The structure of spherulites of bacterial cellulose from Acetobacter xylinum

1974 ◽  
Vol 20 (4) ◽  
pp. 509-512 ◽  
Author(s):  
L. C. Sowden ◽  
J. Ross Colvin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bacterial Cellulose ◽  
Acetobacter Xylinum ◽  
Cellulose Microfibrils ◽  
Polarizing Microscopy ◽  
Scanning Electron

Evidence from phase and polarizing microscopy as well as scanning electron microscopy indicates that the cellulose microfibrils in the spherulites of bacterial cellulose are oriented tangentially, not radially. Also, the orientation may be limited to only a fraction of the thickness of the pellicle. It is suggested that the tangential deposition may be caused by a gradient of concentration of a weakly soluble inhibitor of cellulose formation about a center.

Morphology, microstructure, and development of colonies of Acetobacter xylinum

1978 ◽  
Vol 24 (7) ◽  
pp. 772-779 ◽  
Author(s):  
L. C. Sowden ◽  
J. Ross Colvin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Optical Microscopy ◽  
Cell Mass ◽  
Acetobacter Xylinum ◽  
Cellulose Microfibrils ◽  
Dividing Cells ◽  
Scanning Electron

Development of the morphology and microstructure of colonies of Acetobacter xylinum glowing on agar was studied by optical microscopy, and transmission and scanning electron microscopy. The mass of rapidly dividing cells surrounded by a sheath of cellulose microfibrils passes from a smooth spheroid to a flattened aggregate with a characteristic 'pillowed' surface. This morphology is the result of a repeated extrusion of cells from the confining sheath, followed by regeneration of a new portion of the sheath on the extruded cell mass. Relations of this mechanism to others which produce similar shapes are indicated.

Geochemistry of halloysite-7Å formation from plagioclase in trachyandesite rocks from Limnos Island, Greece

Clay Minerals ◽  
2014 ◽  
Vol 49 (1) ◽  
pp. 75-89 ◽  
Author(s):  
D. Papoulis ◽  
S. Komarneni ◽  
D. Panagiotaras
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chemical Analysis ◽  
Geochemical Data ◽  
X Ray Diffraction ◽  
Polarizing Microscopy ◽  
X Ray ◽  
Geochemical Evaluation ◽  
Scanning Electron ◽  
Southwest Part

AbstractTrachyandesite rocks, occurring over an area of about 1 km2in the southwest part of Limnos Island, Greece, are altered mainly to halloysite. The samples were collected and analysed by polarizing microscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analysis. The alteration of plagioclase to halloysite follows seven discrete stages that are described in detail. The geochemical evaluation of the data shows enrichment of the lightREE(LREE) over heavyREE(HREE) as expressed by the (La/Yb)n ratio. TheΣLREErange from 206.44 to 272.30, while the sum ofHREEvaries from 11.01 to 26.26. The (La/Yb)n ratio ranges from 9.72 to 27.64. Fractionation amongLREEexpressed as (La/Sm)n and between middleREE(MREE) andHREEis shown as (Tb/Yb)n ratios. The most altered rocks close to the fault zone have high (Tb/Yb)n ratios and low (La/Sm)n and Eu/Eu* ratios. Although mineralogy and clay mineral textures indicate hydrothermal genesis of halloysite, the geochemical data are not conclusive due to a secondary weathering effect.

Review — The Orientation of Cellulose Microfibrils in the cell walls of Tracheids in Conifers

IAWA Journal ◽  
2005 ◽  
Vol 26 (2) ◽  
pp. 161-174 ◽  
Author(s):  
Hisashi Abe ◽  
Ryo Funada
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Outer Layer ◽  
Cell Walls ◽  
Secondary Wall ◽  
Middle Layer ◽  
Cellulose Microfibrils ◽  
Conifer Species ◽  
Predominant Orientation ◽  
Scanning Electron

We examined the orientation of cellulose microfibrils (Mfs) in the cell walls of tracheids in some conifer species by field emission-scanning electron microscopy (FE-SEM) and developed a model on the basis of our observations. Mfs depositing on the primary walls in differentiating tracheids were not well-ordered. The predominant orientation of the Mfs changed from longitudinal to transverse, as the differentiation of tracheids proceeded. The first Mfs to be deposited in the outer layer of the secondary wall (S1 layer) were arranged as an S-helix. Then the orientation of Mfs changed gradually, with rotation in the clockwise direction as viewed from the lumen side of tracheids, from the outermost to the innermost S1 layer. Mfs in the middle layer of the secondary wall (S2 layer) were oriented in a steep Z-helix with a deviation of less than 15° within the layer. The orientation of Mfs in the inner layer of the secondary wall (S3 layer) changed, with rotation in a counterclockwise direction as viewed from the lumen side, from the outermost to the innermost S3 layer. The angle of orientation of Mfs that were deposited on the innermost S3 layer varied among tracheids from 40° in a Z-helix to 20° in an S-helix.

Scanning electron microscopy of the spines of the tunic of the ascidian, Boltenia ovifera

1970 ◽  
Vol 48 (3) ◽  
pp. 475-477 ◽  
Author(s):  
A. K. Mishra ◽  
J. Ross Colvin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Continuous Extension ◽  
Cellulose Microfibrils ◽  
Exterior Surface ◽  
Extracellular Synthesis ◽  
Scanning Electron

The presence of small spines on the exterior surface of the tunic of Boltenia ovifera, which contain axially oriented microfibrils of cellulose, was confirmed by scanning electron microscopy. These spines axe a continuous extension of the mass of the tissue without a recognizable discontinuity between them and the rest of the tunic. They show a trilobed form at their base after preparation for electron microscopy but this may be a result of desiccation. Tips of the spines are blunt and they, as well as the axial microfibrils which compose the shaft, are enclosed in a sheath which seems to be amorphous. On the surface of the tunic, the water-insoluble glycoprotein component is sparsely distributed. The distribution and morphology of these spines pose unusual problems for the mechanism of extracellular synthesis and deposition of cellulose microfibrils.

scholarly journals Development of bacterial cellulose–ZnO–MWCNT hybrid membranes: a study of structural and mechanical properties

2020 ◽  
Vol 7 (6) ◽  
pp. 200592
Author(s):  
Bilal El Mrabate ◽  
Mahitha Udayakumar ◽  
Emília Csiszár ◽  
Ferenc Kristály ◽  
Máté Leskó ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bacterial Cellulose ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Area Measurement ◽  
Hybrid Membranes ◽  
X Ray ◽  
Multi Walled Carbon Nanotube ◽  
Scanning Electron

Self-supported and flexible bacterial cellulose (BC) based hybrid membranes were synthesized and decorated with zinc oxide/multi-walled carbon nanotube (ZnO–MWCNT) composite additives in order to modify and tune their surface and bulk properties. Two types of ZnO–MWCNT additives with different morphologies were used in a wide concentration range from 0 to 90% for BC-based hybrids produced by filtration. The interaction between BC and ZnO–MWCNT and the effect of concentration and morphology of additives on the properties like zeta potential, hydrophilicity, electrical conductivity, etc. would be an important factor in various applications. Furthermore, the as-prepared hybrid membranes were characterized with the use of scanning electron microscopy (SEM), focused ion beam scanning electron microscopy (FIB-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and surface area measurement (BET). Applying the presented synthesis routes, the surface properties of BC-based membranes can be tailored easily. Results reveal that the as-prepared BC–ZnO–MWCNT hybrid membranes can be ideal candidates for different kinds of applications, such as water filtration or catalysts.

High-Resolution Field Emission Scanning Electron Microscopy (FESEM) Imaging of Cellulose Microfibril Organization in Plant Primary Cell Walls

2017 ◽  
Vol 23 (5) ◽  
pp. 1048-1054 ◽  
Author(s):  
Yunzhen Zheng ◽  
Daniel J. Cosgrove ◽  
Gang Ning
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Wall ◽  
High Resolution ◽  
Field Emission ◽  
Cell Walls ◽  
Cellulose Microfibrils ◽  
Critical Point Drying ◽  
Sputter Coating ◽  
Scanning Electron

AbstractWe have used field emission scanning electron microscopy (FESEM) to study the high-resolution organization of cellulose microfibrils in onion epidermal cell walls. We frequently found that conventional “rule of thumb” conditions for imaging of biological samples did not yield high-resolution images of cellulose organization and often resulted in artifacts or distortions of cell wall structure. Here we detail our method of one-step fixation and dehydration with 100% ethanol, followed by critical point drying, ultrathin iridium (Ir) sputter coating (3 s), and FESEM imaging at a moderate accelerating voltage (10 kV) with an In-lens detector. We compare results obtained with our improved protocol with images obtained with samples processed by conventional aldehyde fixation, graded dehydration, sputter coating with Au, Au/Pd, or carbon, and low-voltage FESEM imaging. The results demonstrated that our protocol is simpler, causes little artifact, and is more suitable for high-resolution imaging of cell wall cellulose microfibrils whereas such imaging is very challenging by conventional methods.

scholarly journals Sintesis dan Karakterisasi Selulosa Bakteri Tercangkok Poliakrilonitril dan Teramidoksimasi Menggunakan Teknik Pra-iradiasi

2016 ◽  
Vol 11 (1) ◽  
pp. 1 ◽  
Author(s):  
Oktaviani Oktaviani ◽  
Emil Budianto ◽  
Sugiarto Danu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fourier Transform ◽  
Fourier Transform Infrared ◽  
Acetobacter Xylinum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Gravimetry ◽  
Scanning Electron

Penelitian ini bertujuan untuk mempelajari kopolimerisasi cangkok akrilonitril pada selulosa bakteri (SB) dengan inisiasi radiasi serta penambahan hidroksilamin untuk menghasilkan gugus amidoksim. Pencangkokan akrilonitril pada SB diharapkan dapat meningkatkan ketahanan termal SB. Sedangkan SB yang bersifat sebagai pengkelat ion-ion logam berat, diharapkan dapat dihasilkan melalui penambahan hidroksilamin. Film selulosa bakteri telah berhasil dibuat dari air kelapa yang diinokulasi dengan bakteri Acetobacter xylinum. Film selulosa bakteri (SB) selanjutnya diiradiasi dengan berkas elektron pada rentang dosis 15-120 kGy, laju dosis 15 kGy/pass pada suhu 30 + 1 0C. Setelah diiradiasi, SB tersebut dikopolimerisasi cangkok dengan monomer akrilonitril. Kondisi optimum untuk kopolimerisasi cangkok akrilonitril pada SB adalah pada dosis 75 kGy, suhu 600C, waktu 3 jam, dan konsentrasi akrilonitril 30% b/b. Derajat pencangkokan tertinggi yang diperoleh adalah 56,03 %. Selulosa bakteri tercangkok akrilonitril (SB tercangkok PAN) selanjutnya diamidoksimasi. Amidoksimasi dilakukan dengan penambahan hidroksilamin hidroklorida 6 % b/v dalam pelarut metanol:air = 50:50 v/v pada pH 7, dan diperoleh waktu optimum selama 2 jam dengan densitas gugus amidoksim sebesar 5,425 mmol/ g. Hasil karakterisasi dengan Fourier Transform Infrared (FTIR) menunjukkan adanya spektrum spesifik gugus siano setelah proses pencangkokan akrilonitril pada SB dan intensitasnya menurun setelah diamidoksimasi. Hal tersebut diperkuat dengan hasil uji Scanning Electron Microscopy (SEM) yang memperlihatkan adanya gugus siano yang menempel setelah pencangkokan, dan gugus tersebut tidak terlihat lagi setelah amidoksimasi. Dari hasil uji dengan X-ray Diffraction (XRD), indeks kristalinitas SB tercangkok PAN akan semakin rendah dengan meningkatnya derajat pencangkokan dan pengujian dengan Thermal Gravimetry Analysis (TGA) menunjukkan bahwa ketahanan panas SB tercangkok PAN meningkat.

scholarly journals Preparation and Properties of Bacterial Cellulose/Alginate Blend Bio-Fibers

2011 ◽  
Vol 6 (3) ◽  
pp. 155892501100600 ◽  
Author(s):  
Shuai Zhang ◽  
Jin Luo
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Hydrogen Bonds ◽  
Bacterial Cellulose ◽  
Tensile Tests ◽  
Intermolecular Hydrogen Bonds ◽  
Scanning Electron

LiOH/urea/thiourea aqueous systems have been successfully applied to the dissolution of bacterial cellulose (BC) and alginate (AL) to prepare blend fibers. Morphology, compatibility and mechanical properties of the blend fibers were investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and tensile tests. The analyses indicated a good miscibility between alginate and bacterial cellulose, because of the strong interaction from the intermolecular hydrogen bonds. The mechanical properties of BC/AL blend fibers were significantly improved by introducing bacterial cellulose.

Direct in siut identification of cellulose microfibrils associated with Rhizobium leguminosarum biovar trifolii attached to the root epidermis of white clover

1995 ◽  
Vol 41 (2) ◽  
pp. 202-207 ◽  
Author(s):  
Pedro F. Mateos ◽  
David L. Baker ◽  
Saleela Philip-Hollingsworth ◽  
Andrea Squartini ◽  
Angelo D. B. Paruffo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Root Surface ◽  
Cellulose Microfibrils ◽  
Enzyme Cytochemistry ◽  
Root Epidermis ◽  
Scanning Electron

Firm attachment of Rhizobium species to the legume root epidermis involves the elaboration of extracellular microfibrils extending from the bacteria and contacting the root surface at multiple sites. We investigated the nature of these extracellular microfibrils associated in situ with Rhizobium leguminosarum bv. trifolii colonized on the root epidermal surface of its legume host, white clover (Trifoiium repens L.). Scanning electron microscopy of seedling roots inoculated with the wild-type strain ANU843 showed that these extracellular microfibrils were associated with the bacteria attached not only to root hairs but also to the non-root-hair epidermis and the external environment under the influence of the developing root. Polystyrene microspheres adsorbed to the root surface did not accumulate similar microfibrils, ruling out their formation by nonspecific deposition of mucigel or self-assembly of rhizoplane fibrils of plant origin. An isozyme of cellulase was purified from Streptomyces sp. strain A20, shown to exhibit high substrate specificity for β-1,4-glucans, and used in enzyme cytochemistry to investigate the nature of these extracellular microfibrils. Combined scanning electron microscopy and computer-assisted image analysis indicated that the extracellular microfibrils associated with attached bacteria were degraded by a brief exposure to the purified cellulase but not by a broad-spectrum protease. These results provide direct in situ evidence of the cellulosic nature of the extracellular microfibrils associated with cells of R. leguminosarum bv. trifolii that have colonized the root environment of its legume host, white clover.Key words: Rhizobium, clover, cellulose microfibrils, enzyme cytochemistry, surface ecology, rhizoplane.

Comparative Study of Chemical and Mechanical Treatment Effects on Bacterial Cellulose from Nata de Coco

2017 ◽  
Vol 888 ◽  
pp. 256-261
Author(s):  
Rusaini Athirah Ahmad Rusdi ◽  
Zul Hazrin Zainal Abidin ◽  
Hairul Anuar Tajuddin ◽  
Fauziah Abdul Aziz ◽  
Norhana Abdul Halim
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Bacterial Cellulose ◽  
Chemical Treatment ◽  
Mechanical Treatment ◽  
X Ray ◽  
Pure Cellulose ◽  
Scanning Electron

In this work, bacterial cellulose was obtained from nata de coco. Initially, the samples were subjected to three types of different condition which were raw, chemical treatment and mechanical treatment. Bacterial cellulose was characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffractometer (XRD) and Field Emission Scanning Electron Microscopy (FESEM). Bacterial cellulose met the specifications of pure cellulose either using chemical or mechanical treatments proved by IR spectra reading. XRD results indicated that the crystallinity of chemical treatment bacterial cellulose is higher than the mechanical treatment bacterial cellulose which was 68.6% and 59.5% respectively. The FESEM analysis shows that the size of the bacterial cellulose that obtained from chemical treatment is smaller than mechanical treatments which were 19.42μm and 50.35μm.

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