulose and soft cellulose. The structural analysis of the polymer was performed using (13)C solid-state nuclear magnetic resonance (NMR). More interfibrillar space was observed in the case of soft cellulose as compared to normal cellulose. This soft cellulose can find potential applications in the food industry as it can be swallowed easily without chewing.

  18. Method of saccharifying cellulose

    DOEpatents

    Johnson, E.A.; Demain, A.L.; Madia, A.

    1983-05-13

    A method is disclosed of saccharifying cellulose by incubation with the cellulase of Clostridium thermocellum in a broth containing an efficacious amount of thiol reducing agent. Other incubation parameters which may be advantageously controlled to stimulate saccharification include the concentration of alkaline earth salts, pH, temperature, and duration. By the method of the invention, even native crystalline cellulose such as that found in cotton may be completely saccharified.

  19. Method of saccharifying cellulose

    DOEpatents

    Johnson, Eric A.; Demain, Arnold L.; Madia, Ashwin

    1985-09-10

    A method of saccharifying cellulose by incubation with the cellulase of Clostridium thermocellum in a broth containing an efficacious amount of a reducing agent. Other incubation parameters which may be advantageously controlled to stimulate saccharification include the concentration of alkaline earth salts, pH, temperature, and duration. By the method of the invention, even native crystalline cellulose such as that found in cotton may be completely saccharified.

  20. Electrospinning cellulose based nanofibers for sensor applications

    NASA Astrophysics Data System (ADS)

    Nartker, Steven

    2009-12-01

    Bacterial pathogens have recently become a serious threat to the food and water supply. A biosensor based on an electrochemical immunoassay has been developed for detecting food borne pathogens, such as Escherichia coli (E. coli) O157:H7. These sensors consist of several materials including, cellulose, cellulose nitrate, polyaniline and glass fibers. The current sensors have not been optimized in terms of microscale architecture and materials. The major problem associated with the current sensors is the limited concentration range of pathogens that provides a linear response on the concentration conductivity chart. Electrospinning is a process that can be used to create a patterned fiber mat design that will increase the linear range and lower the detection limit of these sensors by improving the microscale architecture. Using the electrospinning process to produce novel mats of cellulose nitrate will offer improved surface area, and the cellulose nitrate can be treated to further improve chemical interactions required for sensor activity. The macro and micro architecture of the sensor is critical to the performance of the sensors. Electrospinning technology can be used to create patterned architectures of nanofibers that will enhance sensor performance. To date electrospinning of cellulose nitrate has not been performed and optimization of the electrospinning process will provide novel materials suitable for applications such as filtration and sensing. The goal of this research is to identify and elucidate the primary materials and process factors necessary to produce cellulose nitrate nanofibers using the electrospinning process that will improve the performance of biosensors. Cellulose nitrate is readily dissolved in common organic solvents such as acetone, tetrahydrofuran (THF) and N,N dimethylformamide (DMF). These solvents can be mixed with other latent solvents such as ethanol and other alcohols to provide a solvent system with good electrospinning behavior

  1. Cellulose Supplementation Early in Life Ameliorates Colitis in Adult Mice

    PubMed Central

    Nagy-Szakal, Dorottya; Hollister, Emily B.; Luna, Ruth Ann; Szigeti, Reka; Tatevian, Nina; Smith, C. Wayne; Versalovic, James; Kellermayer, Richard

    2013-01-01

    Decreased consumption of dietary fibers, such as cellulose, has been proposed to promote the emergence of inflammatory bowel diseases (IBD: Crohn disease [CD] and ulcerative colitis [UC]) where intestinal microbes are recognized to play an etiologic role. However, it is not known if transient fiber consumption during critical developmental periods may prevent consecutive intestinal inflammation. The incidence of IBD peaks in young adulthood indicating that pediatric environmental exposures may be important in the etiology of this disease group. We studied the effects of transient dietary cellulose supplementation on dextran sulfate sodium (DSS) colitis susceptibility during the pediatric period in mice. Cellulose supplementation stimulated substantial shifts in the colonic mucosal microbiome. Several bacterial taxa decreased in relative abundance (e.g., Coriobacteriaceae [p = 0.001]), and other taxa increased in abundance (e.g., Peptostreptococcaceae [p = 0.008] and Clostridiaceae [p = 0.048]). Some of these shifts persisted for 10 days following the cessation of cellulose supplementation. The changes in the gut microbiome were associated with transient trophic and anticolitic effects 10 days following the cessation of a cellulose-enriched diet, but these changes diminished by 40 days following reversal to a low cellulose diet. These findings emphasize the transient protective effect of dietary cellulose in the mammalian large bowel and highlight the potential role of dietary fibers in amelioration of intestinal inflammation. PMID:23437211

  2. 77 FR 25720 - Determination That GRIFULVIN V (Griseofulvin Microcrystalline) Tablets, 250 Milligrams, Was Not...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-01

    ... been discontinued from marketing for reasons other than safety or effectiveness. ANDAs that refer to... Sale for Reasons of Safety or Effectiveness AGENCY: Food and Drug Administration, HHS. ACTION: Notice... microcrystalline) tablets, 250 milligrams (mg), was not withdrawn from sale for reasons of safety or effectiveness...

  3. Effect of roll compaction on granule size distribution of microcrystalline cellulose-mannitol mixtures: computational intelligence modeling and parametric analysis.

    PubMed

    Kazemi, Pezhman; Khalid, Mohammad Hassan; Pérez Gago, Ana; Kleinebudde, Peter; Jachowicz, Renata; Szlęk, Jakub; Mendyk, Aleksander

    2017-01-01

    Dry granulation using roll compaction is a typical unit operation for producing solid dosage forms in the pharmaceutical industry. Dry granulation is commonly used if the powder mixture is sensitive to heat and moisture and has poor flow properties. The output of roll compaction is compacted ribbons that exhibit different properties based on the adjusted process parameters. These ribbons are then milled into granules and finally compressed into tablets. The properties of the ribbons directly affect the granule size distribution (GSD) and the quality of final products; thus, it is imperative to study the effect of roll compaction process parameters on GSD. The understanding of how the roll compactor process parameters and material properties interact with each other will allow accurate control of the process, leading to the implementation of quality by design practices. Computational intelligence (CI) methods have a great potential for being used within the scope of quality by design approach. The main objective of this study was to show how the computational intelligence techniques can be useful to predict the GSD by using different process conditions of roll compaction and material properties. Different techniques such as multiple linear regression, artificial neural networks, random forest, Cubist and k-nearest neighbors algorithm assisted by sevenfold cross-validation were used to present generalized models for the prediction of GSD based on roll compaction process setting and material properties. The normalized root-mean-squared error and the coefficient of determination ( R 2 ) were used for model assessment. The best fit was obtained by Cubist model (normalized root-mean-squared error =3.22%, R 2 =0.95). Based on the results, it was confirmed that the material properties (true density) followed by compaction force have the most significant effect on GSD.

  4. A CsgD-independent pathway for cellulose production and biofilm formation in Escherichia coli.

    PubMed

    Da Re, Sandra; Ghigo, Jean-Marc

    2006-04-01

    Bacterial growth on a surface often involves the production of a polysaccharide-rich extracellular matrix that provides structural support for the formation of biofilm communities. In Salmonella, cellulose is one of the major constituents of the biofilm matrix. Its production is regulated by CsgD and the diguanylate cyclase AdrA that activates cellulose synthesis at a posttranscriptional level. Here, we studied a collection of Escherichia coli isolates, and we found that the ability to produce cellulose is a common trait shared by more than 50% of the tested strains. We investigated the genetic determinants of cellulose production and its role in biofilm formation in the commensal strain E. coli 1094. By contrast with the Salmonella cellulose regulatory cascade, neither CsgD nor AdrA is required in E. coli 1094 to regulate cellulose production. In this strain, an alternative cellulose regulatory pathway is used, which involves the GGDEF domain protein, YedQ. Although AdrA(1094) is functional, it is weakly expressed in E. coli 1094 compared to YedQ, which constitutively activates cellulose production under all tested environmental conditions. The study of cellulose regulation in several other E. coli isolates showed that, besides the CsgD/AdrA regulatory pathway, both CsgD-independent/YedQ-dependent and CsgD-independent/YedQ-independent pathways are found, indicating that alternative cellulose pathways are common in E. coli and possibly in other cellulose-producing Enterobacteriaceae.

  5. Carbon ions irradiation on nano- and microcrystalline CaSO4 : Dy

    NASA Astrophysics Data System (ADS)

    Salah, Numan

    2008-08-01

    Nanoparticles of CaSO4 : Dy phosphor with a particle size of around 30 nm have been prepared by the chemical co-precipitation technique. Pellet samples of the nanomaterials were irradiated by a 75 MeV C6+ ion beam at the fluence range 1 × 109-1 × 1013 ions cm-2. Thermoluminescence (TL) glow curves of the irradiated samples were recorded and studied. The microcrystalline form of this sample is also included in the study with the aim of reporting a comparative measurement. The TL analysis shows that the glow curve of the nanomaterial has two peaks at around 166 and 210 °C. These peaks are similar to those induced in the microcrystalline sample with a slight difference in their TL response. The second peak is more prominent in the case of the microcrystalline sample at low fluences, while the first one dominates in the nanostructured sample mainly at higher fluences. The TRIM code based on Monte Carlo simulation was also used for calculating some ion beam parameters. Dosimetric properties of the carbon ion beam irradiated materials show that the nanostructure material has excellent features such as a simple glow curve structure and a linear TL response over a wider range than the corresponding microcrystalline sample. These results show that the nanostructure form of CaSO4 : Dy might be useful for detecting the high doses of carbon ions used in radiotherapy. Thermal analysis of the prepared nano- and microcrystalline materials was also done in the range 50-500 °C using thermogravimetry analysis and differential thermal analysis. No phase transitions within this range of heating for both the materials are observed.

  6. Characterization of a Cellulomonas fimi exoglucanase/xylanase-endoglucanase gene fusion which improves microbial degradation of cellulosic biomass.

    PubMed

    Duedu, Kwabena O; French, Christopher E

    2016-11-01

    Effective degradation of cellulose requires multiple classes of enzyme working together. However, naturally occurring cellulases with multiple catalytic domains seem to be rather rare in known cellulose-degrading organisms. A fusion protein made from Cellulomonas fimi exo- and endo- glucanases, Cex and CenA which improves breakdown of cellulose is described. A homologous carbohydrate binding module (CBM-2) present in both glucanases was fused to give a fusion protein CxnA. CxnA or unfused constructs (Cex+CenA, Cex, or CenA) were expressed in Escherichia coli and Citrobacter freundii. The latter recombinant strains were cultured at the expense of cellulose filter paper. The expressed CxnA had both exo- and endo- glucanase activities. It was also exported to the supernatant as were the non-fused proteins. In addition, the hybrid CBM from the fusion could bind to microcrystalline cellulose. Growth of C. freundii expressing CxnA was superior to that of cells expressing the unfused proteins. Physical degradation of filter paper was also faster with the cells expressing fusion protein than the other constructs. Our results show that fusion proteins with multiple catalytic domains can improve the efficiency of cellulose degradation. Such fusion proteins could potentially substitute cloning of multiple enzymes as well as improving product yields. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Tertiary model of a plant cellulose synthase

    PubMed Central

    Sethaphong, Latsavongsakda; Haigler, Candace H.; Kubicki, James D.; Zimmer, Jochen; Bonetta, Dario; DeBolt, Seth; Yingling, Yaroslava G.

    2013-01-01

    A 3D atomistic model of a plant cellulose synthase (CESA) has remained elusive despite over forty years of experimental effort. Here, we report a computationally predicted 3D structure of 506 amino acids of cotton CESA within the cytosolic region. Comparison of the predicted plant CESA structure with the solved structure of a bacterial cellulose-synthesizing protein validates the overall fold of the modeled glycosyltransferase (GT) domain. The coaligned plant and bacterial GT domains share a six-stranded β-sheet, five α-helices, and conserved motifs similar to those required for catalysis in other GT-2 glycosyltransferases. Extending beyond the cross-kingdom similarities related to cellulose polymerization, the predicted structure of cotton CESA reveals that plant-specific modules (plant-conserved region and class-specific region) fold into distinct subdomains on the periphery of the catalytic region. Computational results support the importance of the plant-conserved region and/or class-specific region in CESA oligomerization to form the multimeric cellulose–synthesis complexes that are characteristic of plants. Relatively high sequence conservation between plant CESAs allowed mapping of known mutations and two previously undescribed mutations that perturb cellulose synthesis in Arabidopsis thaliana to their analogous positions in the modeled structure. Most of these mutation sites are near the predicted catalytic region, and the confluence of other mutation sites supports the existence of previously undefined functional nodes within the catalytic core of CESA. Overall, the predicted tertiary structure provides a platform for the biochemical engineering of plant CESAs. PMID:23592721

  8. Physico-chemical properties and gasification reactivity of co-pyrolysis char from different rank of coal blended with lignocellulosic biomass: Effects of the cellulose.

    PubMed

    Wu, Zhiqiang; Wang, Shuzhong; Luo, Zhengyuan; Chen, Lin; Meng, Haiyu; Zhao, Jun

    2017-07-01

    In this paper, the influence of cellulose on the physicochemical properties and the gasification reactivity of co-pyrolysis char was investigated. A specific surface area analyzer and an X-ray diffraction system were used to characterize the pore structure and the micro-crystalline structure of char. Fractal theory and deconvolution method were applied to quantitatively investigate the influence of cellulose on the structure of co-pyrolysis char. The results indicate that the improvements in the pore structure due to the presence of cellulose are more pronounced in the case of anthracite char with respect to bituminous char. Cellulose promotes the ordering of micro-scale structure and the uniformity of both anthracite and bituminous char, while the negative synergetic effect was observed during gasification of co-pyrolysis char. The exponential relationships between fractal dimension and specific surface area were determined, along with the relations between the gasification reactivity index and the microcrystalline structure parameter. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Re-constructing our models of cellulose and primary cell wall assembly.

    PubMed

    Cosgrove, Daniel J

    2014-12-01

    The cellulose microfibril has more subtlety than is commonly recognized. Details of its structure may influence how matrix polysaccharides interact with its distinctive hydrophobic and hydrophilic surfaces to form a strong yet extensible structure. Recent advances in this field include the first structures of bacterial and plant cellulose synthases and revised estimates of microfibril structure, reduced from 36 to 18 chains. New results also indicate that cellulose interactions with xyloglucan are more limited than commonly believed, whereas pectin–cellulose interactions are more prevalent. Computational results indicate that xyloglucan binds tightest to the hydrophobic surface of cellulose microfibrils. Wall extensibility may be controlled at limited regions (‘biomechanical hotspots’) where cellulose–cellulose contacts are made, potentially mediated by trace amounts of xyloglucan.

  10. The cellulose resource matrix.

    PubMed

    Keijsers, Edwin R P; Yılmaz, Gülden; van Dam, Jan E G

    2013-03-01

    The emerging biobased economy is causing shifts from mineral fossil oil based resources towards renewable resources. Because of market mechanisms, current and new industries utilising renewable commodities, will attempt to secure their supply of resources. Cellulose is among these commodities, where large scale competition can be expected and already is observed for the traditional industries such as the paper industry. Cellulose and lignocellulosic raw materials (like wood and non-wood fibre crops) are being utilised in many industrial sectors. Due to the initiated transition towards biobased economy, these raw materials are intensively investigated also for new applications such as 2nd generation biofuels and 'green' chemicals and materials production (Clark, 2007; Lange, 2007; Petrus & Noordermeer, 2006; Ragauskas et al., 2006; Regalbuto, 2009). As lignocellulosic raw materials are available in variable quantities and qualities, unnecessary competition can be avoided via the choice of suitable raw materials for a target application. For example, utilisation of cellulose as carbohydrate source for ethanol production (Kabir Kazi et al., 2010) avoids the discussed competition with easier digestible carbohydrates (sugars, starch) deprived from the food supply chain. Also for cellulose use as a biopolymer several different competing markets can be distinguished. It is clear that these applications and markets will be influenced by large volume shifts. The world will have to reckon with the increase of competition and feedstock shortage (land use/biodiversity) (van Dam, de Klerk-Engels, Struik, & Rabbinge, 2005). It is of interest - in the context of sustainable development of the bioeconomy - to categorize the already available and emerging lignocellulosic resources in a matrix structure. When composing such "cellulose resource matrix" attention should be given to the quality aspects as well as to the available quantities and practical possibilities of processing the

  11. Preparation and Characterization of Polyvinyl Alcohol-Chitosan Composite Films Reinforced with Cellulose Nanofiber

    PubMed Central

    Choo, Kaiwen; Ching, Yern Chee; Chuah, Cheng Hock; Julai, Sabariah; Liou, Nai-Shang

    2016-01-01

    In this study microcrystalline cellulose (MCC) was oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The treated cellulose slurry was mechanically homogenized to form a transparent dispersion which consisted of individual cellulose nanofibers with uniform widths of 3–4 nm. Bio-nanocomposite films were then prepared from a polyvinyl alcohol (PVA)-chitosan (CS) polymeric blend with different TEMPO-oxidized cellulose nanofiber (TOCN) contents (0, 0.5, 1.0 and 1.5 wt %) via the solution casting method. The characterizations of pure PVA/CS and PVA/CS/TOCN films were performed in terms of field emission scanning electron microscopy (FESEM), tensile tests, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results from FESEM analysis justified that low loading levels of TOCNs were dispersed uniformly and homogeneously in the PVA-CS blend matrix. The tensile strength and thermal stability of the films were increased with the increased loading levels of TOCNs to a maximum level. The thermal study indicated a slight improvement of the thermal stability upon the reinforcement of TOCNs. As evidenced by the FTIR and XRD, PVA and CS were considered miscible and compatible owing to hydrogen bonding interaction. These analyses also revealed the good dispersion of TOCNs within the PVA/CS polymer matrix. The improved properties due to the reinforcement of TOCNs can be highly beneficial in numerous applications. PMID:28773763

  12. The operable modeling of simultaneous saccharification and fermentation of ethanol production from cellulose.

    PubMed

    Shen, Jiacheng; Agblevor, Foster A

    2010-03-01

    An operable batch model of simultaneous saccharification and fermentation (SSF) for ethanol production from cellulose has been developed. The model includes four ordinary differential equations that describe the changes of cellobiose, glucose, yeast, and ethanol concentrations with respect to time. These equations were used to simulate the experimental data of the four main components in the SSF process of ethanol production from microcrystalline cellulose (Avicel PH101). The model parameters at 95% confidence intervals were determined by a MATLAB program based on the batch experimental data of the SSF. Both experimental data and model simulations showed that the cell growth was the rate-controlling step at the initial period in a series of reactions of cellulose to ethanol, and later, the conversion of cellulose to cellobiose controlled the process. The batch model was extended to the continuous and fed-batch operating models. For the continuous operation in the SSF, the ethanol productivities increased with increasing dilution rate, until a maximum value was attained, and rapidly decreased as the dilution rate approached the washout point. The model also predicted a relatively high ethanol mass for the fed-batch operation than the batch operation.

  13. Observing cellulose biosynthesis and membrane translocation in crystallo

    PubMed Central

    Morgan, Jacob L.W.; McNamara, Joshua T.; Fischer, Michael; Rich, Jamie; Chen, Hong-Ming; Withers, Stephen G.; Zimmer, Jochen

    2016-01-01

    Many biopolymers, including polysaccharides, must be translocated across at least one membrane to reach their site of biological function. Cellulose is a linear glucose polymer synthesized and secreted by a membrane-integrated cellulose synthase. In crystallo enzymology with the catalytically-active bacterial cellulose synthase BcsA-B complex reveals structural snapshots of a complete cellulose biosynthesis cycle, from substrate binding to polymer translocation. Substrate and product-bound structures of BcsA provide the basis for substrate recognition and demonstrate the stepwise elongation of cellulose. Furthermore, the structural snapshots show that BcsA translocates cellulose via a ratcheting mechanism involving a “finger helix” that contacts the polymer's terminal glucose. Cooperating with BcsA's gating loop, the finger helix moves ‘up’ and ‘down’ in response to substrate binding and polymer elongation, respectively, thereby pushing the elongated polymer into BcsA’s transmembrane channel. This mechanism is validated experimentally by tethering BcsA's finger helix, which inhibits polymer translocation but not elongation. PMID:26958837

  14. Calculating cellulose diffraction patterns

    USDA-ARS?s Scientific Manuscript database

    Although powder diffraction of cellulose is a common experiment, the patterns are not widely understood. The theory is mathematical, there are numerous different crystal forms, and the conventions are not standardized. Experience with IR spectroscopy is not directly transferable. An awful error, tha...

  15. Solar cells utilizing pulsed-energy crystallized microcrystalline/polycrystalline silicon

    DOEpatents

    Kaschmitter, J.L.; Sigmon, T.W.

    1995-10-10

    A process for producing multi-terminal devices such as solar cells wherein a pulsed high energy source is used to melt and crystallize amorphous silicon deposited on a substrate which is intolerant to high processing temperatures, whereby the amorphous silicon is converted into a microcrystalline/polycrystalline phase. Dopant and hydrogenation can be added during the fabrication process which provides for fabrication of extremely planar, ultra shallow contacts which results in reduction of non-current collecting contact volume. The use of the pulsed energy beams results in the ability to fabricate high efficiency microcrystalline/polycrystalline solar cells on the so-called low-temperature, inexpensive plastic substrates which are intolerant to high processing temperatures.

  16. Solar cells utilizing pulsed-energy crystallized microcrystalline/polycrystalline silicon

    DOEpatents

    Kaschmitter, James L.; Sigmon, Thomas W.

    1995-01-01

    A process for producing multi-terminal devices such as solar cells wherein a pulsed high energy source is used to melt and crystallize amorphous silicon deposited on a substrate which is intolerant to high processing temperatures, whereby to amorphous silicon is converted into a microcrystalline/polycrystalline phase. Dopant and hydrogenization can be added during the fabrication process which provides for fabrication of extremely planar, ultra shallow contacts which results in reduction of non-current collecting contact volume. The use of the pulsed energy beams results in the ability to fabricate high efficiency microcrystalline/polycrystalline solar cells on the so-called low-temperature, inexpensive plastic substrates which are intolerant to high processing temperatures.

  17. Comparative study on corrosion resistance and in vitro biocompatibility of bulk nanocrystalline and microcrystalline biomedical 304 stainless steel.

    PubMed

    Nie, F L; Wang, S G; Wang, Y B; Wei, S C; Zheng, Y F

    2011-07-01

    SUS 304 stainless steels have been widely used in orthodontics and implants such as archwires, brackets, and screws. The purpose of present study was to investigate the biocompatibility of both the commercial microcrystalline biomedical 304 stainless steel (microcrystalline 304ss) and novel-fabricated nanocrystalline 304 stainless steel (nanocrystalline 304ss). Bulk nanocrystalline 304ss sheets had been successfully prepared by microcrystalline 304ss plates using severe rolling technique. The electrochemical corrosion and ion release behavior immersion in artificial saliva were measured to evaluate the property of biocorrosion in oral environment. The cell lines of murine and human cell lines from oral and endothelial environment were co-cultured with extracts to evaluate the cytotoxicity and provide referential evidence in vivo. The polarization resistance trials indicated that nanocrystalline 304ss is more corrosion resistant than the microcrystalline 304ss in oral-like environment with higher corrosion potential, and the amount of toxic ions released into solution after immersion is lower than that of the microcrystalline 304ss and the daily dietary intake level. The cytotoxicity results also elucidated that nanocrystalline 304ss is biologically compatible in vitro, even better than that of microcrystalline 304ss. Based on the much higher mechanical and physical performances, nanocrystalline 304ss with enhanced biocorrosion property, well-behaved in vitro cytocompatibility can be a promising alternative in orthodontics and fixation fields in oral cavity. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Assembly of synthetic cellulose I.

    PubMed

    Lee, J H; Brown, R M; Kuga, S; Shoda, S; Kobayashi, S

    1994-08-02

    Cellulose microfibrils with an electron diffraction pattern characteristic of crystalline native cellulose I have been assembled abiotically by means of a cellulase-catalyzed polymerization of beta-cellobiosyl fluoride substrate monomer in acetonitrile/acetate buffer. Substantial purification of the Trichoderma viride cellulase enzyme was found to be essential for the formation of the synthetic cellulose I allomorph. Assembly of synthetic cellulose I appears to be a result of a micellar aggregation of the partially purified enzyme and the substrate in an organic/aqueous solvent system favoring the alignment of glucan chains with the same polarity and extended chain conformation, resulting in crystallization to form the metastable cellulose I allomorph.

  19. Mechanisms and kinetics of cellulose fermentation for protein production

    NASA Technical Reports Server (NTRS)

    Dunlap, C. A.

    1971-01-01

    The development of a process (and ancillary processing and analytical techniques) to produce bacterial single-cell protein of good nutritional quality from waste cellulose is discussed. A fermentation pilot plant and laboratory were developed and have been in operation for about two years. Single-cell protein (SCP) can be produced from sugarcane bagasse--a typical agricultural cellulosic waste. The optimization and understanding of this process and its controlling variables are examined. Both batch and continuous fermentation runs have been made under controlled conditions in the 535 liter pilot plant vessel and in the laboratory 14-liter fermenters.

  20. Cellulose Synthesis and Its Regulation

    PubMed Central

    Li, Shundai; Bashline, Logan; Lei, Lei; Gu, Ying

    2014-01-01

    Cellulose, the most abundant biopolymer synthesized on land, is made of linear chains of ß (1–4) linked D-glucose. As a major structural component of the cell wall, cellulose is important not only for industrial use but also for plant growth and development. Cellulose microfibrils are tethered by other cell wall polysaccharides such as hemicellulose, pectin, and lignin. In higher plants, cellulose is synthesized by plasma membrane-localized rosette cellulose synthase complexes. Despite the recent advances using a combination of molecular genetics, live cell imaging, and spectroscopic tools, many aspects of the cellulose synthesis remain a mystery. In this chapter, we highlight recent research progress towards understanding the mechanism of cellulose synthesis in Arabidopsis. PMID:24465174

  1. Growth and field emission properties of globe-like diamond microcrystalline-aggregate

    NASA Astrophysics Data System (ADS)

    Gao, Jin-hai; Zhang, Lan; Zhao, Limin; Hao, Haoshan

    2009-02-01

    The globe-like diamond microcrystalline-aggregates were fabricated by microwave plasma chemical vapor deposition (MPCVD) method. The ceramic with a Ti mental layer was used as substrate. The fabricated diamond was evaluated by Raman scattering spectroscopy, X-ray diffraction spectrum (XRD), and scanning electron microscope (SEM). The field emission properties were tested by using a diode structure in a vacuum. A phosphor-coated indium tin oxide (ITO) anode was used for observing and characterizing the field emission. It was found that the globe-like diamond microcrystalline-aggregates exhibited good electron emission properties. The turn-on field was only 0.55 V/μm, and emission current density as high as 11 mA/cm 2 was obtained under an applied field of 2.9 V/μm for the first operation. The growth mechanism and field emission properties of the globe-like diamond microcrystalline-aggregates are discussed relating to microstructure and electrical conductivity.

  2. Cellulose in Cyanobacteria. Origin of Vascular Plant Cellulose Synthase?

    PubMed Central

    Nobles, David R.; Romanovicz, Dwight K.; Brown, R. Malcolm

    2001-01-01

    Although cellulose biosynthesis among the cyanobacteria has been suggested previously, we present the first conclusive evidence, to our knowledge, of the presence of cellulose in these organisms. Based on the results of x-ray diffraction, electron microscopy of microfibrils, and cellobiohydrolase I-gold labeling, we report the occurrence of cellulose biosynthesis in nine species representing three of the five sections of cyanobacteria. Sequence analysis of the genomes of four cyanobacteria revealed the presence of multiple amino acid sequences bearing the DDD35QXXRW motif conserved in all cellulose synthases. Pairwise alignments demonstrated that CesAs from plants were more similar to putative cellulose synthases from Anabaena sp. Pasteur Culture Collection 7120 and Nostoc punctiforme American Type Culture Collection 29133 than any other cellulose synthases in the database. Multiple alignments of putative cellulose synthases from Anabaena sp. Pasteur Culture Collection 7120 and N. punctiforme American Type Culture Collection 29133 with the cellulose synthases of other prokaryotes, Arabidopsis, Gossypium hirsutum, Populus alba × Populus tremula, corn (Zea mays), and Dictyostelium discoideum showed that cyanobacteria share an insertion between conserved regions U1 and U2 found previously only in eukaryotic sequences. Furthermore, phylogenetic analysis indicates that the cyanobacterial cellulose synthases share a common branch with CesAs of vascular plants in a manner similar to the relationship observed with cyanobacterial and chloroplast 16s rRNAs, implying endosymbiotic transfer of CesA from cyanobacteria to plants and an ancient origin for cellulose synthase in eukaryotes. PMID:11598227

  3. Dietary fructans, but not cellulose, decrease triglyceride accumulation in the liver of obese Zucker fa/fa rats.

    PubMed

    Daubioul, Catherine; Rousseau, Nicolas; Demeure, Roger; Gallez, Bernard; Taper, Henryk; Declerck, Barbara; Delzenne, Nathalie

    2002-05-01

    This study was designed to compare the effects of dietary supplementation with nondigestible carbohydrates, differing in fermentability by colonic bacteria, on hepatic steatosis in growing obese Zucker rats. Male Zucker fa/fa rats were divided into three groups: a control group that received the basal diet, a fructan group that received 10 g highly fermented Synergy 1/100 g diet and a cellulose group that received 10 g poorly fermented Vivapur Microcrystalline cellulose/100 g diet. Rats consuming fructan had a lower energy intake, a lower body weight and less triacylglycerol accumulation in the liver as assessed in vivo by nuclear magnetic resonance (NMR) spectroscopy, and ex vivo by biochemical and histochemical analysis compared with the control and/or cellulose groups. The high fermentation of fructans compared with cellulose was reflected by greater cecal contents and by a twofold greater propionate concentration in the portal vein of rats fed fructan compared with those fed cellulose. By measuring the capacity of hepatocytes isolated from liver of Zucker rats to synthesize triglycerides or total lipids from different precursors, we showed that propionate, at the concentrations measured in the portal vein of rats treated with fructan, selectively decreased the incorporation of acetate into total lipids, a phenomenon that could contribute, along with the lower energy intake, to less triglyceride accumulation in the liver of obese Zucker rats fed dietary fructans.

  4. Different Types of Dietary Fibers Trigger Specific Alterations in Composition and Predicted Functions of Colonic Bacterial Communities in BALB/c Mice

    PubMed Central

    Luo, Yuheng; Zhang, Ling; Li, Hua; Smidt, Hauke; Wright, André-Denis G.; Zhang, Keying; Ding, Xuemei; Zeng, Qiufeng; Bai, Shiping; Wang, Jianping; Li, Jian; Zheng, Ping; Tian, Gang; Cai, Jingyi; Chen, Daiwen

    2017-01-01

    Soluble dietary fibers (SDF) are fermented more than insoluble dietary fibers (IDF), but their effect on colonic bacterial community structure and function remains unclear. Thus, bacterial community composition and function in the colon of BALB/c mice (n = 7) fed with a high level (approximately 20%) of typical SDF, oat-derived β-glucan (G), microcrystalline cellulose (M) as IDF, or their mixture (GM), were compared. Mice in group G showed a lowest average feed intake (p < 0.05) but no change on the average body weight gain (p > 0.05) compared to other groups, which may be associated with the highest concentration of colonic propionate (p < 0.05) in these mice. The bacterial α-diversity of group G was significantly lower than other groups (p < 0.01). In group G, the relative abundance of bacteria belonging to the phylum Bacteroidetes was significantly increased, whereas bacteria from the phylum Firmicutes were significantly decreased (p < 0.01). The core bacteria for different treatments showed distinct differences. Bacteroides, Dehalobacterium, and Prevotella, including known acetogens and carbohydrate fermenting organisms, were significantly increased in relative abundance in group G. In contrast, Adlercreutzia, Odoribacter, and Coprococcus were significantly more abundant in group M, whereas Oscillospira, Desulfovibrio, and Ruminoccaceae, typical hydrogenotrophs equipped with multiple carbohydrate active enzymes, were remarkably enriched in group GM (p < 0.05). The relative abundance of bacteria from the three classes of Proteobacteria, Betaproteobacteria, Gammaproteobacteria (including Enterobacteriaceae) and Deltaproteobacteria, were significantly more abundant in group G, indicating a higher ratio of conditional pathogenic bacteria in mice fed dietary β-glucan in current study. The predicted colonic microbial function showed an enrichment of “Energy metabolism” and “Carbohydrate metabolism” pathways in mice from group G and M, suggesting that the

  5. Different Types of Dietary Fibers Trigger Specific Alterations in Composition and Predicted Functions of Colonic Bacterial Communities in BALB/c Mice.

    PubMed

    Luo, Yuheng; Zhang, Ling; Li, Hua; Smidt, Hauke; Wright, André-Denis G; Zhang, Keying; Ding, Xuemei; Zeng, Qiufeng; Bai, Shiping; Wang, Jianping; Li, Jian; Zheng, Ping; Tian, Gang; Cai, Jingyi; Chen, Daiwen

    2017-01-01

    Soluble dietary fibers (SDF) are fermented more than insoluble dietary fibers (IDF), but their effect on colonic bacterial community structure and function remains unclear. Thus, bacterial community composition and function in the colon of BALB/c mice ( n = 7) fed with a high level (approximately 20%) of typical SDF, oat-derived β-glucan (G), microcrystalline cellulose (M) as IDF, or their mixture (GM), were compared. Mice in group G showed a lowest average feed intake ( p < 0.05) but no change on the average body weight gain ( p > 0.05) compared to other groups, which may be associated with the highest concentration of colonic propionate ( p < 0.05) in these mice. The bacterial α-diversity of group G was significantly lower than other groups ( p < 0.01). In group G, the relative abundance of bacteria belonging to the phylum Bacteroidetes was significantly increased, whereas bacteria from the phylum Firmicutes were significantly decreased ( p < 0.01). The core bacteria for different treatments showed distinct differences. Bacteroides , Dehalobacterium , and Prevotella , including known acetogens and carbohydrate fermenting organisms, were significantly increased in relative abundance in group G. In contrast, Adlercreutzia , Odoribacter , and Coprococcus were significantly more abundant in group M, whereas Oscillospira , Desulfovibrio , and Ruminoccaceae , typical hydrogenotrophs equipped with multiple carbohydrate active enzymes, were remarkably enriched in group GM ( p < 0.05). The relative abundance of bacteria from the three classes of Proteobacteria , Betaproteobacteria , Gammaproteobacteria (including Enterobacteriaceae ) and Deltaproteobacteria , were significantly more abundant in group G, indicating a higher ratio of conditional pathogenic bacteria in mice fed dietary β-glucan in current study. The predicted colonic microbial function showed an enrichment of "Energy metabolism" and "Carbohydrate metabolism" pathways in mice from group G and M, suggesting

  6. Processes for treating cellulosic material

    NASA Technical Reports Server (NTRS)

    Kohlman, Karen L. (Inventor); Weil, Joseph R. (Inventor); Westgate, Paul L. (Inventor); Ladisch, Michael R. (Inventor); Yang, Yiqi (Inventor)

    1998-01-01

    Disclosed are processes for pretreating cellulosic materials in liquid water by heating the materials in liquid water at a temperature at or above their glass transition temperature but not substantially exceeding 220.degree. C., while maintaining the pH of the reaction medium in a range that avoids substantial autohydrolysis of the cellulosic materials. Such pretreatments minimize chemical changes to the cellulose while leading to physical changes which substantially increase susceptibility to hydrolysis in the presence of cellulase.

  7. Cellulose as an extracellular matrix component present in Enterobacter sakazakii biofilms.

    PubMed

    Grimm, Maya; Stephan, Roger; Iversen, Carol; Manzardo, Giuseppe G G; Rattei, Thomas; Riedel, Kathrin; Ruepp, Andreas; Frishman, Dmitrij; Lehner, Angelika

    2008-01-01

    Cellulose was identified and characterized as an extracellular matrix component present in the biofilm of an Enterobacter sakazakii clinical isolate grown in nutrient-deficient (M9) medium. Using a bacterial artificial cloning approach in Escherichia coli and subsequent screening of transformants for fluorescence on calcofluor plates, nine genes organized in two operons were identified as putatively responsible for the biosynthesis of cellulose. In addition to the genes already described for cellulose production, two more genes were identified, putatively transcribed together with the genes from the first operon. Putative cellulose in E. sakazakii ES5 biofilm grown on glass coverslips was visualized by calcofluor staining and confocal fluorescence laser scanning microscopy. For the first time, the presence of cellulose in biofilms produced by E. sakazakii was confirmed by methylation analysis.

  8. Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations.

    PubMed

    Wang, Tuo; Yang, Hui; Kubicki, James D; Hong, Mei

    2016-06-13

    The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D (13)C-(13)C correlation spectra of uniformly (13)C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose (13)C chemical shifts differ significantly from the (13)C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing, and hydrogen bonding from celluloses of other organisms. 2D (13)C-(13)C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Celluloses f and g are well mixed chains on the microfibril surface, celluloses a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of

  9. Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations

    PubMed Central

    Wang, Tuo; Yang, Hui; Kubicki, James D.; Hong, Mei

    2017-01-01

    The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D 13C-13C correlation spectra of uniformly 13C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose 13C chemical shifts differ significantly from the 13C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing and hydrogen bonding from celluloses of other organisms. 2D 13C-13C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Cellulose f and g are well mixed chains on the microfibril surface, cellulose a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of bacterial, algal

  10. Zinc impregnated cellulose nanocomposites: Synthesis, characterization and applications

    NASA Astrophysics Data System (ADS)

    Ali, Attarad; Ambreen, Sidra; Maqbool, Qaisar; Naz, Sania; Shams, Muhammad Fahad; Ahmad, Madiha; Phull, Abdul Rehman; Zia, Muhammad

    2016-11-01

    Nanocomposite materials have broad applicability due to synergistic effect of combined components. In present investigation, cellulose isolated from citrus peel waste is used as a supporting material; impregnation of zinc oxide nanoparticles via co-precipitation method. The characterization of nano composite is carried out through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and Thermo-gravimetric analysis (TGA) resulting less than 10 μm cellulose fiber and approx. 50 nm ZnO NPs. Zinc oxide impregnated cellulose (ZnO-Cel) exhibited significant bacterial devastation property when compared to ZnO NPs or Cellulose via disc diffusion and colony forming unit methods. In addition, the ZnO-Cel exhibited significant total antioxidant, and minor DPPH free radical scavenging and total reducing power activities. The nano composite also showed time dependent increase in photocatalytic by effectively degrading methylene blue dye up to 69.5% under sunlight irradiation within 90 min. The results suggest effective utilization of cellulose obtained from citrus waste and synthesis of pharmacologically important nano-composites that can be exploited in wound dressing; defence against microbial attack and healing due to antioxidative property, furthermore can also be used for waste water treatment.

  11. Gas-phase surface esterification of cellulose microfibrils and whiskers.

    PubMed

    Berlioz, Sophie; Molina-Boisseau, Sonia; Nishiyama, Yoshiharu; Heux, Laurent

    2009-08-10

    A new and highly efficient synthetic method has been developed for the surface esterification of model cellulosic substrates of high crystallinity and accessibility, namely, freeze-dried tunicin whiskers and bacterial cellulose microfibrils dried by the critical point method. The reaction, which is based on the gas-phase action of palmitoyl chloride, was monitored by solid-state CP-MAS (13)C NMR. It was found that the grafting density not only depended on the experimental conditions, but also on the nature and conditioning of the cellulose samples. The structural and morphological modifications of the substrates at various degrees of grafting were revealed by scanning electron microscopy and X-ray diffraction analysis. These characterizations indicated that the esterification proceeded from the surface of the substrate to their crystalline core. Hence, for moderate degree of substitution, the surface was fully grafted whereas the cellulose core remained unmodified and the original fibrous morphology maintained. An almost total esterification could be achieved under certain conditions, leading to highly substituted cellulose esters, presenting characteristic X-ray diffraction patterns.

  12. Fabrication and characterization of regenerated cellulose films obtained from oil palm empty fruit bunch

    NASA Astrophysics Data System (ADS)

    Nor Amalini, A.; Melina Cheah, M. Y.; Wan Rosli, W. D.; Hayati, S.; Mohamad Haafiz, M. K.

    2017-12-01

    Development of regenerated cellulose (RC) derived from underutilized cellulosic biomass has recently gained attention as potential petroleum-based polymer replacers. The objective of this current work is to evaluate the properties of RC films obtained from oil palm empty fruit bunch microcrystalline cellulose (OPEFB-MCC) through environmental process. The RC films were fabricated by using different amounts of OPEFB-MCC (4, 6 and 8 %) and 1-butyl-3-methylimidazolium chloride (BMIMCl) was used as green OPEFB-MCC dissolving medium. The resultant RC films were then characterized by means of Fourier transform infrared (FTIR) spectroscopy, mechanical, thermal and morphological properties by using tensile test, differential scanning colorimetry (DSC), and scanning electron microscopy (SEM) respectively. Increase in OPEFB-MCC amounts from 4 to 8 % enhanced the tensile strength and elongation at break of RC by 101 and 78 %, respectively, indicating stronger and more flexible films were formed. It is interesting to note that the Tg (101-154 °C) and Tm(130-187 °C) were found shifted to higher temperature with higher proportions of OPEFB-MCC in RC films. Meanwhile, FTIR analysis showed no new peak presented in RC films, suggesting that BMIMCl is a non-derivatizing solvent to OPEFB-MCC. Conspicuous changes in the spectra of RC films compared to OPEFB-MCC at 3200-3600 cm-1, 1430 cm-1, 1162 cm-1, 1111 cm-1, 1020-1040 cm-1 and 896 cm-1 were associated with transformation of cellulose I to cellulose II structure or/and decrease in crystallinity occurred after regeneration process. SEM micrographs of the RC films revealed that higher OPEFB-MCC contents exhibited smoother and more homogeneous surfaces morphology. Overall, OPEFB-MCC exhibited good film forming ability for RC production and may offer potential application in various industries including food packaging, medical goods and electronic devices.

  13. The ability of retention, drug release and rheological properties of nanogel bioadhesives based on cellulose derivatives.

    PubMed

    Keshavarz, M; Kaffashi, B

    2014-12-01

    The rheological and drug release behavior of biopolymer nanocomposite gels based on the cellulose derivatives, formulated as the bioadhesive drug delivery platforms, were investigated. The bioadhesive gel is composed of the microcrystalline cellulose, sodium carboxymethyl cellulose and phosphate buffered saline (pH = 7.4 at 20 °C) as the dissolution and release medium. The reinforcing nanofillers such as MMT-clay, fumed porous silica and porous starch were used as additives in the nanogel bioadhesive. The constant steady state viscosities of this nanogels upon incorporation of various nanofillers into the systems is the sign of structural stability. Hence, this system is suitable for use in the controlled drug delivery systems in contact with the biological tissues. Based on the rheological measurements, the shear flow properties (i.e. zero shear viscosity and yield stress) were influenced by the concentration of polymers and nanoparticles. The results indicate that the nonlinear rheological data are fitted properly by the Giesekus model. Furthermore, the results showed that the nonlinear viscoelastic parameters (λ and α) are highly affected by the biogel and nanoparticles concentrations. Finally, the drug release was measured, and the results indicated that the biopolymer-clay nanocomposites have appropriate release pattern as the release is better controlled compared to the other nanogel formulations.

  14. Chitin and Cellulose Processing in Low-Temperature Electron Beam Plasma.

    PubMed

    Vasilieva, Tatiana; Chuhchin, Dmitry; Lopatin, Sergey; Varlamov, Valery; Sigarev, Andrey; Vasiliev, Michael

    2017-11-06

    Polysaccharide processing by means of low-temperature Electron Beam Plasma (EBP) is a promising alternative to the time-consuming and environmentally hazardous chemical hydrolysis in oligosaccharide production. The present paper considers mechanisms of the EBP-stimulated destruction of crab shell chitin, cellulose sulfate, and microcrystalline cellulose, as well as characterization of the produced oligosaccharides. The polysaccharide powders were treated in oxygen EBP for 1-20 min at 40 °C in a mixing reactor placed in the zone of the EBP generation. The chemical structure and molecular mass of the oligosaccharides were analyzed by size exclusion and the reversed phase chromatography, FTIR-spectroscopy, XRD-, and NMR-techniques. The EBP action on original polysaccharides reduces their crystallinity index and polymerization degree. Water-soluble products with lower molecular weight chitooligosaccharides (weight-average molecular mass, M w = 1000-2000 Da and polydispersity index 2.2) and cellulose oligosaccharides with polymerization degrees 3-10 were obtained. The ¹H-NMR analysis revealed 25-40% deacetylation of the EBP-treated chitin and FTIR-spectroscopy detected an increase of carbonyl- and carboxyl-groups in the oligosaccharides produced. Possible reactions of β-1,4-glycosidic bonds' destruction due to active oxygen species and high-energy electrons are given.

  15. A monolithic functional film of nanotubes/cellulose/ionic liquid for high performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Basiricò, Lucia; Lanzara, Giulia

    2014-12-01

    A novel monolithic, pre-fabricated, fully functional film made of a nanostructured free-standing layer is presented for a new and competitive class of easy-to-assemble flexible supercapacitors whose design is in-between the all solid state and the traditional liquid electrolyte. The film is made of two vertically aligned multi-walled carbon nanotube (VANT) electrodes that store ions, embedded-in, and monolithically interspaced by a solution of microcrystalline cellulose in a room temperature ionic liquid (RTIL) electrolyte (1-ethyl-3-methylimidazolium acetate-EMIM Ac). The fine tuning of VANTs length and electrolyte/cellulose amount leads, in a sole and continuous block, to ions storage and physical separation between the electrodes without the need of the additional separator layer that is typically used in supercapacitors. Thus, physical discontinuities that can induce disturbances to ions mobility, are fully eliminated significantly reducing the equivalent series resistance and increasing the knee frequency, hence outclassing the best supercapacitors based on VANTs and non-aqueous electrolytes. The excellent electrochemical response can also be addressed to the chosen electrolyte that, not only has the advantage of leading to a significantly simpler and more affordable fabrication procedure, but has higher ionic conductivity, lower viscosity and higher ions mobility than other electrolytes capable of dissolving cellulose.

  16. Synthesis of galactooligosaccharides by CBD fusion β-galactosidase immobilized on cellulose.

    PubMed

    Lu, Lili; Xu, Shuze; Zhao, Renfei; Zhang, Dayu; Li, Zhengyi; Li, Yumei; Xiao, Min

    2012-07-01

    The β-galactosidase gene (bgaL3) was cloned from Lactobacillus bulgaricus L3 and fused with cellulose binding domain (CBD) using pET-35b (+) vector in Escherichia coli. The resulting fusion protein (CBD-BgaL3) was directly adsorbed onto microcrystalline cellulose with a high immobilization efficiency of 61%. A gram of cellulose was found to absorb 97.6 U of enzyme in the solution containing 100mM NaCl (pH 5.8) at room temperature for 20 min. The enzymatic and transglycosylation characteristics of the immobilized CBD-BgaL3 were similar to the free form. Using the immobilized enzyme as the catalyst, the yield of galactooligosaccharides (GOS) reached a maximum of 49% (w/w) from 400 g/L lactose (pH 7.6) at 45 °C for 75 min, with a high productivity of 156.8 g/L/h. Reusability assay was subsequently performed under the same reaction conditions. The immobilized enzyme could retain over 85% activity after twenty batches with the GOS yields all above 40%. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Multifunctional PLA-PHB/cellulose nanocrystal films: processing, structural and thermal properties.

    PubMed

    Arrieta, M P; Fortunati, E; Dominici, F; Rayón, E; López, J; Kenny, J M

    2014-07-17

    Cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose by acid hydrolysis were added into poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends to improve the final properties of the multifunctional systems. CNC were also modified with a surfactant (CNCs) to increase the interfacial adhesion in the systems maintaining the thermal stability. Firstly, masterbatch pellets were obtained for each formulation to improve the dispersion of the cellulose structures in the PLA-PHB and then nanocomposite films were processed. The thermal stability as well as the morphological and structural properties of nanocomposites was investigated. While PHB increased the PLA crystallinity due to its nucleation effect, well dispersed CNC and CNCs not only increased the crystallinity but also improved the processability, the thermal stability and the interaction between both polymers especially in the case of the modified CNCs based PLA-PHB formulation. Likewise, CNCs were better dispersed in PLA-CNCs and PLA-PHB-CNCs, than CNC. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. PVA bio-nanocomposites: a new take-off using cellulose nanocrystals and PLGA nanoparticles.

    PubMed

    Rescignano, N; Fortunati, E; Montesano, S; Emiliani, C; Kenny, J M; Martino, S; Armentano, I

    2014-01-01

    The formation of a new generation of hybrid bio-nanocomposites is reported: these are intended at modulating the mechanical, thermal and biocompatibility properties of the poly(vinyl alcohol) (PVA) by the combination of cellulose nanocrystals (CNC) and poly (D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) loaded with bovine serum albumin fluorescein isothiocynate conjugate (FITC-BSA). CNC were synthesized from microcrystalline cellulose by hydrolysis, while PLGA nanoparticles were produced by a double emulsion with subsequent solvent evaporation. Firstly, binary bio-nanocomposites with different CNC amounts were developed in order to select the right content of CNC. Next, ternary PVA/CNC/NPs bio-nanocomposites were developed. The addition of CNC increased the elongation properties without compromising the other mechanical responses. Thermal analysis underlined the nucleation effect of the synergic presence of cellulose and nanoparticles. Remarkably, bio-nanocomposite films are suitable to vehiculate biopolymeric nanoparticles to adult bone marrow mesenchymal stem cells successfully, thus representing a new tool for drug delivery strategies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Highly hydrophobic biopolymers prepared by the surface pentafluorobenzoylation of cellulose substrates.

    PubMed

    Cunha, Ana G; Freire, Carmen S R; Silvestre, Armando J D; Pascoal Neto, Carlos; Gandini, Alessandro; Orblin, Elina; Fardim, Pedro

    2007-04-01

    New highly hydrophobic/lipophobic biopolymers were prepared by the controlled heterogeneous pentafluorobenzoylation of cellulose substrates, i.e., plant and bacterial cellulose fibers. The characterization of the modified fibers was performed by elemental analysis, FTIR spectroscopy, X-ray diffraction, thermogravimetry, and surface analysis (XPS, ToF-SIMS, and contact angle measurements). The degree of substitution of the ensuing pentafluorobenzoylated fibers ranged from 0.014 to 0.39. The hydrolytic stability of these perfluorinated cellulose derivatives was also evaluated and showed that they were quite water stable, although of course the fluorinated moieties could readily be removed by hydrolysis in an aqueous alkaline medium.

  20. The effect of cellulose overproduction on binding and biofilm formation on roots by Agrobacterium tumefaciens.

    PubMed

    Matthysse, Ann G; Marry, Mazz; Krall, Leonard; Kaye, Mitchell; Ramey, Bronwyn E; Fuqua, Clay; White, Alan R

    2005-09-01

    Agrobacterium tumefaciens growing in liquid attaches to the surface of tomato and Arabidopsis thaliana roots, forming a biofilm. The bacteria also colonize roots grown in sterile quartz sand. Attachment, root colonization, and biofilm formation all were markedly reduced in celA and chvB mutants, deficient in production of cellulose and cyclic beta-(1,2)-D-glucans, respectively. We have identified two genes (celG and cell) in which mutations result in the overproduction of cellulose as judged by chemical fractionation and methylation analysis. Wild-type and chvB mutant strains carrying a cDNA clone of a cellulose synthase gene from the marine urochordate Ciona savignyi also overproduced cellulose. The overproduction in a wild-type strain resulted in increased biofilm formation on roots, as evaluated by light microscopy, and levels of root colonization intermediate between those of cellulose-minus mutants and the wild type. Overproduction of cellulose by a nonattaching chvB mutant restored biofilm formation and bacterial attachment in microscopic and viable cell count assays and partially restored root colonization. Although attachment to plant surfaces was restored, overproduction of cellulose did not restore virulence in the chvB mutant strain, suggesting that simple bacterial binding to plant surfaces is not sufficient for pathogenesis.

  1. Acid hydrolysis of cellulose to yield glucose

    DOEpatents

    Tsao, George T.; Ladisch, Michael R.; Bose, Arindam

    1979-01-01

    A process to yield glucose from cellulose through acid hydrolysis. Cellulose is recovered from cellulosic materials, preferably by pretreating the cellulosic materials by dissolving the cellulosic materials in Cadoxen or a chelating metal caustic swelling solvent and then precipitating the cellulose therefrom. Hydrolysis is accomplished using an acid, preferably dilute sulfuric acid, and the glucose is yielded substantially without side products. Lignin may be removed either before or after hydrolysis.

  2. Homogeneous suspensions of individualized microfibrils from TEMPO-catalyzed oxidation of native cellulose.

    PubMed

    Saito, Tsuguyuki; Nishiyama, Yoshiharu; Putaux, Jean-Luc; Vignon, Michel; Isogai, Akira

    2006-06-01

    Never-dried native celluloses (bleached sulfite wood pulp, cotton, tunicin, and bacterial cellulose) were disintegrated into individual microfibrils after oxidation mediated by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical followed by a homogenizing mechanical treatment. When oxidized with 3.6 mmol of NaClO per gram of cellulose, almost the totality of sulfite wood pulp and cotton were readily disintegrated into long individual microfibrils by a treatment with a Waring Blendor, yielding transparent and highly viscous suspensions. When observed by transmission electron microscopy, the wood pulp and cotton microfibrils exhibited a regular width of 3-5 nm. Tunicin and bacterial cellulose could be disintegrated by sonication. A bulk degree of oxidation of about 0.2 per one anhydroglucose unit of cellulose was necessary for a smooth disintegration of sulfite wood pulp, whereas only small amounts of independent microfibrils were obtained at lower oxidation levels. This limiting degree of oxidation decreased in the following order: sulfite wood pulp > cotton > bacterial cellulose, tunicin.

  3. HRTEM of microcrystalline opal in chert and porcelanite from the Monterey Formation, California

    SciTech Connect

    Cady, S.L.; Wenk, H.R.; Downing, K.H.

    Microcrystalline opal was investigated using low-dose transmission electron microscopy (TEM) methods to identify microstructural characteristics and possible phase-transformation mechanisms that accommodate silica diagenesis. High-resolution TEM (HRTEM) revealed that microcrystalline opal in opal-CT chert (>90 wt% silica) and opal-CT porcelanite (50-90 wt% silica) from the Miocene Monterey Formation of California displays various amounts of structural disorder and coherent and incoherent lamellar intergrowths. Species of microfibrous opal identified by HRTEM in early-formed opal-CT chert include length-slow opal-C and unidimensionally disordered length-slow opal-CT ({open_quotes}lussatite{close_quotes}). These fibers often display a microstructure characterized by an aperiodic distribution of highly strained domains that separate ordered domainsmore » located at discrete positions along the direction of the fiber axes. Microfibrous opal occurs as several types of fiber-aggregation forms. TEM revealed that the siliceous matrix in later-formed opal-CT porcelanite consists of equidimensional, nanometer-size opal-CT crystallites and lussatite fibers. Pseudo-orthorhombic tridymite (PO-2) was identified by HRTEM in one sample of opal-CT porcelanite. Burial diagenesis of chert and porcelanite results in the precipitation of opal-C and the epitaxial growth of opal-C domains on opal-CT substrates. Diagenetic maturation of lussatite was identified by TEM in banded opal-CT-quartz chert to occur as a result of solid-state ordering. The primary diagenetic silica phase transformations between noncrystalline opal, microcrystalline opal, and quartz occur predominantly by a series of dissolution-precipitation reactions. However, TEM showed that in banded opal-CT-quartz chert, the epitaxial growth of quartz on microfibrous opal enhances the rate of silica diagenesis.« less

  4. Directed Biosynthesis of Oriented Crystalline Cellulose for Advanced Composite Fibers

    DTIC Science & Technology

    2012-05-03

    8 growth rate Table 2. An optimized minimal salts high conductivity growth medium (named 9 Son-Matsuoka- Fructose , SMF) based on the optimized...basis for a high -conductivity medium for Acetobacter that also contained corn steep liquor. List of Figures Figure 1. Scanning electron micrographs of...bacterial cellulose production include corn steep liquor (Matsuoka et al., 1996) apples, beer wort (Brown, 1886; Herrmann, 1928), corn syrup , kale (black

  5. Mechanism of the growth of amorphous and microcrystalline silicon from silicon tetrafluoride and hydrogen

    NASA Astrophysics Data System (ADS)

    Okada, Y.; Chen, J.; Campbell, I. H.; Fauchet, P. M.; Wagner, S.

    1990-02-01

    We study the growth of amorphous (a-Si:H,F) and of microcrystalline (μc-Si) silicon over trench patterns in crystalline silicon substrates. We vary the conditions of the SiF4-H2 glow discharge from deposition to etching. All deposited films form lips at the trench mouth and are uniformly thick on the trench walls. Therefore, surface diffusion is not important. The results of a Monte Carlo simulation suggest that film growth is governed by a single growth species with a low (˜0.2) sticking coefficient, in combination with a highly reactive etching species.

  6. Diversity of Hindgut Bacterial Population in Subterranean Termite, Reticulitermes flavipes

    Treesearch

    Olanrewaju Raji; Dragica Jeremic-Nikolic; Juliet D. Tang

    2017-01-01

    The termite hindgut contains a bacterial community that symbiotically aids in digestion of cellulosic materials. For this paper, a species survey of bacterial hindgut symbionts in termites collected from Saucier, Mississippi was examined. Two methods were tested for optimal genetic material isolation. Genomic DNA was isolated from the hindgut luminal contents of five...

  7. Morphological structure of Gluconacetobacter xylinus cellulose and cellulose-based organic-inorganic composite materials

    NASA Astrophysics Data System (ADS)

    Smyslov, R. Yu; Ezdakova, K. V.; Kopitsa, G. P.; Khripunov, A. K.; Bugrov, A. N.; Tkachenko, A. A.; Angelov, B.; Pipich, V.; Szekely, N. K.; Baranchikov, A. E.; Latysheva, E.; Chetverikov, Yu O.; Haramus, V.

    2017-05-01

    Scanning electron microscopy, ultra-small-angle neutron scattering (USANS), small-angle neutron and X-ray scattering (SANS and SAXS), as well as low-temperature nitrogen adsorption, were used in the studies of micro- and mesostructure of polymer matrix prepared from air-dry preliminarily disintegrated cellulose nano-gel film (synthesized by Gluconacetobacter xylinus) and the composites based on this bacterial cellulose. The composites included ZrO2 nanoparticles, Tb3+ in the form of low molecular weight salt and of metal-polymer complex with poly(vinylpyrrolydone)-poly(methacryloyl-o-aminobenzoic acid) copolymer. The combined analysis of the data obtained allowed revealing three levels of fractal organization in mesostructure of G. xylinus cellulose and its composites. It was shown that both the composition and an aggregation state of dopants have a significant impact on the structural characteristics of the organic-inorganic composites. The composites containing Tb3+ ions demonstrate efficient luminescence; its intensity is an order of magnitude higher in the case of the composites with the metal-polymer complex. It was found that there is the optimal content of ZrO2 nanoparticles in composites resulting in increased Tb3+ luminescence.

  8. Cellulose binding domain fusion proteins

    DOEpatents

    Shoseyov, O.; Yosef, K.; Shpiegl, I.; Goldstein, M.A.; Doi, R.H.

    1998-02-17

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 16 figs.

  9. TEMPO-oxidized cellulose nanofibers

    NASA Astrophysics Data System (ADS)

    Isogai, Akira; Saito, Tsuguyuki; Fukuzumi, Hayaka

    2011-01-01

    Native wood celluloses can be converted to individual nanofibers 3-4 nm wide that are at least several microns in length, i.e. with aspect ratios >100, by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation and successive mild disintegration in water. Preparation methods and fundamental characteristics of TEMPO-oxidized cellulose nanofibers (TOCN) are reviewed in this paper. Significant amounts of C6 carboxylate groups are selectively formed on each cellulose microfibril surface by TEMPO-mediated oxidation without any changes to the original crystallinity (~74%) or crystal width of wood celluloses. Electrostatic repulsion and/or osmotic effects working between anionically-charged cellulose microfibrils, the ζ-potentials of which are approximately -75 mV in water, cause the formation of completely individualized TOCN dispersed in water by gentle mechanical disintegration treatment of TEMPO-oxidized wood cellulose fibers. Self-standing TOCN films are transparent and flexible, with high tensile strengths of 200-300 MPa and elastic moduli of 6-7 GPa. Moreover, TOCN-coated poly(lactic acid) films have extremely low oxygen permeability. The new cellulose-based nanofibers formed by size reduction process of native cellulose fibers by TEMPO-mediated oxidation have potential application as environmentally friendly and new bio-based nanomaterials in high-tech fields.

  10. Cellulose binding domain fusion proteins

    DOEpatents

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc A.; Doi, Roy H.

    1998-01-01

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  11. Ultrasonic dyeing of cellulose nanofibers.

    PubMed

    Khatri, Muzamil; Ahmed, Farooq; Jatoi, Abdul Wahab; Mahar, Rasool Bux; Khatri, Zeeshan; Kim, Ick Soo

    2016-07-01

    Textile dyeing assisted by ultrasonic energy has attained a greater interest in recent years. We report ultrasonic dyeing of nanofibers for the very first time. We chose cellulose nanofibers and dyed with two reactive dyes, CI reactive black 5 and CI reactive red 195. The cellulose nanofibers were prepared by electrospinning of cellulose acetate (CA) followed by deacetylation. The FTIR results confirmed complete conversion of CA into cellulose nanofibers. Dyeing parameters optimized were dyeing temperature, dyeing time and dye concentrations for each class of the dye used. Results revealed that the ultrasonic dyeing produced higher color yield (K/S values) than the conventional dyeing. The color fastness test results depicted good dye fixation. SEM analysis evidenced that ultrasonic energy during dyeing do not affect surface morphology of nanofibers. The results conclude successful dyeing of cellulose nanofibers using ultrasonic energy with better color yield and color fastness results than conventional dyeing. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Cellulose binding domain assisted immobilization of lipase (GSlip-CBD) onto cellulosic nanogel: characterization and application in organic medium.

    PubMed

    Kumar, Ashok; Zhang, Shaowei; Wu, Gaobing; Wu, Cheng Chao; Chen, JunPeng; Baskaran, R; Liu, Ziduo

    2015-12-01

    A cbd gene was cloned into the C-terminal region of a lip gene from Geobacillus stearothermophilus. The native lipase (43.5 kDa) and CBD-Lip fusion protein (60.2 kDa) were purified to homogeneity by SDS-PAGE. A highly stable cellulosic nanogel was prepared by controlled hydrolysis of microcrystalline cellulose onto which the CBD-lip fusion protein was immobilized through bio-affinity based binding. The nanogel-bound lipase showed optimum activity at 55 °C, and it remains stable and active at pH 10-10.5. Furthermore, the immobilized lipase showed an over two-fold increase of relative activity in the presence of DMSO, isopropanol, isoamyl alcohol and n-butanol, but a mild activity decrease at a low concentration of methanol and ethanol. The immobilized biocatalyst retained ~50% activity after eight repetitive hydrolytic cycles. Enzyme kinetic studies of the immobilized lipase showed a 1.24 fold increase in Vmax and 5.25 fold increase in kcat towards p-NPP hydrolysis. Additionally, the nanogel bound lipase was tested to synthesize a biodiesel ester, ethyl oleate in DMSO. Kinetic analysis showed the km 100.5 ± 4.3 mmol and Vmax 0.19 ± 0.015 mmolmin(-1) at varied oleic acid concentration. Also, the values of km and Vmax at varying concentration of ethanol were observed to be 95.9 ± 13.9 mmol and 0.22 ± 0.013 mmolmin(-1) respectively. The maximum yield of ethyl oleate 111.2 ± 1.24 mM was obtained under optimized reaction conditions in organic medium. These results suggest that this immobilized biocatalyst can be used as an efficient tool for the biotransformation reactions on an industrial scale. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. DOPI and PALM imaging of single carbohydrate binding modules bound to cellulose nanocrystals

    NASA Astrophysics Data System (ADS)

    Dagel, D. J.; Liu, Y.-S.; Zhong, L.; Luo, Y.; Zeng, Y.; Himmel, M.; Ding, S.-Y.; Smith, S.

    2011-03-01

    We use single molecule imaging methods to study the binding characteristics of carbohydrate-binding modules (CBMs) to cellulose crystals. The CBMs are carbohydrate specific binding proteins, and a functional component of most cellulase enzymes, which in turn hydrolyze cellulose, releasing simple sugars suitable for fermentation to biofuels. The CBM plays the important role of locating the crystalline face of cellulose, a critical step in cellulase action. A biophysical understanding of the CBM action aids in developing a mechanistic picture of the cellulase enzyme, important for selection and potential modification. Towards this end, we have genetically modified cellulose-binding CBM derived from bacterial source with green fluorescent protein (GFP), and photo-activated fluorescence protein PAmCherry tags, respectively. Using the single molecule method known as Defocused Orientation and Position Imaging (DOPI), we observe a preferred orientation of the CBM-GFP complex relative to the Valonia cellulose nanocrystals. Subsequent analysis showed the CBMs bind to the opposite hydrophobic <110> faces of the cellulose nanocrystals with a welldefined cross-orientation of about { 70°. Photo Activated Localization Microscopy (PALM) is used to localize CBMPAmCherry with a localization accuracy of { 10nm. Analysis of the nearest neighbor distributions along and perpendicular to the cellulose nanocrystal axes are consistent with single-file CBM binding along the fiber axis, and microfibril bundles consisting of close packed { 20nm or smaller cellulose microfibrils.

  14. Cellulose nanofiber board.

    PubMed

    Yousefi, Hossein; Azad, Sona; Mashkour, Mahdi; Khazaeian, Abolghasem

    2018-05-01

    A cellulose nanofiber board (CNF-board) with a nominal thickness of 3 mm was fabricated without adhesive or additive. To provide comparison, a cellulose fiber board (CF-board) was also fabricated. A novel cold pre-press apparatus was made to dewater highly absorbent CNF gel prior to drying. A mild drying condition in the vacuum oven at 70 °C and 0.005 MPa was enough to provide the CNF-board with a density of 1.3 g/cm 3 thanks to its self-densification capability. Unlike the CF-board, the fabricated CNF-board had a high water-activated dimensional recovery ratio (averagely 96%) during the five cyclic wetting-drying process. The flexural and tensile strengths of CNF-board obtained were 162 MPa and 85 MPa, respectively. The corresponding values for CF-board were 28 MPa and 11 MPa, respectively. The specific flexural and tensile strengths of CNF-board obtained were higher than those of CF-board as well as some other traditional wood-based composites, polymers and structural ASTM A36 steel. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Spatial and temporal dynamics of cellulose degradation and biofilm formation by Caldicellulosiruptor obsidiansis and Clostridium thermocellum Caldicellulosiruptor obsidiansis

    SciTech Connect

    Wang, Zhiwu; Lee, Sueng-Hwan; Elkins, James G

    2011-01-01

    Cellulose degradation is one of the major bottlenecks of a consolidated bioprocess that employs cellulolytic bacterial cells as catalysts to produce biofuels from cellulosic biomass. In this study, we investigated the spatial and temporal dynamics of cellulose degradation by Caldicellulosiruptor obsidiansis, which does not produce cellulosomes, and Clostridium thermocellum, which does produce cellulosomes. Results showed that the degradation of either regenerated or natural cellulose was synchronized with biofilm formation, a process characterized by the formation and fusion of numerous crater-like depressions on the cellulose surface. In addition, the dynamics of biofilm formation were similar in both bacteria, regardless of cellulosomemore » production. Only the areas of cellulose surface colonized by microbes were significantly degraded, highlighting the essential role of the cellulolytic biofilm in cellulose utilization. After initial attachment, the microbial biofilm structure remained thin, uniform and dense throughout the experiment. A cellular automaton model, constructed under the assumption that the attached cells divide and produce daughter cells that contribute to the hydrolysis of the adjacent cellulose, can largely simulate the observed process of biofilm formation and cellulose degradation. This study presents a model, based on direct observation, correlating cellulolytic biofilm formation with cellulose degradation.« less

  16. Optical Absorption Spectra of Hydrogenated Microcrystalline Silicon Films by Resonant Photothermal Bending Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kunii, Toshie; Yoshida, Norimitsu; Hori, Yasuro; Nonomura, Shuichi

    2006-05-01

    A resonant photothermal bending spectroscopy (PBS) is demonstrated for the measurement of absorption coefficient spectra in hydrogenated microcrystalline silicon (μc-Si:H) and hydrogenated microcrystalline cubic silicon carbide (μc-3C-SiC:H) films. The resonant vibration technique utilized in PBS establishes the sensitivity as α d˜ 5× 10-5 in a vacuum measurement. Appling resonant PBS to μc-Si:H films, a new extra absorption coefficient αex spectrum is observed from 0.6 to 1.2 eV. The αex spectrum has a peak at ˜1.0 eV, and the localized states inducing the αex are located ˜0.35 eV below the conduction band edge of μc-Si:H. A possible explanation for the observed localized state is that an oxidation produces weak bonds at the grain boundaries and/or amorphous silicon tissues. In μc-3C-SiC:H film, an optical band-gap energy of ˜2.2 eV was demonstrated assuming an indirect optical transition. The temperature coefficient of the optical band-gap energy was ˜2.3× 10-4 eV K-1. The αex spectrum of μc-3C-SiC:H film is plateau-shaped and its magnitude is in accord with an increase in grain size.

  17. Extraction of the defect density of states in microcrystalline silicon from experimental results and simulation studies

    NASA Astrophysics Data System (ADS)

    Tibermacine, T.; Merazga, A.; Ledra, M.; Ouhabab, N.

    2015-09-01

    The constant photocurrent method in the ac-mode (ac-CPM) is used to determine the defect density of states (DOS) in hydrogenated microcrystalline silicon (μc-Si:H) prepared by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD). The absorption coefficient spectrum (ac-α(hv)), is measured under ac-CPM conditions at 60 Hz. The measured ac-α(hv) is converted by the CPM spectroscopy into a DOS distribution covering a portion in the lower energy range of occupied states. We have found that the density of valence band-tail states falls exponentially towards the gap with a typical band-tail width of 63 meV. Independently, computer simulations of the ac-CPM are developed using a DOS model that is consistent with the measured ac-α(hv) in the present work and a previously measured transient photocurrent (TPC) for the same material. The DOS distribution model suggested by the measurements in the lower and in the upper part of the energy-gap, as well as by the numerical modelling in the middle part of the energy-gap, coincide reasonably well with the real DOS distribution in hydrogenated microcrystalline silicon because the computed ac-α(hv) is found to agree satisfactorily with the measured ac-α(hv).

  18. Microcrystalline diamond cylindrical resonators with quality-factor up to 0.5 million

    NASA Astrophysics Data System (ADS)

    Saito, Daisuke; Yang, Chen; Heidari, Amir; Najar, Hadi; Lin, Liwei; Horsley, David A.

    2016-02-01

    We demonstrate high quality-factor 1.5 mm diameter batch-fabricated microcrystalline diamond cylindrical resonators (CR) with quality-factors limited by thermoelastic damping (TED) and surface loss. Resonators were fabricated 2.6 and 5.3 μm thick in-situ boron-doped microcrystalline diamond films deposited using hot filament chemical vapor deposition. The quality-factor (Q) of as-fabricated CR's was found to increase with the resonator diameter and diamond thickness. Annealing the CRs at 700 °C in a nitrogen atmosphere led to a three-fold increase in Q, a result we attribute to thinning of the diamond layer via reaction with residual O2 in the annealing furnace. Post-anneal Q exceeding 0.5 million (528 000) was measured at the 19 kHz elliptical wineglass modes, producing a ring-down time of 8.9 s. A model for Q versus diamond thickness and resonance frequency is developed including the effects of TED and surface loss. Measured quality factors are shown to agree with the predictions of this model.

  19. Effect of silane/hydrogen ratio on microcrystalline silicon thin films by remote inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Guo, Y. N.; Wei, D. Y.; Xiao, S. Q.; Huang, S. Y.; Zhou, H. P.; Xu, S.

    2013-05-01

    Hydrogenated microcrystalline silicon (μc-Si:H) thin films were prepared by remote low frequency inductively coupled plasma (ICP) chemical vapor deposition system, and the effect of silane/hydrogen ratio on the microstructure and electrical properties of μc-Si:H films was systematically investigated. As silane/hydrogen ratio increases, the crystalline volume fraction Fc decreases and the ratio of the intensity of (220) peak to that of (111) peak drops as silane flow rate is increased. The FTIR result indicates that the μc-Si:H films prepared by remote ICP have a high optical response with a low hydrogen content, which is in favor of reducing light-induced degradation effect. Furthermore, the processing window of the phase transition region for remote ICP is much wider than that for typical ICP. The photosensitivity of μc-Si:H films can exceed 100 at the transition region and this ensures the possibility of the fabrication of microcrystalline silicon thin film solar cells with a open-circuit voltage of about 700 mV.

  20. Magnetization and photomagnetic effects in diluted magnetic microcrystalline Cd 1-xMn xTe

    NASA Astrophysics Data System (ADS)

    He, X.-F.; Kotlicki, A.; Dosanjh, P.; Turrell, B. G.; Carolan, J. F.; Jimenez-Sandoval, S.; Lozano-Tovar, P.

    1993-12-01

    We have investigated the magnetic and photomagnetic properties of microcrystalline Cd 1-xMn xTe prepared by rf sputtering. Magnetization measurements were carried out using an rf SQUID magnetometer in the temperature range of 1.8 to 300 K at various magnetic fields up to 5.5 T. For temperatures above 40 K, the sample showed Curie-Weiss behaviour with a Curie temperature indicating predominantly antiferromagnetic interactions. A spin-glass phase transition was also observed. Photomagnetization measurements were performed using a fibre-optic system. The light was shone onto the sample utilizing an optical fibre and the subsequent change in the magnetization was sensed by the SQUID. Photo-induced magnetization was observed when the sample was illuminated by unpolarized light. Our results enable qualitative and quantitative conclusions to be drawn on the magnetic behaviour and the interplay between optical and magnetic properties of the diluted magnetic microcrystalline semiconductors. PACS: 68.55.Gi; 75.50.Pp.

  1. Microcrystalline diamond cylindrical resonators with quality-factor up to 0.5 million

    SciTech Connect

    Saito, Daisuke; Yang, Chen; Lin, Liwei

    2016-02-01

    We demonstrate high quality-factor 1.5 mm diameter batch-fabricated microcrystalline diamond cylindrical resonators (CR) with quality-factors limited by thermoelastic damping (TED) and surface loss. Resonators were fabricated 2.6 and 5.3 μm thick in-situ boron-doped microcrystalline diamond films deposited using hot filament chemical vapor deposition. The quality-factor (Q) of as-fabricated CR's was found to increase with the resonator diameter and diamond thickness. Annealing the CRs at 700 °C in a nitrogen atmosphere led to a three-fold increase in Q, a result we attribute to thinning of the diamond layer via reaction with residual O{sub 2} in the annealing furnace. Post-anneal Q exceeding 0.5 million (528 000)more » was measured at the 19 kHz elliptical wineglass modes, producing a ring-down time of 8.9 s. A model for Q versus diamond thickness and resonance frequency is developed including the effects of TED and surface loss. Measured quality factors are shown to agree with the predictions of this model.« less

  2. Broadband absorption enhancement in plasmonic nanoshells-based ultrathin microcrystalline-Si solar cells

    NASA Astrophysics Data System (ADS)

    Raja, Waseem; Bozzola, Angelo; Zilio, Pierfrancesco; Miele, Ermanno; Panaro, Simone; Wang, Hai; Toma, Andrea; Alabastri, Alessandro; de Angelis, Francesco; Zaccaria, Remo Proietti

    2016-04-01

    With the objective to conceive a plasmonic solar cell with enhanced photocurrent, we investigate the role of plasmonic nanoshells, embedded within a ultrathin microcrystalline silicon solar cell, in enhancing broadband light trapping capability of the cell and, at the same time, to reduce the parasitic loss. The thickness of the considered microcrystalline silicon (μc-Si) layer is only ~1/6 of conventional μc-Si based solar cells while the plasmonic nanoshells are formed by a combination of silica and gold, respectively core and shell. We analyze the cell optical response by varying both the geometrical and optical parameters of the overall device. In particular, the nanoshells core radius and metal thickness, the periodicity, the incident angle of the solar radiation and its wavelength are varied in the widest meaningful ranges. We further explain the reason for the absorption enhancement by calculating the electric field distribution associated to resonances of the device. We argue that both Fabry-Pérot-like and localized plasmon modes play an important role in this regard.

  3. Approaching zero cellulose loss in cellulose nanocrystal (CNC) production: recovery and characterization of cellulosic solid residues (CSR) and CNC

    Treesearch

    Q.Q. Wang; J.Y. Zhu; R.S. Reiner; S.P. Verrill; U. Baxa; S.E. McNeil

    2012-01-01

    This study demonstrated the potential of simultaneously recovering cellulosic solid residues (CSR) and producing cellulose nanocrystals (CNCs) by strong sulfuric acid hydrolysis to minimize cellulose loss to near zero. A set of slightly milder acid hydrolysis conditions than that considered as “optimal” were used to significantly minimize the degradation of cellulose...

  4. Cellulose Derivatives for Water Repellent Properties

    USDA-ARS?s Scientific Manuscript database

    Synthesis and structural characterizations of nitro-benzyl cellulose, amino-benzyl cellulose and pentafluoro –benzyl cellulose were carried out. Cellulose derivatives were synthesized by etherification process in lithium chloride/N,N-dimethylacetamide homogeneous solution. Nitrobenzylation was effec...

  5. Structure of the Cellulose Synthase Complex of Gluconacetobacter hansenii at 23.4 Å Resolution

    PubMed Central

    Du, Juan; Vepachedu, Venkata; Cho, Sung Hyun; Kumar, Manish; Nixon, B. Tracy

    2016-01-01

    Bacterial crystalline cellulose is used in biomedical and industrial applications, but the molecular mechanisms of synthesis are unclear. Unlike most bacteria, which make non-crystalline cellulose, Gluconacetobacter hansenii extrudes profuse amounts of crystalline cellulose. Its cellulose synthase (AcsA) exists as a complex with accessory protein AcsB, forming a 'terminal complex' (TC) that has been visualized by freeze-fracture TEM at the base of ribbons of crystalline cellulose. The catalytic AcsAB complex is embedded in the cytoplasmic membrane. The C-terminal portion of AcsC is predicted to form a translocation channel in the outer membrane, with the rest of AcsC possibly interacting with AcsD in the periplasm. It is thus believed that synthesis from an organized array of TCs coordinated with extrusion by AcsC and AcsD enable this bacterium to make crystalline cellulose. The only structural data that exist for this system are the above mentioned freeze-fracture TEM images, fluorescence microscopy images revealing that TCs align in a row, a crystal structure of AcsD bound to cellopentaose, and a crystal structure of PilZ domain of AcsA. Here we advance our understanding of the structural basis for crystalline cellulose production by bacterial cellulose synthase by determining a negative stain structure resolved to 23.4 Å for highly purified AcsAB complex that catalyzed incorporation of UDP-glucose into β-1,4-glucan chains, and responded to the presence of allosteric activator cyclic diguanylate. Although the AcsAB complex was functional in vitro, the synthesized cellulose was not visible in TEM. The negative stain structure revealed that AcsAB is very similar to that of the BcsAB synthase of Rhodobacter sphaeroides, a non-crystalline cellulose producing bacterium. The results indicate that the crystalline cellulose producing and non-crystalline cellulose producing bacteria share conserved catalytic and membrane translocation components, and support the

  6. Structure of the cellulose synthase complex of Gluconacetobacter hansenii at 23.4 Å resolution

    DOE PAGES

    Du, Juan; Vepachedu, Venkata; Cho, Sung Hyun; ...

    2016-05-23

    Bacterial crystalline cellulose is used in biomedical and industrial applications, but the molecular mechanisms of synthesis are unclear. Unlike most bacteria, which make non-crystalline cellulose, Gluconacetobacter hansenii extrudes profuse amounts of crystalline cellulose. Its cellulose synthase (AcsA) exists as a complex with accessory protein AcsB, forming a 'terminal complex' (TC) that has been visualized by freeze-fracture TEM at the base of ribbons of crystalline cellulose. The catalytic AcsAB complex is embedded in the cytoplasmic membrane. The C-terminal portion of AcsC is predicted to form a translocation channel in the outer membrane, with the rest of AcsC possibly interacting with AcsDmore » in the periplasm. It is thus believed that synthesis from an organized array of TCs coordinated with extrusion by AcsC and AcsD enable this bacterium to make crystalline cellulose. The only structural data that exist for this system are the above mentioned freeze-fracture TEM images, fluorescence microscopy images revealing that TCs align in a row, a crystal structure of AcsD bound to cellopentaose, and a crystal structure of PilZ domain of AcsA. Here we advance our understanding of the structural basis for crystalline cellulose production by bacterial cellulose synthase by determining a negative stain structure resolved to 23.4 angstrom for highly purified AcsAB complex that catalyzed incorporation of UDP-glucose into β-1,4-glucan chains, and responded to the presence of allosteric activator cyclic diguanylate. Although the AcsAB complex was functional in vitro, the synthesized cellulose was not visible in TEM. The negative stain structure revealed that AcsAB is very similar to that of the BcsAB synthase of Rhodobacter sphaeroides, a non-crystalline cellulose producing bacterium. Furthermore, the results indicate that the crystalline cellulose producing and non-crystalline cellulose producing bacteria share conserved catalytic and membrane translocation

  7. Structure of the cellulose synthase complex of Gluconacetobacter hansenii at 23.4 Å resolution

    SciTech Connect

    Du, Juan; Vepachedu, Venkata; Cho, Sung Hyun

    Bacterial crystalline cellulose is used in biomedical and industrial applications, but the molecular mechanisms of synthesis are unclear. Unlike most bacteria, which make non-crystalline cellulose, Gluconacetobacter hansenii extrudes profuse amounts of crystalline cellulose. Its cellulose synthase (AcsA) exists as a complex with accessory protein AcsB, forming a 'terminal complex' (TC) that has been visualized by freeze-fracture TEM at the base of ribbons of crystalline cellulose. The catalytic AcsAB complex is embedded in the cytoplasmic membrane. The C-terminal portion of AcsC is predicted to form a translocation channel in the outer membrane, with the rest of AcsC possibly interacting with AcsDmore » in the periplasm. It is thus believed that synthesis from an organized array of TCs coordinated with extrusion by AcsC and AcsD enable this bacterium to make crystalline cellulose. The only structural data that exist for this system are the above mentioned freeze-fracture TEM images, fluorescence microscopy images revealing that TCs align in a row, a crystal structure of AcsD bound to cellopentaose, and a crystal structure of PilZ domain of AcsA. Here we advance our understanding of the structural basis for crystalline cellulose production by bacterial cellulose synthase by determining a negative stain structure resolved to 23.4 angstrom for highly purified AcsAB complex that catalyzed incorporation of UDP-glucose into β-1,4-glucan chains, and responded to the presence of allosteric activator cyclic diguanylate. Although the AcsAB complex was functional in vitro, the synthesized cellulose was not visible in TEM. The negative stain structure revealed that AcsAB is very similar to that of the BcsAB synthase of Rhodobacter sphaeroides, a non-crystalline cellulose producing bacterium. Furthermore, the results indicate that the crystalline cellulose producing and non-crystalline cellulose producing bacteria share conserved catalytic and membrane translocation

  8. Magnetic cellulose-derivative structures

    DOEpatents

    Walsh, M.A.; Morris, R.S.

    1986-09-16

    Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorption agents can be incorporated during the manufacture of the structure. 3 figs.

  9. Magnetic cellulose-derivative structures

    DOEpatents

    Walsh, Myles A.; Morris, Robert S.

    1986-09-16

    Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorbtion agents can be incorporated during the manufacture of the structure.

  10. Acetone-based cellulose solvent.

    PubMed

    Kostag, Marc; Liebert, Tim; Heinze, Thomas

    2014-08-01

    Acetone containing tetraalkylammonium chloride is found to be an efficient solvent for cellulose. The addition of an amount of 10 mol% (based on acetone) of well-soluble salt triethyloctylammonium chloride (Et3 OctN Cl) adjusts the solvent's properties (increases the polarity) to promote cellulose dissolution. Cellulose solutions in acetone/Et3 OctN Cl have the lowest viscosity reported for comparable aprotic solutions making it a promising system for shaping processes and homogeneous chemical modification of the biopolymer. Recovery of the polymer and recycling of the solvent components can be easily achieved. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Thermophilic degradation of cellulosic biomass

    NASA Astrophysics Data System (ADS)

    Ng, T.; Zeikus, J. G.

    1982-12-01

    The conversion of cellulosic biomass to chemical feedstocks and fuel by microbial fermentation is an important objective of developing biotechnology. Direct fermentation of cellulosic derivatives to ethanol by thermophilic bacteria offers a promising approach to this goal. Fermentations at elevated temperatures lowers the energy demand for cooling and also facilitates the recovery of volatile products. In addition, thermophilic microorganisms possess enzymes with greater stability than those from mesophilic microorganisms. Three anaerobic thermophilic cocultures that ferment cellulosic substrate mainly to ethanol have been described: Clostridium thermocellum/Clostriidium thermohydrosulfuricum, C. thermocellum/Clostridium thermosaccharolyticum, and C. thermocellum/Thermoanaerobacter ethanolicus sp. nov. The growth characteristics and metabolic features of these cocultures are reviewed.

  12. Method of fabricating n-type and p-type microcrystalline semiconductor alloy material including band gap widening elements

    DOEpatents

    Guha, Subhendu; Ovshinsky, Stanford R.

    1990-02-02

    A method of fabricating doped microcrystalline semiconductor alloy material which includes a band gap widening element through a glow discharge deposition process by subjecting a precursor mixture which includes a diluent gas to an a.c. glow discharge in the absence of a magnetic field of sufficient strength to induce electron cyclotron resonance.

  13. Cellulose microfibril structure: inspirations from plant diversity

    NASA Astrophysics Data System (ADS)

    Roberts, A. W.

    2018-03-01

    Cellulose microfibrils are synthesized at the plasma membrane by cellulose synthase catalytic subunits that associate to form cellulose synthesis complexes. Variation in the organization of these complexes underlies the variation in cellulose microfibril structure among diverse organisms. However, little is known about how the catalytic subunits interact to form complexes with different morphologies. We are using an evolutionary approach to investigate the roles of different catalytic subunit isoforms in organisms that have rosette-type cellulose synthesis complexes.

  14. Synthesis of Cellulose-2,3-bis(3,5-dimethylphenylcarbamate) in an Ionic Liquid and Its Chiral Separation Efficiency as Stationary Phase

    PubMed Central

    Liu, Runqiang; Zhang, Yijun; Bai, Lianyang; Huang, Mingxian; Chen, Jun; Zhang, Yuping

    2014-01-01

    A chiral selector of cellulose-2,3-bis(3,5-dimethylphenylcarbamate) (CBDMPC) was synthesized by reacting 3,5-dimethylphenyl isocyanate with microcrystalline cellulose dissolved in an ionic liquid of 1-allyl-3-methyl-imidazolium chloride (AMIMCl). The obtained chiral selector was effectively characterized by infrared spectroscopy, elemental analysis and 1H NMR. The selector was reacted with 3-aminopropylsilanized silica gel and the CBDMPC bonded chiral stationary phase (CSP) was obtained. Chromatographic evaluation of the prepared CSPs was conducted by high performance liquid chromatographic (HPLC) and baseline separation of three typical fungicides including hexaconazole, metalaxyl and myclobutanil was achieved using n-hexane/isopropanol as the mobile phase with a flow rate 1.0 mL/min. Experimental results also showed that AMIMCl could be recycled easily and reused in the preparation of CSPs as an effective reaction media. PMID:24733066

  15. Synthesis of cellulose-2,3-bis(3,5-dimethylphenylcarbamate) in an ionic liquid and its chiral separation efficiency as stationary phase.

    PubMed

    Liu, Runqiang; Zhang, Yijun; Bai, Lianyang; Huang, Mingxian; Chen, Jun; Zhang, Yuping

    2014-04-11

    A chiral selector of cellulose-2,3-bis(3,5-dimethylphenylcarbamate) (CBDMPC) was synthesized by reacting 3,5-dimethylphenyl isocyanate with microcrystalline cellulose dissolved in an ionic liquid of 1-allyl-3-methyl-imidazolium chloride (AMIMCl). The obtained chiral selector was effectively characterized by infrared spectroscopy, elemental analysis and 1H NMR. The selector was reacted with 3-aminopropylsilanized silica gel and the CBDMPC bonded chiral stationary phase (CSP) was obtained. Chromatographic evaluation of the prepared CSPs was conducted by high performance liquid chromatographic (HPLC) and baseline separation of three typical fungicides including hexaconazole, metalaxyl and myclobutanil was achieved using n-hexane/isopropanol as the mobile phase with a flow rate 1.0 mL/min. Experimental results also showed that AMIMCl could be recycled easily and reused in the preparation of CSPs as an effective reaction media.

  16. Chemical and thermal studies on esterification of EDTA with raw cellulose and mercerized cellulose EFB

    NASA Astrophysics Data System (ADS)

    Azamkamal, Fatihah; Zakaria, Sarani; Gan, Sinyee; Kaco, Hatika

    2018-04-01

    Oil palm empty fruit bunch fibre (EFB) was bleached using four stages bleaching sequences (DEED) where D was a bleaching process composed of 1.7 wt% NaClO2 and buffer solution while E was composed of NaOH solution. Raw cellulose and mercerized cellulose which treated with 3.5 N sodium hydroxide were used as a raw material for esterification with ethylenediaminetetraacetic acid (EDTA) and enhancement with acetic acid. The samples of raw cellulose and mercerized cellulose were observed using optical microscope. The thermal properties of raw cellulose and mercerized cellulose esterified with EDTA were studied. The effect of mercerized cellulose on esterification process of EDTA was investigated. The studies suggested that the mercerization process affect the thermal stability of the cellulose. The transmittance of FTIR band showed that raw cellulose gave better esterification product compared to mercerized cellulose. Hence, the mercerization process of cellulose does not improve the esterification of cellulose with EDTA.

  17. Salmonella biofilm formation on Aspergillus niger involves cellulose--chitin interactions.

    PubMed

    Brandl, Maria T; Carter, Michelle Q; Parker, Craig T; Chapman, Matthew R; Huynh, Steven; Zhou, Yaguang

    2011-01-01

    Salmonella cycles between host and nonhost environments, where it can become an active member of complex microbial communities. The role of fungi in the environmental adaptation of enteric pathogens remains relatively unexplored. We have discovered that S. enterica Typhimurium rapidly attaches to and forms biofilms on the hyphae of the common fungus, Aspergillus niger. Several Salmonella enterica serovars displayed a similar interaction, whereas other bacterial species were unable to bind to the fungus. Bacterial attachment to chitin, a major constituent of fungal cell walls, mirrored this specificity. Pre-incubation of S. Typhimurium with N-acetylglucosamine, the monomeric component of chitin, reduced binding to chitin beads by as much as 727-fold and inhibited attachment to A. niger hyphae considerably. A cellulose-deficient mutant of S. Typhimurium failed to attach to chitin beads and to the fungus. Complementation of this mutant with the cellulose operon restored binding to chitin beads to 79% of that of the parental strain and allowed for attachment and biofilm formation on A. niger, indicating that cellulose is involved in bacterial attachment to the fungus via the chitin component of its cell wall. In contrast to cellulose, S. Typhimurium curli fimbriae were not required for attachment and biofilm development on the hyphae but were critical for its stability. Our results suggest that cellulose-chitin interactions are required for the production of mixed Salmonella-A. niger biofilms, and support the hypothesis that encounters with chitinaceous alternate hosts may contribute to the ecological success of human pathogens.

  18. Bacterial Sialidase

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Data shows that elevated sialidase in bacterial vaginosis patients correlates to premature births in women. Bacterial sialidase also plays a significant role in the unusual colonization of Pseudomonas aeruginosa in cystic fibrosis patients. Crystals of Salmonella sialidase have been reproduced and are used for studying the inhibitor-enzyme complexes. These inhibitors may also be used to inhibit a trans-sialidase of Trypanosome cruzi, a very similar enzyme to bacterial sialidase, therefore preventing T. cruzi infection, the causitive agent of Chagas' disease. The Center for Macromolecular Crystallography suggests that inhibitors of bacterial sialidases can be used as prophylactic drugs to prevent bacterial infections in these critical cases.

  19. Cellulose biosynthesis in Acetobacter xylinum

    SciTech Connect

    Lin, F.C.

    1988-01-01

    Time-lapse video microscopy has shown periodic reversals during the synthesis of cellulose. In the presence of Congo Red, Acetobacter produces a band of fine fibrils. The direction of cell movement is perpendicular to the longitudinal axis of cell, and the rate of movement was decreased. A linear row of particles, presumably the cellulose synthesizing complexes, was found on the outer membrane by freeze-fracture technique. During the cell cycle, the increase of particles in linear row, the differentiation to four linear rows and the separation of the linear rows have been observed. A digitonin-solubilized cellulose synthase was prepared from A. xylinum,more » and incubated under conditions known to lead to active in vitro synthesis of 1,4-{beta}-D-glucan polymer. Electron microscopy revealed that clusters of fibrils were assembled within minutes. Individual fibrils are 17 {plus minus} 2 angstroms in diameter. Evidence for the cellulosic composition of newly synthesized fibrils was based on incorporation of tritium from UDP-({sup 3}H) glucose binding of gold-labeled cellobiohydrolase, and an electron diffraction pattern identified as cellulose II polymorph instead of cellulose I.« less

  20. Fungal-type carbohydrate binding modules from the coccolithophore Emiliania huxleyi show binding affinity to cellulose and chitin

    PubMed Central

    Rooijakkers, Bart J. M.

    2018-01-01

    Six fungal-type cellulose binding domains were found in the genome of the coccolithophore Emiliania huxleyi and cloned and expressed in Escherichia coli. Sequence comparison indicate high similarity to fungal cellulose binding domains, raising the question of why these domains exist in coccolithophores. The proteins were tested for binding with cellulose and chitin as ligands, which resulted in the identification of two functional carbohydrate binding modules: EHUX2 and EHUX4. Compared to benchmark fungal cellulose binding domain Cel7A-CBM1 from Trichoderma reesei, these proteins showed slightly lower binding to birch and bacterial cellulose, but were more efficient chitin binders. Finally, a set of cellulose binding domains was created based on the shuffling of one well-functioning and one non-functional domain. These were characterized in order to get more information of the binding domain’s sequence–function relationship, indicating characteristic differences between the molecular basis of cellulose versus chitin recognition. As previous reports have showed the presence of cellulose in coccoliths and here we find functional cellulose binding modules, a possible connection is discussed. PMID:29782536

  1. Fungal-type carbohydrate binding modules from the coccolithophore Emiliania huxleyi show binding affinity to cellulose and chitin.

    PubMed

    Rooijakkers, Bart J M; Ikonen, Martina S; Linder, Markus B

    2018-01-01

    Six fungal-type cellulose binding domains were found in the genome of the coccolithophore Emiliania huxleyi and cloned and expressed in Escherichia coli. Sequence comparison indicate high similarity to fungal cellulose binding domains, raising the question of why these domains exist in coccolithophores. The proteins were tested for binding with cellulose and chitin as ligands, which resulted in the identification of two functional carbohydrate binding modules: EHUX2 and EHUX4. Compared to benchmark fungal cellulose binding domain Cel7A-CBM1 from Trichoderma reesei, these proteins showed slightly lower binding to birch and bacterial cellulose, but were more efficient chitin binders. Finally, a set of cellulose binding domains was created based on the shuffling of one well-functioning and one non-functional domain. These were characterized in order to get more information of the binding domain's sequence-function relationship, indicating characteristic differences between the molecular basis of cellulose versus chitin recognition. As previous reports have showed the presence of cellulose in coccoliths and here we find functional cellulose binding modules, a possible connection is discussed.

  2. Steady-state solution growth of microcrystalline silicon on nanocrystalline seed layers on glass

    NASA Astrophysics Data System (ADS)

    Bansen, R.; Ehlers, C.; Teubner, Th.; Boeck, T.

    2016-09-01

    The growth of polycrystalline silicon layers on glass from tin solutions at low temperatures is presented. This approach is based on the steady-state solution growth of Si crystallites on nanocrystalline seed layers, which are prepared in a preceding process step. Scanning electron microscopy and atomic force microscopy investigations reveal details about the seed layer surfaces, which consist of small hillocks, as well as about Sn inclusions and gaps along the glass substrate after solution growth. The successful growth of continuous microcrystalline Si layers with grain sizes up to several ten micrometers shows the feasibility of the process and makes it interesting for photovoltaics. Project supported by the German Research Foundation (DFG) (No. BO 1129/5-1).

  3. Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis.

    PubMed

    Gan, Patrick; Foord, John S; Compton, Richard G

    2015-10-01

    Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur.

  4. Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis

    PubMed Central

    Gan, Patrick; Foord, John S; Compton, Richard G

    2015-01-01

    Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur. PMID:26491640

  5. A Solar-Blind UV Detector Based on Graphene-Microcrystalline Diamond Heterojunctions.

    PubMed

    Wei, Minsong; Yao, Kaiyuan; Liu, Yumeng; Yang, Chen; Zang, Xining; Lin, Liwei

    2017-09-01

    An ultraviolet detector is demonstrated through a whole-wafer, thin diamond film transfer process to realize the heterojunction between graphene and microcrystalline diamond (MCD). Conventional direct transfer processes fail to deposit graphene onto the top surface of the MCD film. However, it is found that the 2 µm thick MCD diamond film can be easily peeled off from the growth silicon substrate to expose its smooth backside for the graphene transfer process for high-quality graphene/MCD heterojunctions. A vertical graphene/MCD/metal structure is constructed as the photodiode device using graphene as the transparent top electrode for solar-blind ultraviolet sensing with high responsivity and gain factor. As such, this material system and device architecture could serve as the platform for next-generation optoelectronic systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Superconducting Sweet-Spot in Microcrystalline Graphite Revealed by Point-Contact Spectroscopy

    NASA Astrophysics Data System (ADS)

    Arnold, F.; Nyéki, J.; Saunders, J.

    2018-05-01

    In this letter we describe the observation of a magnetic field dependent electronic gap, suggestive of local superconductivity, in the point-contact spectrum of micro-crystalline graphite. Magnetic field dependent point-contact spectroscopy was carried out at a temperature of 1.8K using an etched aluminium tip. At zero field a gap structure in the differential conductance is observed, showing a gap of Δ = 4.2 meV. On applying magnetic fields of up to 500mT, this gap gradually closes, following the theoretical prediction by Ginzburg and Landau for a fully flux-penetrated superconductor. By applying BCS-theory, we infer a critical superconducting temperature of 14K.

  7. Microcrystalline dolomite within massive Japan Sea methane hydrate: origin and development ascertained by inclusions within inclusions.

    NASA Astrophysics Data System (ADS)

    Snyder, G. T.; Kakizaki, Y.; Matsumoto, R.; Suzuki, Y.; Takahata, N.; Sano, Y.; Tanaka, K.; Tomaru, H.; Imajo, T.; Iguchi, A.

    2017-12-01

    Microcrystalline dolomite grains were recently discovered as inclusions within relatively pure massive gas hydrate recovered from the Joetsu Basin area of the Japan Sea. These grains presumably formed as a consequence of the highly saline conditions in fluid inclusions which developed between coalescing grain boundaries within the growing hydrate. Stable carbon and oxygen isotopic composition of the dolomite is consistent with crystal growth occurring within such fluids. In addition to stable isotopes, we investigate trends in Mg/Ca ratios of the grains as well as the composition of inclusions which exist within the dolomites. Preliminary research shows that these inclusions retain valuable information as to the conditions which existed at the time of formation, as well as the dynamics of these extensive hydrate deposits over time. This study was conducted under the commission from AIST as a part of the methane hydrate research project funded by METI (the Ministry of Economy, Trade and Industry, Japan).

  8. Nano- and microcrystalline diamond deposition on pretreated WC-Co substrates: structural properties and adhesion

    NASA Astrophysics Data System (ADS)

    Fraga, M. A.; Contin, A.; Rodríguez, L. A. A.; Vieira, J.; Campos, R. A.; Corat, E. J.; Trava Airoldi, V. J.

    2016-02-01

    Many developments have been made to improve the quality and adherence of CVD diamond films onto WC-Co hard metal tools by the removing the cobalt from the substrate surface through substrate pretreatments. Here we compare the efficiency of three chemical pretreatments of WC-Co substrates for this purpose. First, the work was focused on a detailed study of the composition and structure of as-polished and pretreated substrate surfaces to characterize the effects of the substrate preparation. Considering this objective, a set of WC-9% Co substrates, before and after pretreatment, was analyzed by FEG-SEM, EDS and x-ray diffraction (XRD). The second stage of the work was devoted to the evaluation of the influence of seeding process, using 4 nm diamond nanoparticles, on the morphology and roughness of the pretreated substrates. The last and most important stage was to deposit diamond coatings with different crystallite sizes (nano and micro) by hot-filament CVD to understand fully the mechanism of growth and adhesion of CVD diamond films on pretreated WC-Co substrates. The transition from nano to microcrystalline diamond was achieved by controlling the CH4/H2 gas ratio. The nano and microcrystalline samples were grown under same time at different substrate temperatures 600 °C and 800 °C, respectively. The different substrate temperatures allowed the analysis of the cobalt diffusion from the bulk to the substrate surface during CVD film growth. Furthermore, it was possible to evaluate how the coating adhesion is affected by the diffusion. The diamond coatings were characterized by Raman spectroscopy, XRD, EDS, FEG-SEM, atomic force microscope and 1500 N Rockwell indentation to evaluate the adhesion.

  9. Cellulose production in Pseudomonas syringae pv. syringae: a compromise between epiphytic and pathogenic lifestyles.

    PubMed

    Arrebola, Eva; Carrión, Víctor J; Gutiérrez-Barranquero, José Antonio; Pérez-García, Alejandro; Rodríguez-Palenzuela, Pablo; Cazorla, Francisco M; de Vicente, Antonio

    2015-07-01

    Genome sequencing and annotation have revealed a putative cellulose biosynthetic operon in the strain Pseudomonas syringae pv. syringae UMAF0158, the causal agent of bacterial apical necrosis. Bioinformatics analyses and experimental methods were used to confirm the functionality of the cellulose biosynthetic operon. In addition, the results showed the contribution of the cellulose operon to important aspects of P. syringae pv. syringae biology, such as the formation of biofilms and adhesion to the leaf surface of mango, suggesting that this operon increases epiphytic fitness. However, based on the incidence and severity of the symptoms observed in tomato leaflets, cellulose expression reduces virulence, as cellulose-deficient mutants increased the area of necrosis, whereas the cellulose-overproducing strain decreased the area of necrosis compared with the wild type. In conclusion, the results of this study show that the epiphytic and pathogenic stages of the P. syringae pv. syringae UMAF0158 lifestyle are intimately affected by cellulose production. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. The disulfide bonding system suppresses CsgD-independent cellulose production in Escherichia coli.

    PubMed

    Hufnagel, David A; DePas, William H; Chapman, Matthew R

    2014-11-01

    The bacterial extracellular matrix encases cells and protects them from host-related and environmental insults. The Escherichia coli master biofilm regulator CsgD is required for the production of the matrix components curli and cellulose. CsgD activates the diguanylate cyclase AdrA, which in turn stimulates cellulose production through cyclic di-GMP (c-di-GMP). Here, we identified and characterized a CsgD- and AdrA-independent cellulose production pathway that was maximally active when cultures were grown under reducing conditions or when the disulfide bonding system (DSB) was compromised. The CsgD-independent cellulose activation pathway was dependent on a second diguanylate cyclase, called YfiN. c-di-GMP production by YfiN was repressed by the periplasmic protein YfiR, and deletion of yfiR promoted CsgD-independent cellulose production. Conversely, when YfiR was overexpressed, cellulose production was decreased. Finally, we found that YfiR was oxidized by DsbA and that intraprotein YfiR disulfide bonds stabilized YfiR in the periplasm. Altogether, we showed that reducing conditions and mutations in the DSB system caused hyperactivation of YfiN and subsequent CsgD-independent cellulose production. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  11. Quantitative analysis of cellulose degradation and growth of cellulolytic bacteria in the rumen.

    PubMed

    Russell, James B; Muck, Richard E; Weimer, Paul J

    2009-02-01

    Ruminant animals digest cellulose via a symbiotic relationship with ruminal microorganisms. Because feedstuffs only remain in the rumen for a short time, the rate of cellulose digestion must be very rapid. This speed is facilitated by rumination, a process that returns food to the mouth to be rechewed. By decreasing particle size, the cellulose surface area can be increased by up to 10(6)-fold. The amount of cellulose digested is then a function of two competing rates, namely the digestion rate (K(d)) and the rate of passage of solids from the rumen (K(p)). Estimation of bacterial growth on cellulose is complicated by several factors: (1) energy must be expended for maintenance and growth of the cells, (2) only adherent cells are capable of degrading cellulose and (3) adherent cells can provide nonadherent cells with cellodextrins. Additionally, when ruminants are fed large amounts of cereal grain along with fiber, ruminal pH can decrease to a point where cellulolytic bacteria no longer grow. A dynamic model based on STELLA software is presented. This model evaluates all of the major aspects of ruminal cellulose degradation: (1) ingestion, digestion and passage of feed particles, (2) maintenance and growth of cellulolytic bacteria and (3) pH effects.

  12. The Disulfide Bonding System Suppresses CsgD-Independent Cellulose Production in Escherichia coli

    PubMed Central

    Hufnagel, David A.; DePas, William H.

    2014-01-01

    The bacterial extracellular matrix encases cells and protects them from host-related and environmental insults. The Escherichia coli master biofilm regulator CsgD is required for the production of the matrix components curli and cellulose. CsgD activates the diguanylate cyclase AdrA, which in turn stimulates cellulose production through cyclic di-GMP (c-di-GMP). Here, we identified and characterized a CsgD- and AdrA-independent cellulose production pathway that was maximally active when cultures were grown under reducing conditions or when the disulfide bonding system (DSB) was compromised. The CsgD-independent cellulose activation pathway was dependent on a second diguanylate cyclase, called YfiN. c-di-GMP production by YfiN was repressed by the periplasmic protein YfiR, and deletion of yfiR promoted CsgD-independent cellulose production. Conversely, when YfiR was overexpressed, cellulose production was decreased. Finally, we found that YfiR was oxidized by DsbA and that intraprotein YfiR disulfide bonds stabilized YfiR in the periplasm. Altogether, we showed that reducing conditions and mutations in the DSB system caused hyperactivation of YfiN and subsequent CsgD-independent cellulose production. PMID:25112475

  13. Nanomechanics of cellulose crystals and cellulose-based polymer composites

    NASA Astrophysics Data System (ADS)

    Pakzad, Anahita

    Cellulose-polymer composites have potential applications in aerospace and transportation areas where lightweight materials with high mechanical properties are needed. In addition, these economical and biodegradable composites have been shown to be useful as polymer electrolytes, packaging structures, optoelectronic devices, and medical implants such as wound dressing and bone scaffolds. In spite of the above mentioned advantages and potential applications, due to the difficulties associated with synthesis and processing techniques, application of cellulose crystals (micro and nano sized) for preparation of new composite systems is limited. Cellulose is hydrophilic and polar as opposed to most of common thermoplastics, which are non-polar. This results in complications in addition of cellulose crystals to polymer matrices, and as a result in achieving sufficient dispersion levels, which directly affects the mechanical properties of the composites. As in other composite materials, the properties of cellulose-polymer composites depend on the volume fraction and the properties of individual phases (the reinforcement and the polymer matrix), the dispersion quality of the reinforcement through the matrix and the interaction between CNCs themselves and CNC and the matrix (interphase). In order to develop economical cellulose-polymer composites with superior qualities, the properties of individual cellulose crystals, as well as the effect of dispersion of reinforcements and the interphase on the properties of the final composites should be understood. In this research, the mechanical properties of CNC polymer composites were characterized at the macro and nano scales. A direct correlation was made between: - Dispersion quality and macro-mechanical properties - Nanomechanical properties at the surface and tensile properties - CNC diameter and interphase thickness. Lastly, individual CNCs from different sources were characterized and for the first time size-scale effect on

  14. Characterization of cellulose degrading bacteria from the larval gut of the white grub beetle Lepidiota mansueta (Coleoptera: Scarabaeidae).

    PubMed

    Handique, Gautam; Phukan, Amrita; Bhattacharyya, Badal; Baruah, Abu Adil Lutful Haque; Rahman, Syed Wasifur; Baruah, Rajen

    2017-02-01

    The goal of this study is to identify and characterize the cellulose degrading microorganisms in the larval gut of the white grub beetle, Lepidiota mansueta. Thirty bacterial strains were isolated and tested for cellulolytic activity using soluble carboxymethyl cellulose (CMC) degrading assays. Of these strains, five (FGB1, FB2, MB1, MB2, and HB1) degrade cellulose. Cellulolytic activity was determined based on formation of clear zone and cellulolytic index on CMC plate media. The highest cellulolytic index (2.14) was found in FGB1. Partial 16S rDNA sequencing, morphological, and biochemical tests were used to identify and characterize the five isolates, all Citrobacter sp. (Enterobacteriaceae). This study identifies new cellulose degrading microorganisms from the larval gut of L. mansueta. The significance of identifying these strains lies in possible application in cellulose degradation. © 2017 Wiley Periodicals, Inc.

  15. Ionic liquid processing of cellulose.

    PubMed

    Wang, Hui; Gurau, Gabriela; Rogers, Robin D

    2012-02-21

    Utilization of natural polymers has attracted increasing attention because of the consumption and over-exploitation of non-renewable resources, such as coal and oil. The development of green processing of cellulose, the most abundant biorenewable material on Earth, is urgent from the viewpoints of both sustainability and environmental protection. The discovery of the dissolution of cellulose in ionic liquids (ILs, salts which melt below 100 °C) provides new opportunities for the processing of this biopolymer, however, many fundamental and practical questions need to be answered in order to determine if this will ultimately be a green or sustainable strategy. In this critical review, the open fundamental questions regarding the interactions of cellulose with both the IL cations and anions in the dissolution process are discussed. Investigations have shown that the interactions between the anion and cellulose play an important role in the solvation of cellulose, however, opinions on the role of the cation are conflicting. Some researchers have concluded that the cations are hydrogen bonding to this biopolymer, while others suggest they are not. Our review of the available data has led us to urge the use of more chemical units of solubility, such as 'g cellulose per mole of IL' or 'mol IL per mol hydroxyl in cellulose' to provide more consistency in data reporting and more insight into the dissolution mechanism. This review will also assess the greenness and sustainability of IL processing of biomass, where it would seem that the choices of cation and anion are critical not only to the science of the dissolution, but to the ultimate 'greenness' of any process (142 references).

  16. Preparation and physical properties of tara gum film reinforced with cellulose nanocrystals.

    PubMed

    Ma, Qianyun; Hu, Dongying; Wang, Lijuan

    2016-05-01

    Cellulose nanocrystals (CNC) prepared from microcrystalline cellulose were blended in tara gum solution to prepare nanocomposite films. The morphology, crystallinity, and thermal properties of the CNC and films were evaluated by using transmission electron microscopy, X-ray diffractometry, and thermogravimetric analysis, respectively. The resultant CNC was rod-shaped with diameters of around 8.6 nm. The effect of CNC content on physical and thermal properties of films was studied. The composite film tensile strength increased from 27.86 to 65.73 MPa, elastic modulus increased from 160.98 MPa to 882.49 MPa and the contact angle increased from 55.8° to 98.7° with increasing CNC content from 0 to 6 wt%. However, CNC addition increased the thermal stability slightly and CNC content above 6 wt% decreased the tensile strength by CNC aggregation in the matrix. The nanocomposite film containing 6 wt% CNC possessed the highest light transmittance, mechanical properties, and lowest oxygen permeability. CNC addition is a suitable method to modify tara gum matrix polymer properties. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Partial replacement effect of montmorillonite with cellulose nanowhiskers on polylactic acid nanocomposites.

    PubMed

    Arjmandi, Reza; Hassan, Azman; Mohamad Haafiz, M K; Zakaria, Zainoha

    2015-11-01

    In this study, hybrid montmorillonite/cellulose nanowhiskers (MMT/CNW) reinforced polylactic acid (PLA) nanocomposites were produced through solution casting. The CNW filler was first isolated from microcrystalline cellulose by chemical swelling technique. The partial replacement of MMT with CNW in order to produce PLA/MMT/CNW hybrid nanocomposites was performed at 5 parts per hundred parts of polymer (phr) fillers content, based on highest tensile strength values as reported in our previous study. MMT were partially replaced with various amounts of CNW (1, 2, 3, 4 and 5phr). The tensile, thermal, morphological and biodegradability properties of PLA hybrid nanocomposites were investigated. The highest tensile strength of hybrid nanocomposites was obtained with the combination of 4phr MMT and 1phr CNW. Interestingly, the ductility of hybrid nanocomposites increased significantly by 79% at this formulation. The Young's modulus increased linearly with increasing CNW content. Thermogravimetric analysis illustrated that the partial replacement of MMT with CNW filler enhanced the thermal stability of the PLA. This is due to the relatively good dispersion of fillers in the hybrid nanocomposites samples as revealed by transmission electron microscopy. Interestingly, partial replacements of MMT with CNW improved the biodegradability of hybrid nanocomposites compared to PLA/MMT and neat PLA. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Effect of hydrolysed cellulose nanowhiskers on properties of montmorillonite/polylactic acid nanocomposites.

    PubMed

    Arjmandi, Reza; Hassan, Azman; Haafiz, M K M; Zakaria, Zainoha; Islam, Md Saiful

    2016-01-01

    Polylactic acid (PLA) nanocomposites reinforced with hybrid montmorillonite/cellulose nanowhiskers [MMT/CNW(SO4)] were prepared by solution casting. The CNW(SO4) nanofiller was first isolated from microcrystalline cellulose using acid hydrolysis treatment. PLA/MMT/CNW(SO4) hybrid nanocomposites were prepared by the addition of various amounts of CNW(SO4) [1-9 parts per hundred parts of polymer (phr)] into PLA/MMT nanocomposite at 5 phr MMT content, based on highest tensile strength values as reported previously. The biodegradability, thermal, tensile, morphological, water absorption and transparency properties of PLA/MMT/CNW(SO4) hybrid nanocomposites were investigated. The Biodegradability, thermal stability and crystallinity of hybrid nanocomposites increased compared to PLA/MMT nanocomposite and neat PLA. The highest tensile strength of hybrid nanocomposites was obtained by incorporating 1 phr CNW(SO4) [∼ 36 MPa]. Interestingly, the ductility of hybrid nanocomposites increased significantly by 87% at this formulation. The Young's modulus increased linearly with increasing CNW(SO4) content. This is due to the relatively good dispersion of nanofillers in the hybrid nanocomposites, as revealed by transmission electron microscopy. Fourier transform infrared spectroscopy indicated the formation of some polar interactions. In addition, water resistance of the hybrid nanocomposites improved and the visual transparency of neat PLA film did not affect by addition of CNW(SO4). Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Ruminococcus champanellensis sp. nov., a cellulose-degrading bacterium from human gut microbiota.

    PubMed

    Chassard, Christophe; Delmas, Eve; Robert, Céline; Lawson, Paul A; Bernalier-Donadille, Annick

    2012-01-01

    A strictly anaerobic, cellulolytic strain, designated 18P13(T), was isolated from a human faecal sample. Cells were Gram-positive non-motile cocci. Strain 18P13(T) was able to degrade microcrystalline cellulose but the utilization of soluble sugars was restricted to cellobiose. Acetate and succinate were the major end products of cellulose and cellobiose fermentation. 16S rRNA gene sequence analysis revealed that the isolate belonged to the genus Ruminococcus of the family Ruminococcaceae. The closest phylogenetic relative was the ruminal cellulolytic strain Ruminococcus flavefaciens ATCC 19208(T) (<95% 16S rRNA gene sequence similarity). The DNA G+C content of strain 18P13(T) was 53.05±0.7 mol%. On the basis of phylogenetic analysis, and morphological and physiological data, strain 18P13(T) can be differentiated from other members of the genus Ruminococcus with validly published names. The name Ruminococcus champanellensis sp. nov. is proposed, with 18P13(T) (=DSM 18848(T)=JCM 17042(T)) as the type strain.

  20. Cellulose Biorefinery Based on a Combined Catalytic and Biotechnological Approach for Production of 5-HMF and Ethanol.

    PubMed

    Sorokina, Ksenia N; Taran, Oxana P; Medvedeva, Tatiana B; Samoylova, Yuliya V; Piligaev, Alexandr V; Parmon, Valentin N

    2017-02-08

    In this study, a combination of catalytic and biotechnological processes was proposed for the first time for application in a cellulose biorefinery for the production of 5-hydroxymethylfurfural (5-HMF) and bioethanol. Hydrolytic dehydration of the mechanically activated microcrystalline cellulose over a carbon-based mesoporous Sibunt-4 catalyst resulted in moderate yields of glucose and 5-HMF (21.1-25.1 and 6.6-9.4 %). 5-HMF was extracted from the resulting mixture with isobutanol and subjected to ethanol fermentation. A number of yeast strains were isolated that also revealed high thermotolerance (up to 50 °C) and resistance to inhibitors found in the hydrolysates. The strains Kluyveromyces marxianus C1 and Ogataea polymorpha CBS4732 were capable of producing ethanol from processed catalytic hydrolysates of cellulose at 42 °C, with yields of 72.0±5.7 and 75.2±4.3 % from the maximum theoretical yield of ethanol, respectively. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Cellulose nanocrystals as templates for cetyltrimethylammonium bromide mediated synthesis of Ag nanoparticles and their novel use in PLA films.

    PubMed

    Yalcinkaya, E E; Puglia, D; Fortunati, E; Bertoglio, F; Bruni, G; Visai, L; Kenny, J M

    2017-02-10

    In the present paper, we reported how cellulose nanocrystals (CNC) from microcrystalline cellulose have the capacity to assist in the synthesis of metallic nanoparticles chains. A cationic surfactant, cetyltrimethylammonium bromide (CTAB), was used as modifier for CNC surface. Silver nanoparticles were synthesized on CNC, and nanoparticle density and size were optimized by varying concentrations of nitrate and reducing agents, and the reduction time. The experimental conditions were optimized for the synthesis and the resulting Ag grafted CNC (Ag-g-CNC) were characterized by means of TGA, SEM, FTIR and XRD, and then introduced in PLA matrix. PLA nanocomposite containing silver grafted cellulose nanocrystals (PLA/0.5Ag-g-1CNC) was characterized by optical and thermal analyses and the obtained data were compared with results from PLA nanocomposites containing 1% wt. of CNC (PLA/1CNC), 0.5% wt. of silver nanoparticles (PLA/0.5Ag) and hybrid system containing CNC and silver in the same amount (PLA/1CNC/0.5Ag). The results demonstrated that grafting of silver nanoparticles on CNC positively affected the thermal degradation process and cold crystallization processes of PLA matrix. Finally, the antibacterial activity of the different systems was studied at various incubation times and temperatures, showing the best performance for PLA/1CNC/0.5Ag based nanocomposite. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. An alkaline thermostable recombinant Humicola grisea var. thermoidea cellobiohydrolase presents bifunctional (endo/exoglucanase) activity on cellulosic substrates.

    PubMed

    Oliveira, G S; Ulhoa, C J; Silveira, M H L; Andreaus, J; Silva-Pereira, I; Poças-Fonseca, M J; Faria, F P

    2013-01-01

    Humicola grisea var. thermoidea is a deuteromycete which secretes a large spectrum of hydrolytic enzymes when grown on lignocellulosic residues. This study focused on the heterologous expression and recombinant enzyme analysis of the major secreted cellulase when the fungus is grown on sugarcane bagasse as the sole carbon source. Cellobiohydrolase 1.2 (CBH 1.2) cDNA was cloned in Pichia pastoris under control of the AOX1 promoter. Recombinant protein (rCBH1.2) was efficiently produced and secreted as a functional enzyme, presenting a molecular mass of 47 kDa. Maximum enzyme production was achieved at 96 h, in culture medium supplemented with 1.34 % urea and 1 % yeast extract and upon induction with 1 % methanol. Recombinant enzyme exhibited optimum activity at 60 °C and pH 8, and presented a remarkable thermostability, particularly at alkaline pH. Activity was evaluated on different cellulosic substrates (carboxymethyl cellulose, filter paper, microcrystalline cellulose and 4-para-nitrophenyl β-D-glucopyranoside). Interestingly, rCBH1.2 presented both exoglucanase and endoglucanase activities and mechanical agitation increased substrate hydrolysis. Results indicate that rCBH1.2 is a potential biocatalyst for applications in the textile industry or detergent formulation.

  3. One-Step Production of Amphiphilic Nanofibrillated Cellulose Using a Cellulose-Producing Bacterium.

    PubMed

    Tajima, Kenji; Kusumoto, Ryo; Kose, Ryota; Kono, Hiroyuki; Matsushima, Tokuo; Isono, Takuya; Yamamoto, Takuya; Satoh, Toshifumi

    2017-10-09

    Nanofibrillated bacterial cellulose (NFBC) is produced by culturing a cellulose-producing bacterium (Gluconacetobacter intermedius NEDO-01) with rotation or agitation in medium supplemented with carboxymethylcellulose (CMC). Despite a high yield and dispersibility in water, the product immediately aggregates in organic solvents. To broaden its applicability, we prepared amphiphilic NFBC by culturing strain NEDO-01 in medium supplemented with hydroxyethylcellulose or hydroxypropylcellulose instead of CMC. Transmission electron microscopy analysis revealed that the resultant materials (HE-NFBC and HP-NFBC, respectively) comprised relatively uniform fibers with diameters of 33 ± 7 and 42 ± 8 nm, respectively. HP-NFBC was dispersible in polar organic solvents such as methanol, acetone, isopropyl alcohol, acetonitrile, tetrahydrofuran (THF), and dimethylformamide, and was also dispersible in poly(methyl methacrylate) (PMMA) by solvent mixing using THF. HP-NFBC/PMMA composite films were highly transparent and had a higher tensile strength than neat PMMA film. Thus, HP-NFBC has a broad range of applications, including as a filler material.

  4. 2013 Cellulosic Biofuel Standard: Direct Final Rule

    EPA Pesticide Factsheets

    The direct final action is to revise the 2013 cellulosic biofuel standard. This action follows from EPA having granted API's and AFPM's petitions for reconsideration of the 2013 cellulosic biofuel standard published on August 15, 2013.

  5. Characterization of Cellulose Synthesis in Plant Cells

    PubMed Central

    Maleki, Samaneh Sadat; Mohammadi, Kourosh; Ji, Kong-shu

    2016-01-01

    Cellulose is the most significant structural component of plant cell wall. Cellulose, polysaccharide containing repeated unbranched β (1-4) D-glucose units, is synthesized at the plasma membrane by the cellulose synthase complex (CSC) from bacteria to plants. The CSC is involved in biosynthesis of cellulose microfibrils containing 18 cellulose synthase (CesA) proteins. Macrofibrils can be formed with side by side arrangement of microfibrils. In addition, beside CesA, various proteins like the KORRIGAN, sucrose synthase, cytoskeletal components, and COBRA-like proteins have been involved in cellulose biosynthesis. Understanding the mechanisms of cellulose biosynthesis is of great importance not only for improving wood production in economically important forest trees to mankind but also for plant development. This review article covers the current knowledge about the cellulose biosynthesis-related gene family. PMID:27314060

  6. Cellulose Modifications and Their Future Application

    USDA-ARS?s Scientific Manuscript database

    In this poster, we will describe the synthesis and structural characterizations of a benzyl-, nitrobenzyl-, and aminobenzyl celluloses. Nitrobenzyl- and aminobenzyl cellulose derivatives are synthesized by etherification process in lithium chloride/N,N-dimethylacetamide homogeneous solution. Nitrobe...

  7. Raman spectroscopy in the analysis of cellulose nanomaterials

    Treesearch

    Umesh P. Agarwal

    2017-01-01

    Cellulose nanomaterials (CNs) are new types of materials derived from celluloses and offer unique challenges and opportunities for Raman spectroscopic investigations. CNs can be classified into the categories of cellulose nanocrystals (CNCs, also known as cellulose whisker) and cellulose nanofibrils (CNFs, also known as nanofibrillated cellulose or NFCs) which when...

  8. Development of nonflammable cellulosic foams

    NASA Technical Reports Server (NTRS)

    Luttinger, M.

    1972-01-01

    The development of a moldable cellulosic foam for use in Skylab instrument storage cushions is considered. Requirements include density of 10 lb cu ft or less, minimal friability with normal handling, and nonflammability in an atmosphere of 70 percent oxygen and 30 percent nitrogen at 6.2 psia. A study of halogenated foam components was made, including more highly chlorinated binders, halogen-containing additives, and halogenation of the cellulose. The immediate objective was to reduce the density of the foam through reduction in inorganic phosphate without sacrificing flame-retarding properties of the foams. The use of frothing techniques was investigated, with particular emphasis on a urea-formaldehyde foam. Halogen-containing flame retardants were deemphasized in favor of inorganic salts and the preparation of phosphate and sulphate esters of cellulose. Utilization of foam products for civilian applications was also considered.

  9. Microbial Cellulose Assembly in Microgravity

    NASA Technical Reports Server (NTRS)

    Brown, R. Malcolm, Jr.

    1998-01-01

    Based on evidence indicating a possible correlation between hypo-gravity conditions and alteration of cellulose production by the gram negative bacterium, Acetobacter xylinum, a ground-based study for a possible long term Space Shuttle flight has been conducted. The proposed experiment for A. xylinum aboard the Shuttle is the BRIC (Biological Research in a Canister), a metal container containing spaces for nine Petri plates. Using a common experimental design, the cellulose production capability as well as the survivability of the A. xylinum strains NQ5 and AY201 have been described. It should now be possible to use the BRIC for the first long term microgravity experiments involving the biosynthesis of cellulose.

  10. Magnetic field effect for cellulose nanofiber alignment

    NASA Astrophysics Data System (ADS)

    Kim, Jaehwan; Chen, Yi; Kang, Kwang-Sun; Park, Young-Bin; Schwartz, Mark

    2008-11-01

    Regenerated cellulose formed into cellulose nanofibers under strong magnetic field and aligned perpendicularly to the magnetic field. Well-aligned microfibrils were found as the exposure time of the magnetic field increased. Better alignment and more crystalline structure of the cellulose resulted in the increased decomposition temperature of the material. X-ray crystallograms showed that crystallinity index of the cellulose increased as the exposure time of the magnetic field increased.

  11. [Bacterial meningitis].

    PubMed

    Brouwer, M C; van de Beek, D

    2012-05-01

    Bacterial meningitis is a severe disease which affects 35.000 Europeans each year and has a mortality rate of about 20%. During the past 25 years the epidemiology of bacterial meningitis has changed significantly due to the implementation of vaccination against Haemophilus influenzae, Neisseria meningtidis group C and Streptococcus pneumoniae. Due to these vaccines, meningitis is now predominantly a disease occurring in adults, caused especially by Streptococcus pneumoniae, while it was formerly a child disease which was largely caused by Haemophilus influenzae. Bacterial meningitis is often difficult to recognize since the classical presentation with neck stiffness, reduced awareness and fever occurs in less than half of the patients. The only way to diagnose or exclude bacterial meningitis is by performing low-threshold cerebrospinal fluid examination with a suspicion of bacterial meningitis. The treatment consists of the prescription of antibiotics and dexamethasone.

  12. Organoselenium coating on cellulose inhibits the formation of biofilms by Pseudomonas aeruginosa and Staphylococcus aureus.

    PubMed

    Tran, Phat L; Hammond, Adrienne A; Mosley, Thomas; Cortez, Janette; Gray, Tracy; Colmer-Hamood, Jane A; Shashtri, Mayank; Spallholz, Julian E; Hamood, Abdul N; Reid, Ted W

    2009-06-01

    Among the most difficult bacterial infections encountered in treating patients are wound infections, which may occur in burn victims, patients with traumatic wounds, necrotic lesions in people with diabetes, and patients with surgical wounds. Within a wound, infecting bacteria frequently develop biofilms. Many current wound dressings are impregnated with antimicrobial agents, such as silver or antibiotics. Diffusion of the agent(s) from the dressing may damage or destroy nearby healthy tissue as well as compromise the effectiveness of the dressing. In contrast, the antimicrobial agent selenium can be covalently attached to the surfaces of a dressing, prolonging its effectiveness. We examined the effectiveness of an organoselenium coating on cellulose discs in inhibiting Pseudomonas aeruginosa and Staphylococcus aureus biofilm formation. Colony biofilm assays revealed that cellulose discs coated with organoselenium completely inhibited P. aeruginosa and S. aureus biofilm formation. Scanning electron microscopy of the cellulose discs confirmed these results. Additionally, the coating on the cellulose discs was stable and effective after a week of incubation in phosphate-buffered saline. These results demonstrate that 0.2% selenium in a coating on cellulose discs effectively inhibits bacterial attachment and biofilm formation and that, unlike other antimicrobial agents, longer periods of exposure to an aqueous environment do not compromise the effectiveness of the coating.

  13. Improved in situ saccharification of cellulose pretreated by dimethyl sulfoxide/ionic liquid using cellulase from a newly isolated Paenibacillus sp. LLZ1.

    PubMed

    Hu, Dongxue; Ju, Xin; Li, Liangzhi; Hu, Cuiying; Yan, Lishi; Wu, Tianyun; Fu, Jiaolong; Qin, Ming

    2016-02-01

    A cellulase producing strain was newly isolated from soil samples and identified as Paenibacillus sp. LLZ1. A novel aqueous-dimethyl sulfoxide (DMSO)/1-ethyl-3-methylimidazolium diethyl phosphate ([Emin]DEP)-cellulase system was designed and optimized. In the pretreatment, DMSO was found to be a low-cost substitute of up to 70% ionic liquid to enhance the cellulose dissolution. In the enzymatic saccharification, the optimum pH and temperature of the Paenibacillus sp. LLZ1 cellulase were identified as 6.0 and 40°C, respectively. Under the optimized reaction condition, the conversion of microcrystalline cellulose and bagasse cellulose increased by 39.3% and 37.6%, compared with unpretreated cellulose. Compared to current methods of saccharification, this new approach has several advantages including lower operating temperature, milder pH, and less usage of ionic liquid, indicating a marked progress in environmental friendly hydrolysis of biomass-based materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. CelR, an Ortholog of the Diguanylate Cyclase PleD of Caulobacter, Regulates Cellulose Synthesis in Agrobacterium tumefaciens

    PubMed Central

    Barnhart, D. Michael; Su, Shengchang; Baccaro, Brenna E.; Banta, Lois M.

    2013-01-01

    Cellulose fibrils play a role in attachment of Agrobacterium tumefaciens to its plant host. While the genes for cellulose biosynthesis in the bacterium have been identified, little is known concerning the regulation of the process. The signal molecule cyclic di-GMP (c-di-GMP) has been linked to the regulation of exopolysaccharide biosynthesis in many bacterial species, including A. tumefaciens. In this study, we identified two putative diguanylate cyclase genes, celR (atu1297) and atu1060, that influence production of cellulose in A. tumefaciens. Overexpression of either gene resulted in increased cellulose production, while deletion of celR, but not atu1060, resulted in decreased cellulose biosynthesis. celR overexpression also affected other phenotypes, including biofilm formation, formation of a polar adhesion structure, plant surface attachment, and virulence, suggesting that the gene plays a role in regulating these processes. Analysis of celR and Δcel mutants allowed differentiation between phenotypes associated with cellulose production, such as biofilm formation, and phenotypes probably resulting from c-di-GMP signaling, which include polar adhesion, attachment to plant tissue, and virulence. Phylogenetic comparisons suggest that species containing both celR and celA, which encodes the catalytic subunit of cellulose synthase, adapted the CelR protein to regulate cellulose production while those that lack celA use CelR, called PleD, to regulate specific processes associated with polar localization and cell division. PMID:24038703

  15. Regioselective Synthesis of Cellulose Ester Homopolymers

    Treesearch

    Daiqiang Xu; Kristen Voiges; Thomas Elder; Petra Mischnick; Kevin J. Edgar

    2012-01-01

    Regioselective synthesis of cellulose esters is extremely difficult due to the small reactivity differences between cellulose hydroxyl groups, small differences in steric demand between acyl moieties of interest, and the difficulty of attaching and detaching many protecting groups in the presence of cellulose ester moieties without removing the ester groups. Yet the...

  16. Method of producing thin cellulose nitrate film

    DOEpatents

    Lupica, S.B.

    1975-12-23

    An improved method for forming a thin nitrocellulose film of reproducible thickness is described. The film is a cellulose nitrate film, 10 to 20 microns in thickness, cast from a solution of cellulose nitrate in tetrahydrofuran, said solution containing from 7 to 15 percent, by weight, of dioctyl phthalate, said cellulose nitrate having a nitrogen content of from 10 to 13 percent.

  17. Cellulose nanomaterials review: structure, properties and nanocomposites

    Treesearch

    Robert J. Moon; Ashlie Martini; John Nairn; John Simonsen; Jeff Youngblood

    2011-01-01

    This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The...

  18. Cellulosic ethanol byproducts as a bulking agent

    Treesearch

    J.M. Considine; D. Coffin; J.Y. Zhu; D.H. Mann; X. Tang

    2017-01-01

    Financial enhancement of biomass value prior to pulping requires subsequent use of remaining materials; e.g., high value use of remaining stock material after cellulosic ethanol production would improve the economics for cellulosic ethanol. In this work, use of enzymatic hydrolysis residual solids (EHRS), a cellulosic ethanol byproduct, were investigated as a bulking...

  19. Microbial Cellulose Utilization: Fundamentals and Biotechnology

    PubMed Central

    Lynd, Lee R.; Weimer, Paul J.; van Zyl, Willem H.; Pretorius, Isak S.

    2002-01-01

    Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for “consolidated bioprocessing” (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts. PMID:12209002

  20. 21 CFR 573.420 - Ethyl cellulose.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance with the following prescribed conditions: (a) The food additive is a cellulose ether containing...

  1. 21 CFR 573.420 - Ethyl cellulose.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance with the following prescribed conditions: (a) The food additive is a cellulose ether containing...

  2. 21 CFR 573.420 - Ethyl cellulose.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance with the following prescribed conditions: (a) The food additive is a cellulose ether containing...

  3. 21 CFR 573.420 - Ethyl cellulose.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance with the following prescribed conditions: (a) The food additive is a cellulose ether containing...

  4. 21 CFR 573.420 - Ethyl cellulose.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance with the following prescribed conditions: (a) The food additive is a cellulose ether containing...

  5. Synthesis and characterization of seaweed cellulose derived carboxymethyl cellulose.

    PubMed

    Lakshmi, Duraikkannu Shanthana; Trivedi, Nitin; Reddy, C R K

    2017-02-10

    In the present study, cellulose (SWC) extracted from green seaweed Ulva fasciata was processed to synthesize carboxymethyl cellulose (SWCMC). The seaweed cellulose (∼15% DW) was first processed for α cellulose extraction (10.1% on DW) followed by the synthesis and characterization of SWCMC. Thin films were prepared using commercial CMC (CCMC), SWCMC and SWCMC-metal nanoparticle (2% wt/v) by solvent evaporation technique. Films were studied for molecular weight, degree of carboxylation, viscosity and characterized by FT-IR and TGA. AFM surface morphology of SWCMC-metal nanoparticle film confirms the uniform distribution of sphere shaped metal nanoparticle on the film surface with the size in the range of 50-75nm. Further, SWCMC film showed antimicrobial activity when prepared with Ag and leaf extract of Azadirachta indica. The biodegradable nature of SWCMC film was confirmed by growing marine fungus Cladosporium spherospermum on CMC agar plates. Thus, SWCMC films exhibit potential applications in cosmetic, food, textiles, medical, agricultural and pharmaceutical industries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Ionic Liquids and Cellulose: Dissolution, Chemical Modification and Preparation of New Cellulosic Materials

    PubMed Central

    Isik, Mehmet; Sardon, Haritz; Mecerreyes, David

    2014-01-01

    Due to its abundance and a wide range of beneficial physical and chemical properties, cellulose has become very popular in order to produce materials for various applications. This review summarizes the recent advances in the development of new cellulose materials and technologies using ionic liquids. Dissolution of cellulose in ionic liquids has been used to develop new processing technologies, cellulose functionalization methods and new cellulose materials including blends, composites, fibers and ion gels. PMID:25000264

  7. Bioconversion of cellulose into electrical energy in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Rismani-Yazdi, Hamid

    In microbial fuel cells (MFCs), bacteria generate electricity by mediating the oxidation of organic compounds and transferring the resulting electrons to an anode electrode. The first objective of this study was to test the possibility of generating electricity with rumen microorganisms as biocatalysts and cellulose as the electron donor in two-compartment MFCs. Maximum power density reached 55 mW/m2 (1.5 mA, 313 mV) with cellulose as the electron donor. Cellulose hydrolysis and electrode reduction were shown to support the production of current. The electrical current was sustained for over two months with periodic cellulose addition. Clarified rumen fluid and a soluble carbohydrate mixture, serving as the electron donors, could also sustain power output. The second objective was to analyze the composition of the bacterial communities enriched in the cellulose-fed MFCs. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes revealed that the microbial communities differed when different substrates were used in the MFCs. The anode-attached and the suspended consortia were shown to be different within the same MFC. Cloning and analysis of 16S rRNA gene sequences indicated that the most predominant bacteria in the anode-attached consortia were related to Clostridium spp., while Comamonas spp. was abundant in the suspended consortia. The external resistance affects the characteristic outputs of MFCs by controlling the flow of electrons from the anode to the cathode. The third objective of this study was to determine the effect of various external resistances on power output and coulombic efficiency of cellulose-fed MFCs. Four external resistances (20, 249, 480, and 1000 ohms) were tested with a systematic approach of operating parallel MFCs independently at constant circuit loads for three months. A maximum power density of 66 mWm-2 was achieved by MFCs with 20 ohms circuit load, while MFCs with 249, 480 and1000 ohms external resistances produced 57

  8. Cellulose and Their Characteristic Ice Nucleation Activity- Freezing on a Chip

    NASA Astrophysics Data System (ADS)

    Häusler, Thomas; Felgitsch, Laura; Grothe, Hinrich

    2016-04-01

    The influence of clouds on the Earth's climate system is well known (IPCC, 2013). Cloud microphysics determines for example cloud lifetime and precipitation properties. Clouds are cooling the climate system by reflecting incoming solar radiation and warm its surface by trapping outgoing infrared radiation (Baker and Peter, 2008). In all these processes, aerosol particles play a crucial role by acting as cloud condensation nuclei (CCN) for liquid droplets and as an ice nucleation particle (INP) for the formation of ice particles. Freezing processes at higher temperatures than -38°C occur heterogeneously (Pruppacher and Klett 1997). Therefore aerosol particles act like a catalyst, which reduces the energy barrier for nucleation. The nucleation mechanisms, especially the theory of functional sites are not entirely understood. It remains unclear which class of compound nucleates ice. Here we present a unique technique to perform drop- freezing experiments in a more efficient way. A self-made freezing- chip will be presented. Measurements done to proof the efficiency of our setup as well as advantages compared with other setups will be discussed. Furthermore we present a proxy for biological INPs, microcrystalline cellulose. Cellulose is the main component of herbal cell walls (about 50 wt%). It is a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose can contribute to the diverse spectrum of ice nucleation particles. We present results of the nucleation activity measurements of MCCs as well as the influence of concentration, preparation or chemical modification.

  9. Ultrasound-assisted acid hydrolysis of cellulose to chemical building blocks: Application to furfural synthesis.

    PubMed

    Santos, Daniel; Silva, Ubiratan F; Duarte, Fabio A; Bizzi, Cezar A; Flores, Erico M M; Mello, Paola A

    2018-01-01

    In this work, the use of ultrasound energy for the production of furanic platforms from cellulose was investigated and the synthesis of furfural was demonstrated. Several systems were evaluated, as ultrasound bath, cup horn and probe, in order to investigate microcrystalline cellulose conversion using simply a diluted acid solution and ultrasound. Several acid mixtures were evaluated for hydrolysis, as diluted solutions of HNO 3 , H 2 SO 4 , HCl and H 2 C 2 O 4 . The influence of the following parameters in the ultrasound-assisted acid hydrolysis (UAAH) were studied: sonication temperature (30 to 70°C) and ultrasound amplitude (30 to 70% for a cup horn system) for 4 to 8molL -1 HNO 3 solutions. For each evaluated condition, the products were identified by ultra-performance liquid chromatography with high-resolution time-of-flight mass spectrometry (UPLC-ToF-MS), which provide accurate information regarding the products obtained from biomass conversion. The furfural structure was confirmed by nuclear magnetic resonance ( 1 H and 13 C NMR) spectroscopy. In addition, cellulosic residues from hydrolysis reaction were characterized using scanning electron microscopy (SEM), which contributed for a better understanding of physical-chemical effects caused by ultrasound. After process optimization, a 4molL -1 HNO 3 solution, sonicated for 60min at 30°C in a cup horn system at 50% of amplitude, lead to 78% of conversion to furfural. This mild temperature condition combined to the use of a diluted acid solution represents an important contribution for the selective production of chemical building blocks using ultrasound energy. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Cellulose-Organic Montmorillonite Nanocomposites as Biomacromolecular Quorum-Sensing Inhibitor.

    PubMed

    Demircan, Deniz; Ilk, Sedef; Zhang, Baozhong

    2017-10-09

    The aim of this study was to develop simple cellulose nanocomposites that can interfere with the quorum-sensing (QS)-regulated physiological process of bacteria, which will provide a sustainable and inexpensive solution to the serious challenges caused by bacterial infections in various products like food packaging or biomedical materials. Three cellulose nanocomposites with 1-5 w% octadecylamine-modified montmorillonite (ODA-MMT) were prepared by regeneration of cellulose from ionic liquid solutions in the presence of ODA-MMT suspension. Structural characterization of the nanocomposites showed that the ODA-MMT can be exfoliated or intercalated, depending on the load level of the nanofiller. Thermal gravimetric analysis showed that the incorporation of ODA-MMT nanofiller can improve the thermal stability of the nanocomposites compared with regenerated cellulose. Evaluation of the anti-QS effect against a pigment-producing bacteria C. violaceum CV026 by disc diffusion assay and flask incubation assay revealed that the QS-regulated violacein pigment production was significantly inhibited by the cellulose nanocomposites without interfering the bacterial vitality. Interestingly, the nanocomposite with the lowest load of ODA-MMT exhibited the most significant anti-QS effect, which may be correlated to the exfoliation of nanofillers. To our knowledge, this is the first report on the anti-QS effect of cellulose nanocomposites without the addition of any small molecular agents. Such inexpensive and nontoxic biomaterials will thus have great potential in the development of new cellulosic materials that can effectively prevent the formation of harmful biofilms.

  11. Bacterial prostatitis.

    PubMed

    Gill, Bradley C; Shoskes, Daniel A

    2016-02-01

    The review provides the infectious disease community with a urologic perspective on bacterial prostatitis. Specifically, the article briefly reviews the categorization of prostatitis by type and provides a distillation of new findings published on bacterial prostatitis over the past year. It also highlights key points from the established literature. Cross-sectional prostate imaging is becoming more common and may lead to more incidental diagnoses of acute bacterial prostatitis. As drug resistance remains problematic in this condition, the reemergence of older antibiotics such as fosfomycin, has proven beneficial. With regard to chronic bacterial prostatitis, no clear clinical risk factors emerged in a large epidemiological study. However, bacterial biofilm formation has been associated with more severe cases. Surgery has a limited role in bacterial prostatitis and should be reserved for draining of a prostatic abscess or the removal of infected prostatic stones. Prostatitis remains a common and bothersome clinical condition. Antibiotic therapy remains the basis of treatment for both acute and chronic bacterial prostatitis. Further research into improving prostatitis treatment is indicated.

  12. Cellulose-pectin composite hydrogels: Intermolecular interactions and material properties depend on order of assembly.

    PubMed

    Lopez-Sanchez, Patricia; Martinez-Sanz, Marta; Bonilla, Mauricio R; Wang, Dongjie; Gilbert, Elliot P; Stokes, Jason R; Gidley, Michael J

    2017-04-15

    Plant cell walls have a unique combination of strength and flexibility however, further investigations are required to understand how those properties arise from the assembly of the relevant biopolymers. Recent studies indicate that Ca 2+ -pectates can act as load-bearing components in cell walls. To investigate this proposed role of pectins, bioinspired wall models were synthesised based on bacterial cellulose containing pectin-calcium gels by varying the order of assembly of cellulose/pectin networks, pectin degree of methylesterification and calcium concentration. Hydrogels in which pectin-calcium assembly occurred prior to cellulose synthesis showed evidence for direct cellulose/pectin interactions from small-angle scattering (SAXS and SANS), had the densest networks and the lowest normal stress. The strength of the pectin-calcium gel affected cellulose structure, crystallinity and material properties. The results highlight the importance of the order of assembly on the properties of cellulose composite networks and support the role of pectin in the mechanics of cell walls. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Cellulose Biosynthesis: Current Views and Evolving Concepts

    PubMed Central

    SAXENA, INDER M.; BROWN, R. MALCOLM

    2005-01-01

    • Aims To outline the current state of knowledge and discuss the evolution of various viewpoints put forth to explain the mechanism of cellulose biosynthesis. • Scope Understanding the mechanism of cellulose biosynthesis is one of the major challenges in plant biology. The simplicity in the chemical structure of cellulose belies the complexities that are associated with the synthesis and assembly of this polysaccharide. Assembly of cellulose microfibrils in most organisms is visualized as a multi-step process involving a number of proteins with the key protein being the cellulose synthase catalytic sub-unit. Although genes encoding this protein have been identified in almost all cellulose synthesizing organisms, it has been a challenge in general, and more specifically in vascular plants, to demonstrate cellulose synthase activity in vitro. The assembly of glucan chains into cellulose microfibrils of specific dimensions, viewed as a spontaneous process, necessitates the assembly of synthesizing sites unique to most groups of organisms. The steps of polymerization (requiring the specific arrangement and activity of the cellulose synthase catalytic sub-units) and crystallization (directed self-assembly of glucan chains) are certainly interlinked in the formation of cellulose microfibrils. Mutants affected in cellulose biosynthesis have been identified in vascular plants. Studies on these mutants and herbicide-treated plants suggest an interesting link between the steps of polymerization and crystallization during cellulose biosynthesis. • Conclusions With the identification of a large number of genes encoding cellulose synthases and cellulose synthase-like proteins in vascular plants and the supposed role of a number of other proteins in cellulose biosynthesis, a complete understanding of this process will necessitate a wider variety of research tools and approaches than was thought to be required a few years back. PMID:15894551

  14. Cellulose biosynthesis: current views and evolving concepts.

    PubMed

    Saxena, Inder M; Brown, R Malcolm

    2005-07-01

    To outline the current state of knowledge and discuss the evolution of various viewpoints put forth to explain the mechanism of cellulose biosynthesis. * Understanding the mechanism of cellulose biosynthesis is one of the major challenges in plant biology. The simplicity in the chemical structure of cellulose belies the complexities that are associated with the synthesis and assembly of this polysaccharide. Assembly of cellulose microfibrils in most organisms is visualized as a multi-step process involving a number of proteins with the key protein being the cellulose synthase catalytic sub-unit. Although genes encoding this protein have been identified in almost all cellulose synthesizing organisms, it has been a challenge in general, and more specifically in vascular plants, to demonstrate cellulose synthase activity in vitro. The assembly of glucan chains into cellulose microfibrils of specific dimensions, viewed as a spontaneous process, necessitates the assembly of synthesizing sites unique to most groups of organisms. The steps of polymerization (requiring the specific arrangement and activity of the cellulose synthase catalytic sub-units) and crystallization (directed self-assembly of glucan chains) are certainly interlinked in the formation of cellulose microfibrils. Mutants affected in cellulose biosynthesis have been identified in vascular plants. Studies on these mutants and herbicide-treated plants suggest an interesting link between the steps of polymerization and crystallization during cellulose biosynthesis. * With the identification of a large number of genes encoding cellulose synthases and cellulose synthase-like proteins in vascular plants and the supposed role of a number of other proteins in cellulose biosynthesis, a complete understanding of this process will necessitate a wider variety of research tools and approaches than was thought to be required a few years back.

  15. Salmonella Biofilm Formation on Aspergillus niger Involves Cellulose – Chitin Interactions

    PubMed Central

    Brandl, Maria T.; Carter, Michelle Q.; Parker, Craig T.; Chapman, Matthew R.; Huynh, Steven; Zhou, Yaguang

    2011-01-01

    Salmonella cycles between host and nonhost environments, where it can become an active member of complex microbial communities. The role of fungi in the environmental adaptation of enteric pathogens remains relatively unexplored. We have discovered that S. enterica Typhimurium rapidly attaches to and forms biofilms on the hyphae of the common fungus, Aspergillus niger. Several Salmonella enterica serovars displayed a similar interaction, whereas other bacterial species were unable to bind to the fungus. Bacterial attachment to chitin, a major constituent of fungal cell walls, mirrored this specificity. Pre-incubation of S. Typhimurium with N-acetylglucosamine, the monomeric component of chitin, reduced binding to chitin beads by as much as 727-fold and inhibited attachment to A. niger hyphae considerably. A cellulose-deficient mutant of S. Typhimurium failed to attach to chitin beads and to the fungus. Complementation of this mutant with the cellulose operon restored binding to chitin beads to 79% of that of the parental strain and allowed for attachment and biofilm formation on A. niger, indicating that cellulose is involved in bacterial attachment to the fungus via the chitin component of its cell wall. In contrast to cellulose, S. Typhimurium curli fimbriae were not required for attachment and biofilm development on the hyphae but were critical for its stability. Our results suggest that cellulose–chitin interactions are required for the production of mixed Salmonella-A. niger biofilms, and support the hypothesis that encounters with chitinaceous alternate hosts may contribute to the ecological success of human pathogens. PMID:22003399

  16. Advancing cellulose-based nanotechnology

    Treesearch

    Theodore H. Wegner; Philip E. Jones

    2006-01-01

    Nanotechnology has applications across most economic sectors and allows the development of new enabling science with broad commercial potential. Cellulose and lignocellulose have great potential as nanomaterials because they are abundant, renewable, have a nanofibrillar structure, can be made multifunctional, and self-assemble into well-defined architectures. To...

  17. Microcrystalline silicon thin-film transistors for large area electronic applications

    NASA Astrophysics Data System (ADS)

    Chan, Kah-Yoong; Bunte, Eerke; Knipp, Dietmar; Stiebig, Helmut

    2007-11-01

    Thin-film transistors (TFTs) based on microcrystalline silicon (µc-Si:H) exhibit high charge carrier mobilities exceeding 35 cm2 V-1 s-1. The devices are fabricated by plasma-enhanced chemical vapor deposition at substrate temperatures below 200 °C. The fabrication process of the µc-Si:H TFTs is similar to the low temperature fabrication of amorphous silicon TFTs. The electrical characteristics of the µc-Si:H-based transistors will be presented. As the device charge carrier mobility of short channel TFTs is limited by the contacts, the influence of the drain and source contacts on the device parameters including the device charge carrier mobility and the device threshold voltage will be discussed. The experimental data will be described by a modified standard transistor model which accounts for the contact effects. Furthermore, the transmission line method was used to extract the device parameters including the contact resistance. The modified standard transistor model and the transmission line method will be compared in terms of the extracted device parameters and contact resistances.

  18. Direct observation and mechanism of increased emission sites in Fe-coated microcrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Panda, Kalpataru; Sundaravel, B.; Panigrahi, B. K.; Huang, Pin-Chang; Shih, Wen-Ching; Chen, Huang-Chin; Lin, I.-Nan

    2012-06-01

    The electron field emission (EFE) properties of microcrystalline diamond (MCD) films are significantly enhanced due to the Fe coating and post-annealing processes. The 900 °C post-annealed Fe coated diamond films exhibit the best EFE properties, with a turn on field (E0) of 3.42 V/μm and attain EFE current density (Je) of 170 μA/cm2 at 7.5 V/μm. Scanning tunnelling spectroscopy (STS) in current imaging tunnelling spectroscopy mode clearly shows the increased number density of emission sites in Fe-coated and post-annealed MCD films than the as-prepared ones. Emission is seen from the boundaries of the Fe (or Fe3C) nanoparticles formed during the annealing process. In STS measurement, the normalized conductance dI /dV/I/V versus V curves indicate nearly metallic band gap, at the boundaries of Fe (or Fe3C) nanoparticles. Microstructural analysis indicates that the mechanism for improved EFE properties is due to the formation of nanographite that surrounds the Fe (or Fe3C) nanoparticles.

  19. Elasticity and anelasticity of microcrystalline aluminum samples having various deformation and thermal histories

    NASA Astrophysics Data System (ADS)

    Betekhtin, V. I.; Kadomtsev, A. G.; Kardashev, B. K.

    2006-08-01

    The effect of the amplitude of vibrational deformation on the elastic modulus and internal friction of microcrystalline aluminum samples produced by equal-channel angular pressing was studied. The samples have various deformation and thermal histories. The elastic and inelastic (microplastic) properties of the samples are investigated. As the degree of plastic deformation increases, the Young’s modulus E, the amplitude-independent decrement δi, and the microplastic flow stress σ increase. As the annealing temperature increases, the quantities δi and σ decrease noticeably and the modulus E exhibits a more complex behavior. The experimental data are discussed under the assumption that the dislocation mobility depends on both the spectrum of point defects and the internal stresses, whose level is determined by the degree of plastic deformation and the temperature of subsequent annealing. The concept of internal stresses is also used to analyze the data on the effect of the degree of deformation and annealing on the rupture strength of the samples.

  20. Integration of Light Trapping Silver Nanostructures in Hydrogenated Microcrystalline Silicon Solar Cells by Transfer Printing

    PubMed Central

    Mizuno, Hidenori; Sai, Hitoshi; Matsubara, Koji; Takato, Hidetaka; Kondo, Michio

    2015-01-01

    One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly known as plasmonic effects, play an important role. Research in this field has, however, been impeded owing to the difficulty of fabricating devices containing the desired functional metal nanostructures. In order to provide a viable strategy to this issue, we herein show a transfer printing-based approach that allows the quick and low-cost integration of designed metal nanostructures with a variety of device architectures, including solar cells. Nanopillar poly(dimethylsiloxane) (PDMS) stamps were fabricated from a commercially available nanohole plastic film as a master mold. On this nanopatterned PDMS stamps, Ag films were deposited, which were then transfer-printed onto block copolymer (binding layer)-coated hydrogenated microcrystalline Si (µc-Si:H) surface to afford ordered Ag nanodisk structures. It was confirmed that the resulting Ag nanodisk-incorporated µc-Si:H solar cells show higher performances compared to a cell without the transfer-printed Ag nanodisks, thanks to plasmonic light trapping effect derived from the Ag nanodisks. Because of the simplicity and versatility, further device application would also be feasible thorough this approach. PMID:26575244

  1. Iron Oxide Nanoparticles Employed as Seeds for the Induction of Microcrystalline Diamond Synthesis

    PubMed Central

    2008-01-01

    Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. X-ray diffraction, visible, and ultraviolet Raman Spectroscopy, energy-filtered transmission electron microscopy , electron energy-loss spectroscopy, and X-ray photoelectron spectroscopy (XPS) were employed to study the carbon bonding nature of the films and to analyze the carbon clustering around the seed nanoparticles leading to diamond synthesis. The results indicate that iron oxide nanoparticles lose the O atoms, becoming thus active C traps that induce the formation of a dense region of trigonally and tetrahedrally bonded carbon around them with the ensuing precipitation of diamond-type bonds that develop into microcrystalline diamond films under chemical vapor deposition conditions. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods.

  2. Formation and characterization of microcrystalline semiconductor particles on bilayer lipid membranes

    SciTech Connect

    Baral, S.; Zhao, X.K.; Rolandi, R.

    Microcrystalline cadmium, indium, copper, and zinc sulfides were generated in situ on the surface of bilayer lipid membranes (BLMs) prepared from bovine-brain phosphatidylserine (PS), glyceryl monooleate (GMO), and a synthetic, polymerizable surfactant (n-C/sub 15/H/sub 31/CO/sub 2/(CH/sub 2/)/sub 2/)/sub 2/N/sup +/(CH/sub 3/)CH/sub 2/C/sub 6/H/sub 4/CH double bond CH/sub 2/, Cl/sup -/ (STYRS). Semiconductor-containing BLMs remained stable for days. Semiconductor formation on the BLM surface was monitored by optical microscopy, voltage-dependent capacitance measurements, and absorption and intracavity-laser-absorption spectroscopy. Band gap excitation of GMO- BLM-incorporated CdS resulted in the development of photovoltage. Irradiation of CdS incorporated into BLMs formed from STYRS (using amore » 350-nm cutoff filter) led to absorption losses due to the styrene moiety in the surfactant. Apparently, CdS sensitized the photopolymerization of STRYS BLMs.« less

  3. Applicability of low-melting-point microcrystalline wax to develop temperature-sensitive formulations.

    PubMed

    Matsumoto, Kohei; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

    2017-10-30

    Low-melting-point substances are widely used to develop temperature-sensitive formulations. In this study, we focused on microcrystalline wax (MCW) as a low-melting-point substance. We evaluated the drug release behavior of wax matrix (WM) particles using various MCW under various temperature conditions. WM particles containing acetaminophen were prepared using a spray congealing technique. In the dissolution test at 37°C, WM particles containing low-melting-point MCWs whose melting was starting at approx. 40°C (Hi-Mic-1045 or 1070) released the drug initially followed by the release of only a small amount. On the other hand, in the dissolution test at 20 and 25°C for WM particles containing Hi-Mic-1045 and at 20, 25, and 30°C for that containing Hi-Mic-1070, both WM particles showed faster drug release than at 37°C. The characteristic drug release suppression of WM particles containing low-melting-point MCWs at 37°C was thought attributable to MCW melting, as evidenced by differential scanning calorimetry analysis and powder X-ray diffraction analysis. Taken together, low-melting-point MCWs may be applicable to develop implantable temperature-sensitive formulations that drug release is accelerated by cooling at administered site. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Microstructure and mechanical properties of Ni and Fe-base boride-dispersion-strengthened microcrystalline alloys

    SciTech Connect

    Wade, C.S.; Park, H.G.; Hoagland, R.G.

    This paper considers the relation between microstructure and mechanical properties of two Ni-base and two Fe-base Boride-Dispersion-Strengthened Microcrystalline (BDSM) alloys. In these very fine grained materials the borides were primarily Cr, Mo, and MoFe in a fcc matrix in three of the alloys, and a bcc in one of the Fe-base alloys. Strength data and resistance to stress corrosion cracking are reported and, in the latter case, extraordinary resistance to SCC in NaCl, Na{sub 2}S{sub 2}O{sub 3} and boiling MgCl{sub 2} environments was observed in every case. The fcc BDSM alloys also demonstrated excellent thermal stability in terms of strengthmore » and fracture roughness up to 1000 C. The bcc alloy suffered severe loss of toughness. The fracture mode involved ductile rupture in all alloys and they display a reasonably linear correlation between K{sub Ic} and the square root of particle spacing.« less

  5. Structure and engineering of celluloses.

    PubMed

    Pérez, Serge; Samain, Daniel

    2010-01-01

    This chapter collates the developments and conclusions of many of the extensive studies that have been conducted on cellulose, with particular emphasis on the structural and morphological features while not ignoring the most recent results derived from the elucidation of unique biosynthetic pathways. The presentation of structural and morphological data gathered together in this chapter follows the historical development of our knowledge of the different structural levels of cellulose and its various organizational levels. These levels concern features such as chain conformation, chain polarity, chain association, crystal polarity, and microfibril structure and organization. This chapter provides some historical landmarks related to the evolution of concepts in the field of biopolymer science, which parallel the developments of novel methods for characterization of complex macromolecular structures. The elucidation of the different structural levels of organization opens the way to relating structure to function and properties. The chemical and biochemical methods that have been developed to dissolve and further modify cellulose chains are briefly covered. Particular emphasis is given to the facets of topochemistry and topoenzymology where the morphological features play a key role in determining unique physicochemical properties. A final chapter addresses what might be considered tomorrow's goal in amplifying the economic importance of cellulose in the context of sustainable development. Selected examples illustrate the types of result that can be obtained when cellulose fibers are no longer viewed as inert substrates, and when the polyhydroxyl nature of their surfaces, as well as their entire structural complexity, are taken into account. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. Immobilization of Acetobacter aceti on cellulose ion exchangers: adsorption isotherms

    SciTech Connect

    Bar, R.; Gainer, J.L.; Kirwan, D.J.

    1986-08-01

    The adsorptive behavior of cells of Acetobacter aceti, ATCC 23746, on DEAE-, TEAE-, and DEHPAE-cellulose ion exchangers in a modified Hoyer's medium at 30 degrees Centigrade was investigated. The maximum observed adsorption capacities varied from 46 to 64 mg dry wt/g resin. The Langmuir isotherm form was used to fit the data, since the cells formed a monolayer on the resin and exhibited saturation. The equilibrium constant in the Langmuir expression was qualitatively correlated with the surface charge density of the resin. The adsorption was also ''normalized'' by considering the ionic capacities of the resins. The exceptionally high normalized adsorptionmore » capacity of ECTEOLA-cellulose, 261 mg dry/meq, may be explained by an interaction between the cell wall and the polyglyceryl chains of the exchanging groups in addition to the electrostatic effects. The effect of pH on the bacterial adsorption capacity of ECTEOLA-, TEAE-, and phosphate-cellulose resins was studied and the pH of the bacteria was estimated to be 3.0. 17 references.« less

  7. Cellulose nanocrystals: synthesis, functional properties, and applications

    PubMed Central

    George, Johnsy; Sabapathi, SN

    2015-01-01

    Cellulose nanocrystals are unique nanomaterials derived from the most abundant and almost inexhaustible natural polymer, cellulose. These nanomaterials have received significant interest due to their mechanical, optical, chemical, and rheological properties. Cellulose nanocrystals primarily obtained from naturally occurring cellulose fibers are biodegradable and renewable in nature and hence they serve as a sustainable and environmentally friendly material for most applications. These nanocrystals are basically hydrophilic in nature; however, they can be sur