Pilot-scale production of bacterial cellulose by a spherical type bubble column bioreactor using saccharified food wastes

Optimizing the synthesis of yeast Beta-glucan via response surface methodology for nanotechnology application

BACKGROUND

The production of biopolymers from waste resources is a growing trend, especially in high-population countries like Egypt. Beta-glucan (β-glucan) belongs to natural polysaccharides that are derived from plant and microbial origins. In this study, following increasing demands for β-glucan owing to its bioactive properties, a statistical model to enhance microbial β-glucan production was evaluated for its usefulness to the food and pharmaceutical industries. In addition, a trial to convert β-glucan polymer to nanostructure form was done to increase its bioactivity.

RESULTS

Ingredients of low-cost media based on agro-industrial wastes were described using Plackett-Burman and central composite design of response surface methodology for optimizing yeast β-glucan. Minerals and vitamin concentrations significantly influenced β-glucan yield for Kluyveromyces lactis and nitrogen and phosphate sources for Meyerozyma guilliermondii. The maximum predicted yields of β-glucan recovered from K. lactis and M. guilliermondii after optimizing the medium ingredients were 407 and 1188 mg/100 ml; respectively. For the first time, yeast β-glucan nanoparticles (βGN) were synthesized from the β-glucan polymer using N-dimethylformamide as a stabilizer and characterized using UV-vis spectroscopy, transmission electron microscope (TEM), dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FT-IR). The average size of βGN was about 300 nm as determined by DLS. The quantitative variation of functional groups between β-glucan polymer and βGN was evaluated by FT-IR for explaining the difference in their biological activity against Normal Homo sapiens-Hela contaminant and Hepatic cancer cell lines.

CONCLUSIONS

Enriching the low-cost media based on agro-industrial wastes with nutritional ingredients improves the yield of yeast β-glucan. The present study succeeds to form β-glucan nanoparticles by a simple method.

Membrane Technological Pathways and Inherent Structure of Bacterial Cellulose Composites for Drug Delivery

This report summarizes efforts undertaken in the area of drug delivery, with a look at further efforts made in the area of bacterial cellulose (BC) biomedical applications in general. There are many current methodologies (past and present) for the creation of BC membrane composites custom-engineered with drug delivery functionality, with brief consideration for very close applications within the broader category of biomedicine. The most emphasis was placed on the crucial aspects that open the door to the possibility of drug delivery or the potential for use as drug carriers. Additionally, consideration has been given to laboratory explorations as well as already established BC-drug delivery systems (DDS) that are either on the market commercially or have been patented in anticipation of future commercialization. The cellulose producing strains, current synthesis and growth pathways, critical aspects and intrinsic morphological features of BC were given maximum consideration, among other crucial aspects of BC DDS.

Static Culture Combined with Aeration in Biosynthesis of Bacterial Cellulose

One of the ways to enhance the yield of bacterial cellulose (BC) is by using dynamic aeration and different-type bioreactors because the microbial producers are strict aerobes. But in this case, the BC quality tends to worsen. Here we have combined static culture with aeration in the biosynthesis of BC by symbiotic Medusomyces gisevii Sa-12 for the first time. A new aeration method by feeding the air onto the growth medium surface is proposed herein. The culture was performed in a Binder-400 climate chamber. The study found that the air feed at a rate of 6.3 L/min allows a 25% increase in the BC yield. Moreover, this aeration mode resulted in BC samples of stable quality. The thermogravimetric and X-ray structural characteristics were retained: the crystallinity index in reflection and transmission geometries were 89% and 92%, respectively, and the allomorph Iα content was 94%. Slight decreases in the degree of polymerization (by 12.0% compared to the control-no aeration) and elastic modulus (by 12.6%) are not critical. Thus, the simple aeration by feeding the air onto the culture medium surface has turned out to be an excellent alternative to dynamic aeration. Usually, when the cultivation conditions, including the aeration ones, are changed, characteristics of the resultant BC are altered either, due to the sensitivity of individual microbial strains. In our case, the stable parameters of BC samples under variable aeration conditions are explained by the concomitant factors: the new efficient aeration method and the highly adaptive microbial producer-symbiotic Medusomyces gisevii Sa-12.

Bacterial nanocellulose: engineering, production, and applications

Bacterial nanocellulose (BNC) has been emerging as a biomaterial of considerable significance in a number of industrial sectors because of its remarkable physico-chemical and biological characteristics. High capital expenses, manufacturing costs, and a paucity of some well-scalable methods, all of which lead to low BNC output in commercial scale, are major barriers that must be addressed. Advances in production methods, including bioreactor technologies, static intermittent, and semi-continuous fed batch technologies, and innovative outlay substrates, may be able to overcome the challenges to BNC production at the industrial scale. The novelty of this review is that it highlights genetic modification possibilities in BNC production to overcome existing impediments and open up viable routes for large-scale production, suitable for real-world applications. This review focuses on various production routes of BNC, its properties, and applications, especially the major advancement in food, personal care, biomedical and electronic industries.

Highly efficient production of bacterial cellulose from corn stover total hydrolysate by Enterobacter sp. FY-07

Bacterial cellulose (BC) has a huge global market due to its excellent properties and wide range of applications. However, due to high production costs, low productivity, and unsatisfactory scale-up production, industrialisation has been slow. Herein, stabilization of strain, optimisation of culture conditions, and a cheap carbon source were combined to achieve highly efficient, low-cost, large-scale BC production in 20 L containers. Optimisation of culture conditions increased both BC productivity and sugar conversion ratio significantly, from 2.08 g/L/day and 9.78% to 17.13 g/L/day and 70.31%, respectively. Furthermore, BC productivity and sugar conversion ratio reached 13.96 g/L/day and 85.50% using corn stover total hydrolysate as carbon source. The low-cost, facile, and highly efficient process can generate large quantities of BC, and could promote industrialisation of BC production.

Preparation of Komagataeibacter xylinus Inoculum for Bacterial Cellulose Biosynthesis Using Magnetically Assisted External-Loop Airlift Bioreactor

The aim of this study was to demonstrate the applicability of a novel magnetically assisted external-loop airlift bioreactor (EL-ALB), equipped with rotating magnetic field (RMF) generators for the preparation of Komagataeibacterxylinus inoculum during three-cycle repeated fed-batch cultures, further used for bacterial cellulose (BC) production. The fermentation carried out in the RMF-assisted EL-ALB allowed to obtain an inoculum of more than 200× higher cellular density compared to classical methods of inoculum preparation. The inoculum obtained in the RMF-assisted EL-ALB was characterized by a high and stable metabolic activity during repeated batch fermentation process. The application of the RMF-assisted EL-ALB for K. xylinus inoculum production did not induce the formation of cellulose-deficient mutants. It was also confirmed that the ability of K. xylinus to produce BC was at the same level (7.26 g/L of dry mass), regardless of inoculum age. Additionally, the BC obtained from the inoculum produced in the RMF-assisted EL-ALB was characterized by reproducible water-related properties, mechanical strength, nano-fibrillar structure and total crystallinity index. The lack of any negative impact of inoculum preparation method using RMF-assisted EL-ALB on BC properties is of paramount value for its future applications, including use as a biomaterial in tissue engineering, wound healing, and drug delivery, where especially BC liquid capacity, nanostructure, crystallinity, and mechanical properties play essential roles.

Bacterial Nanocellulose toward Green Cosmetics: Recent Progresses and Challenges

In the skin care field, bacterial nanocellulose (BNC), a versatile polysaccharide produced by non-pathogenic acetic acid bacteria, has received increased attention as a promising candidate to replace synthetic polymers (e.g., nylon, polyethylene, polyacrylamides) commonly used in cosmetics. The applicability of BNC in cosmetics has been mainly investigated as a carrier of active ingredients or as a structuring agent of cosmetic formulations. However, with the sustainability issues that are underway in the highly innovative cosmetic industry and with the growth prospects for the market of bio-based products, a much more prominent role is envisioned for BNC in this field. Thus, this review provides a comprehensive overview of the most recent (last 5 years) and relevant developments and challenges in the research of BNC applied to cosmetic, aiming at inspiring future research to go beyond in the applicability of this exceptional biotechnological material in such a promising area.

A Novel Approach Using Conventional Methodologies to Scale up BNC Production Using Komagataeibacter medellinensis and Rotten Banana Waste as Alternative

Currently, cellulose nanostructures are among the most promising structures, and extensive work in materials and biotechnology industries is aimed at identifying an efficient process of production. Even when production at the laboratory scale is successful, crucial aspects of increased commercial applications for cellulose nanostructures are linked to large-scale production. Large-scale production requires a balance between the cost of the culture medium and product value. Therefore, in this work, for the optimization and scaling up of bacterial nanocellulose, a culture medium consisting of rotten banana unsuitable for human consumption was used for the first time as an inexpensive feedstock. Initially, the bacterial nanocellulose (BNC) culture medium conditions were optimized, and it was established that a glucose concentration of 26.4 g/L and a V/A ratio of 2.2 cm were the optimal conditions for production reaching a BNC yield of 5 g/L, which was 42.4% higher than the best result initially obtained. Finally, the scale-up process was performed, implementing a regime analysis methodology by comparing the characteristic times of the critical mechanisms involved in BNC production, namely, microbial growth, glucose consumption, BNC production, and glucose diffusion into the BNC membrane, as the first approach for this type of BNC production process. The mechanism underlying the BNC production process is glucose diffusion into the BNC membrane (characteristic time, 675.47 h). Thus, the V/A ratio was selected as the scale-up criterion most suitable for producing BNC under static culture conditions, allowing the production of 16 g of BNC after 12 d of fermentation in a plastic bioreactor, which was 3378% higher than that produced in glass vessels. The results obtained in this study may initiate further improvements in BNC commercial production by exploiting different feedstocks.

Formulation and Characterization of Gelatin-Based Hydrogels for the Encapsulation of Kluyveromyces lactis-Applications in Packed-Bed Reactors and Probiotics Delivery in Humans

One of the main issues when orally administering microorganism-based probiotics is the significant loss of bioactivity as they pass through the gastrointestinal (GI) tract. To overcome these issues, here, we propose to encapsulate the probiotic yeast Kluyveromyces lactis on chemically crosslinked gelatin hydrogels as a means to protect the bioactive agents in different environments. Hydrogels were prepared by the chemical crosslinking of gelatin, which is commercially available and inexpensive. This is crucial to ensure scalability and cost-effectiveness. To explore changes in key physicochemical parameters and their impact on cell viability, we varied the concentration of the crosslinking agent (glutaraldehyde) and the gelatin. The synthesized hydrogels were characterized in terms of morphological, physical-chemical, mechanical, thermal and rheological properties. This comprehensive characterization allowed us to identify critical parameters to facilitate encapsulation and enhance cell survival. Mainly due to pore size in the range of 5-10 μm, sufficient rigidity (breaking forces of about 1 N), low brittleness and structural stability under swelling and relatively high shear conditions, we selected hydrogels with a high concentration of gelatin (7.5% (w/v)) and concentrations of the crosslinking agent of 3.0% and 5.0% (w/w) for cell encapsulation. Yeasts were encapsulated with an efficiency of about 10% and subsequently tested in bioreactor operation and GI tract simulated media, thereby leading to cell viability levels that approached 95% and 50%, respectively. After testing, the hydrogels' firmness was only reduced to half of the initial value and maintained resistance to shear even under extreme pH conditions. The mechanisms underlying the observed mechanical response will require further investigation. These encouraging results, added to the superior structural stability after the treatments, indicate that the proposed encapsulates are suitable to overcome most of the major issues of oral administration of probiotics and open the possibility to explore additional biotech applications further.

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.

Improved bacterial nanocellulose production from glucose without the loss of quality by evaluating thirteen agitator configurations at low speed

Thirteen agitator configurations were investigated at low speed in stirred-tank reactors (STRs) to determine if improved crude bacterial nanocellulose (BNC) productivity can be achieved from glucose-based media while maintaining high BNC quality using Komagataeibacter xylinus ATCC 23770 as a model organism. A comparison of five single impellers showed the pitched blade (large) was the optimal impeller at 300 rpm. The BNC production was further increased by maintaining the pH at 5.0. Among the single helical ribbon and frame impellers and the combined impellers, the twin pitched blade provided the best results. The combined impellers at 150 rpm performed better than the single impellers, and after optimizing the agitation conditions, the twin pitched blade (large) and helical ribbon impellers performed the best at 100 rpm. The performances of different agitators at low speed during BNC production were related to how efficiently the agitators improved the oxygen mass transfer coefficient. The twin pitched blade (large) was verified as providing the optimum performance by an observed crude BNC production of 1.97 g (L×d)-1 and a BNC crude yield of consumed glucose of 0.41 g g-1 , which were 2.25 and 2.37 times higher than the initial values observed using the single impeller respectively. Further characterization indicated that the BNC obtained at 100 rpm from the STR equipped with the optimal agitator maintained high degree of polymerization and crystallinity.

Bacterial cellulose production, properties and applications with different culture methods - A review

Bacterial cellulose (BC) is an organic compound produced by certain types of bacteria. In natural habitats, the majority of bacteria synthesize extracellular polysaccharides, such as cellulose, which form protective envelopes around the cells. Many methods are currently being investigated to enhance cellulose growth. The various celluloses produced by different bacteria possess different morphologies, structures, properties, and applications. However, the literature lacks a comprehensive review of the different methods of BC production, which are critical to BC properties and their final applications. The aims of this review are to provide an overview of the production of BC from different culture methods, to analyze the characteristics of particular BC productions, to indicate existing problems associated with different methods, and to choose suitable culture approaches for BC applications in different fields. The main goals for future studies have also been discussed here.

Efficient and economic process for the production of bacterial cellulose from isolated strain of Acetobacter pasteurianus of RSV-4 bacterium

In the present investigation, several residues from agro-forestry industries such as rice straw acid hydrolysate, corn cob acid hydrolysate, tomato juice, cane molasses and orange pulp were evaluated as the economical source for the production of bacterial cellulose. The bacterial cellulose attained the significant yield of 7.8 g/L using tomato juice, followed by 3.6 g/L using cane molasses and 2.8 g/L using orange pulp after 7 days of incubation. Furthermore, the optimum pH and temperature of fermentation for maximum production of bacterial cellulose was 4.5 and 30 ± 1 °C. The identified bacterium Acetobacter pasteurianus RSV-4 has been deposited at repository under the accession number MTCC 25117. The produced bacterial cellulose was characterized through FTIR, SEM, TGA and DSC and found to be of very good quality. The bacterial cellulose produced by identified strain on these various agro-waste residues could be a cost effective technology for commercial its production.

Ecofriendly green conversion of potato peel wastes to high productivity bacterial cellulose

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

Progress in bacterial cellulose matrices for biotechnological applications

Bacterial cellulose (BC) is an extracellular polymer produced by many microorganisms. The Komagataeibacter genus is the best producer using semi-synthetic media and agricultural wastes. The main advantages of BC are the nanoporous structure, high water content and free hydroxyl groups. Modification of BC can be made by two strategies: in-situ, during the BC production, and ex-situ after BC purification. In bioprocesses, multilayer BC nanocomposites can contain biocatalysts designed to be suitable for outside to inside cell activities. These nanocomposites biocatalysts can (i) increase productivity in bioreactors and bioprocessing, (ii) provide cell activities does not possess without DNA cloning and (iii) provide novel nano-carriers for cell inside activity and bioprocessing. In nanomedicine, BC matrices containing therapeutic molecules can be used for pathologies like skin burns, and implantable therapeutic devices. In nanoelectronics, semiconductors BC-based using salts and synthetic polymers brings novel films showing excellent optical and photochemical properties.

Recent developments in the production and applications of bacterial cellulose fibers and nanocrystals

Cellulosic nanomaterials provide a novel and sustainable platform for the production of high performance materials enabled by nanotechnology. Bacterial cellulose (BC) is a highly crystalline material and contains pure cellulose without lignin and hemicellulose. BC offers an opportunity to provide control of the products' properties in-situ, via specific BC production methods and culture conditions. The BC potential in advanced material applications are hindered by a limited knowledge of optimal BC production conditions, efficient process scale-up, separation methods, and purification methods. There is a growing body of work on the production of bacterial cellulose nanocrystals (BCNs) from BC fibers. However, there is limited information regarding the effect of BC fibers' characteristics on the production of nanocrystals. This review describes developments in BC and BCNs production methods and factors affecting their yield and physical characteristics.

Bacterial Cellulose Production from Industrial Waste and by-Product Streams

The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102-138 g · water/g · dry bacterial cellulose, viscosities of 4.7-9.3 dL/g, degree of polymerization of 1889.1-2672.8, stress at break of 72.3-139.5 MPa and Young's modulus of 0.97-1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.