Bacterial cellulose as an ideal potential treatment for burn wounds: A comprehensive review.

Burn wound regeneration is a complex process, which has many serious challenges such as slow wound healing, secondary infection, and inflammation. Therefore, it is essential to utilise appropriate biomaterials to accelerate and guide the wound healing process. Bacterial cellulose (BC), a natural polymer synthesised by some bacteria, has attracted much attention for wound healing applications due to its unique properties including excellent physicochemical and mechanical properties, simple purification process, three-dimensional (3D) network structure similar to extracellular matrix, high purity, high water holding capacity and significant permeability to gas and liquid. BC's lack of antibacterial activity significantly limits its biomedical and tissue engineering application, but adding antimicrobial agents to it remarkably improves its performance in tissue regeneration applications. Burn wound healing is a complex long-lasting process. Using biomaterials in wound treatment has shown that they can satisfactorily accelerate wound healing. The purpose of this review is to elaborate on the importance of BC-based structures as one of the most widely used modern wound dressings in the treatment of burn wounds. In addition, the combination of various drugs, agents, cells and biomolecules with BC to expand its application in burn injury regeneration is discussed. Finally, the main challenges and future development direction of BC-based structures for burn wound repair are considered. The four most popular search engines PubMed/MEDLINE, Science Direct, Scopus and Google Scholar were used to help us find relevant papers. The most frequently used keywords were bacterial cellulose, BC-based biocomposite, wound healing, burn wound and vascular graft.

Revolutionizing agriculture: Harnessing nano-innovations for sustainable farming and environmental preservation.

The agricultural sector is currently confronted with a significant crisis stemming from the rapid changes in climate patterns, declining soil fertility, insufficient availability of essential macro and micronutrients, excessive reliance on chemical fertilizers and pesticides, and the presence of heavy metals in soil. These numerous challenges pose a considerable threat to the agriculture industry. Furthermore, the exponential growth of the global population has led to a substantial increase in food consumption, further straining agricultural systems worldwide. Nanotechnology holds great promise in revolutionizing the food and agriculture industry, decreasing the harmful effects of agricultural practices on the environment, and improving productivity. Nanomaterials such as inorganic, lipid, and polymeric nanoparticles have been developed for increasing productivity due to their unique properties. Various strategies can enhance product quality, such as the use of nano-clays, nano zeolites, and hydrogel-based materials to regulate water absorption and release, effectively mitigating water scarcity. The production of nanoparticles can be achieved through various methods, each of which has its own unique benefits and limitations. Among these methods, chemical synthesis is widely favored due to the impact that various factors such as concentration, particle size, and shape have on product quality and efficiency. This review provides a detailed examination of the roles of nanotechnology and nanoparticles in sustainable agriculture, including their synthetic methods, and presents an analysis of their associated advantages and disadvantages. To date, there are serious concerns and awareness about healthy agriculture and the production of healthy products, therefore the development of nanotech-enabled devices that act as preventive and early warning systems to identify health issues, offering remedial measures is necessary.

Poly-γ-glutamic acid overproduction of Bacillus licheniformis ATCC 9945a by developing a novel optimum culture medium and glutamate pulse feeding using different experimental design approaches.

The commercial production of multifunctional, biocompatible, and biodegradable biopolymers such as poly-γ-glutamic acid via microbial fermentation requires the development of simple and cheap methods for mass production. This study optimized the poly-γ-glutamic acid production of Bacillus licheniformis ATCC 9945a in several steps. At first, the most critical components of the culture medium, including l-glutamic acid, citric acid, and glycerol, were selected by screening nine factors through the Plackett-Burman experimental design and then were optimized using the response surface method and the central composite design algorithm. Under optimal conditions, the production of poly-γ-glutamic acid increased by more than 4.2 times from 11.2 to 47.2 g/L. This is one of the highest production rates of this strain in submerged batch fermentation reported so far using the optimized medium compared to the conventional base medium. A novel and efficient sudden pulse feeding strategy (achieved by a novel one-factorial statistical technique) of l-glutamic acid to the optimized medium increased biopolymer production from 47.2 to 66.1 g/L, the highest value reported in published literature with this strain. This simple, reproducible, and cheap fermentation process can considerably enhance the commercial applications of the poly-γ-glutamic acid synthesized by B. licheniformis ATCC 9945a .

Pre-polymerization process simulation, synthesis and investigation the properties of dipicolinic acid molecularly imprinted polymers.

Molecularly imprinted polymers (MIPs) have attracted much attention in recent years due to their structure predictability, recognition specificity, and universal application, as well as robustness, simplicity, and cheapness. In this study, firstly, the pre-polymerization process of molecularly imprinted polymer of dipicolinic acid (DPA) was simulated by molecular dynamics. Then, the appropriate functional monomer molecule for printing was selected and its intermolecular bond with the DPA molecule was evaluated. The monomers 2-vinyl pyridine, acrylic acid (AA), and methacrylic acid (MAA) were selected with potential energies of 3.93 kcal/mol, 3.15 kcal/mol, and 2.78 kcal/mol, respectively. Finally, the ability of functional groups to form hydrogen bonds was estimated, and molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were synthesized by bulk polymerization. MAA and AA were used as functional monomers to identify DPA molecules. The morphology of MIP and NIP was investigated using a scanning electron microscope (SEM). Their performance was evaluated in the absorption of DPA molecules and picolinic acid (PA) molecules and the printing factor of synthesis polymers. The results showed that fabricated MIPs can be used in the structure of sensors, and the synthesis process is a key factor that significantly affects the polymer properties. The MIP based on the AA monomer showed a higher adsorption rate/capacity and maximum printing factor than MAA monomer-based MIP.

Bacterial cellulose-based composites as vehicles for dermal and transdermal drug delivery: A review.

In recent years, a significant amount of drugs have been taken orally, which are not as effective as desired. To solve this problem, bacterial cellulose-based dermal/transdermal drug delivery systems (BC-DDSs) with unique properties such as cell compatibility, hemocompatibility, tunable mechanical properties, and the ability to encapsulate various therapeutic agents with the controlled release have been introduced. A BC-dermal/transdermal DDS reduces first-pass metabolism and systematic side effects while improving patient compliance and dosage effectiveness by controlling drug release through the skin. The barrier function of the skin, especially the stratum corneum, can interfere with drug delivery. Few drugs can pass through the skin to reach effective concentrations in the blood to treat diseases. Due to their unique physicochemical properties and high potential to reduce immunogenicity and improve bioavailability, BC-dermal/transdermal DDSs are widely used to deliver various types of drugs for disease treatment. In this review, we describe the different types of BC-dermal/ transdermal DDSs, along with a critical discussion of the advantages and disadvantages of these systems. After the general presentation, the review is focused on recent advances in the preparation and applications of BC-based dermal/transdermal DDSs in various types of disease treatment.

Comprehensive review on biosynthesis of hyaluronic acid with different molecular weights and its biomedical applications.

Hyaluronic acid (HA), an anionic and nonsulfated glycosaminoglycan, is the main structural component of various tissues and plays an important role in various biological processes. Given the promising properties of HA, such as high cellular compatibility, moisture retention, antiaging, proper interaction with cells, and CD44 targeting, HA can be widely used extensively in drug delivery, tissue engineering, wound healing, and cancer therapy. HA can obtain from animal tissues and microbial fermentation, but its applications depend on its molecular weight. Microbial fermentation is a common method for HA production on an industrial scale and S. zooepidemicus is the most frequently used strain in HA production. Culture conditions including pH, temperature, agitation rate, aeration speed, shear stress, dissolved oxygen, and bioreactor type significantly affect HA biosynthesis properties. In this review all the HA production methods and purification techniques to improve its physicochemical and biological properties for various biomedical applications are discussed in details. In addition, we showed that how HA molecular weight can significantly affect its properties and applications.

Economical Optimization of Industrial Medium Culture for Bacterial Cellulose Production.

The competitiveness of bacterial cellulose (BC) production with plant cellulose can be achieved by production on cost-effective media. It was found that the bacterial cell number ratio of BC to culture medium increases over time so that from the fourth day, the entrapped cell number in the cellulose network exceeds the suspended cells. Optimization based on 23-full factorial showed that inoculum development at 50 rpm and the main culture process under static conditions significantly increases BC production. A cost-effective culture medium containing molasses (ML) and corn steep liquor (CSL) was developed based on the same C/N ratio to HS medium, with 7.24 g/l cellulose at C/N ratio 12.6 is competitive with maximum production 8.7 g/L in HS medium. The BC production cost was reduced about 94% using the proposed cheap and locally available medium containing ML and CSL, while BC mechanical properties increased by about 50%.

Bacterial cellulose-based composites for nerve tissue engineering.

Nerve injuries and neurodegenerative disorders are very serious and costly medical challenges. Damaged nerve tissue may not be able to heal and regain its function, and scar tissue may restrict nerve cell regeneration. In recent years, new electroactive biomaterials have attracted widespread attention in the neural tissue engineering field. Bacterial cellulose (BC) due to its unique properties such as good mechanical properties, high water retention, biocompatibility, high crystallinity, large surface area, high purity, very fine network, and inability to absorb in the human body due to cellulase deficiency, can be considered a promising treatment for neurological injuries and disorders that require long-term support. However, BC lacks electrical activity, but can significantly improve the nerve regeneration rate by combining with conductive structures. Electrical stimulation has been shown to be an effective means of increasing the rate and accuracy of nerve regeneration. Many factors, such as the intensity and pattern of electrical current, have positive effects on cellular activity, including cell adhesion, proliferation, migration and differentiation, and cell-cell/tissue/molecule/drug interaction. This study discusses the importance and essential role of BC-based biomaterials in neural tissue regeneration and the effects of electrical stimulation on cellular behaviors.

Culture and maintenance of neural progressive cells on cellulose acetate/graphene­gold nanocomposites.

In this study, the first CA nanofibers were fabricated by electrospinning under optimal conditions: flow rate of 0.5 ml/h, a voltage of 20 kV, electrospinning distance of 15 cm, and an internal temperature of 25 °C, and humidity of 38%. The used Graphene/gold nanoparticles for CA performance improvement were examined by TGA, XRD, and SEM analysis. Then the CA/graphene­gold nanocomposite was synthesized under optimum electrospinning conditions: flow rate 3 ml/h, voltage 20 kV, electrospinning distance 15 cm, internal temperature 26 °C, and humidity 36%. The SEM images revealed that the nanofibers' thicknesses of Graphene­gold NPs (CA1) and Chitosan (CA2) were 350 and 120 nm, respectively. The XRD diagrams of CA0, CA1 and CA2 revealed the peaks at 2θ, 8°, and 21° with Miller indices of (001) and (110) are related to CA (CA0), which proves its presence in other scaffolds. The FTIR analysis of samples indicated the presence of graphene­gold NPs in scaffolding CA1 and CA2. The CA2 nanofibers exhibited a high-water absorption capacity of about 2500% with the water contact-angle and Swelling method. The antibacterial properties of this nanocomposite were also confirmed by an antibacterial test on Staphylococcus aureus bacteria. The growth of Schwann cells on three scaffolds showed the highest growth of cells on CA1 scaffolds.

Enhanced production of poly-γ-glutamic acid by Bacillus licheniformis ATCC 9945a using simultaneous pulse-feedings of citrate and glutamate.

Poly-γ-glutamic acid (γ-PGA) is a versatile biopolymer with widespread applications in the food, pharmaceutical, and medical industries. One of the main challenges in expanding γ-PGA industrial applications is the high cost of production. Developing an efficient and low-cost fermentation process such as bacterial cultivation with pulsed feeding can significantly reduce production costs. Thus, initially, a new pulsed-feeding strategy of citrate and glutamate was developed for γ-PGA production enhancement in the fed-batch culture of Bacillus licheniformis ATCC 9945a. Then, the effects of pulse number, feeding amount, feeding times, the addition time of calcium and manganese solutions, the pH of the added citrate solution, and the concentration of feed stock solutions of pulse-feeds on γ-PGA production were investigated. Under optimal conditions: feeding two pulses at 8 and 24 hours of culture, 20 g citrate and glutamate per liter of culture medium per pulse (about 52 mL of each of citrate and glutamate feeding solutions prepared with a concentration of 384 g/L by adding distilled water) about 88 ± 4 g/L of γ-PGA was obtained. It is one of the highest values ever reported for γ-PGA production with Bacillus licheniformis ATCC 9945a, of course with a much simpler process than the other fed-batch processes.

The dilution effect of media culture on mixing time, Kla O2, and hyaluronic acid production in S. zooepidemicus fed-batch culture.

OBJECTIVES: Microbial production of biopolymers is typically associated with high viscosity and suitable mixing plays an important role in their production. Due to the nature of Streptococcus strains in high production of lactic acid and consequently high consumption of NaOH, which is associated with increased viscosity and reduced mixing caused by hyaluronic acid production, the injected NaOH accumulates and causes cells loss, and decreases in quantity and quality of the produced hyaluronic acid. RESULTS: In this study, the effect of increasing dilution of media culture of Streptococcus zooepidemicus fed-batch culture during pH control by NaOH on mixing time, volumetric oxygen transfer coefficient, and increasing hyaluronic acid production in a 2-L fermenter were studied. The results showed that significant increasing dilution causes reduction mixing time, remarkable improvement volumetric oxygen transfer coefficient, hyaluronic acid production enhancement from 6.6 to 8.4 g/L, and diminution the consumption of NaOH. CONCLUSION: Dilution of media culture of S. zooepidemicus fed-batch culture by the pH controlling agent achieved one of the highest amounts of hyaluronic acid that was reported recently. This method does not require any automatic control and can be used at a low cost to produce other soluble extracellular biopolymers.

High cell density culture of recombinant E. coli in the miniaturized bubble columns.

Miniaturized bubble columns (MBCs) can provide mass transfer characteristics similar to stirred tank bioreactors. In this study, a new application was developed for MBCs to investigate the effect of feeding strategy and medium type on the fed-batch culture of recombinant E. coli. The results showed that the exponential feeding strategy and defined M9 medium were more suitable to achieve the high cell density culture (HCDC). The maximum obtained cell concentration in exponential feeding strategy in the defined medium without induction, was at OD600 of 169, while glucose concentration was maintained under 2 g/L. To the best of our knowledge, this cell concentration cannot be achieved in lab or pilot scale bubble columns. At the end of the process, adverse effect of the metabolic burden due to induction and mass transfer limitations decreased the obtained final cell concentration to OD600 of 116. Finally, a comparison of the results for fed-batch culture in the stirred tank bioreactor with those of the MBCs showed that their lower cell concentrations were due to the hydrodynamics limitations of MBCs. Yet, it was found that the MBCs are efficient tools in development of feeding strategies and evaluation of medium components for HCDC of recombinant E. coli.

Design, construction and optimization a flexible bench-scale rotating biological contactor (RBC) for enhanced production of bacterial cellulose by Acetobacter Xylinium.

In this research a bench scale rotating biological contactor (RBC) was designed and constructed to produce BC. The effects of variables including rotation speed of the disk, distance between disks, disk type and external aeration on BC productivity were investigated. Results showed that the highest weight of BC produced on the surface of integrated polyethylene discs which rotated at 13 rpm. It was also found that the highest amount of BC was obtained when the space between two adjacent discs was adjusted to 1 cm and the disk number was 16. An aquarium pump was used to investigate the impact of aeration on RBC made of 12 integrated polyethylene discs and operated at optimal rotation speed of 13 rpm. Disk spacing distance was adjusted to 1.5 cm to consider the possible increasing of the thickness of BC film by aeration. Wet weight and dry weight of BC resulted from aerated fermentation increased more than 64 and 47%, respectively as compared to non-aerated RBC. In comparison with static culture, wet weight and dry weight of BC produced in aerated RBC fermentation increased more than 90.7 and 71%, respectively. Nanoscale structure of produced bacterial cellulose was confirmed by SEM analysis.

Efficient process development for high-level production, purification, formulation, and characterization of recombinant mecasermin in Escherichia coli.

Overproduction of recombinant mecasermin was achieved by investigation of effect of three factors, temperature, inducer amount, and culture media, at three levels according to the Taguchi statistical design in Escherichia coli in a bench-scale bioreactor. In optimal conditions (induction temperature 28 °C, terrific broth with glucose (TB+G) medium, with 0.1 mM IPTG as inducer) 0.84 g/L mecasermin with expression levels of 38% of total protein and 4.13 g/L final dry cell biomass was produced, that is one of the highest values of recombinant protein has been reported in the batch system. The cell disruption was done by lysozyme pretreatment with sonication to the efficient purification of mecasermin. The isolated and washed inclusion bodies were solubilized in Gdn-HCl at pH 5.4 and folded with glutathione and purified with gel filtration. The purified rhIGF-1 (mecasermin) was formulated with arginine. Mecasermin protein remained t stable at 4 °C for up to 2 years. The quantitative and qualitative control indicated that mecasermin is expressed correctly (without the initial methionine by mass spectrometry), pure (without endotoxin and other protein impurities), correct folding (FTIR, RF-HPLC), monomer form (SEC-HPLC), and active (bioactivity test). Also, the purification results revealed that expression at low temperature results in the efficient purification of the overproduced mecasermin with high quantity and quality.

Overexpression, overproduction, purification, and characterization of rhGH in Escherichia coli.

Overexpression of insoluble human growth hormone (hGH) in cytoplasm was achieved by E. coli Rosetta-gami B(DE3) [pET21a (+)-hGH]). For overexpression of hGH, effects of eight factors including temperature, type and concentration of carbon source, IPTG and MgSO4 , buffering capacity, induction time, yeast extract/peptone ratio on rhGH production were studied by Plackett-Burman screening. Maximum production of rhGH was 0.681 g/L, and results of statistical analysis showed that induction temperature and glucose have the greatest effect and the presence of MgSO4 increases rhGH expression and reduces biomass concentration. So, the effect of ethanol and MgSO4 concentrations on the rhGH production was examined according to the central composite experimental design. The ANOVA of the results showed rhGH production increases to 1.128 g/L in 4 g/L MgSO4 and 1% ethanol. Then, the impact of glucose concentration and induction time on the rhGH production was evaluated in two levels in the fermenter by Taguchi statistical method. Under optimum conditions, OD600nm 4 and 10 g/L glucose crude rhGH concentration 4.17 g/L was obtained, which is one of the highest value ever reported. Finally, rhGH was purified using the biophysical and biochemical techniques comprising circular dichroism, fluorescent spectroscopy, and dynamic light scattering, and it was confirmed that the produced protein is comparable to the commercial standard sample.

Reconstruction, verification and in-silico analysis of a genome-scale metabolic model of bacterial cellulose producing Komagataeibacter xylinus.

In this study, a comprehensive genome-scale metabolic network of Komagataeibacter xylinus as the model microorganism was reconstructed based on genome annotation, for better understanding of metabolic growth and biosynthesis of bacterial cellulose (BC). The reconstructed network included 640 genes, 783 metabolic reactions and 865 metabolites. The model was completely successful to predict the lack of growth under anaerobic conditions. Model validation by the data for the growth of acetic acid bacteria with ethanol-limited chemostat cultures showed that there is a good agreement for the O2 and CO2 fluxes with actual growth conditions. Then the model was used to forecast the simultaneous production of BC and by-products. The obtained data showed that the rate of BC production is consistent with experimental data with an accuracy of 93.7%. Finally, the study of flux balance analysis (FBA) data showed that the pentose phosphate pathway and the TCA cycle play an important role in growth-promoting metabolism in K. xylinus and have a close relationship with BC biosynthesis. By integrating this model with various metabolic engineering and systems biology tools in the future, it is possible to overcome the common challenges in the large-scale BC production, such as low yield and productivity.

Optimization and One-Step Purification of Recombinant V Antigen Production from Yersinia pestis.

The purpose of this study was to develop an efficient and inexpensive method for the useful production of recombinant protein V antigen, an important virulence factor for Yersinia pestis. To this end, the synthetic gene encoding the V antigen was subcloned into the downstream of the intein (INT) and chitin-binding domain (CBD) from the pTXB1 vector using specific primers. In the following, the produced new plasmid, pTX-V, was transformed into E. coli ER2566 strain, and the expression accuracy was confirmed using electrophoresis and Western blotting. In addition, the effects of medium, inducer, and temperature on the enhancement of protein production were studied using the Taguchi method. Finally, the V antigen was purified by a chitin affinity column using INT and CBD tag. The expression was induced by 0.05 mM IPTG at 25 °C under optimal conditions including TB medium. It was observed that the expression of the V-INT-CBD fusion protein was successfully increased to more than 40% of the total protein. The purity of V antigen was as high as 90%. This result indicates that V antigen can be produced at low cost and subjected to one-step purification using a self-cleaving INT tag.

Increased cellulose production by heterologous expression of bcsA and B genes from Gluconacetobacterxylinus in E. coli Nissle 1917.

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

Expression and production of recombinant scorpine as a potassium channel blocker protein in Escherichia coli.

Scorpine is a cationic protein from the venom of Pandinus imperator, belonging to potassium channel blocker family, which has been shown to have antibacterial, antiviral, and antiplasmodia activities. In the present study, a pET-44a vector containing scorpine synthetic gene with T7 Promoter (pET 44a-His6-Nus-His6-tev-scorpine) was transferred into Escherichia coli Rosetta-gami B (DE3) for soluble expression of the protein in the cytoplasm and its overproduction. After confirming recombinant scorpine peptide expression using SDS-PAGE and Western blot, augmentation of production was performed during two stages. At first, effects of three parameters including carbon source concentration of medium, temperature, and induction time were investigated in terrific broth (TB) medium. Afterward, the overexpression was performed by response surface methodology in TB + glucose. Under the optimized conditions, the highest production of 3.5 g/L in the TB + glucose medium (7.5 g/L glucose, induction at OD600 = 3.5 and 25 °C) was increased to 4.1 g/L in TB medium (2.5 g/L glycerol, induction at OD600 = 0.7 and 25 °C). Then, in order to increase the amount of protein production, effects of carbon concentration in the fermenter under the primary optimized condition was investigated. The amount of produced recombinant protein increased from 0.12 to 2.1 g/L.H. The results were similar to previous studies on optimizing and increasing the production of recombinant protein and in particular recombinant scorpine.

Hydrodynamics and mass transfer in miniaturized bubble column bioreactors.

Miniaturized bubble columns (MBCs) have different hydrodynamics in comparison with the larger ones, but there is a lack of scientific data on MBCs. Hence, in this study, the effect of gas hold-up, flow regimes, bubble size distribution on volumetric oxygen mass transfer coefficient at different pore size spargers and gas flow rates in MBCs in the presence and absence of microorganisms were investigated. It was found that flow regime transition occurred around low gas flow rates of 1.18 and 0.85 cm/s for small (16-40 µm) and large (40-100 µm) pore size spargers, respectively. Gas hold-up and KLa in MBC with small size sparger were higher than those with larger one, with an increasing effect in the presence of microorganisms. A comparison revealed that the wall effect on the flow regime and gas hold-up in MBCs was greater than bench-scale bubble columns. The KLa values significantly increased up to tenfold using small pore size sparger. In the MBC and stirred tank bioreactors, the maximum obtained cell concentrations were OD600 of 41.5 and 43.0, respectively. Furthermore, it was shown that in MBCs, higher KLa and lower turbulency could be achieved at the end of bubbly flow regime.