Recent advancements in development and application of microbial cellulose in food and non-food systems.

Microbial cellulose is a fermented form of very pure cellulose with a fibrous structure. The media rich in glucose or other carbon sources are fermented by bacteria to produce microbial cellulose. The bacteria use the carbon to produce cellulose, which grows as a dense, gel-like mat on the surface of the medium. The product was then collected, cleaned, and reused in various ways. The properties of microbial cellulose, such as water holding capacity, gas permeability, and ability to form a flexible, transparent film make it intriguing for food applications. Non-digestible microbial cellulose has been shown to improve digestive health and may have further advantages. It is also very absorbent, making it a great option for use in wound dressings. The review discusses the generation of microbial cellulose and several potential applications of microbial cellulose in fields including pharmacy, biology, materials research, and the food industry.

Cubosome-carrying bacterial cellulose membrane as a versatile drug delivery platform.

Using advanced nanotechnology membranes has opened up new possibilities in the field of biomedicine, particularly for controlled drug delivery and especially for topical use. Bacterial cellulose membranes (BCM), particularly, have gained prominence owing to their distinctive attributes, including remarkable water retention, safety, biodegradability, and tunable gas exchange. However, they are aqueous matrices and, for this reason, of limited capacity for incorporation of apolar compounds. Cubosomes are lipid nanoparticles composed of a surfactant bicontinuous reverse cubic phase, which, owing to their bicontinuous structure, can incorporate both polar and apolar compounds. Therefore, these particles present a promising avenue for encapsulating and releasing drugs and biomolecules due to their superior entrapment efficiency. In this study, we aim to extend earlier investigations using polymeric hydrogels for cubosome immobilization, now using BCMs, a more resilient biocompatible matrix. Phytantriol cubosome-loaded BCMs were prepared by three distinct protocols: ex situ incorporation into wet BCMs, ex situ incorporation by swelling of dry BCMs, and an in situ process with the growth of BCMs in a sterile medium already containing cubosomes. Our investigation revealed that these methodologies ensured that cubosomes remained integral, uniformly distributed, and thoroughly dispersed within the membrane, as confirmed using Small-Angle X-ray Scattering (SAXS) and high-resolution confocal microscopy. The effective incorporation and sustained release of diclofenac were validated across the different BCMs and compared with hyaluronic acid (HA) hydrogel in our previous studies. Furthermore, the resistance against cubosome leaching from the three BCM and HA hydrogel samples was quantitatively evaluated and contrasted. We hope that the outcomes from this research will pave the way for innovative use of this platform in the incorporation and controlled release of varied active agents, amplifying the already multifaceted applicability of BCMs.

Three-dimensional electro-Fenton system supplied with a nanocomposite of microbial cellulose/Fe3O4 for effective degradation of tetracycline.

In this study, the catalytic activity of the modified microbial cellulose/Fe3O4 (MMC/ Fe3O4) composite was studied for tetracycline (TC) degradation and mineralization in a three-dimensional electro-Fenton system (3D-EF). The MC/Fe3O4 was modified at 400 °C for 60 min. The MMC/ Fe3O4 was fully analyzed (morphological, structural, chemical properties). Complete degradation and 65% mineralization of TC was achieved in the 3D-EF process (0.5 g L-1 MMC/ Fe3O4, 10 mM NaCl electrolyte, and neutral pH) within 20 min and electrical energy consumption (EEC) 0.86 kwh g-1 TC under the 6.66 mA cm-2. High degradation efficiency TC, in 3D-EF system was attributed to significant single oxygen (1O2), superoxide(O2•-) participation and less to Hydroxyl radical (OH•). Reusability of the MMC/ Fe3O4 was successfully carried out for five consecutive runs. Accordingly, greencompositeof MMC/ Fe3O4 can be considered as an efficient and durable particle electrode (PE) to degrade and mineralize emerging pollutants in an aquatic environment.

Bacterial Cellulose and Its Applications.

The sharp increase in the use of cellulose seems to be in increasing demand in wood; much more research related to sustainable or alternative materials is necessary as a lot of the arable land and natural resources use is unsustainable. In accordance, attention has focused on bacterial cellulose as a new functional material. It possesses a three-dimensional, gelatinous structure consisting of cellulose with mechanical and thermal properties. Moreover, while a plant-originated cellulose is composed of cellulose, hemi-cellulose, and lignin, bacterial cellulose attributable to the composition of a pure cellulose nanofiber mesh spun is not necessary in the elimination of other components. Moreover, due to its hydrophilic nature caused by binding water, consequently being a hydrogel as well as biocompatibility, it has only not only used in medical fields including artificial skin, cartilage, vessel, and wound dressing, but also in delivery; some products have even been commercialized. In addition, it is widely used in various technologies including food, paper, textile, electronic and electrical applications, and is being considered as a highly versatile green material with tremendous potential. However, many efforts have been conducted for the evolution of novel and sophisticated materials with environmental affinity, which accompany the empowerment and enhancement of specific properties. In this review article, we summarized only industry and research status regarding BC and contemplated its potential in the use of BC.

Use of Industrial Wastes as Sustainable Nutrient Sources for Bacterial Cellulose (BC) Production: Mechanism, Advances, and Future Perspectives.

A novel nanomaterial, bacterial cellulose (BC), has become noteworthy recently due to its better physicochemical properties and biodegradability, which are desirable for various applications. Since cost is a significant limitation in the production of cellulose, current efforts are focused on the use of industrial waste as a cost-effective substrate for the synthesis of BC or microbial cellulose. The utilization of industrial wastes and byproduct streams as fermentation media could improve the cost-competitiveness of BC production. This paper examines the feasibility of using typical wastes generated by industry sectors as sources of nutrients (carbon and nitrogen) for the commercial-scale production of BC. Numerous preliminary findings in the literature data have revealed the potential to yield a high concentration of BC from various industrial wastes. These findings indicated the need to optimize culture conditions, aiming for improved large-scale production of BC from waste streams.

Microbial cellulases - An update towards its surface chemistry, genetic engineering and recovery for its biotechnological potential.

The inherent resistance of lignocellulosic biomass makes it impervious for industrially important enzymes such as cellulases to hydrolyze cellulose. Further, the competitive absorption behavior of lignin and hemicellulose for cellulases, due to their electron-rich surfaces augments the inappropriate utilization of these enzymes. Hence, modification of the surface charge of the cellulases to reduce its non-specific binding to lignin and enhance its affinity for cellulose is an urgent necessity. Further, maintaining the stability of cellulases by the preservation of their secondary structures using immobilization techniques will also play an integral role in its industrial production. In silico approaches for increasing the catalytic activity of cellulase enzymes is also significant along with a range of substrate specificity. In addition, enhanced productivity of cellulases by tailoring the related genes through the process of genetic engineering and higher cellulase recovery after saccharification seems to be promising areas for efficient and large-scale enzyme production concepts.

Limbal Stem Cells on Bacterial Nanocellulose Carriers for Ocular Surface Regeneration.

Limbal stem cells (LSCs) are already used in cell-based treatments for ocular surface disorders. Clinical translation of LSCs-based therapies critically depends on the successful delivery, survival, and retention of these therapeutic cells to the desired region. Such a major bottleneck could be overcome by using an appropriate carrier to provide anchoring sites and structural support to LSC culture and transplantation. Bacterial nanocellulose (BNC) is an appealing, yet unexplored, candidate for this application because of its biocompatibility, animal-free origin and mechanical stability. Here, BNC as a vehicle for human embryonic stem cells-derived LSC (hESC-LSC) are investigated. To enhance cell-biomaterial interactions, a plasma activation followed by a Collagen IV and Laminin coating of the BNC substrates is implemented. This surface functionalization with human extracellular matrix proteins greatly improved the attachment and survival of hESC-LSC without compromising the flexible, robust and semi-transparent nature of the BNC. The surface characteristics of the BNC substrates are described and a preliminary ex vivo test in simulated transplantation scenarios is provided. Importantly, it is shown that hESC-LSC retain their self-renewal and stemness characteristics up to 21 days on BNC substrates. These results open the door for future research on hESC-LSC/BNC constructs to treat severe ocular surface pathologies.

Evaluation of EpiProtect® microbial cellulose burns dressings in young children.

INTRODUCTION: EpiProtect® is a biosynthetic cellulose dressing indicated for the treatment of superficial burns and the dressing of deep burns. Prior to this study the youngest reported patient treated with EpiProtect® was aged 13 years. METHOD: Data were collected prospectively for patients aged < 5 years, presenting to the Children's Burns Unit with ⩾ 2% total body surface area (TBSA) burns sustained by any mechanism. RESULTS: Thirty children were treated (median age = 17 months, age range = 1-61 months). Thirty-six burn depths were documented: superficial partial thickness (SPT) in 53% (n=19); mid-partial thickness (MPT) in 33% (n=12); deep partial thickness (DPT) in 11% (n=4); and full thickness (FT) in 3% (n=1). Median burn size was 4.5% TBSA (range = 2%-12%). EpiProtect® was applied under general anaesthesia in all cases. The median length of stay (LOS) was two days (range = 0-6 days). EpiProtect® was tolerated well and provided effective analgesia for subsequent dressing changes. Median healing time was 13 days (SPT burns), 14 days (MPT) and 24 days (DPT burns). Three patients required split skin grafting. Hypertrophic scarring arose in one patient. DISCUSSION: This case series represents the youngest published patient group to have been treated with EpiProtect®. Authors conclude that EpiProtect® provides a safe, reliable and well-tolerated dressing option for all burn depths in young children. Importantly, EpiProtect® is culturally neutral and may be used in situations which, for cultural reasons, may preclude the use of animal-derived products. Further studies are warranted to evaluate pain scores, burn depth, size and LOS correlation, and comparative analysis between dressing types. LAY SUMMARY: Burn injuries in the paediatric population are common and often require multiple dressing changes. Dressing changes can be painful and distressing to both children and their care givers. This article describes the experience of using a synthetically derived burns dressing, called EpiProtect®, in children aged ⩽ 5 years. Thirty patients were recruited with varying depths of scald burns and all underwent application of EpiProtect® dressing. The results suggested that EpiProtect® was a user-friendly dressing that can be used to treat partial-thickness burns and to dress full-thickness (FT) burns. It was well-tolerated and provided effective analgesia at the time of dressing changes. There was no incidence of increased burn wound infection rates and all wounds healed. In addition, as EpiProtect® is a synthetic product, it has the benefit of being culturally neutral, which is advantageous in a culturally diverse population. Further studies are warranted to evaluate the effectiveness of this dressing and to compare it to similar dressings that are available.

The Nanofication and Functionalization of Bacterial Cellulose and Its Applications.

Since economic and environmental issues have become critical in the last several years, the amount of sustainable bio-based production has increased. In this article, microbial polysaccharides, including bacterial cellulose (BC), are analyzed as promising resources with the potential for applications in biofields and non-biofields. Many scientists have established various methods of BC production, nanofication, and functionalization. In particular, this review will address the essential advances in recent years focusing on nanofication methods and nanoficated BC applications as well as functionalization methods and functionalized BC applications.

Bacterial Nanocellulose and Titania Hybrids: Cytocompatible and Cryopreservable Cell Carriers.

Carrier-assisted cell transplantation offers new strategies to improve the clinical outcomes of cellular therapies. Bacterial nanocellulose (BC) is an emerging biopolymer that might be of great value in the development of animal-free, customizable, and temperature-stable novel cell carriers. Moreover, BC exhibits a myriad of modification possibilities to incorporate additional functionalities. Here, we have synthesized BC-titanium dioxide (TiO2) nanocomposites (BC/TiO2) to evaluate and compare the suitability of not only BC but also a model hybrid nanobiomaterial as cell transplantation supports. This work provides thorough information on the interactions between BC-based substrates and model human cells in terms of cell attachment, morphology, proliferation rate, and metabolic activity. Two methods to partially retrieve the adhered cells are also reported. Both BC and BC/TiO2 substrates are positively evaluated in terms of cytocompatibility and endotoxin content without detecting major differences between BC and BC nanocomposites. Lastly, the effective cryopreservation of cells-BC and cells-BC/TiO2 constructs, yielding high cell viability and intact cell carrier's characteristics after thawing, is demonstrated. Taken together, our results show that both BC and BC/TiO2 enable to integrate the processes of expansion and long-term storage of human cells in transportable, robust and easy to manipulate supports.

Microbial Degradation of Cellulosic Material and Gas Generation: Implications for the Management of Low- and Intermediate-Level Radioactive Waste.

Deep geologic repositories (DGR) in Canada are designed to contain and isolate low- and intermediate-level radioactive waste. Microbial degradation of the waste potentially produces methane, carbon dioxide and hydrogen gas. The generation of these gases increase rock cavity pressure and limit water ingress which delays the mobility of water soluble radionuclides. The objective of this study was to measure gas pressure and composition over 7 years in experiments containing cellulosic material with various starting conditions relevant to a DGR and to identify micro-organisms generating gas. For this purpose, we conducted experiments in glass bottles containing (1) wet cellulosic material, (2) wet cellulosic material with compost Maker, and (3) wet cellulosic material with compost Accelerator. Results demonstrated that compost accelerated the pressure build-up in the containers and that methane gas was produced in one experiment with compost and one experiment without compost because the pH remained neutral for the duration of the 464 days experiment. Methane was not formed in the other experiment because the pH became acidic. Once the pressure became similar in all containers after 464 days, we then monitored gas pressure and composition in glass bottle containing wet cellulosic material in (1) acidic conditions, (2) neutral conditions, and (3) with an enzyme that accelerated degradation of cellulose over 1965 days. In these experiments, acetogenic bacteria degraded cellulose and produced acetic acid, which acidity suppressed methane production. Microbial community analyses suggested a diverse community of archaea, bacteria and fungi actively degrading cellulose. DNA analyses also confirmed the presence of methanogens and acetogens in our experiments. This study suggests that methane gas will be generated in DGRs if pH remains neutral. However, our results showed that microbial degradation of cellulose not only generated gas, but also generated acidity. This finding is important as acids can limit bentonite swelling and potentially degrade cement and rock barriers, thus this requires consideration in the safety case as appropriate.

Understanding Kombucha Tea Fermentation: A Review.

Kombucha is a beverage of probable Manchurian origins obtained from fermented tea by a microbial consortium composed of several bacteria and yeasts. This mixed consortium forms a powerful symbiosis capable of inhibiting the growth of potentially contaminating bacteria. The fermentation process also leads to the formation of a polymeric cellulose pellicle due to the activity of certain strains of Acetobacter sp. The tea fermentation process by the microbial consortium was able to show an increase in certain biological activities which have been already studied; however, little information is available on the characterization of its active components and their evolution during fermentation. Studies have also reported that the use of infusions from other plants may be a promising alternative. PRACTICAL APPLICATION: Kombucha is a traditional fermented tea whose consumption has increased in the recent years due to its multiple functional properties such as anti-inflammatory potential and antioxidant activity. The microbiological composition of this beverage is quite complex and still more research is needed in order to fully understand its behavior. This study comprises the chemical and microbiological composition of the tea and the main factors that may affect its production.

Study on the Use of Microbial Cellulose as a Biocarrier for 1,3-Dihydroxy-2-Propanone and Its Potential Application in Industry.

Can microbial cellulose (MC) be used as a bio-carrier for 1,3-dihydroxy-2-propanone (DHA)? The aim of this study was to examine the possibility of using MC as a biomaterial for DHA transferring into the stratum corneum and inducing changes in skin color. The MC patches were obtained from Gluconacetobacter xylinus strain and incubated in solutions with various concentrations of DHA (g·L-1: 20; 50; 80; 110) at 22 °C for 24 h. Afterwards; the patches were applied onto the skin for 15, 30, or 60 min. Skin color changes were assessed visually compared to a control patches without DHA. The intensity of skin color was increasing with the increase of DHA concentration and time of patches application. Application of MC patches with DHA (50 g·L-1) for 30 min ensured the color which was considered the closest to the desired natural tan effect. MC patches containing DHA can be biocarriers enabling DHA transport into the stratum corneum and causing skin color changes. Study results indicate a new possibility for industrial applications of MC; e.g., as a biocarrier in masking the symptoms of vitiligo or production of self-tanning agents in the form of masks.

Conductive microbial cellulose as a novel biocathode for Cr (VI) bioreduction.

In the present study, microbial cellulose (MC) as a carbohydrate polymer was made conductive by oxidative polymerization with aniline. Sulfate-reducing bacteria (SRB) were immobilized on the surface of the conductive biopolymer, and this was used as a biocathode in a bioreduction process to reduce Cr (VI) as a model of heavy metals. The results of Fourier transform infrared analysis confirmed that the polyaniline was distributed on the cellulose surface. The maximum tensile stress of the conductive biopolymer was obtained 23MPa using calculating Young's modulus. A current density of 60mA/m2 was determined as optimal, and an increase in pH from 5 to 7 significantly reduced the required time for reduction of Cr (VI). The system reached >99% removal of Cr (VI) within 1.5h at pH 7. Kinetic experiment studies showed a high constant rate (mean Kobs 0.78, R2 0.95). The results showed that the conductive MC can be used as an appropriate bioelectrode to reduce Cr (VI) in bioelectrochemical processes. It is expected that experimental results could be used as a reference for the utilization of MC in bioelectrochemical systems.

Fabrication of bacterial cellulose thin films self-assembled from sonochemically prepared nanofibrils and its characterization.

Bacterial cellulose (BC) film formation could be a critical issue in nanotechnology applications such as biomedical or smart materials products. In this research, purified pretreated BC was subjected to high intensity ultrasound (HIUS) and was investigated for the development of BC films. The morphological, structural and thermal properties of the obtained films were studied by using FE-SEM, AFM, FT-IR, XRD, TGA and DSC characterizations. Results showed that the most favorable purification treatment was the 0.01 M NaOH at 70°C for 2h under continuous stirring. The most suitable ultrasound operating conditions were found to be, 1cm distance of ultrasonic probe from the bottom of the beaker, submerged in cold water bath cooling around 12 ± 2°C. The power (25 W/cm(2)), time (30 min), BC concentration (0.1%w/w), amplitude (20 µm) and frequency (20 kHz) were maintained constant.

Nisin based stabilization of novel fruit and vegetable functional juices containing bacterial cellulose at ambient temperature.

The current study reports the preparation and stabilization of novel functional drinks based on fruit and vegetable juices incorporating bacterial cellulose from Acetobacter xylinum. Pineapple, musk melon, carrot, tomato, beet root and a blend juice containing 20 % each of carrot and tomato juice with 60 % beet root juice has been studied. These juices have been stabilized over a storage period of 90 days at 28 °C, by the use of nisin and maintaining a low pH circumventing the need for any chemical preservatives or refrigeration. Instrumental color values have been correlated with the pigment concentrations present in the fresh as well as stored juices. There was 36, 72 and 60 % loss of total carotenoids in the case of carrot, pineapple and musk melon juices respectively while the lycopene content remained unchanged after 90 days of storage. The betanin content decreased 37 % in the case of beetroot juice and 25 % in the case of beetroot juice blended with carrot and tomato juices. Sensory analysis has revealed a clear preference for the beetroot blended mixed juice.

A novel biomaterial: bacterial cellulose and its new era applications.

Bacterial cellulose (BC) is a promising natural polymer that is produced by bacteria and that has unique and desirable structural, physical, and chemical properties. From the time when the remarkable properties of BC were found 15 years ago compared with plant cellulose, interest has grown in BC and it has become an article of trade in diverse applications. Following this trend, this paper reviews the progress of relevant studies, including general information about cellulose, production by microorganisms as well as BC cultivation, and its properties. The applications reviewed in the present article comprise biological and nonbiological fields. The latest use of BC in the biomedical, environmental, agricultural, electronic, food, and industrial fields is discussed with its applications in composite form. The present article attempts to amass the assorted uses of BC under one umbrella. Thus, recent advances in BC applications in different fields are thoroughly reviewed. This article concludes with the need for future research of BC to make it commercialized as vital biomaterial.

Laser-structured bacterial nanocellulose hydrogels support ingrowth and differentiation of chondrocytes and show potential as cartilage implants.

The small size and heterogeneity of the pores in bacterial nanocellulose (BNC) hydrogels limit the ingrowth of cells and their use as tissue-engineered implant materials. The use of placeholders during BNC biosynthesis or post-processing steps such as (touch-free) laser perforation can overcome this limitation. Since three-dimensionally arranged channels may be required for homogeneous and functional seeding, three-dimensional (3-D) laser perforation of never-dried BNC hydrogels was performed. Never-dried BNC hydrogels were produced in different shapes by: (i) the cultivation of Gluconacetobacter xylinus (DSM 14666; synonym Komagataeibacter xylinus) in nutrient medium; (ii) the removal of bacterial residues/media components (0.1M NaOH; 30 min; 100 °C) and repeated washing (deionized water; pH 5.8); (iii) the unidirectional or 3-D laser perforation and cutting (pulsed CO2 Rofin SC × 10 laser; 220 µm channel diameter); and (iv) the final autoclaving (2M NaOH; 121 °C; 20 min) and washing (pyrogen-free water). In comparison to unmodified BNC, unidirectionally perforated--and particularly 3-D-perforated - BNC allowed ingrowth into and movement of vital bovine/human chondrocytes throughout the BNC nanofiber network. Laser perforation caused limited structural modifications (i.e. fiber or globular aggregates), but no chemical modifications, as indicated by Fourier transform infrared spectroscopy, X-ray photoelectron scattering and viability tests. Pre-cultured human chondrocytes seeding the surface/channels of laser-perforated BNC expressed cartilage-specific matrix products, indicating chondrocyte differentiation. 3-D-perforated BNC showed compressive strength comparable to that of unmodified samples. Unidirectionally or 3-D-perforated BNC shows high biocompatibility and provides short diffusion distances for nutrients and extracellular matrix components. Also, the resulting channels support migration into the BNC, matrix production and phenotypic stabilization of chondrocytes. It may thus be suitable for in vivo application, e.g. as a cartilage replacement material.

The possibility of microbial cellulose for dressing and scaffold materials.

In recent years, natural polymers such as cellulose, alginate and chitosan have been used worldwide as biomedical materials and devices, as they offer more advantages over synthetic polymers. The aim of this study was to clarify the usefulness of microbial cellulose (MC) for use as a dressing and scaffold material. For evaluating the biodegradability and toxicity of MC, we divided the rats (n = 12) into two groups (the implanted group and the non-implanted group). In the implanted group, we implanted the film type of MC in the backs of six rats. In the non-implanted group, however, we did not implant the film type of MC in the backs of the six rats. Four weeks later, we compared two groups by the gross, histological and biochemical characteristics by using blood and tissue samples. To evaluate the wound healing effects of MC, three full-thickness skin defects were made on the backs of each rat (n = 20). Three wounds on the backs of the same rats were treated with other dressing materials, namely, Vaseline gauze (group Con), Algisite M(®) (group Alg) and MC (group MC). We analysed the gross, histological and biochemical characteristics by western blotting. MC was found to be biodegradable and non-toxic. On day 3, the MC film was visible under the subcutaneous tissue; however, after 4 weeks, no remnants of the film were visible under the subcutaneous tissue. Furthermore, there was no evidence of MC-induced toxicity. Moreover, group MC showed more rapid wound healing compared with group Con. On day 14 after skin excision, group MC showed greater decrease in wound size compared with group Con (33% versus 7·2%). The wound healing effects were also substantiated by the histological findings (greater reduction in inflammation and rapid collagen deposition as well as neovascularisation) and western blotting (decreased expression of vascular endothelial growth factor and transforming growth factor-ß1 in group MC on day 14 after skin excision, unlike group Con). This study showed that, in addition to having wound healing effects, MC is biodegradable and non-toxic and can, therefore, be used as a dressing and scaffold material.

Production of microbial cellulose: Response surface methodology approach.

The present work was carried out to test the potential of Acetobacter aceti MTCC 2623 for the production of cellulose and optimization of various process conditions. Response surface methodology (RSM) was applied to optimize the process parameters for microbial cellulose production. The optimized parameters for maximum cellulose production (1.73g/L) and sugar utilization (99.8%) obtained were 2.25% (w/v) glucose concentration, 1.16% (w/v) sodium nitrate concentration, pH 7, 27.5°C temperature, and 159h of incubation time. The structure of produced microbial cellulose was established by using FT-IR spectroscopy.