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1.
J Agric Food Chem ; 68(9): 2696-2701, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32031789

RESUMO

All-cellulose composites are usually prepared by removing impurities and using a surface-selective dissolution approach, which detract significantly from their environment-friendly properties. In this paper, we report an environment-friendly approach to fabricate all-cellulose nanofiber composites from stack-up bacterial cellulose (BC) hydrogels via self-aggregation forces of the hydrogen bond by water-based processing. Structural and mechanical properties of BC-laminated composites have been investigated. The results indicated that BC composites possess the structure of all nanofibers, a tensile strength of 116 MPa, and a storage modulus of 25 GPa. Additionally, the interfacial shear strength and tensile strength of piece-hot-press BC demonstrate the strong self-aggregation forces of BC nanofibers. Thus, BC-laminated composites will be attractive in structural material.


Assuntos
Celulose/química , Gluconacetobacter xylinus/química , Hidrogéis/química , Nanofibras/química , Celulose/metabolismo , Gluconacetobacter xylinus/crescimento & desenvolvimento , Gluconacetobacter xylinus/metabolismo , Hidrogéis/metabolismo , Fenômenos Mecânicos , Resistência à Tração
2.
Carbohydr Polym ; 232: 115788, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31952596

RESUMO

Bacterial cellulose (BC) has received considerable attention as an environment-friendly, biodegradable nanomaterial. In this study, the strain Komagataeibacter sp. nov. CGMCC 17276, which showed rapid cell growth and high BC-production ability, was isolated and classified into a novel species in the Komagataeibacter genus. Four BC synthase operons were annotated using whole-genome analysis, partially explaining the high BC yield of strain CGMCC 17276. Operons bcs Ⅱ and bcs Ⅲ showed high transcriptional levels under static and agitated culture conditions, indicating their importance in BC synthesis. Of the eight suitable carbon sources identified by whole-genome analysis, the highest BC production was achieved using glycerol as a single carbon source. Finally, waste glycerol was successfully used as an eco-friendly and sustainable strategy for BC production. This study provides valuable insights into the mechanism of BC synthesis, genetic structure of BC-producing strains, and industrialization of BC production using an eco-friendly and low-cost strategy.


Assuntos
Celulose/biossíntese , Gluconacetobacter xylinus/genética , Celulose/genética , DNA Bacteriano/genética , Fermentação , Gluconacetobacter xylinus/metabolismo , Análise de Sequência de DNA
3.
Appl Microbiol Biotechnol ; 103(21-22): 9143-9154, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31650194

RESUMO

In this work, recycled paper sludge (RPS), composed of non-recyclable fibres, was used as a carbon source for bacterial nanocellulose (BNC) production. The biomass was enzymatically hydrolysed with Cellic CTec 2 to produce a sugar syrup with 45.40 g/L glucose, 1.69 g/L cellobiose and 2.89 g/L xylose. This hydrolysate was used for the optimization of BNC fermentation by static culture, using Komagataeibacter xylinus ATCC 700178, through response surface methodology (RSM). After analysis and validation of the model, a maximum BNC yield (5.69 g/L, dry basis) was obtained using 1.50% m/v RPS hydrolysate, 1.0% v/v ethanol and 1.45% m/v yeast extract/peptone (YE/P). Further, the BNC obtained was used to produce composites. A mixture of an amino-PolyDiMethylSiloxane-based softener, polyethyleneglycol (PEG) 400 and acrylated epoxidized soybean oil (AESO), was incorporated into the BNC membranes through an exhaustion process. The results show that BNC composites with distinct performances can be easily designed by simply varying the polymers percentage contents. This strategy represents a simple approach towards the production of BNC and BNC-based composites.


Assuntos
Celulose/metabolismo , Gluconacetobacter xylinus/metabolismo , Esgotos/microbiologia , Purificação da Água/métodos , Fermentação , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier
4.
Nat Commun ; 10(1): 4650, 2019 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-31604956

RESUMO

Gluconacetobacter xylinus (G. xylinus) metabolism is activated by oxygen, which makes the formation of an air-medium interface critical. Here we report solid matrix-assisted 3D printing (SMAP) of an incubation medium surface and the 3D fabrication of bacterial cellulose (BC) hydrogels by in situ biosynthesis of G. xylinus. A printing matrix of polytetrafluoroethylene (PTFE) microparticles and a hydrogel ink containing an incubation medium, bacteria, and cellulose nanofibers (CNFs) are used in the SMAP process. The hydrogel ink can be printed in the solid matrix with control over the topology and dimensional stability. Furthermore, bioactive bacteria produce BC hydrogels at the surface of the medium due to the permeability of oxygen through the PTFE microparticle layer. The flexibility of the design is verified by fabricating complex 3D structures that were not reported previously. The resulting tubular BC structures suggest future biomedical applications, such as artificial blood vessels and engineered vascular tissue scaffolding. The fabrication of a versatile free-form structure of BC has been challenged due to restricted oxygen supplies at the medium and the dimensional instability of hydrogel printing. SMAP is a solution to the problem of fabricating free-form biopolymer structures, providing both printability and design diversity.


Assuntos
Gluconacetobacter xylinus/fisiologia , Engenharia Tecidual/métodos , Técnicas de Cultura de Células/instrumentação , Celulose , Meios de Cultura , Gluconacetobacter xylinus/crescimento & desenvolvimento , Gluconacetobacter xylinus/metabolismo , Hidrogéis/química , Nanofibras , Oxigênio , Impressão Tridimensional , Tecidos Suporte/química
5.
Bioprocess Biosyst Eng ; 42(12): 2023-2034, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31489493

RESUMO

Based on cellulose biosynthesis pathway of Gluconacetobacterxylinus BPR2001 and E. coli Nissle 1917, bcsA and bcsB genes have been selected and bioinformatics studies done to the analyses of nucleotide and amino acid sequence alignment, stability of RNA, protein, and promotor power. We amplify and clone bcsA, bcsB, and bcsAB genes of G. xylinus BPR2001 in Escherichiacoli Nissle 1917 under the inducible tac promoter. Our results of bioinformatics predictions demonstrate similar active site and three-dimensional structure of BcsA and BcsB proteins in two different bacteria. In addition, our data reveal that BcsA and BcsB proteins of E. coli have weaker promotor power, RNA secondary structure, and protein stability than that of the same proteins in G. xylinus. Some of the reasons of BcsAB protein selection from G. xylinus and its heterologous expression in E. coli is the noted points. Production of the related proteins visualized using SDS-PAGE. We find out that Congo red absorbance at 490 nm has no significant difference in wild-type strain (E. coli Nissle 1917) compared to recombinants bcsA+ or bcsB+, but recombinant bcsAB+ could produce more cellulose than that of the wild-type strain. Furthermore, the measurement of cellulose dry weights of all samples confirms bacterial cellulose production enhancement in recombinant bcsAB+ (1.94 g l-1). The FTIR analysis reveals that the crystallinity indices do not change significantly after over expressing each of genes.


Assuntos
Proteínas de Bactérias/metabolismo , Celulose/biossíntese , Escherichia coli/metabolismo , Genes Bacterianos , Gluconacetobacter xylinus/metabolismo , Microbiologia Industrial/métodos , Sítios de Ligação , Biologia Computacional , Vermelho Congo/química , Proteínas de Escherichia coli/metabolismo , Gluconacetobacter xylinus/genética , Glucosiltransferases/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Conformação de Ácido Nucleico , Plasmídeos , Regiões Promotoras Genéticas , Conformação Proteica , Proteínas Recombinantes/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier
6.
Carbohydr Polym ; 219: 210-218, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31151519

RESUMO

Scaffold plays a critical role in stem cell differentiation and tissue regeneration. Composite scaffolds composed of bacterial cellulose (BC) and collagen (Col) in different ratios (1:1, 3:1, 5:1) were fabricated in this study. The composite scaffolds exhibit a well-organized interconnected porous structure, significantly better physical stability than Col scaffold, and more water uptake up to 400%. They were also favorable with cell attachment and growth. After osteogenic induction of umbilical cord blood derived mesenchymal stem cells (UCB-MSCs) for 3 weeks, we found more up-regulated osteogenic markers (collagen type 1, osteocalcin, bone sialoprotein) and significantly elevated proteins and calcium deposition, particularly with BC/Col (5:1) scaffold. When PKH-26 pre-labelled MSC-loaded scaffolds were subcutaneously transplanted in a mouse model, they showed many PKH-26-labelled cells and positive signals of α-smooth muscle actin, for neovascularization in the BC/Col (5:1). The current work demonstrates that our BC/Col composites may be promising as a bone tissue-engineered scaffold.


Assuntos
Celulose/química , Colágeno/química , Gluconacetobacter xylinus/metabolismo , Engenharia Tecidual/métodos , Tecidos Suporte/química , Animais , Regeneração Óssea/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Celulose/uso terapêutico , Colágeno/uso terapêutico , Humanos , Células-Tronco Mesenquimais/efeitos dos fármacos , Camundongos , Células NIH 3T3 , Osteogênese/efeitos dos fármacos
7.
Carbohydr Polym ; 220: 170-175, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31196537

RESUMO

It's long been understood that antimicrobial properties are one of the most important function in the field of biomedicine. In this thesis, we introduce a new technique to functionalize bacterial cellulose (BC) with antimicrobial properties by in situ method. We design a series of experiments on hydrolyzing mulberry leaves and exploring the methods of fermenting and purifying to obtain a BC complex with antimicrobial properties. Meanwhile, the anti-bacterial performances of MH-BC (fermented by the mulberry leaves acid hydrolysate fermentation medium) were evaluated with Escherichia coli and Staphylococcus aureus, and the experimental results showed that the MH-BC have excellent anti-bacterial activities. Considering the excellent biocompatibility of MH-BC towards hMSCs, we expect that this antibacterial functional BC composite will find potential applications in biomedicine and regenerative medicine.


Assuntos
Antibacterianos/farmacologia , Materiais Biocompatíveis/farmacologia , Celulose/farmacologia , Escherichia coli/efeitos dos fármacos , Gluconacetobacter xylinus/metabolismo , Células-Tronco Mesenquimais/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Fermentação , Humanos , Hidrólise , Teste de Materiais/métodos , Células-Tronco Mesenquimais/citologia , Morus/microbiologia , Folhas de Planta/microbiologia
8.
Carbohydr Polym ; 215: 280-288, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30981355

RESUMO

The impact of strain selection and culture conditions on bacterial nanocellulose (BNC) productivity and quality was investigated by using four strains, static and agitated cultures, and an initial pH in the range 4-6. With agitation, strain DHU-ATCC-1 displayed highest productivity [1.14 g/(L × d)]. In static cultures, DHU-ZGD-1186 exhibited superior BNC yield on consumed glucose (0.79 g/g), and lowest by-product formation with respect to gluconic acids [≤0.07 g/(L × d)]. By-product formation typically decreased in the order gluconic acid >2-keto-gluconic acid >5-keto-gluconic acid, and was lowest in cultures with high initial pH. The BNC from DHU-ZGD-1186 exhibited higher average viscometric degree of polymerization (DPv), higher crystallinity index, and higher tear index. In conclusion, both strain selection and cultivation conditions had an impact on BNC productivity and properties. Productivity, DPv, crystallinity, and mechanical strength of BNC from agitated cultures could be similar to or even higher than the corresponding values for static cultures.


Assuntos
Celulose/biossíntese , Gluconacetobacter xylinus/crescimento & desenvolvimento , Técnicas de Cultura de Células , Celulose/química , Celulose/metabolismo , Fermentação , Gluconacetobacter xylinus/metabolismo , Gluconatos/metabolismo , Glucose/metabolismo , Concentração de Íons de Hidrogênio
9.
Carbohydr Polym ; 211: 75-83, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30824106

RESUMO

Potato peel waste (PPW) is employed as the first report on bacterial cellulose (BC) production by Gluconacetobacter xylinus. Scharification of PPW was performed by 2 M different mineral acids individually. The suitable pre-treatment conditions were determined by reducing sugar release. Although all acid PPW-hydrolysates culture media are studied to produce BCs. Nitric acid hydrolysate gives the high productivity value The influence of nitric acid PPW-hydrolysate culture condition parameters were applied throughout the Taguchi method and the optimum conditions for the highest BC yield (4.7 g/L) was observed after 6 days at 35 °C, pH 9, medium volume 55 ml and with 8% inoculum size. The instrumental analysis of PPW-BC, included FT-IR, Particle size distribution, BET, DSC, XRD and SEM are cleared that the PPW-BC recorded high crystalliny82.5%, excellent PDI. In general, this study revealed that nitric acid PPW-hydrolysate could be used as cost effective alternative medium for production of BC with sustainable processes that can overcome the environmental pollution.


Assuntos
Celulose/metabolismo , Gluconacetobacter xylinus/metabolismo , Solanum tuberosum , Química Verde , Ácido Nítrico/química , Reciclagem , Resíduos
10.
Mater Sci Eng C Mater Biol Appl ; 97: 302-312, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30678915

RESUMO

Bionanocellulose (BNC) is a clear polymer produced by the bacterium Gluconacetobacter xylinus. In our current study, "Research on the use of bacterial nanocellulose (BNC) in regenerative medicine as a function of the biological implants in cardiac and vascular surgery", we carried out material analysis, biochemical analysis, in vitro tests and in vivo animal model testing. In stage 1 of the project, we carried out physical and biological tests of BNC. This allowed us to modify subsequent samples of bacterial bionanocellulose. Finally, we obtained a sample that was accepted for testing on an animal model. That sample we define BNC1. Patches of BNC1 were then implanted into pigs' vessel walls. During the surgical procedures, we evaluated the technical aspects of sewing in the bioimplant, paying special attention to bleeding control and tightness of the suture line and the BNC1 bioimplant itself. We carried out studies evaluating the reaction of an animal body to an implantation of BNC1 into the circulatory system, including the general and local inflammatory reaction to the bioimplant. These studies allowed us to document the potential usefulness of BNC as a biological implant of the circulatory system and allowed for additional modifications of the BNC to improve the properties of this new implantable biological material.


Assuntos
Celulose/biossíntese , Celulose/química , Gluconacetobacter xylinus/metabolismo , Implantes Experimentais , Animais , Candida albicans/crescimento & desenvolvimento , Candida albicans/metabolismo , Procedimentos Cirúrgicos Cardíacos/instrumentação , Celulose/farmacologia , Hemólise/efeitos dos fármacos , Ácido Hialurônico/metabolismo , Implantes Experimentais/efeitos adversos , Inflamação/etiologia , Teste de Materiais , Suínos , Resistência à Tração
11.
Int J Biol Macromol ; 122: 280-288, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30342939

RESUMO

Bacterial cellulose (BC) is gaining considerable attention due to its unique physicochemical and mechanical properties. In this study, BC production by Gluconacetobacter xylinus PTCC 1734 in sugar beet molasses, cheese whey and standard Hestrin-Schramm (HS) media was evaluated. The synthesized BC was hydrolyzed by sulfuric acid to prepare bacterial cellulose nanocrystals (BCNC). The results showed that treated sugar beet molasses led to the highest BC concentration and productivity, followed by treated cheese whey. Structural analysis of BC and BCNC was carried out by Fourier Transform Infrared (FTIR) spectroscopy. The crystallinity index of the BCNC determined by X-ray diffraction (XRD) was higher than BC. The morphological analysis carried out by FE-SEM showed that microfibrils diameter decreases with acid treatment. TEM images confirmed the formation of rod like cellulose nanocrystals having an average diameter and length of 25 ±â€¯5 and 306 ±â€¯112 nm, respectively. In conclusion, food industrial byproducts can be used as cost-effective culture media to produce BC for large-scale industrial production and isolated cellulose nanocrystals are useful in the fabrication of bio-nanocomposite films for food packaging applications.


Assuntos
Beta vulgaris/química , Celulose/biossíntese , Meios de Cultura/química , Gluconacetobacter xylinus/metabolismo , Melaço , Nanopartículas , Soro do Leite/química , Celulose/química , Queijo/análise
12.
Macromol Biosci ; 19(2): e1800225, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30451373

RESUMO

Surgical clipping and endovascular coiling are well recognized as conventional treatments of Penetrating Brain Injury aneurysms. These clinical approaches show partial success, but often result in thrombus formation and the rupture of aneurysm near arterial walls. The authors address these challenging brain traumas with a unique combination of a highly biocompatible biopolymer hydrogel rendered magnetic in a flexible and resilient membrane coating integrated to a scaffold stent platform at the aneurysm neck orifice, which enhances the revascularization modality. This work focuses on the in situ diagnosis of nano-mechanical behavior of bacterial nanocellulose (BNC) membranes in an aqueous environment used as tissue reconstruction substrates for cerebral aneurysmal neck defects. Nano-mechanical evaluation, performed using instrumented nano-indentation, shows with very low normal loads between 0.01 to 0.5 mN, in the presence of deionized water. Mechanical testing and characterization reveals that the nano-scale response of BNC behaves similar to blood vessel walls with a very low Young´s modulus, E (0.0025 to 0.04 GPa), and an evident creep effect (26.01 ± 3.85 nm s-1 ). These results confirm a novel multi-functional membrane using BNC and rendered magnetic with local adhesion of iron-oxide magnetic nanoparticles.


Assuntos
Revascularização Cerebral/métodos , Procedimentos Endovasculares/métodos , Hidrogéis/uso terapêutico , Aneurisma Intracraniano/cirurgia , Nanopartículas de Magnetita/uso terapêutico , Celulose/uso terapêutico , Procedimentos Endovasculares/efeitos adversos , Gluconacetobacter xylinus/metabolismo , Humanos , Aneurisma Intracraniano/fisiopatologia , Fenômenos Mecânicos , Instrumentos Cirúrgicos
13.
Appl Biochem Biotechnol ; 187(1): 211-220, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29915916

RESUMO

Bio-cellulose is the microbial extracellular cellulose that is produced by growing several microorganisms on agriculture by-products, and it is used in several food applications. This study aims to utilize sago by-product, coconut water, and the standard medium Hestrin-Schramm as the carbon sources in the culture medium for bio-cellulose production. The bacteria Beijerinkia fluminensis WAUPM53 and Gluconacetobacter xylinus 0416 were selected based on their bio-cellulose production activity. The structure was determined by Fourier transform infrared spectroscopy and scanning electron microscopy, while the toxicity safety was evaluated by brine shrimp lethality test. The results of Fourier transform infrared spectroscopy showed that the bio-cellulose produced by B. fluminensis cultivated in sago by-products was of high quality. The bio-cellulose production by B. fluminensis in the sago by-product medium was slightly higher than that in the coconut water medium and was comparable with the production in the Hestrin-Schramm medium. Brine shrimp lethality test confirmed that the bio-cellulose produced by B. fluminensis in the sago by-product medium has no toxicity, which is safe for applications in the food industry. This is the first study to determine the high potential of sago by-product to be used as a new carbon source for the bio-cellulose production.


Assuntos
Beijerinckiaceae/metabolismo , Celulose/biossíntese , Gluconacetobacter xylinus/metabolismo
14.
Bioresour Technol ; 274: 518-524, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30553964

RESUMO

In this study, bacterial cellulose (BC) was synthesized by Acetobacter xylinum ATCC 23767 using tobacco waste extract (TWE) as a carbon source. Nicotine was found to be an inhibitory factor for BC synthesis, but it can be removed at pH 9.0 by steam distillation. After removing nicotine, the BC production was 2.27 g/L in TWE prepared with solid-liquid (S-L) ratio at 1:10. To further enhance the BC production, two fermentation stages were performed over 16 days by re-adjusting the pH to 6.5 at 7 days, after the first fermentation stage was completed. Using this two-stage fermentation, the BC production could reach 5.2 g/L. Structural and thermal analysis by FE-SEM, FT-IR, XRD and TGA showed the properties of BC obtained from TWE were similar to that from Hestrin-Schramm (HS) medium. Considering the huge disposal tobacco waste in China, the present study provides an alternative methodology to synthesize BC.


Assuntos
Celulose/metabolismo , Gluconacetobacter xylinus/metabolismo , Tabaco/metabolismo , Metabolismo dos Carboidratos , Carbono/metabolismo , China , Meios de Cultura , Fermentação , Espectroscopia de Infravermelho com Transformada de Fourier
15.
Carbohydr Polym ; 198: 620-630, 2018 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-30093042

RESUMO

The influences of nano-bacterial cellulose (Nano-BC)/soy protein isolate (SPI) complex gel on the textural, rheological, and sensory properties of the ice cream model were investigated. Nano-BC/SPI mixtures with different ratios (Nano-BC:SPI, 1:20, 1:15, 1:10, and 1:5 w/w) were prepared with constant total solid content (16%). Compared with pure SPI, the thermal stability, textural, rheological and emulsifying properties of nano-BC/SPI mixtures were improved. Microstructure of nano-BC/SPI complex gels showed that low doses of nano-BC (1:20, 1:15, and 1:10) had good compatibility with SPI matrix according to images of confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Nano-BC/SPI (1:20) had the most similar textural properties to the cream. When 20% of nano-BC/SPI (1:20) mixture was added into ice cream as the cream substitute, the anticipated ice cream with low calorie, melting resistance, and good textural properties was achieved.


Assuntos
Celulose/química , Substitutos da Gordura/química , Sorvetes , Proteínas de Soja/química , Celulose/metabolismo , Cor , Emulsões , Congelamento , Géis , Gluconacetobacter xylinus/metabolismo , Humanos , Reologia , Método Simples-Cego , Paladar
16.
Appl Microbiol Biotechnol ; 102(17): 7417-7428, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29982923

RESUMO

A strain of acetic acid bacteria, Komagataeibacter xylinus B-12068, was studied as a source for bacterial cellulose (BC) production. The effects of cultivation conditions (carbon sources, temperature, and pH) on BC production and properties were studied in surface and submerged cultures. Glucose was found to be the best substrate for BC production among the sugars tested; ethanol concentration of 3% (w/v) enhanced the productivity of BC. Optimization of medium and cultivation conditions ensures a high production of BC on glucose and glycerol, up to 2.4 and 3.3 g/L/day, respectively. C/N elemental analysis, emission spectrometry, SEM, DTA, and X-ray were used to investigate the structure and physical and mechanical properties of the BC produced under different conditions. MTT assay and SEM showed that native cellulose membrane did not cause cytotoxicity upon direct contact with NIH 3T3 mouse fibroblast cells and was highly biocompatible.


Assuntos
Celulose/biossíntese , Gluconacetobacter xylinus/metabolismo , Microbiologia Industrial/métodos , Animais , Etanol/metabolismo , Glucose/metabolismo , Concentração de Íons de Hidrogênio , Temperatura
17.
Int J Biol Macromol ; 117: 967-973, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29883701

RESUMO

The morphology and structure of the biosynthesized cellulose are related to the culture methods and conditions. In order to investigate the detail culture conditions, the Gluconacetbacter xylinum 1.1812 (ATCC 23767) strains were cultivated in static culture at 12 and 30 °C, and agitated culture at 12 °C. The cellulose samples were analyzed by FESEM, FTIR, CP/MAS 13C NMR, WAXRD and TGA. The cellulose membrane produced in static medium at 30 °C is made up of the microfibrils with a width of 60-90 nm, which has highest crystallinity index and the most content of cellulose Iα. The cellulose membrane produced in static medium at 12 °C is accumulated by the pellicles with a thickness of ~10 nm and a width of 700-3000 nm, which is cellulose I crystalline structure. The macroscopic sphere-like cellulose produced in agitated culture at 12 °C is composed of flat, strongly twisted cellulose bands with a width of 700-1200 nm, and reveals completely amorphous structure which exhibits only the diffuse X-ray diffraction pattern, lack of characteristic crystalline peaks. This work provides a new method to prepare amorphous cellulose.


Assuntos
Celulose/biossíntese , Celulose/química , Temperatura , Reatores Biológicos/microbiologia , Técnicas de Cultura , Gluconacetobacter xylinus/crescimento & desenvolvimento , Gluconacetobacter xylinus/metabolismo
18.
Appl Microbiol Biotechnol ; 102(16): 6885-6898, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29926141

RESUMO

Bacterial cellulose is an attractive biopolymer for a number of applications including food, biomedical, cosmetics, and engineering fields. In addition to renewability and biodegradability, its unique structure and properties such as chemical purity, nanoscale fibrous 3D network, high water-holding capacity, high degree of polymerization, high crystallinity index, light transparency, biocompatibility, and mechanical features offer several advantages when it is used as native polymer or in composite materials. Structure and properties play a functional role in both the biofilm life cycle and biotechnological applications. Among all the cellulose-producing bacteria, acetic acid bacteria of the Komagataeibacter xylinus species play the most important role because they are considered the highest producers. Bacterial cellulose from acetic acid bacteria is widely investigated as native and modified biopolymer in functionalized materials, as well as in terms of differences arising from the static or submerged production system. In this paper, the huge amount of knowledge on basic and applied aspects of bacterial cellulose is reviewed to the aim to provide a comprehensive viewpoint on the intriguing interplay between the biological machinery of synthesis, the native structure, and the factors determining its nanostructure and applications. Since in acetic acid bacteria biofilm and cellulose production are two main phenotypes with industrial impact, new insights into biofilm production are provided.


Assuntos
Biofilmes/crescimento & desenvolvimento , Celulose/biossíntese , Celulose/química , Gluconacetobacter xylinus/metabolismo , Glucosiltransferases/genética , Ácido Acético/metabolismo , Biotecnologia , Fermentação
19.
Carbohydr Polym ; 194: 200-207, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-29801830

RESUMO

This study aimed to characterize the structural and physico-mechanical properties of bacterial cellulose (BC) produced by Gluconoacetobacter xylinus TJU-S8 which was isolated from Chinese persimmon vinegar. Thermogravimetric analysis (TGA) showed that BC exhibited a good thermal stability. Solid-state nuclear magnetic resonance (NMR), fourier transform infrared spectroscopy (FT-IR) and x-ray diffraction (XRD) analysis revealed that BC had a typical crystalline form of the cellulose I. The BC membrane had typical characteristics such as nanodimensional network and microfibrils obtained by scanning electron microscopy (SEM). Moreover, the bacterial cellulose chitosan (BC-C) membrane and bacterial cellulose carboxymethyl chitosan (BC-CC) membrane were synthesized which showed significant inhibition against the growth of both Escherichia coli and Staphylococcus aureus. These results indicated superior properties of BC that advocated its effectiveness for various applications.


Assuntos
Ácido Acético/química , Celulose/biossíntese , Celulose/isolamento & purificação , Gluconacetobacter xylinus/química , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Celulose/química , China , Quitosana/síntese química , Quitosana/química , Quitosana/farmacologia , Escherichia coli/efeitos dos fármacos , Gluconacetobacter xylinus/metabolismo , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície
20.
Sci Rep ; 8(1): 6266, 2018 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-29674724

RESUMO

Complete genome sequence of Gluconacetobacter xylinus CGMCC 2955 for fine control of bacterial cellulose (BC) synthesis is presented here. The genome, at 3,563,314 bp, was found to contain 3,193 predicted genes without gaps. There are four BC synthase operons (bcs), among which only bcsI is structurally complete, comprising bcsA, bcsB, bcsC, and bcsD. Genes encoding key enzymes in glycolytic, pentose phosphate, and BC biosynthetic pathways and in the tricarboxylic acid cycle were identified. G. xylinus CGMCC 2955 has a complete glycolytic pathway because sequence data analysis revealed that this strain possesses a phosphofructokinase (pfk)-encoding gene, which is absent in most BC-producing strains. Furthermore, combined with our previous results, the data on metabolism of various carbon sources (monosaccharide, ethanol, and acetate) and their regulatory mechanism of action on BC production were explained. Regulation of BC synthase (Bcs) is another effective method for precise control of BC biosynthesis, and cyclic diguanylate (c-di-GMP) is the key activator of BcsA-BcsB subunit of Bcs. The quorum sensing (QS) system was found to positively regulate phosphodiesterase, which decomposed c-di-GMP. Thus, in this study, we demonstrated the presence of QS in G. xylinus CGMCC 2955 and proposed a possible regulatory mechanism of QS action on BC production.


Assuntos
Celulose/biossíntese , Genoma Bacteriano , Gluconacetobacter xylinus/genética , Celulose/metabolismo , Regulação Enzimológica da Expressão Gênica , Gluconacetobacter xylinus/metabolismo , Glucosiltransferases/genética , Redes e Vias Metabólicas , Óperon , Percepção de Quorum
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