Metagenomic, organoleptic profiling, and nutritional properties of fermented kombucha tea substituted with recycled substrates

Kombucha fermentation yields a diverse range of beneficial macro and micronutrients. In our study, we examined the metabolites, antioxidant activity, organoleptic characteristics, and nutritional attributes of traditionally prepared kombucha tea, using black tea and sugar (control) as substrates, and compared them with tea made from tea dust and blackstrap molasses (test). Kombucha tea crafted from functional raw materials exhibited enhanced sensory qualities and improved health-promoting properties. The levels of tannins, flavonoids, and phenols play a crucial role in determining the antioxidant activity of kombucha tea. Using the DPPH and FRAP methods, we investigated the antioxidant activity throughout the fermentation period, ranging from day 0 to day 12, under optimized conditions. The results consistently demonstrated an initial increase in antioxidant activity from day 0 to 6, followed by a decline from day 6 to 12. Notably, statistical analysis revealed that the antioxidant activity of the test sample was significantly better (p > 0.001) compared to the control sample. The nutritional content of the kombucha from day 6 of the test sample is higher than the control sample provided sugars (fructose 0.4 ± 0.1, glucose 0.7 ± 0.1, sucrose 1.4 ± 0.1) g/100 mL, minerals (calcium, 19.4 ± 0.15, iron 23.1 ± 0.25, and potassium 28.3 ± 0.25) mg/100 mL, vitamins (B1 0.58 ± 0.01, B2 0.30 ± 0.02, B3 0.33 ± 0.02, B6 0.75 ± 0.02, B9 0.19 ± 0.03, B12 0.9 ± 0.03, and C 1.38 ± 0.06) mg/100 mL, sodium 4.35 ± 0.25 mg/100 mL, calories 14.85 ± 0.25 mg/100 mL, carbohydrates 3.135 ± 0.12, and acids (acetic acid 4.20 ± 0.02, glucuronic acid 1.78 ± 0.02) mg/100 mL on day 12. The predominant microbial species identified in both control and test samples included Komagataeibacter rhaeticus, Gluconobacter oxydans, Brettanomyces bruxellensis, and Zygosaccharomyces bailli, each with varying dominance levels. These microorganisms play essential roles in metabolizing sugars, generating acids, and contributing to the distinctive flavor profile of kombucha. Sensory evaluations of the control and test samples were analyzed, and the overall preference was 88% for the test sample with tea dust and molasses. The sensory characteristics of the test sample included a fruity smell (41%), fizzy texture (66%), bright color (47%), and a fruity taste (67%), with overall acceptability (56%) rating it as excellent. Our research contributes to a deeper understanding of the interplay between raw materials, microbial composition, and the resulting composition of bioactive compounds.

Citrate-buffered Yamanaka medium allows to produce high-yield bacterial nanocellulose in static culture using Komagataeibacter strains isolated from apple cider vinegar

Bacterial nanocellulose (BNC) is a sustainable, renewable, and eco-friendly nanomaterial, which has gained great attentions in both academic and industrial fields. Two bacterial nanocellulose-producing strains (CVV and CVN) were isolated from apple vinegar sources, presenting high 16S rRNA gene sequence similarities (96%-98%) with Komagataeibacter species. The biofilm was characterized by scanning electron microscopy (SEM), revealing the presence of rod-shaped bacteria intricately embedded in the polymeric matrix composed of nanofibers of bacterial nanocellulose. FTIR spectrum and XRD pattern additionally confirmed the characteristic chemical structure associated with this material. The yields and productivities achieved during 10 days of fermentation were compared with Komagataeibacter xylinus ATCC 53524, resulting in low levels of BNC production. However, a remarkable increase in the BNC yield was achieved for CVV (690% increase) and CVN (750% increase) strains at day 6 of the fermentation upon adding 22 mM citrate buffer into the medium. This effect is mainly attributed to the buffering capacity of the modified Yakamana medium, which allowed to maintain pH close to 4.0 until day 6, though in combination with additional factors including stimulation of the gluconeogenesis pathway and citrate assimilation as a carbon source. In addition, the productivities determined for both isolated strains (0.850 and 0.917 g L-1 d-1) compare favorably to previous works, supporting current efforts to improve fermentation performance in static cultures and the feasibility of scaling-up BNC production in these systems.

Bacterial Cellulose Applied in Wound Dressing Materials: Production and Functional Modification - A Review

In recent years, the development of new type wound dressings has gradually attracted more attention. Bacterial cellulose (BC) is a natural polymer material with various unique properties, such as ultrafine 3D nanonetwork structure, high water retention capacity, and biocompatibility. These properties allow BC to be used independently or in combination with different components (such as biopolymers and nanoparticles) to achieve diverse effects. This means that BC has great potential as a wound dressing. However, systematic summaries for the production and commercial application of BC-based wound dressings are still lacking. Therefore, this review provides a detailed introduction to the production fermentation process of BC, including various production strains and their biosynthetic mechanisms. Subsequently, with regard to the functional deficiencies of bacterial cellulose as a wound dressing, recent research progress in this area is enumerated. Finally, prospects are discussed for the low-cost production and high-value-added product development of BC-based wound dressings.

Biosynthesis and characterization of antibacterial bacterial cellulose composite membrane composed of montmorillonite and exopolysaccharides

Bacterial cellulose (BC), as a natural renewable polymer material, has the advantages of porous nanonetwork structure, high degree of polymerization, high purity, high crystallinity, excellent mechanical properties and biocompatibility. However, BC lacks antibacterial properties, which leads to the limitation of BC material in food packaging and medical materials. In this study, a new antibacterial material using the combination of montmorillonite (MMT), BC and exopolysaccharides (EPS) produced by Weissella confusa H2 was synthesized. Fourier infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analysis showed that BC-EPS, BC-MMT and BC-EPS-MMT composite membranes conformed to the typical type I cellulose structure. Compared to BC membrane, scanning electron microscopy (SEM) showed that the porosity of BC-EPS, BC-MMT and BC-EPS-MMT composite membranes was low and compact. The physical properties of BC-EPS, BC-MTT and BC-EPS-MTT composite membranes showed lower water vapor transmittance. The BC-MTT and BC-EPS-MTT composite membranes exhibit a lower swelling ratio in 120 min. The thermal properties show that BC-EPS, BC-MTT and BC-EPS-MTT composite membranes have higher thermal stability (352 °C, 310 °C, 314 °C). Additionally, both BC-MMT and BC-EPS-MMT demonstrated strong inhibitory effects against various bacterial strains, including Staphylococcus aureus, Escherichia coli, Salmonella paratyphi A, and Bacillus subtilis. The exceptional properties exhibited by composite membranes establishes them as a highly promising option in the field of food packaging and medical material applications.

Enhanced mechanical properties and biocompatibility of bacterial cellulose composite films with inclusion of 2D MoS2 and helical carbon nanotubes for use as antimicrobial drug carriers

Bacterial cellulose (BC) is a biomaterial being investigated for a range of applications. Herein, BC films derived from nata de coco pieces are reinforced by two-dimensional molybdenum disulfide (MoS2) and helical carbon nanotubes (HCNTs) to enhance their tensile mechanical properties, and the biocompatibility of the BC composite films is demonstrated. A simple preparation is presented using a kitchen blender to disperse and blend the BC fibers and additives in a common fabrication medium, followed by vacuum filtration. The mechanical properties of the BC/MoS2/HCNTs composite films are enhanced due to the synergistic effect of MoS2 and HCNTs embedded in the BC films. The MoS2/HCNTs binary additive (1 phr) is capable of increasing the strength and Young's modulus by 148 % and 333 %, respectively, relative to the BC films. The cell cytotoxicity of the BC/MoS2/HCNTs films was assessed using an MTT assay. The composite films are biocompatible with a cell viability of L929 fibroblast cells >70 %, coupled with observations of direct cell attachment on the films. The composite films also exhibited good performance in absorbing and releasing gentamicin antibiotics to inhibit the growth of Escherichia coli and Staphylococcus aureus. The BC/MoS2/HCNTs films are thus potential BC-based candidates as biocompatible robust antibiotic carriers.

Engineered Living Materials for Advanced Diseases Therapy

Natural living materials serving as biotherapeutics exhibit great potential for treating various diseases owing to their immunoactivity, tissue targeting, and other biological activities. In this review, the recent developments in engineered living materials, including mammalian cells, bacteria, viruses, fungi, microalgae, plants, and their active derivatives that are used for treating various diseases are summarized. Further, the future perspectives and challenges of such engineered living material-based biotherapeutics are discussed to provide considerations for future advances in biomedical applications.

Functionalization of Bacterial Cellulose and Related Surfaces Using a Facile Coupling Reaction by Thermoresponsive Catalyst

Recently, bacterial cellulose and related materials attracted significant attention for applications such as leather-like materials, wound healing materials, etc., due to their abundance in pure form and excellent biocompatibility. Chemical modification of bacterial cellulose further helps to improve specific properties for practical utility and economic viability. However, in most cases, chemical modification of cellulose materials involves harsh experimental conditions such as higher temperatures or organic solvents, which may destroy the 3-dimensional network of bacterial cellulose, thereby altering its characteristic properties. Hence, in this work, we have adopted the Suzuki coupling methodology, which is relatively unexplored for chemically modifying cellulose materials. As the Suzuki coupling reaction is tolerable against air and water, modification can be done under mild conditions so that the covalently modified cellulose materials remain intact without destroying their 3-dimensional form. We performed Suzuki coupling reactions on cellulose surfaces using a recently developed thermoresponsive catalyst consisting of poly(N-isopropylacrylamide) (PNIPAM)-tagged N-heterocyclic carbene (NHC)-based palladium(II) complex. The thermoresponsive nature of the catalyst particularly helped to perform reactions in a water medium under mild conditions considering the biological nature of the substrates, where separation of the catalyst can be easily achieved by tuning temperature. The boronic acid derivatives have been chosen to alter the wettability behavior of bacterial cellulose. Bacterial cellulose (BC) obtained from fermentation on a lab scale using a cellulose-producing bacterium called Gluconacetobacter kombuchae (MTCC 6913) under Hestrin-Schramm (HS) medium, or kombucha-derived bacterial cellulose (KBC) obtained from kombucha available in the market or cotton-cellulose (CC) was chosen for the surface functionalization to find the methodology's diversity. Movie files in the Supporting Information and figures in the manuscript demonstrated the utility of the methodology for fluorescent labeling of bacterial cellulose and related materials. Finally, contact angle analysis of the surfaces showed the hydrophobic natures of some functionalized BC-based materials, which are important for the practical use of biomaterials in wet climatic conditions.

Solving urban water microplastics with bacterial cellulose hydrogels: Leveraging predictive computational models

The prevalence of microplastics (MPs) in both urban and aquatic ecosystems is concerning, with wastewater treatment plants being considered one of the major sources of the issue. As the focus on developing sustainable solutions increases, unused remnants from bacterial cellulose (BC) membranes were ground to form BC hydrogels as potential bioflocculants of MPs. The influence of operational parameters such as BC:MPs ratio, hydrogel grinding, immersion and mixing time, temperature, pH, ionic strength, and metal cations on MPs flocculation and dispersion were evaluated. A response surface methodology based on experimental data sets was computed to understand how these parameters influence the flocculation process. Further, both the BC hydrogel and the hetero-aggregation of MPs were characterised by UV-Vis, ATR-FTIR, IGC, water uptake assays, fluorescence, and scanning electron microscopy. These highlights that the BC hydrogel would be fully effective at hetero-aggregating MPs in naturally-occurring concentrations, thereby not constituting a limiting performance factor for MPs' optimal flocculation and aggregation. Even considering exceptionally high concentrations of MPs (2 g/L) that far exceed naturally-occurring concentrations, the BC hydrogel was shown to have elevated MPs flocculation activity (reaching 88.6%: 1.77 g/L). The computation of bioflocculation activity showed high reliability in predicting flocculation performance, unveiling that the BC:MPs ratio and grinding times were the most critical variables modulating flocculation rates. Also, short exposure times (5 min) were sufficient to drive robust particle aggregation. The microporous nature of the hydrogel revealed by electron microscopy is the likely driver of strong MPs bioflocculant activity, far outperforming dispersive commercial bioflocculants like xanthan gum and alginate. This pilot study provides convincing evidence that even BC remainings can be used to produce highly potent and circular bioflocculators of MPs, with prospective application in the wastewater treatment industry.

Bacterial cellulose production from Komagataeibacter xylinus TISTR 1011 and Komagataeibacter nataicola TISTR 975 using yam bean juice as a nutrient source

The present study investigated the efficacy of bacterial cellulose production by K. xylinus TISTR 1011 and K. nataicola TISTR 975 using yam bean juice as a nutrient source, and the physicochemical and sensory characteristics of bacterial cellulose were examined. Bacterial cellulose content, production yield, and production rate were significantly higher when K. xylinus TISTR 1011 rather than K. nataicola TISTR 975 was used as the bacterial strain. The analysis of physicochemical characteristics revealed that bacterial cellulose produced by K. xylinus TISTR 1011 using yam bean juice medium had higher scores for CIE L*, a*, and b* values, wet weight, moisture content, firmness, and gel strength than bacterial cellulose produced by K. nataicola TISTR 975. In contrast, sensory evaluation showed that the acceptability scores and preference of all attributes of bacterial cellulose produced by K. nataicola TISTR 975 using yam bean juice medium were higher than those of bacterial cellulose produced by K. xylinus TISTR 1011. The results of this study indicate that yam bean juice from yam bean tubers, an alternative raw material agricultural product, can be used as a nutrient source for producing bacterial cellulose or nata by Komagataeibacter strains.

An overview of probiotic health booster-kombucha tea

Traditional herbal medicine (THM) is a significant division of traditional Chinese medicine (TCM) that plays an important role in maintaining health and disease prevention. WHO has consistently highlighted the significance of traditional, complementary, and alternative medicine in human healthcare. Most people in Eastern Asia will start their day with a cup of tea. The tea provides a nourishing effect, and it has become an inevitable part of life. There are several types of tea, like black tea, green tea, oolong tea, white tea, and herbal tea. Besides the refreshments, it is important to consume beverages that benefit health. One such alternative is a healthy probiotic drink called kombucha, a fermented tea. Kombucha tea is aerobically fermented by infusing sweetened tea with a cellulose mat/ pellicle called SCOBY (symbiotic culture of bacteria and yeast). Kombucha is a source of bioactive compounds that include organic acids and amino acids, vitamins, probiotics, sugars, polyphenols, and antioxidants. Currently, studies on kombucha tea and SCOBY are gaining attention for their remarkable properties and applications in the food and health industries. The review gives an overview of the production, fermentation, microbial diversity, and metabolic products of kombucha. The possible implications for human health are also discussed.

Nanobacterial Cellulose Production and Its Antibacterial Activity in Biodegradable Poly(vinyl alcohol) Membranes for Food Packaging Applications

Nanobacterial cellulose (NBC) was produced and incorporated into biodegradable poly(vinyl alcohol) (PVA) in different weight ratios to obtain polymer nanocomposite membranes. The physicochemical properties of the membranes were studied using Fourier transform infrared (FTIR) spectroscopy, a universal testing machine (UTM), thermogravimetric analysis (TGA), wide-angle X-ray diffraction (WAXD) techniques, and field emission scanning electron microscopy (FESEM). FTIR confirmed the consolidation of NBC into PVA by exhibiting significant changes in the peaks compared to NBC and PVA individually. The highest tensile strength of 53.33 MPa and 235.30% elongation at break of the membrane M-10 mass % NBC was obtained, illuminating that NBC provides stiffness and PVA imparts elasticity. WAXD revealed that the crystalline nature of the membrane increases up to 10 mass % and decreases beyond it. The effect of NBC on the poly(vinyl alcohol) membranes for food packaging was investigated systematically. Among all the membranes, M-10 mass % NBC was found to be the most suitable for packaging applications. Membranes had antimicrobial activity against food microbes and showed degradability behavior in the soil. The tests on membranes for packaging revealed that fruits were protected from spoilage caused by microorganisms. Hence, the prepared membranes could be used as an alternative to conventional plastics for packaging applications.

Stoichiometric Analysis and Production of Bacterial Cellulose by Gluconacetobacter liquefaciens using Borassus flabellifer L. Jaggery

The objective of the work is to examine the potential utilization of Palmyra palm jaggery (PPJ) for the enhancement of bacterial cellulose (BC) production by Gluconacetobacter liquefaciens. To evaluate the culturing condition, the production of BC fermentation was carried out in batch mode using different carbon sources namely glucose, sucrose and PPJ. PPJ in the HS medium (PHS medium) resulted maximum concentration of BC (14.35 ± 0.18 g/L) under shaking condition than other carbon sources in HS medium. The influence of different medium variables including initial pH and nitrogen sources on BC production was investigated using PHS medium under shaking condition. The maximum BC concentration of 17.79 ± 2.4 g/L was obtained in shaking condition at an initial pH of 5.6 using yeast extract as nitrogen source. Stoichiometric equation for the cell growth and BC synthesis was developed using elemental balance approach. The metabolic heat of reaction (40 kcal generated per liter of medium) was evaluated using electron balance approach. Based on the process economic analysis and the yield of BC during the fermentation, PHS medium without nitrogen source could be a promising cost-effective nutrient than HS medium. Thermal stability, crystallinity index and structural characterizations of produced BC using PPJ medium were evaluated using TGA, XRD and FTIR and the obtained results were compared with HS medium containing glucose and sucrose.

Multiscale engineering of microbial cell factories: A step forward towards sustainable natural products industry

Microbial cell factories (bacteria and fungi) are the leading producers of beneficial natural products such as lycopene, carotene, herbal medicine, and biodiesel etc. These microorganisms are considered efficient due to their effective bioprocessing strategy (monoculture- and consortial-based approach) under distinct processing conditions. Meanwhile, the advancement in genetic and process optimization techniques leads to enhanced biosynthesis of natural products that are known functional ingredients with numerous applications in the food, cosmetic and medical industries. Natural consortia and monoculture thrive in nature in a small proportion, such as wastewater, food products, and soils. In similitude to natural consortia, it is possible to engineer artificial microbial consortia and program their behaviours via synthetic biology tools. Therefore, this review summarizes the optimization of genetic and physicochemical parameters of the microbial system for improved production of natural products. Also, this review presents a brief history of natural consortium and describes the functional properties of monocultures. This review focuses on synthetic biology tools that enable new approaches to design synthetic consortia; and highlights the syntropic interactions that determine the performance and stability of synthetic consortia. In particular, the effect of processing conditions and advanced genetic techniques to improve the productibility of both monoculture and consortial based systems have been greatly emphasized. In this context, possible strategies are also discussed to give an insight into microbial engineering for improved production of natural products in the future. In summary, it is concluded that the coupling of genomic modifications with optimum physicochemical factors would be promising for producing a robust microbial cell factory that shall contribute to the increased production of natural products.

Characterization of Bacterial Cellulose Produced by Komagataeibacter maltaceti P285 Isolated from Contaminated Honey Wine

Bacterial cellulose (BC), a biopolymer, is synthesized by BC-producing bacteria. Almost all producing strains are classified in the family Acetobacteraceae. In this study, bacterial strain P285 was isolated from contaminated honey wine in a honey factory in northern Thailand. Based on 16S rRNA gene sequence identification, the strain P285 revealed 99.8% identity with Komagataeibacter maltaceti LMG 1529 T. K. maltaceti P285 produced the maximum BC production at 20–30 °C and an initial media pH of 9.0. The highest BC production in modified mineral salt medium (MSM) was exhibited when glucose (16%, w/v) and yeast extract (3.2%, w/v) were applied as carbon and nitrogen sources, respectively. When sugarcane (8–16%, w/v) or honey (ratio of honey to water = 1: 4) supplemented with yeast extract was used, the BC production was greater. The characterization of BC synthesized by K. maltaceti P285 was undertaken using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectrometry. Meanwhile, X-ray diffraction results confirmed the presence of crystalline cellulose (2θ = 18.330, 21.390 and 22.640°). The maximum temperature of BC degradation was observed at 314 °C. Tensile properties analysis of hydrated and dried BC showed breaking strength of 1.49 and 0.66 MPa, respectively. These results demonstrated that K. maltaceti P285 has a high potential for BC production especially when grown in high initial media pH. Therefore, the strain would be suitable as an agent to make BC, the value-added product in the related factories.

Cellulose nanocrystals: Fundamentals and biomedical applications

The present review explores the recent developments of cellulose nanocrystals, a class of captivating nanomaterials in variety of applications. CNCs are made by acid hydrolysing cellulosic materials like wood, cotton, tunicate, flax fibers by sonochemistry. It has many desirable properties, including a high tensile strength, wide surface area, stiffness, exceptional colloidal stability, and the ability to be modified. CNCs are colloidally stable, hydrophilic, and rigid rod-shaped bio-based nanomaterials in the form of rigid rods with high strength and surface area that has a diverse set of applications and properties. The intriguing features emerging from numerous fibers studies, such as renewable character and biodegradability, piqued the curiosity of many researchers who worked on lowering the size of these fibers. Physicochemical properties such as rheological, mechanical, thermal, lipid crystalline, swelling capacity, microstructural properties result in affecting surface-area to volume ratio and crystallinity of cellulose nanocrystals. The present article highlights the fundamentals of cellulose nanocrystals such as sources, isolation, fabrication, properties and surface modification with an emphasis on plethora of biomedical applications. Selected nanocellulose studies with significant findings on cellular labelling and bioimaging, tissue engineering, biosensors, gene delivery, anti-viral property, anti-bacterial property, ocular delivery, modified drug release, anti-cancer activity and enzyme immobilization are emphasized.

Highly Stretchable Bacterial Cellulose Produced by Komagataeibacter hansenii SI1

A new strain of bacteria producing cellulose was isolated from Kombucha and identified as Komagataeibacter hansenii, named SI1. In static conditions, the strain synthesises bacterial nanocellulose with an improved ability to stretch. In this study, utilisation of various carbon and nitrogen sources and the impact of initial pH was assessed in terms of bacterial nanocellulose yield and properties. K. hansenii SI1 produces cellulose efficiently in glycerol medium at pH 5.0-6.0 with a yield of 3.20-3.60 g/L. Glucose medium led to the synthesis of membrane characterised by a strain of 77%, which is a higher value than in the case of another Komagataeibacter species. Supplementation of medium with vitamin C results in an enhanced porosity and improves the ability of bacterial nanocellulose to stretch (up to 123%). The properties of modified membranes were studied by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and mechanical tests. The results show that bacterial nanocellulose produced in SH medium and vitamin C-supplemented medium has unique properties (porosity, tensile strength and strain) without changing the chemical composition of cellulose. The method of production BNC with altered properties was the issue of Polish patent application no. P.431265.

Bacterial Cellulose: Production, Characterization, and Application as Antimicrobial Agent

Bacterial cellulose (BC) is recognized as a multifaceted, versatile biomaterial with abundant applications. Groups of microorganisms such as bacteria are accountable for BC synthesis through static or agitated fermentation processes in the presence of competent media. In comparison to static cultivation, agitated cultivation provides the maximum yield of the BC. A pure cellulose BC can positively interact with hydrophilic or hydrophobic biopolymers while being used in the biomedical domain. From the last two decades, the reinforcement of biopolymer-based biocomposites and its applicability with BC have increased in the research field. The harmony of hydrophobic biopolymers can be reduced due to the high moisture content of BC in comparison to hydrophilic biopolymers. Mechanical properties are the important parameters not only in producing green composite but also in dealing with tissue engineering, medical implants, and biofilm. The wide requisition of BC in medical as well as industrial fields has warranted the scaling up of the production of BC with added economy. This review provides a detailed overview of the production and properties of BC and several parameters affecting the production of BC and its biocomposites, elucidating their antimicrobial and antibiofilm efficacy with an insight to highlight their therapeutic potential.

Implantation of stem cells on synthetic or biological scaffolds: an overview of bone regeneration

Humans are exposed to a wide range of bone tissue injuries. In severe cases, bone damages could be only treated with transplantation of autologous or allogeneic grafting.In recent years, tissue engineering has become a promising strategy for repairing damaged organs and tissues, providing a great opportunity to cure several diseases. Bone tissue engineering consists of three components: scaffold, cells, and growth factors. Current bone tissue engineering strategies combine the use of stem cells with biologically active materials and gene therapy to mimic the natural microenvironment of bone. The combination of the scaffold with growth factors and extracellular matrix protein molecules can promote cell attachment, proliferation, and induce osteogenesis, which could provide signals for cell migration to begin the healing process during repair and bone formation.This article reviews the principles of bone regeneration and the most current developments of bone tissue engineering related to bone growth factors, the biologically active materials, such as bacterial cellulose, and stem cells.

Bacterial Cellulose: Functional Modification and Wound Healing Applications

Significance: Wound dressings are frequently used for wound covering and healing. Ideal wound dressings should provide a moist environment for wounds and actively promote wound healing and skin recovery. The materials used as ideal wound dressings should possess specific properties, thus accelerating skin tissue regeneration process. Recent Advances: Bacterial cellulose (BC) is a natural polymer synthesized by some bacteria. As a kind of natural biopolymer, BC shows good biological activity, biodegradability, and biological adaptability. It has many unique physical, chemical, and biological properties, such as ultrafine nanofiber network, high crystallinity, high water absorption and retention capacity, and high tensile strength and elastic modulus. These excellent properties of BC have laid the foundation for its application as dressing in wound healing. Critical Issues: To optimize the biocompatibility and antimicrobial activity of BC, different methods including microbial fermentation, physical modification, chemical modification, and compound modification have been adopted to modify BC to ensure a better application in wound healing. BC-based wound dressings have been applied in infected wounds, acute traumatic injuries, burns, and diabetic wounds, showing remarkable therapeutic effects on promoting wound healing. Furthermore, there have been some commercial BC-based dressings and they have been utilized in clinical practice. Future Directions: Because of its excellent physicochemical characteristics and biological properties, BC shows high clinical value to be used as a wound dressing for skin tissue regeneration.

Preparation, Marriage Chemistry and Applications of Graphene Quantum Dots-Nanocellulose Composite: A Brief Review

Graphene quantum dots (GQDs) are zero-dimensional carbon-based materials, while nanocellulose is a nanomaterial that can be derived from naturally occurring cellulose polymers or renewable biomass resources. The unique geometrical, biocompatible and biodegradable properties of both these remarkable nanomaterials have caught the attention of the scientific community in terms of fundamental research aimed at advancing technology. This study reviews the preparation, marriage chemistry and applications of GQDs-nanocellulose composites. The preparation of these composites can be achieved via rapid and simple solution mixing containing known concentration of nanomaterial with a pre-defined composition ratio in a neutral pH medium. They can also be incorporated into other matrices or drop-casted onto substrates, depending on the intended application. Additionally, combining GQDs and nanocellulose has proven to impart new hybrid nanomaterials with excellent performance as well as surface functionality and, therefore, a plethora of applications. Potential applications for GQDs-nanocellulose composites include sensing or, for analytical purposes, injectable 3D printing materials, supercapacitors and light-emitting diodes. This review unlocks windows of research opportunities for GQDs-nanocellulose composites and pave the way for the synthesis and application of more innovative hybrid nanomaterials.

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.

Research progress of the biosynthetic strains and pathways of bacterial cellulose

Bacterial cellulose is a glucose biopolymer produced by microorganisms and widely used as a natural renewable and sustainable resource in the world. However, few bacterial cellulose-producing strains and low yield of cellulose greatly limited the development of bacterial cellulose. In this review, we summarized the 30 cellulose-producing bacteria reported so far, including the physiological functions and the metabolic synthesis mechanism of bacterial cellulose, and the involved three kinds of cellulose synthases (type I, type II, and type III), which are expected to provide a reference for the exploration of new cellulose-producing microbes.

Optimization of Moist and Oven-Dried Bacterial Cellulose Production for Functional Properties

Bacterial cellulose (BC) is a natural polymer with properties suitable for tissue engineering and possible applications in scaffold production. However, current procedures have limitations in obtaining BC pellicles with the desired structural, physical, and mechanical properties. Thus, this study analyzed the optimal culture conditions of BC membranes and two types of processing: draining and oven-drying. The aim was to obtain BC membranes with properties suitable for a wound dressing material. Two studies were carried out. In the preliminary study, the medium (100 mL) was inoculated with varying volumes (1, 2, 3, 4, and 5 mL) and incubated statically for different periods (3, 6, 9, 12, and 18 days), using a full factorial experimental design. Thickness, uniformity, weight, and yield were evaluated. In the optimization study, a Box–Behnken design was used. Two independent variables were used: inoculum volume (X₁: 1, 3, and 5 mL) and fermentation period (X₂: 6, 12, and 18 d) to determine the target response variables: thickness, swelling ratio, drug release, fiber diameter, tensile strength, and Young’s modulus for both dry and moist BC membranes. The mathematical modelling of the effect of the two independent variables was performed by response surface methodology (RSM). The obtained models were validated with new experimental values and confirmed for all tested properties, except Young’s modulus of oven-dried BC. Thus, the optimal properties in terms of a scaffold material of the moist BC were obtained with an inoculum volume of 5% (v/v) and 16 d of fermentation. While, for the oven-dried membranes, optimal properties were obtained with a 4% (v/v) and 14 d of fermentation.

Production of Bacterial Cellulose from Acetobacter Species and Its Applications – A Review

Bacterial cellulose (BC) is a natural polymer secreted as a protective cell covering of certain bacterial species. In contrary to plant cellulose, BC possesses some unique features like high moisture-holding capacity, high durability, high liquid absorbing capabilities, biostability, and biodegradability, makes BC an excellent raw material in wide-ranging areas like biomedical, food, agriculture, paper, textile industries and electronics. The main objective of this review is to discuss various aspects of BC production (different sources for bacterial strain isolation, culture media and, its alternatives also major culture techniques). In addition, various applications of BC are also reviewed.

Nanobioengineered Sensing Technologies Based on Cellulose Matrices for Detection of Small Molecules, Macromolecules, and Cells

Recent advancement has been accomplished in the field of biosensors through the modification of cellulose as a nano-engineered matrix material. To date, various techniques have been reported to develop cellulose-based matrices for fabricating different types of biosensors. Trends of involving cellulosic materials in paper-based multiplexing devices and microfluidic analytical technologies have increased because of their disposable, portable, biodegradable properties and cost-effectiveness. Cellulose also has potential in the development of cytosensors because of its various unique properties including biocompatibility. Such cellulose-based sensing devices are also being commercialized for various biomedical diagnostics in recent years and have also been considered as a method of choice in clinical laboratories and personalized diagnosis. In this paper, we have discussed the engineering aspects of cellulose-based sensors that have been reported where such matrices have been used to develop various analytical modules for the detection of small molecules, metal ions, macromolecules, and cells present in a diverse range of samples. Additionally, the developed cellulose-based biosensors and related analytical devices have been comprehensively described in tables with details of the sensing molecule, readout system, sensor configuration, response time, real sample, and their analytical performances.

Effects of Bacterial Nanocellulose Loaded with Curcumin and Its Degradation Products on Human Dermal Fibroblasts

Bacterial nanocellulose has found applications in tissue engineering, in skin tissue repair, and in wound healing. Its large surface area enables the adsorption of various substances. Bacterial nanocellulose with adsorbed substances can serve as a substrate for drug-delivery of specific bioactive healing agents into wounds. In this study, we loaded a bacterial nanocellulose hydrogel with curcumin, i.e., an important anti-bacterial and healing agent, and its degradation products. These products were prepared by thermal decomposition of curcumin (DC) at a temperature of 180 °C (DC 180) or of 300 °C (DC 300). The main thermal decomposition products were tumerone, vanillin, and feruloylmethane. Curcumin and its degradation products were loaded into the bacterial nanocellulose by an autoclaving process. The increased temperature during autoclaving enhanced the solubility and the penetration of the agents into the nanocellulose. The aim of this study was to investigate the cytotoxicity and the antimicrobial activity of pure curcumin, its degradation products, and finally of bacterial nanocellulose loaded with these agents. In vitro tests performed on human dermal fibroblasts revealed that the degradation products of curcumin, i.e., DC 180 and DC 300, were more cytotoxic than pure curcumin. However, if DC 300 was loaded into nanocellulose, the cytotoxic effect was not as strong as in the case of DC 300 powder added into the culture medium. DC 300 was found to be the least soluble product in water, which probably resulted in the poor loading of this agent into the nanocellulose. Nanocellulose loaded with pure curcumin or DC 180 exhibited more antibacterial activity than pristine nanocellulose.

Optimized culture conditions for bacterial cellulose production by Acetobacter senegalensis MA1

Background

Cellulose, the most versatile biomolecule on earth, is available in large quantities from plants. However, cellulose in plants is accompanied by other polymers like hemicellulose, lignin, and pectin. On the other hand, pure cellulose can be produced by some microorganisms, with the most active producer being Acetobacter xylinum. A. senengalensis is a gram-negative, obligate aerobic, motile coccus, isolated from Mango fruits in Senegal, capable of utilizing a variety of sugars and produce cellulose. Besides, the production is also influenced by other culture conditions. Previously, we isolated and identified A. senengalensis MA1, and characterized the bacterial cellulose (BC) produced.

Results

The maximum cellulose production by A. senengalensis MA1 was pre-optimized for different parameters like carbon, nitrogen, precursor, polymer additive, pH, temperature, inoculum concentration, and incubation time. Further, the pre-optimized parameters were pooled, and the best combination was analyzed by using Central Composite Design (CCD) of Response Surface Methodology (RSM). Maximum BC production was achieved with glycerol, yeast extract, and PEG 6000 as the best carbon and nitrogen sources, and polymer additive, respectively, at 4.5 pH and an incubation temperature of 33.5 °C. Around 20% of inoculum concentration gave a high yield after 30 days of inoculation. The interactions between culture conditions optimized by CCD included alterations in the composition of the HS medium with 50 mL L^− 1 of glycerol, 7.50 g L^− 1 of yeast extract at pH 6.0 by incubating at a temperature of 33.5 °C along with 7.76 g L^− 1 of PEG 6000. This gave a BC yield of wet weight as 469.83 g L^− 1.

Conclusion

The optimized conditions of growth medium resulted in enhanced production of bacterial cellulose by A. senegalensis MA1, which is around 20 times higher than that produced using an unoptimized HS medium. Further, the cellulose produced can be used in food and pharmaceuticals, for producing high-quality paper, wound dressing material, and nanocomposite films for food packaging.

Effect of production process scale-up on the characteristics and properties of bacterial nanocellulose obtained from overripe Banana culture medium

In this study, the effect of bioreactor size was evaluated with respect to the production and characteristics of the nanocellulose membranes produced by two different bioreactors: one with an 1800 cm² cross-sectional area (BC-B44) and a lab-scale bioreactor with a 41 cm² cross-sectional area (BC-B1). The culture conditions were kept the same, and the substrate consisted of overripe bananas, which are inexpensive because they are unsuitable for human consumption. The X-ray diffraction pattern showed that the two samples had similar crystalline structures, but changes were observed at the morphological level in the nanofibers that make up the BNC membranes. These changes generated, in turn, variations in the mechanical and thermal properties of the samples. This result represents a novel scale-up effect related to the static mode fermentation of BNC.

Bacterial cellulose micro-nano fibres for wound healing applications

Bacterial cellulose (BC) is cellulose produced by a few limited species of bacteria in given conditions. BC has many remarkable properties such as its attractive mechanical properties, water uptake ability and biocompatibility which makes it a very desirable material to be used for wound healing. Inherently due to these important properties, the material is very resistant to easy processing and thus difficult to produce into useful entities. Additionally, being rate limited by the dependency on bacterial production, high yield is difficult to obtain and thus secondary material processing is sought after. In this review, BC is explained in terms of synthesis, structure and properties. These beneficial properties are directly related to the material's great potential in wound healing where it has also been trialled commercially but ultimately failed due to processing issues. However, more recently there has been increased frequency in scientific work relating to BC processing into hybrid polymeric fibres using common laboratory fibre forming techniques such as electrospinning and pressurised gyration. This paper summarises current progress in BC fibre manufacturing, its downfalls and also gives a future perspective on how the landscape should change to allow BC to be utilised in wound care in the current environment.

Rheological Properties of Aqueous Dispersions of Bacterial Cellulose

Bacterial cellulose as polysaccharide possessing outstanding chemical purity and a unique structure compared with wood cellulose, attracts great attention as a hydrocolloid system. It was shown, that at intense mechanical action on a neat bacterial cellulose film in presence of water, the gel-like dispersions are obtained. They retain stability in time (at least, up to several months) and temperature (at least, up to 60 °C) without macro-phase separation on aqueous and cellulose phases. The main indicator of the stability is constant viscosity values in time, as well as fulfilling the Arrhenius dependence for temperature dependence of viscosity. Flow curves of diluted dispersions (BC content less than 1.23%) show strong non-Newtonian behavior over the entire range of shear rates. It is similar with dispersions of micro- and nanocrystalline cellulose, but the absolute viscosity value is much higher in the case of BC due to more long fibrils forming more dense entanglements network than in other cases. Measuring the viscosity in increase and decrease shear rate modes indicate an existence of hysteresis loop, i.e., thixotropic behavior with time lag for recovering the structural network. MCC and NCC dispersions even at cellulose content more than 5% do not demonstrate such behavior. According to oscillatory measurements, viscoelastic behavior of dispersions corresponds to gel-like systems with almost total independence of moduli on frequency and essentially higher values of the storage modulus compared with the loss modulus.

Current progress on the production, modification, and applications of bacterial cellulose

Adoption of biomass for the development of biobased products has become a routine agenda in evolutionary metabolic engineering. Cellulose produced by bacteria is a "rising star" for this sustainable development. Unlike plant cellulose, bacterial cellulose (BC) shows several unique properties like a high degree of crystallinity, high purity, high water retention, high mechanical strength, and enhanced biocompatibility. Favored with those extraordinary properties, BC could serve as ideal biomass for the development of various industrial products. However, a low yield and the requirement for large growth media have been a persistent challenge in mass production of BC. A significant number of techniques has been developed in achieving efficient BC production. This includes the modification of bioreactors, fermentation parameters, and growth media. In this article, we summarize progress in metabolic engineering in order to solve BC growth limitation. This article emphasizes current engineered BC production by using various bioreactors, as well as highlighting the structure of BC fermented by different types of engineered-bioreactors. The comprehensive overview of the future applications of BC, aims to provide readers with insight into new economic opportunities of BC and their modifiable properties for various industrial applications. Modifications in chemical composition, structure, and genetic regulation, which preceded the advancement of BC applications, were also emphasized.

Comparison of bacterial nanocellulose produced by different strains under static and agitated culture conditions

Bacterial nanocellulose (BNC) has many advantages over plant cellulose, which make it widely used in many fields, especially in the food industry. In this study, three strains including BCA263, BCC529, and P1 were selected for characteristics analysis of BNCs under static and agitated culture conditions. The BNCs produced under static culture condition were in the shape of uniform membrane, while BNCs produced under agitated culture were in form of small agglomerates and fragments. BCA263 and BCC529 strains were more suitable for static culture, while P1 strain was more suitable for agitated culture. BNCs produced under static culture condition exhibited higher crystallinity, stronger tensile strength, denser network structure, higher temperature resistance and good flame retardancy; while BNCs produced under agitated culture condition exhibited larger porous and lower crystallinity. Furthermore, BNCs produced under agitated culture condition were more suitable as a stabilizer of coffee milk beverage.

From a Basic Microalga and an Acetic Acid Bacterium Cellulose Producer to a Living Symbiotic Biofilm

Bacterial cellulose (BC) has recently been the subject of a considerable amount of research, not only for its environmentally friendly biosynthesis, but also for its high potential in areas such as biomedicine or biomaterials. A symbiotic relationship between a photosynthetic microalga, Chlamydomonas debaryana, and a cellulose producer bacterium, Komagataeibacter saccharivorans, was established in order to obtain a viable and active biofilm. The effect of the growth media composition ratio on the produced living material was investigated, as well as the microalgae biomass quantity, temperature, and incubation time. The optimal temperature for higher symbiotic biofilm production was 30 °C with an incubation period of 14 days. The high microalgae presence, 0.75% w/v, and 60:40 HS:BG-11 medium (v/v) induced a biofilm microalgae incorporation rate of 85%. The obtained results report, for the first time, a successful symbiotic interaction developed in situ between an alkaline photosynthetic microalga and an acetic acid bacterium. These results are promising and open a new window to BC living biofilm applications in medical fields that have not yet been explored.

Komagataeibacter xylinus as a novel probiotic candidate with high glucose conversion rate properties

Promoting general health in terms of obesity and diabetes prevention is recommended by health care systems. The objectives of this study were to isolate an efficient glucose-converting Komagataeibacter xylinus to cellulose and to evaluate the safety of the selected strain as a new generation of probiotics in the fight against obesity. Of the 97 samples, 43 K xylinus strains were isolated and evaluated for their glucose conversion rate and 5 strains were examined for probiotic activities by in vitro assays. A strain with significant performance was fed to rats in order to determine its safety status in vivo. The results revealed that the strain K.X.1 had high level of glucose conversion rate and significant survival rate in acidic pH and bile salt. No adverse clinical signs and bacterial translocation to rats’ organs were observed. The results showed that the strain of K. xylinus K.X.1 has suitable probiotic properties.

“Deceived” Concentrated Immobilized Cells as Biocatalyst for Intensive Bacterial Cellulose Production from Various Sources

A new biocatalyst in the form of Komagataeibacter xylinum B-12429 cells immobilized in poly(vinyl alcohol) cryogel for production of bacterial cellulose was demonstrated. Normally, the increased bacteria concentration causes an enlarged bacterial cellulose synthesis while cells push the polysaccharide out to pack themselves into this polymer and go into a stasis. Immobilization of cells into the poly(vinyl alcohol) cryogel allowed “deceiving” them: bacteria producing cellulose pushed it out, which further passed through the pores of cryogel matrix and was accumulated in the medium while not covering the cells; hence, the latter were deprived of a possible transition to inactivity and worked on the synthesis of bacterial cellulose even more actively. The repeated use of immobilized cells retaining 100% of their metabolic activity for at least 10 working cycles (60 days) was performed. The immobilized cells produce bacterial cellulose with crystallinity and porosity similar to polysaccharide of free cells, but having improved stiffness and tensile strength. Various media containing sugars and glycerol, based on hydrolysates of renewable biomass sources (aspen, Jerusalem artichoke, rice straw, microalgae) were successfully applied for bacterial cellulose production by immobilized cells, and the level of polysaccharide accumulation was 1.3–1.8-times greater than suspended cells could produce.

Effect of Temperature and Gamma Radiation on Salmonella Hadar Biofilm Production on Different Food Contact Surfaces

Salmonella is a pathogen transmitted by foods and it is one of the most important target bacteria in food irradiation studies. Few works were carried out on the effectiveness of gamma radiation against biofilms formed by this bacterium. Salmonella can form a biofilm on different material surfaces. The physicochemical properties of surfaces and environmental factors influence the adhesion of this pathogen. The present study investigated the effect of gamma radiation (1 and 2 kGy) and temperature (28°C and 37°C) on the development of Salmonella Hadar biofilm on polyvinyl chloride (PVC), glass, cellophane paper (CELLO), and polystyrene (POLY). The obtained results indicated that biofilm production is surface and temperature dependent. In addition, biofilm formation decreased significantly after gamma irradiation at either 1 or 2 kGy doses. However, the agfD and adrA genes expression did not demonstrate significant decrease. This work highlighted that gamma radiation treatment could reduce the biofilm formation of Salmonella enterica serovar Hadar on different food contact surfaces.

Production of Bacterial Cellulose by Gluconacetobacter hansenii Using Corn Steep Liquor As Nutrient Sources

Cellulose is mainly produced by plants, although many bacteria, especially those belonging to the genus Gluconacetobacter, produce a very peculiar form of cellulose with mechanical and structural properties that can be exploited in numerous applications. However, the production cost of bacterial cellulose (BC) is very high to the use of expensive culture media, poor yields, downstream processing, and operating costs. Thus, the purpose of this work was to evaluate the use of industrial residues as nutrients for the production of BC by Gluconacetobacter hansenii UCP1619. BC pellicles were synthesized using the Hestrin-Schramm (HS) medium and alternative media formulated with different carbon (sugarcane molasses and acetylated glucose) and nitrogen sources [yeast extract, peptone, and corn steep liquor (CSL)]. A jeans laundry was also tested. None of the tested sources (beside CSL) worked as carbon and nutrient substitute. The alternative medium formulated with 1.5% glucose and 2.5% CSL led to the highest yield in terms of dry and hydrated mass. The BC mass produced in the alternative culture medium corresponded to 73% of that achieved with the HS culture medium. The BC pellicles demonstrated a high concentration of microfibrils and nanofibrils forming a homogenous, compact, and three-dimensional structure. The biopolymer produced in the alternative medium had greater thermal stability, as degradation began at 240°C, while degradation of the biopolymer produced in the HS medium began at 195°C. Both biopolymers exhibited high crystallinity. The mechanical tensile test revealed the maximum breaking strength and the elongation of the break of hydrated and dry pellicles. The dry BC film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The dry film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The values obtained for the Young's modulus in the mechanical tests in the hydrated samples indicated low values for the variable rigidity. The presence of water in the interior and between the nanofibers of the hydrated BC only favored the results for the elasticity, which was 56.37% higher when compared to the dry biomaterial.