Development of a bacterial cellulose-gelatin composite as a suitable scaffold for cardiac tissue engineering.

PURPOSE: Cardiac tissue engineering is suggested as a promising approach to overcome problems associated with impaired myocardium. This is the first study to investigate the use of BC and gelatin for cardiomyocyte adhesion and growth. METHODS: Bacterial cellulose (BC) membranes were produced by Komagataeibacter xylinus and coated or mixed with gelatin to make gelatin-coated BC (BCG) or gelatin-mixed BC (mBCG) scaffolds, respectively. BC based-scaffolds were characterized via SEM, FTIR, XRD, and AFM. Neonatal rat-ventricular cardiomyocytes (nr-vCMCs) were cultured on the scaffolds to check the capability of the composites for cardiomyocyte attachment, growth and expansion. RESULTS: The average nanofibrils diameter in all scaffolds was suitable (~ 30-65 nm) for nr-vCMCs culture. Pore diameter (≥ 10 µm), surface roughness (~ 182 nm), elastic modulus (0.075 ± 0.015 MPa) in mBCG were in accordance with cardiomyocyte requirements, so that mBCG could better support attachment of nr-vCMCs with high concentration of gelatin, and appropriate surface roughness. Also, it could better support growth and expansion of nr-vCMCs due to submicron scale of nanofibrils and proper elasticity (~ 0.075 MPa). The viability of nr-vCMCs on BC and BCG scaffolds was very low even at day 2 of culture (~ ≤ 40%), but, mBCG could promote a metabolic active state of nr-vCMCs until day 7 (~ ≥ 50%). CONCLUSION: According to our results, mBCG scaffold was the most suitable composite for cardiomyocyte culture, regarding its physicochemical and cell characteristics. It is suggested that improvement in mBCG stability and cell attachment features may provide a convenient scaffold for cardiac tissue engineering.

Effects of bacterial cellulose/thyme essential oil emulsion coating on the shelf life of chilled chicken meat.

BACKGROUND: Bacterial cellulose (BC) is a fiber substance produced by microbial fermentation. It is widely used in the food preservation industry because of its extremely pure texture, high crystallinity and high biocompatibility. In the present study, bacterial cellulose/thyme essential oil (BC/TEO-E) with antibacterial and fresh-keeping functions was prepared by ultrasonic treatment of modified bacterial cellulose for encapsulation of thyme essential oil, which effectively inhibited the spoilage of chilled chicken. RESULTS: The purified BC, produced by Acetobacter xylinum ATCC 53524, was ultrasonically treated wih different times (0, 30, 60 and 90 min). Transmission electron microscopy, scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and zeta potential were used to characterize the structure of BC after ultrasound, showing that BC, treated for 30 min, had the optimal fiber structure, crystallinity (85.8%), thermal stability (347.77 °C) and solution stability (-26.63 ± 1.96 mV). BC/TEO-E was prepared by a homogenizer for the preservation of chilled chicken. Optical microscopy indicated that the BC/TEO-E prepared by 0.5% BC had optimal dispersion and stability, and even no delamination was observed in the emulsion. Compared with other groups (control, 0.5% BC and Tween-E), the total number of colonies and coliforms in chilled chicken treated with 0.5% BC/TEO-E was the lowest during the whole storage period (12 days), indicating that it can effectively inhibit bacterial growth. In addition, total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances, pH and drip loss results showed that 0.5% BC/TEO-E could effectively inhibit the spoilage of chilled chicken compared to the other treatment groups. CONCLUSION: All of the results acquired in the present study indicate that BC/TEO-E has a potential application in chilled chicken preservation. © 2024 Society of Chemical Industry.

Physical and antibacterial properties of bacterial cellulose films supplemented with cell-free supernatant enterocin-producing Enterococcus faecium TJUQ1.

In this study, a composite film was prepared with bacterial cellulose (BC) of Gluconacetobacter xylinus and cell-free supernatant (CFS) of Enterococcus faecium TJUQ1, which was named BC-E. The optimum conditions for the preparation of the composite film with a minimal antibacterial activity were the soak of BC in 80 AU/mL CFS for 6 h. By scanning electron microscope observation, the surface network structure of BC-E was denser than that of BC. The tensile strength of BC and BC-E was 4.65 ± 0.88 MPa and 16.30 ± 0.92 MPa, the elongation at break of BC and BC-E was 3.33 ± 0.89% and 31.60 ± 1.15%, respectively, indicating the mechanical properties of BC-E were significantly higher than that of BC (P < 0.05). The swelling ratio of BC-E (456.67 ± 7.20%) was lower than that of BC (1377.78 ± 9.07%), demonstrating BC-E films presented better water resistance. BC-E films were soaked with 320 AU/mL CFS, and then used to pack the ground meat with 6.55 log10 CFU/g of Listeria monocytogenes. After 8 days of storage, the number of bacteria decreased by 3.16 log10 CFU/g. Similarly, total mesophilic bacterial levels in the ground meat decreased by 2.41 log10 CFU/g compared to control groups.

Synthesis and SERS application of gold and iron oxide functionalized bacterial cellulose nanocrystals (Au@Fe3O4@BCNCs).

Bacterial cellulose nanocrystals (BCNCs) are biocompatible cellulose nanomaterials that can host guest nanoparticles to form hybrid nanocomposites with a wide range of applications. Herein, we report the synthesis of a hybrid nanocomposite that consists of plasmonic gold nanoparticles (AuNPs) and superparamagnetic iron oxide (Fe3O4) nanoparticles supported on BCNCs. As a proof of concept, the hybrid nanocomposites were employed to isolate and detect malachite green isothiocyanate (MGITC) via magnetic separation and surface-enhanced Raman scattering (SERS). Different initial gold precursor (Au3+) concentrations altered the size and morphology of the AuNPs formed on the nanocomposites. The use of 5 and 10 mM Au3+ led to a heterogenous mix of spherical and nanoplate AuNPs with increased SERS enhancements, as compared to the more uniform AuNPs formed using 1 mM Au3+. Rapid and sensitive detection of MGITC at concentrations as low as 10-10 M was achieved. The SERS intensity of the normalized Raman peak at 1175 cm-1 exhibited a log-linear relationship for MGITC concentrations between 2 × 10-10 and 2 × 10-5 M for Au@Fe3O4@BCNCs. These results suggest the potential of these hybrid nanocomposites for application in a broad range of analyte detection strategies.

Soft Bacterial Cellulose Microcapsules with Adaptable Shapes.

Microcapsules with controlled stability and permeability are in high demand for applications in separation and encapsulation. We have developed a biointerfacial process to fabricate strong, but flexible, porous microcapsules from bacterial cellulose at an oil-water emulsion interface. A broad range of microcapsule sizes has been successfully produced, from 100 µm to 5 cm in diameter. The three-dimensional capsule microstructure was imaged using confocal microscopy, showing a cellulose membrane thickness of around 30 µm that is highly porous, with some pores larger than 0.5 µm that are permeable to most macromolecules by free diffusion but can exclude larger structures like bacteria. The mechanical deformation of cellulose microcapsules reveals their flexibility, enabling them to pass through constrictions with a much smaller diameter than their initial size by bending and folding. Our work provides a new approach for producing soft, permeable, and biocompatible microcapsules for substance encapsulation and protection. The capsules may offer a replacement for suspended polymer beads in commercial applications and could potentially act as a framework for artificial cells.

Bacterial-Derived, Compressible, and Hierarchical Porous Carbon for High-Performance Potassium-Ion Batteries.

Hierarchical-structured electrodes having merits of superior cycling stability and high rate performance are highly desired for next-generation energy storage. For the first time, we reported a compressible and hierarchical porous carbon nanofiber foam (CNFF) derived from a sustainable and abundant biomaterial resource, bacterial cellulose, for boosting the electrochemical performance of potassium-ion batteries. The CNFF free-standing electrode with a hierarchical porous three-dimensional structure demonstrated excellent rate performance and outstanding cyclic stability in the extended cycling test. Specifically, in the long-term cycling-stability test, the CNFF electrode maintained a stable capacity of 158 mA h g-1 after 2000 cycles at a high current density of 1000 mA g-1, which has an average capacity decay of 0.006% per cycle. After that, the CNFF electrode maintained a capacity of 141 mA h g-1 at a current density of 2000 mA g-1 for another 1500 cycles, and a capacity of 122 mA h g-1 at a current density of 5000 mA g-1 for an additional 1000 cycles. The mechanism for the outstanding performance is that the hierarchical porous and stable CNFF with high surface area and high electronic conductivity provides sufficient sites for potassium-ion storage. Furthermore, quantitative kinetics analysis has validated the capacitive- and diffusion-controlled charge-storage contributions in the carbon-foam electrode. This work will inspire the search for cost-effective and sustainable materials for potassium electrochemical energy storage.

Encapsulation of Micro- and Milli-Sized Particles with a Hollow-Type Spherical Bacterial Cellulose Gel via Particle-Preloaded Droplet Cultivation.

A hollow-type spherical bacterial cellulose (HSBC) gel prepared using conventional methods cannot load particles larger than the pore size of the cellulose nanofiber network of bacterial cellulose (BC) gelatinous membranes. In this study, we prepared a HSBC gel encapsulating target substances larger than the pore size of the BC gelatinous membranes using two encapsulating methods. The first method involved producing the BC gelatinous membrane on the surface of the core that was a spherical alginate gel with a diameter of 2 to 3 mm containing the target substances. With this method, the BC gelatinous membrane was biosynthesized using Gluconacetobacter xylinus at the interface between the cell suspension attached onto the alginate gel and the silicone oil. The second method involved producing the BC gel membrane on the interface between the silicone oil and cell suspension, as well as the spherical alginate gel with a diameter of about 1 mm containing target substances. After the BC gelatinous membrane was biosynthesized, an alginate gel was dissolved in a phosphate buffer to prepare an HSBC gel with the target substances. These encapsulated substances could neither pass through the BC gelatinous membrane of the HSBC gel nor leak from the interior space of the HSBC gel. These results suggest that the HSBC gel had a molecular sieving function. The HSBC gel walls prepared using these methods were observed to be uniform and would be useful for encapsulating bioactive molecules, such as immobilized enzymes in HSBC gel, which is expected to be used as a drug carrier.

Free-standing three-dimensional hollow bacterial cellulose structures with controlled geometry via patterned superhydrophobic-hydrophilic surfaces.

Bacteria can produce cellulose, one of the most abundant biopolymer on earth, and emerge as an interesting candidate to fabricate advanced materials. Cellulose produced by Komagataeibacter Xylinus, a bacterial strain, is a pure water insoluble biopolymer, without hemicellulose or lignin. Bacterial cellulose (BC) exhibits a nanofibrous porous network microstructure with high strength, low density and high biocompatibility and it has been proposed as cell scaffold and wound healing material. The formation of three dimensional (3D) cellulose self-standing structures is not simple. It either involves complex multi-step synthetic procedures or uses chemical methods to dissolve cellulose and remold it. Here we present an in situ single-step method to produce self-standing 3D-BC structures with controllable wall thickness, size and geometry in a reproducible manner. Parameters such as hydrophobicity of the surfaces, volume of the inoculum and time of culture define the resulting 3D-BC structures. Hollow spheres and convex domes can be easily obtained by changing the surface wettability. The potential of these structures as a 3D cell scaffold is exemplified supporting the growth of mouse embryonic stem cells within a hollow spherical BC structure, indicating its biocompatibility and future prospective.

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

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].

Production of nanocellulose in miniature-bioreactor: Optimization and characterization.

Bacterial cellulose (BC) is a very fascinating microbial biopolymer which is mainly produced by Gluconacetobacter xylinum. Optimization of BC production by G. xylinum was performed based on scale-down studies in miniature-bioreactor and response surface methodology in which the optimum pH value (6.5) and shaking rate (50 rpm) were obtained. The static culture condition for BC production has newly been defined. Nanostructure of BC includes nanofibers up to (60 nm) and nanoporosity up to (265 nm) was observed by scanning electron microscopy. By Fourier transform infrared spectroscopy study, the most expected BC interaction is nucleophilic interaction. MTT assay showed high biocompatibility. Appropriate mechanical strength (0.37 MPa) and Young's modulus (3.36 MPa) evinced BC scaffold utilization for skin tissue. The results indicate that BC sheets can be utilized in biomedical application and nanotechnology approaches.

Characterisation and in vitro antimicrobial activity of biosynthetic silver-loaded bacterial cellulose hydrogels.

Wounds that remain in the inflammatory phase for a prolonged period of time are likely to be colonised and infected by a range of commensal and pathogenic microorganisms. Treatment associated with these types of wounds mainly focuses on controlling infection and providing an optimum environment capable of facilitating re-epithelialisation, thus promoting wound healing. Hydrogels have attracted vast interest as moist wound-responsive dressing materials. In the current study, biosynthetic bacterial cellulose hydrogels synthesised by Gluconacetobacter xylinus and subsequently loaded with silver were characterised and investigated for their antimicrobial activity against two representative wound infecting pathogens, namely S. aureus and P. aeruginosa. Silver nitrate and silver zeolite provided the source of silver and loading parameters were optimised based on experimental findings. The results indicate that both AgNO3 and AgZ loaded biosynthetic hydrogels possess antimicrobial activity (p < .05) against both S. aureus and P. aeruginosa and may therefore be suitable for wound management applications.

Stable-Isotope Probing Identifies Uncultured Planctomycetes as Primary Degraders of a Complex Heteropolysaccharide in Soil.

The exopolysaccharides (EPSs) produced by some bacteria are potential growth substrates for other bacteria in soil. We used stable-isotope probing (SIP) to identify aerobic soil bacteria that assimilated the cellulose produced by Gluconacetobacter xylinus or the EPS produced by Beijerinckia indica. The latter is a heteropolysaccharide comprised primarily of l-guluronic acid, d-glucose, and d-glycero-d-mannoheptose. (13)C-labeled EPS and (13)C-labeled cellulose were purified from bacterial cultures grown on [(13)C]glucose. Two soils were incubated with these substrates, and bacteria actively assimilating them were identified via pyrosequencing of 16S rRNA genes recovered from (13)C-labeled DNA. Cellulose C was assimilated primarily by soil bacteria closely related (93 to 100% 16S rRNA gene sequence identities) to known cellulose-degrading bacteria. However, B. indica EPS was assimilated primarily by bacteria with low identities (80 to 95%) to known species, particularly by different members of the phylum Planctomycetes. In one incubation, members of the Planctomycetes made up >60% of all reads in the labeled DNA and were only distantly related (<85% identity) to any described species. Although it is impossible with SIP to completely distinguish primary polysaccharide hydrolyzers from bacteria growing on produced oligo- or monosaccharides, the predominance of Planctomycetes suggested that they were primary degraders of EPS. Other bacteria assimilating B. indica EPS included members of the Verrucomicrobia, candidate division OD1, and the Armatimonadetes. The results indicate that some uncultured bacteria in soils may be adapted to using complex heteropolysaccharides for growth and suggest that the use of these substrates may provide a means for culturing new species.

Interactions of arabinoxylan and (1,3)(1,4)-ß-glucan with cellulose networks.

To identify interactions of relevance to the structure and properties of the primary cell walls of cereals and grasses, we used arabinoxylan and (1,3)(1,4)-ß-glucan, major polymers in cereal/grass primary cell walls, to construct composites with cellulose produced by Gluconacetobacter xylinus. Both polymers associated prolifically with cellulose without becoming rigid or altering the nature or extent of cellulose crystallinity. Mechanical properties were modestly affected compared with xyloglucan or pectin (characteristic components of nongrass primary cell walls) composites with cellulose. In situ depletion of arabinoxylan arabinose side chains within preformed cellulose composites resulted in phase separation, with only limited enhancement of xylan-cellulose interactions. These results suggest that arabinoxylan and (1 → 3)(1 → 4)-ß-d-glucan are not functional homologues for either xyloglucan or pectin in the way they interact with cellulose networks. Association of cell-wall polymers with cellulose driven by entropic amelioration of high energy cellulose/water interfaces should be considered as a third type of interaction within cellulose-based cell walls, in addition to molecular binding (enthalpic driving force) exhibited by, for example, xyloglucans or mannans, and interpenetrating networks based on, for example, pectins.

Bacterial cellulose as a support for the growth of retinal pigment epithelium.

The feasibility of bacterial cellulose (BC) as a novel substrate for retinal pigment epithelium (RPE) culture was evaluated. Thin (41.6 ± 2.2 µm of average thickness) and heat-dried BC substrates were surface-modified via acetylation and polysaccharide adsorption, using chitosan and carboxymethyl cellulose. All substrates were characterized according to their surface chemistry, wettability, energy, topography, and also regarding their permeability, dimensional stability, mechanical properties, and endotoxin content. Then, their ability to promote RPE cell adhesion and proliferation in vitro was assessed. All surface-modified BC substrates presented similar permeation coefficients with solutes of up to 300 kDa. Acetylation of BC decreased it's swelling and the amount of endotoxins. Surface modification of BC greatly enhanced the adhesion and proliferation of RPE cells. All samples showed similar stress-strain behavior; BC and acetylated BC showed the highest elastic modulus, but the latter exhibited a slightly smaller tensile strength and elongation at break as compared to pristine BC. Although similar proliferation rates were observed among the modified substrates, the acetylated ones showed higher initial cell adhesion. This difference may be mainly due to the moderately hydrophilic surface obtained after acetylation.

Antimicrobial Poly(lactic acid)-Based Nanofibres Developed by Solution Blow Spinning.

The present study reports on the development of hybrid poly(lactic acid) (PLA) fibres loaded with highly crystalline bacterial cellulose nanowhiskers (BCNW) by the novel solution blow spinning method. Furthermore, fibres with antimicrobial properties were generated by incorporating carvacrol and THC as antimicrobial agents and the biocide effect against Listeria monocytogenes was studied. Initially, PLA blow spun fibres containing BCNW were optimized in terms of morphology and thermal properties. The addition of BCNW was seen to significantly increase the viscosity and surface tension of solutions, restricting the capacity to form fibres for concentrations greater than 30 wt.-% BCNW. 15 wt.-% BCNW was selected as the optimum nanofiller loading as it led to the most uniform fibres morphology, with BCNW homogeneously distributed along the fibres' axis. Subsequently, carvacrol and THC were incorporated into the fibres to confer them with antimicrobial properties, although the hydrophobic PLA matrix did not provide an efficient release of the antimicrobials. Thus, hydrophilic substances were added in order to trigger the antimicrobials release through water sorption mechanisms. The addition of the BCNW filler was not seen to significantly increase the antimicrobial capacity of the fibres by itself and, hence, gelatin was added to help promoting further the hydrophylicity and biocide performance of the fibres. Nevertheless, for the more hydrophilic THC, the biocide capacity of the fibres with gelatin was accentuated further by the presence of the BCNW.

The characteristics of bacterial nanocellulose gel releasing silk sericin for facial treatment.

BACKGROUND: Recently, naturally derived facial masks with beneficial biological properties have received increasing interest. In this study, silk sericin-releasing bacterial nanocellulose gel was developed to be applied as a bioactive mask for facial treatment. RESULTS: The silk sericin-releasing bacterial nanocellulose gel produced at a pH of 4.5 had an ultrafine and extremely pure fiber network structure. The mechanical properties and moisture absorption ability of the gel were improved, compared to those of the commercially available paper mask. Silk sericin could be control-released from the gel. A peel test with porcine skin showed that the gel was less adhesive than the commercially available paper mask, which would be removed from the face more easily without pain. The in vitro cytotoxicity test showed that the gel was not toxic to L929 mouse fibroblast and HaCaT human keratinocyte cells. Furthermore, when implanted subcutaneously and evaluated according to ISO10993-6 standard, the gel was not irritant to tissue. CONCLUSION: The silk sericin-releasing bacterial nanocellulose gel had appropriate physical and biological properties and safety for the facial treatment application.

Hydration control of the mechanical and dynamical properties of cellulose.

The mechanical and dynamical properties of cellulose, the most abundant biomolecule on earth, are essential for its function in plant cell walls and advanced biomaterials. Cellulose is almost always found in a hydrated state, and it is therefore important to understand how hydration influences its dynamics and mechanics. Here, the nanosecond-time scale dynamics of cellulose is characterized using dynamic neutron scattering experiments and molecular dynamics (MD) simulation. The experiments reveal that hydrated samples exhibit a higher average mean-square displacement above ∼240 K. The MD simulation reveals that the fluctuations of the surface hydroxymethyl atoms determine the experimental temperature and hydration dependence. The increase in the conformational disorder of the surface hydroxymethyl groups with temperature follows the cellulose persistence length, suggesting a coupling between structural and mechanical properties of the biopolymer. In the MD simulation, 20% hydrated cellulose is more rigid than the dry form, due to more closely packed cellulose chains and water molecules bridging cellulose monomers with hydrogen bonds. This finding may have implications for understanding the origin of strength and rigidity of secondary plant cell walls. The detailed characterization obtained here describes how hydration-dependent increased fluctuations and hydroxymethyl disorder at the cellulose surface lead to enhancement of the rigidity of this important biomolecule.

Effects of plant cell wall matrix polysaccharides on bacterial cellulose structure studied with vibrational sum frequency generation spectroscopy and X-ray diffraction.

The crystallinity, allomorph content, and mesoscale ordering of cellulose produced by Gluconacetobacter xylinus cultured with different plant cell wall matrix polysaccharides were studied with vibrational sum frequency generation (SFG) spectroscopy and X-ray diffraction (XRD). Crystallinity and ordering were assessed as the intensity of SFG signals in the CH/CH2 stretch vibration region (and confirmed by XRD), while Iα content was assessed by the relative intensity of the OH stretch vibration at 3240 cm(-1). A key finding is that the presence of xyloglucan in the culture medium greatly reduced Iα allomorph content but with a relatively small effect on cellulose crystallinity, whereas xylan resulted in a larger decrease in crystallinity with a relatively small decrease in the Iα fraction. Arabinoxylan and various pectins had much weaker effects on cellulose structure as assessed by SFG and XRD. Homogalacturonan with calcium ion reduced the SFG signal, evidently by changing the ordering of cellulose microfibrils. We propose that the distinct effects of matrix polysaccharides on cellulose crystal structure result, at least in part, from selective interactions of the backbone and side chains of matrix polysaccharides with cellulose chains during the formation of the microfibril.

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.

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 Iß 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 Iß). 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.

Morphology and structure characterization of bacterial celluloses produced by different strains in agitated culture.

AIMS: The influence of bacterial species/strains in agitated culture was investigated on the morphology and structure characteristics of bacterial cellulose. METHODS AND RESULTS: Komagataeibacter nataicola Y19 and Gluconacetobacter entanii ACCC10215 were inoculated in Hestrin-Schramm (HS) medium and subjected to agitated cultivation. Different kinds of BCs were obtained including flocky asterisk-like BC by G. entanii ACCC10215 and solid sphere-like BC by K. nataicola Y19. The SEM results showed that the asterisk-like BC had larger pores than the solid sphere-like BC. The FT-IR and X-ray diffraction results showed the asterisk-like BC had lower crystallinity (81·43%), higher cellulose Iα mass fraction (79·74%) and smaller crystallite size. CONCLUSIONS: The different species/strains can influence the morphology and structure characteristics of BC in agitated culture. SIGNIFICANCE AND IMPACT OF THE STUDY: We examined the influence of different species/strains on the morphology, macro- and microstructure of BCs produced in agitated culture for the first time, which suggest that different BCs with potential applications could be obtained by choosing different species or strains and fermentation method.