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AbstractBacterial cellulose (BC) is becoming a promising biopolymeric material due to its potential applications in biomedicine and emerging industrial technologies, among other exciting new uses. In the current work, BC nanofibres were produced by Gluconacetobacter xylinus using alternative sources of nutrients derived from agricultural by-products, pineapple peel and banana extracts, which are cheaper and very abundant. The production yield and thickness of BC produced in a non-conventional culture medium from pineapple peel extract with additional yeast extract and peptone was higher than that produced from Hestrin and Schramm’s medium. Three prominent and characteristic diffraction peaks from X-ray diffraction patterns corresponding to the crystal planes of [Formula: see text] (110) and (200) indicate a typical cellulose [Formula: see text] structure. The Fourier transform infrared spectroscopy of BC fabrics also shows evidence of peaks characteristic of cellulose [Formula: see text] Scanning electron microscopy analysis of BC fabrics reveals ribbon-like microfibrils with widths less than 100 nm in all media. Thermogravimetric analysis shows the degradation of BC with similar characteristics among the samples. Alternative sources of nutrients derived from agricultural by-products found in this work could be utilized as a new culture medium to produce suitable BC for industrial applications and its composites in future work.

Bacterial cellulose (BC) is becoming a promising biopolymeric material due to its potential applications in biomedicine and emerging industrial technologies, among other exciting new uses. In the current work, BC nanofibres were produced by Gluconacetobacter xylinus using alternative sources of nutrients derived from agricultural by-products, pineapple peel and banana extracts, which are cheaper and very abundant. The production yield and thickness of BC produced in a non-conventional culture medium from pineapple peel extract with additional yeast extract and peptone was higher than that produced from Hestrin and Schramm's medium. Three prominent and characteristic diffraction peaks from X-ray diffraction patterns corresponding to the crystal planes of (1 1 ¯ 0) , (110) and (200) indicate a typical cellulose I structure. The Fourier transform infrared spectroscopy of BC fabrics also shows evidence of peaks characteristic of cellulose I. Scanning electron microscopy analysis of BC fabrics reveals ribbon-like microfibrils with widths less than 100 nm in all media. Thermogravimetric analysis shows the degradation of BC with similar characteristics among the samples. Alternative sources of nutrients derived from agricultural by-products found in this work could be utilized as a new culture medium to produce suitable BC for industrial applications and its composites in future work. [ABSTRACT FROM AUTHOR]

Microbial-assisted synthesis can advance nanocellulose production, while addressing the economics and environmental friendliness of conventional techniques. Bacterial nanocellulose (BNC) is a linear exopolysaccharide with 3-D structures and nanofibril networks synthesized by various bacteria. The physical, chemical and mechanical properties of BNC have been characterized for various applications. However, limited knowledge of the thermal degradation and kinetic properties of BNC currently hampers its utilization as renewable biopolymers as heat, temperature, and heating rates influence life span and future applications. Therefore, this study examines the thermal, chemical, morphological, microstructure, and kinetic properties of Gluconacetobacter xylinus synthesized BNC through thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and isoconversional Ozawa–Flynn–Wall (OFW) kinetic modeling. The SEM results showed that BNC has a highly dense fibril structure with overlapping knots, which denotes a high surface area, porosity and crystallinity, whereas EDX revealed C, O, and Na. TGA revealed BNC undergoes three-stage thermal degradation with mass loss of 53.57% and residual mass of 46.43% on average. Kinetic modeling revealed the average activation energy (Ea = 59.39 kJ/mol) and pre-exponential factor (ko = 1.62 × 1010 min−1) for BNC indicating high thermal reactivity. Thus, G. xylinus- synthesized BNC has potential for many applications in the future.

This work investigated the suitability of using date syrup for producing bacterial cellulose (BC) by Gluconacetobacter xylinus (PTCC 1734). In the preliminary study, BC was produced in Hesterin-Schramm (HS) medium. The highest production yield was achieved after 12 days of cultivation at the initial pH of 8. Considering this result, BC was produced in modified HS media containing date syrup. In the modified HS1 (MHS1) medium, glucose was omitted, and in the modified HS2 (MHS2) medium, neither glucose nor peptone was present. Interestingly, the production yield in the modified media was about 75% higher than the production using HS medium. The amounts of BC produced using MHS1 and MHS2 media were obtained as 5.03 gL-1 and 5.17 gL-1, respectively. Structure analysis of these specimens indicated long fibrils, with diameters less than 70 nm. However, the crystallinity index of BC obtained from MHS1 media, containing peptone, was higher than that of BS produced in MHS2. [ABSTRACT FROM AUTHOR]

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microbial-assisted synthesis can advance nanocellulose production, while addressing the economics and environmental friendliness of conventional techniques. Bacterial nanocellulose (BNC) is a linear exopolysaccharide with 3-D structures and nanofibril networks synthesized by various bacteria. The physical, chemical and mechanical properties of BNC have been characterized for various applications. However, limited knowledge of the thermal degradation and kinetic properties of BNC currently hampers its utilization as renewable biopolymers as heat, temperature, and heating rates influence life span and future applications. Therefore, this study examines the thermal, chemical, morphological, microstructure, and kinetic properties of Gluconacetobacter xylinus synthesized BNC through thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and isoconversional Ozawa–Flynn–Wall (OFW) kinetic modeling. The SEM results showed that BNC has a highly dense fibril structure with overlapping knots, which denotes a high surface area, porosity and crystallinity, whereas EDX revealed C, O, and Na. TGA revealed BNC undergoes three-stage thermal degradation with mass loss of 53.57% and residual mass of 46.43% on average. Kinetic modeling revealed the average activation energy (Ea = 59.39 kJ/mol) and pre-exponential factor (ko = 1.62 × 1010 min−1) for BNC indicating high thermal reactivity. Thus, G. xylinus- synthesized BNC has potential for many applications in the future. [ABSTRACT FROM AUTHOR]

Bacterial nanocellulose (BNC) is an indomitable biomaterial of utmost usage in different technological areas. Previously, the BNC production has been reported in the simplified bioreactors. Thus, pioneering bioreactor-assisted strategies are desirable for the commendable BNC production. Advanced bioreactors must be corroborated along with different bacterial strains to obtain creditable BNC yield. This study deals with BNC production in rotary disc bioreactor (RDBR) using Gluconacetobacter xylinus NCIM 2526 strain. RDBR-based production of BNC provided 189 ± 14 gL−1 of wet BNC, i.e., equivalent to 6.6 ± 0.3 gL−1 dry BNC yield in 10 days. However, in static cultivation mode, 56 ± 12 gL−1 wet weight of BNC, corresponding to 2.4 ± 0.4 gL−1 dry weight, was produced. Thus, BNC production was approximately 2.75 folds higher in RDBR than statically produced BNC from the same volume of the media. The sugar to BNC conversion yield (12.2 ± 0.8%) was doubled in RDBR-based production as compared to static BNC production (6.2 ± 1.4%) with efficient sugar consumption (90.0 ± 3.3%). The maximum amount of BNC was produced at 7 RPM and pH 6. RDBR-based BNC showed a more hydrophilic nature than statically produced BNC. The RDBR might be appropriate for large-scale BNC production, especially for wet-end applications, as an ample amount of BNC can be produced from a single fermentation process. These BNC pellicles might have the potential for biomedical applications like wound dressings, biofacial masks, hydrogels, and tissue engineering scaffolds. [ABSTRACT FROM AUTHOR]

Abstract Although the unique nanostructure of bacterial cellulose (BC) imparts superior mechanochemical properties and thus allows for diverse applications, the high production cost of BC necessitates the development of more cost‐effective solutions, for example, those using lignocellulosic biomass as a substrate and relying on its pretreatment and saccharification to generate fermentable sugars. However, the various species (e.g., aliphatic acids, furans, and phenolics) produced during pretreatment may interfere with bacterial cell growth and BC production. Herein, we investigated the effects of aliphatic (acetic and formic) acids, furans (5‐hydroxymethylfurfural [5‐HMF] and furfural), and phenolics (syringaldehyde and p‐coumaric acid) on the production of BC. This production was enhanced at low aliphatic acid concentrations (1 g/L acetic acid and 0.5 g/L formic acid) but was suppressed by at least 90% in cases of 0.75 g/L formic acid, 0.4 g/L furfural, 4 g/L 5‐HMF, 2.5 g/L syringaldehyde, and 2.5 g/L p‐coumaric acid. BC production efficiencies of 97.86%, 76.66%, and 73.50% were observed for Miscanthus, barley straw, and pine tree hydrolysates, respectively, under optimal conditions. Therefore, these results provided the possibility to utilize the most abundant and sustainable lignocellulose on the planet for BC production.

Nanocellulose with increasing attention in basic research and for use in advanced materials is usually considered to have a symmetrical nanofibril, nanorod or fibrillated nanofiber shape, regardless of the asymmetric effects owing to the presence of one reducing end. The production of asymmetrical nanocellulose would considerably extend its usefulness in new applications. Here, we propose an asymmetric form of cellulose nanofibrils having a shape that changed from a thick nanobarrel at one end to a thinner cylinder with a few flourishes towards the reducing end. The "cellulose nanoanemone" fibrils, named after sea anemone, were fabricated by aqueous counter collision of bacterial cellulose pellicle cultured under dissolved oxygen conditions. The characteristics of the "cellulose nanoanemone" fibrils were determined both in the dry and the in situ water-dispersed states by selective staining of the fibrillated ends in a single nanofibril by using confocal laser scanning microscopy, together with their unique thixotropic behavior. [ABSTRACT FROM AUTHOR]

Quorum sensing is a mechanism that facilitates cell-to-cell communication. Through signal molecular density for signal recognition, which leads to the regulation of some physiological and biochemical functions. Gluconacetobacter xylinus CGMCC 2955, which produces bacterial cellulose (BC), synthesizes the LuxR protein belonging to the LuxI/LuxR type QS system. Here, a luxR overexpression vector was transformed into G. xylinus CGMCC 2955. The overexpression of luxR increased the yield of BC by 15.6% after 16 days static culture and reduced the cell density by 15.5% after 120-h-agitated culture. The glucose was used up by G. xylinus-pMV24-luxR at 72-h-agitated fermentation, which 12 h earlier than the wild-type (WT). The total N-acylhomoserine lactones (AHL) content of the luxR-overexpressing strain and the WT strain attained 1367.9 ± 57.86 mg/L and 842.9 ± 54.22 mg/L, respectively. The C12-HSL and C14-HSL contents of G. xylinus-pMV24-luxR were 202 ± 21.66 mg/L and 409.6 ± 0.91 mg/L, which were significantly lower than that of WT. In contrast, C6-HSL showed opposite results. The difference of AHL content proved that overexpression of luxR improved the binding of AHL and showed preference for some specific AHL. The metabolic results demonstrated that upon glucose exhaustion, the consumption of gluconic acid was promoted by luxR overexpression, and the content of D- (+)-trehalose, an antiretrograde metabolite, increased significantly. Key points: • The overexpression of luxR increased the yield of bacterial cellulose • The content of signal molecules was significantly different • Differential metabolites were involved in multiple metabolic pathways [ABSTRACT FROM AUTHOR]

Although the unique nanostructure of bacterial cellulose (BC) imparts superior mechanochemical properties and thus allows for diverse applications, the high production cost of BC necessitates the development of more cost‐effective solutions, for example, those using lignocellulosic biomass as a substrate and relying on its pretreatment and saccharification to generate fermentable sugars. However, the various species (e.g., aliphatic acids, furans, and phenolics) produced during pretreatment may interfere with bacterial cell growth and BC production. Herein, we investigated the effects of aliphatic (acetic and formic) acids, furans (5‐hydroxymethylfurfural [5‐HMF] and furfural), and phenolics (syringaldehyde and p‐coumaric acid) on the production of BC. This production was enhanced at low aliphatic acid concentrations (1 g/L acetic acid and 0.5 g/L formic acid) but was suppressed by at least 90% in cases of 0.75 g/L formic acid, 0.4 g/L furfural, 4 g/L 5‐HMF, 2.5 g/L syringaldehyde, and 2.5 g/L p‐coumaric acid. BC production efficiencies of 97.86%, 76.66%, and 73.50% were observed for Miscanthus, barley straw, and pine tree hydrolysates, respectively, under optimal conditions. Therefore, these results provided the possibility to utilize the most abundant and sustainable lignocellulose on the planet for BC production. [ABSTRACT FROM AUTHOR]

The search for innovation and new approaches to mitigate environmental impact encourages the cosmetic industry to explore new methodologies and materials. Bacterial cellulose has been the focus of research because it has high biocompatibility, skin adhesion, and water retention, in addition to being a sustainable alternative material. This review paper explored the perspectives emerging in the scientific literature on the use of bacterial cellulose in cosmetics. This bibliometric review was performed using four databases along with three software programs to obtain a more complete analysis. The search identified 18 articles related to the topic. Because the highest number of articles was published in the year 2019, it was estimated that more publications will appear in the near future. Studies have demonstrated the potential for the use of bacterial cellulose in face masks for the delivery of active compounds and increased skin hydration, and it can also act as an emulsion stabilizer.

Introdution: Natural cellulose is a normal wound healing remedy that can improve the wound healing properties by combining with some herbal extracts. The aim of this study was to evaluate the production of bacterial cellulose containing Zingiber extract and to evaluate its healing effects in rat cutaneous wounds. Methods: In this experimental study, Gluconacetobacter xylinus was first cultured in a hysterine-scrum culture medium under static conditions and aqueous extract of Zingiber officinale plant was prepared. Then, Microculture Tetrazolium Test (MTT) was performed to evaluate the cytotoxicity of the aqueous extract of Zingiber officinale, and finally the healing process was investigated on rat cutaneous ulcers in different days of treatment. Results: The results of this study have shown that the cellulose layer was manufactured, tight, non-fracture and with pH = 7/005, which had the proper repair wound of 80%. The extract of the Zingiber officinale plant in the MTT test had toxicity to the cells, which has the same toxicity for cancerous and non-cancerous cells. For wound healing, the non-toxic concentration of the extract was used, and the results of the wound healing showed that cellulose and Zingiber officinale extract can be used as a suitable drug for wound healing. Conclusion: Gluconacetobacter xylinus is effective in healing and wound, also the Zingiber officinale plant has a miraculous effect on open wounds.

Background: Bacterial cellulose membrane (BCM) produced by Gluconacetobacter xylinus is an advantageous bacterial product and because of its unique properties could be used as an ideal dressing. The aim of this study was to consider the capability of this biomaterial in the release of Metronidazole. In the case of proving this capability, it provides the basis for the production of a dressing containing this type of antibiotic. Materials and Methods: In this study, BCM was initially synthesized by Gluconacetobacter xylinus. The BCM was loaded by Metronidazole. Then the release process was considered in distilled water and buffer phosphate Saline. The ultra violet spectrophotometry was applied for measuring the concentration of the released drug. Results: The chemical structure of bacterial cellulose was confirmed by Fourier Transform Infrared (FT-IR) spectroscopy. The release of Metronidazole in distilled water and phosphate buffered Saline was reached to 84.27% and 84.71%, respectively. Due to higher release in phosphate buffered Saline media, it seems that the trend of release in vitro provides efficient results. Conclusion: Results of this study provides the basis for future research on supplying an ideal dressing from this microbial product.

The aim of the present study was to evaluate the impact of a rotating magnetic field (RMF) on cellular and biochemical properties of Gluconacetobacter xylinus during the process of cellulose synthesis by these bacteria. The application of the RMF during bacterial cellulose (BC) production intensified the biochemical processes in G. xylinus as compared to the RMF-unexposed cultures. Moreover, the RMF had a positive impact on the growth of cellulose-producing bacteria. Furthermore, the application of RMF did not increase the number of mutants unable to produce cellulose. In terms of BC production efficacy, the most favorable properties were found in the setting where RMF generator was switched off for the first 72 h of cultivation and switched on for the further 72 h. The results obtained can be used in subsequent studies concerning the optimization of BC production using different types of magnetic fields including RMF, especially.

The structural characteristics of the nascent fibril produced by Gluconacetobacter xylinum (G. xylinum) have been studied under the influence of the cellulose binding dye brilliant yellow (BY) by wide angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR) and 13C solid-state nuclear magnetic resonance. BY is found to be more effective at reducing crystallinity than fluorescent brightener 28 (FB28), pontamine fast scarlet 4 (S4B) and other dyes previously studied. Under static cultivation conditions, increasing concentrations of brilliant yellow in the growth media from 20, 50, 100 to 250 μM, result in decreasing cellulose crystallinity from 73 to 18%, respectively, as compared to 82% exhibited by the control. FTIR data indicate that the presence of BY is most effective at suppressing intra-molecular hydrogen bonding. After boiling in 70 vol% aqueous EtOH solution for 12 h, the extracted dye-altered cellulose becomes more ordered, which may be due to the extraction of BY from the BY-cellulose complex. FTIR data indicate that compared to control cellulose, the reclaimed brilliant yellow-altered cellulose contains more cellulose Iβ, where the FB28 and S4B altered cellulose remains principally Iα. Based on WAXD and NMR data we propose a dye-cellulose complex structure associated with BY. This model supports the hypothesis that microfibrils assemble through the hydrogen bonding of formed mini-sheets that consist of stacked glucan chains linked by van der Waals forces. [ABSTRACT FROM AUTHOR]

• Polyurethane foam allows bacterial cellulose production in solid state culture. • The highest yield was 2.46 g L-1 with 0.125 cm3 foam and 15% inoculum for 96 h. • Polyurethane foam presents high water storage capacity and oxygen diffusion. • Bacteria synthesize the biopolymer as biofilm adhered to the solid matrix scaffold. The polyurethane foam (PUF) allowed the growth of Gluconacetobacter xylinus for prompt production of bacterial cellulose (BC) due to high water storage capacity that let high water activity, as well as diffusion of oxygen through the PUF pores. PUF was studied in two sizes cut (0.13 cm3) and minced (0.08 cm3). Additionally, the study assessed the level of inoculum on the growth and the formation of BC. The highest yield of BC was 2.46 g L-1 of cellulose achieved with cut foam and 15% inoculum at 96 h. Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD) and solid state 13C cross polarization and magic angle spinning nuclear magnetic resonance (CP/MAS NMR) analyses evidence crystalline structure type I for the produced microbial cellulose. According to scanning electron microscopy (SEM) analysis, the bacteria synthesized the biopolymer as a biofilm adhered to the solid support; thereby BC displays a honeycomb geometry. [ABSTRACT FROM AUTHOR]

Oranges (Citrus sinensis) are the world's most processed fruit. The waste from processing is rich in soluble sugars, cellulose, hemicelluloses and pectin and therefore has potential as feedstock for bacterial cellulose (BC) production. In this study, cellulase and pectinase were used to hydrolyze orange peel in order to increase the amount of fermentable sugars. Response surface methodology was used to evaluate the effects of reaction parameters, and 80.99 g/L reducing sugar was obtained with cellulase of 1589.41 U/g, pectinase of 31.75 U/g and a reaction time of 5.28 h. Besides, the orange peel fluid and orange peel hydrolysate were used as the culture media for Gluconacetobacter xylinus during BC production. The orange peel media have no significant inhibiting effect on the fermentation activity of G. xylinus for BC production. As an acetic acid buffer was used or nitrogen source was added to the orange peel media, BC production was 4.2-6.32 times higher than that in traditional Hestrin and Schramm (HS) medium. The SEM and IR spectra showed that the BC produced was not much different than that produced in HS medium. These results demonstrate that orange peel not only can be used as a low cost feedstock to produce BC, but it also provides a solution to the waste disposal problem of the orange juice industry. [ABSTRACT FROM AUTHOR]

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of the study was to analyze the changes in the parameters of bacterial cultures and bacterial cellulose (BC) synthesized by four reference strains of Gluconacetobacter xylinus during 31-day cultivation in stationary conditions. The study showed that the most visible changes in the analyzed parameters of BC, regardless of the bacterial strain used for their synthesis, were observed in the first 10–14 days of the experiment. It was also revealed, that among parameters showing dependence associated with the particular bacterial strain were the rate and period of BC synthesis, the growth rate of bacteria anchored to the cellulose fibrils, the capacity to absorb water and the water release rate. The results presented in this work may be useful in the selection of optimum culturing conditions and period from the point of view of good efficiency of the cellulose synthesis process.

Mature black Spear grass (Heteropogon contortus) was hydrolyzed using different concentrations of dilute sulphuric acid for the first time as lignocellulosic substrate for producing reducing sugars at different pH and retention time. The maximum total reducing sugar (TRS) from Spear grass hydrolysate (SGH) was 2.48g/L using 6% H2SO4 at 121oC for 4h with higher amount of xylose than glucose and arabinose. BC yield was comparable to those from reported lignocellulosic hydrolysates. The result of the study proved that mature back spear grass, commonly known as tanglehead, which is less useful as fooder due to lower nutrient, clogs animal furs and, sticks to human walker’s clothes, can be hydrolyzed with little cost to produce fermentable sugars used as substrates for producing such biotechnological products as, biofuels, biogas, and bacterial cellulose. Keywords: Reducing sugar, Spear grass hydrolysate, pH, Gluconacetobacter xylinus

ABSTRACT Because of the widespread occurrence of cellulose in nature, many organisms use glycerol as a source of carbon and energy, so these organisms have drawn attention to the potential use of glycerol bioconversion. The bacteria Gluconacetobacter xylinus, a strictly aerobic strain that performing incomplete oxidation of various sugars and alcohols to cellulose biosynthesis. For this reason, we modify the Hestrim-Schram medium, associating glycerol, glucose and sucrose varying their concentration. The fermentations were performed statically at a temperature of 28˚C for a period of 10 days. The pH, membrane formation, crystallinity and the production of some metabolites of the 4th, 7th and 10th days was evaluated. The results showed a higher yield of membrane in the medium containing glucose, gly 1 + glu2 on 10 fermentation of 3.5 g %. Through solid-state NMR gave the crystallinity of the membranes, where there was a clear trend toward higher crystallinity membranes with 7 days of fermentation. Metabolic products found in the media by analysis of NMR spectroscopy in liquid were similar, especially for the production of alanine and lactate that were present in all media. The leucine and threonine were present in various media, although in small quantities has been found glutamate.

Abstract A new biological approach was explored to harvest microalgae in situ with bacterial cellulose produced by Gluconacetobacter xylinus grown in microalgal culture by adding different proportions of glucose/yeast extract (GY) media. This study attempted to optimize this process in terms of GY media concentration, process time, microalgae cell concentration, and oscillation speed. Bacterial cellulose successfully harvested nearly 90% of Scenedesmus obliqnus and Chlamydomonas reinhardtii after only 8 h, and 92% of Chlorella vulgaris after 48 h, with supplementation of 30% (v/v) GY media to the microalgae culture. This method allows harvested media to be recycled instead of GY media, and can be used for a variety of cell densities. Scanning electron microscopy revealed that microalgae cells were harvested after being embedded in a network of bacterial cellulose. These results suggest this effective and simple operation has the potential for developing a cost-effective harvest method for microalgae production. Highlights • Microalgae were harvested in situ with bacterial cellulose produced by G. xylinus. • Supplementation of glucose/yeast extract media influenced harvesting efficiency. • This method is effective for a wide variety of microalgal species. • After microalgae harvest, the media was successfully recycled for subsequent growth and flocculation with G. xylinus. [ABSTRACT FROM AUTHOR]

Mature black Spear grass (Heteropogon contortus) was hydrolyzed using different concentrations of dilute sulphuric acid for the first time as lignocellulosic substrate for producing reducing sugars at different pH and retention time. The maximum total reducing sugar (TRS) from Spear grass hydrolysate (SGH) was 2.48g/L using 6% H2SO4 at 121°C for 4h with higher amount of xylose than glucose and arabinose. BC yield was comparable to those from reported lignocellulosic hydrolysates. The result of the study proved that mature back spear grass, commonly known as tanglehead, which is less useful as fooder due to lower nutrient, clogs animal furs and, sticks to human walker's clothes, can be hydrolyzed with little cost to produce fermentable sugars used as substrates for producing such biotechnological products as, biofuels, biogas, and bacterial cellulose. [ABSTRACT FROM AUTHOR]

A bacterial cellulose (BC) synthesizing strain (Gluconacetobacter xylinus ZHCJ618) was isolated from kombucha and selected as the species for commercial applications owing to its high phenotypic stability and sustainable production capacity of 7.56 ± 0.57 g/L under static culturing conditions and 8.31 ± 0.79 g/L under shaking conditions. The morphological, physiological and biochemical characteristics of the strain were similar to those of Gluconacetobacter genus. The 16S rDNA sequence homologies with G. xylinus NCIB 11664 reached 99%, showing that the isolated strain can be identified as G. xylinus. The material properties of BC were studied by fourier transform infrared spectroscopy, scanning electronic microscopy, X-ray diffraction, thermogravimetric analysis, and tensile test. The results showed that BC synthesized under static conditions exhibited stronger tear strength, higher crystallinity, superior waterhold and rehydration rate than BC synthesized under shaking conditions. [ABSTRACT FROM AUTHOR]

Oxygen plays a key role during bacterial cellulose (BC) biosynthesis by Gluconacetobacter xylinus. In this study, the Vitreoscilla hemoglobin (VHb)-encoding gene vgb, which has been widely applied to improve cell survival during hypoxia, was heterologously expressed in G. xylinus via the pBla-VHb-122 plasmid. G. xylinus and G. xylinus-vgb were statically cultured under hypoxic (10 and 15% oxygen tension in the gaseous phase), atmospheric (21%), and oxygen-enriched conditions (40 and 80%) to investigate the effect of oxygen on cell growth and BC production. Irrespective of vgb expression, we found that cell density increased with oxygen tension (10-80%) during the exponential growth phase but plateaued to the same value in the stationary phase. In contrast, BC production was found to significantly increase at lower oxygen tensions. In addition, we found that BC production at oxygen tensions of 10 and 15% was 26.5 and 58.6% higher, respectively, in G. xylinus-vgb than that in G. xylinus. The maximum BC yield and glucose conversion rate, of 4.3 g/L and 184.7 mg/g, respectively, were observed in G. xylinus-vgb at an oxygen tension of 15%. Finally, BC characterization suggested that hypoxic conditions enhance BC's mass density, Young's modulus, and thermostability, with G. xylinus-vgb synthesizing softer BC than G. xylinus under hypoxia as a result of a decreased Young's modulus. These results will facilitate the use of static culture for the production of BC. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of high hydrostatic pressure (HHP) and co-fermentation by Lactobacillus rhamnosus and Gluconacetobacter xylinus on the quality of yacon-litchi-longan (YLL) juice. The carbohydrates, organic acids, free amino acids (FAAs), and volatile compounds in YLL juice were analyzed. Thermal processing (TP) increased the content of total carbohydrates, organic acids and FAAs, and destroyed the aroma components, whereas HHP treatment had a negligible effect. Carbohydrate content was lower, and content of lactic acid, acetic acid, and exopolysaccharide (EPS) were higher in co-fermented juice than in unfermented juice. Furthermore, the content of bitter FAAs in fermented TP and HHP-treated YLL juices decreased by 88.7% and 86.9%, respectively. Co-fermentation also increased ketones and the sum of individual volatile constituents, and improved the overall flavor of juice. Taken together, HHP treatment prior to co-fermentation can be used to improve the quality of YLL juice, especially the flavor thereof.

Durian is one important tropical fruit with high nutritional value, but its shell is usually useless and considered as waste. To explore the efficient and high-value utilization of this agricultural and food waste, in this study, durian shell was simply hydrolyzed by dilute sulfuric acid, and the durian shell hydrolysate after detoxification was used for bacterial cellulose (BC) production by Gluconacetobacter xylinus for the first time. BC was synthesized in static culture for 10 days and the highest BC yield (2.67 g/L) was obtained at the 8th day. The typical carbon sources in the substrate including glucose, xylose, formic acid, acetic acid, etc. can be utilized by G. xylinus. The highest chemical oxygen demand (COD) removal (16.40%) was obtained at the 8th day. The highest BC yield on COD consumption and the highest BC yield on sugar consumption were 93.51% and 22.98% (w/w), respectively, suggesting this is one efficient bioconversion for BC production. Durian shell hydrolysate showed small influence on the BC structure by comparison with the structure of BC generated in traditional Hestrin-Schramm medium detected by FE-SEM, FTIR, and XRD. Overall, this technology can both solve the issue of waste durian shell and produce valuable bio-polymer (BC). [ABSTRACT FROM AUTHOR]

Copyright of Investigacion & Educacion en Enfermeria is the property of Universidad de Antioquia, Facultad de Enfermeria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objectives: To evaluate the crystallinity index of the cellulose produced by Escherichia coli Nissle 1917 after heterologous expression of the cellulose synthase subunit D ( bcsD) gene of Gluconacetobacter xylinus BPR2001. Results: The bcsD gene of G. xylinus BPR2001 was expressed in E. coli and its protein product was visualized using SDS-PAGE. FTIR analysis showed that the crystallinity index of the cellulose produced by the recombinants was 0.84, which is 17% more than that of the wild type strain. The increased crystallinity index was also confirmed by X-ray diffraction analysis. The cellulose content was not changed significantly after over-expressing the bcsD. Conclusion: The bcsD gene can improve the crystalline structure of the bacterial cellulose but there is not any significant difference between the amounts of cellulose produced by the recombinant and wild type E. coli Nissle 1917. [ABSTRACT FROM AUTHOR]

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 14 days. 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. [ABSTRACT FROM AUTHOR]