Utilization of residues from agro-forest industries in the production of high value bacterial cellulose

Processing of Grape Bagasse and Potato Wastes for the Co-Production of Bacterial Cellulose and Gluconic Acid in an Airlift Bioreactor

The feasibility of using Garnacha Tintorera bagasse and potato wastes as substrate for the co-production of bacterial cellulose (BC) and gluconic acid by Komagataibacter xylinus fermentation was studied. Firstly, the sulfuric acid hydrolysis of bagasse was evaluated depending on the sulfuric acid concentration (2-4%), temperature (105-125 °C), and time (60-180 min). The bagasse hydrolysates showed a low monosaccharide concentration profile: glucose 3.24-5.40 g/L; cellobiose 0.00-0.48 g/L; arabinose 0.66-1.64 g/L and xylose 3.24-5.40 g/L. However, the hydrolysis treatment enhanced the total phenolic content of the bagasse extract (from 4.39 up to 12.72 mg GAE/g dried bagasse). The monosaccharide profile of the culture medium was improved by the addition of potato residues. From a medium containing bagasse-potato powder (50:50 w/w) and optimal hydrolysate conditions (125 °C for 60 min and 2% H2SO4), the composition of glucose increased up to 30.14 g/L. After 8 days of fermentation in an airlift bioreactor by Komagataibacter xylinus, 4 g dried BC/L and 26.41 g gluconic acid/L were obtained with a BC productivity of 0.021 g/L·h, an efficiency of 0.37 g/g and yield of 0.47 g/g. The productivity of gluconic acid was 0.14 g/L·h with an efficiency of 0.93 g/g and yield of 0.72 g/g. This research demonstrates the promising potential of utilizing waste materials, specifically Garnacha Tintorera bagasse and potato residues, as sustainable substrates for the co-production of valuable bioproducts, such as bacterial cellulose and gluconic acid.

Production of Bacterial Exopolysaccharides: Xanthan and Bacterial Cellulose

Recently, degradable biopolymers have become increasingly important as potential environmentally friendly biomaterials, providing a wide range of applications in various fields. Bacterial exopolysaccharides (EPSs) are biomacromolecules, which due to their unique properties have found applications in biomedicine, foodstuff, textiles, cosmetics, petroleum, pharmaceuticals, nanoelectronics, and environmental remediation. One of the important commercial polysaccharides produced on an industrial scale is xanthan. In recent years, the range of its application has expanded significantly. Bacterial cellulose (BC) is another unique EPS with a rapidly increasing range of applications. Due to the great prospects for their practical application, the development of their highly efficient production remains an important task. The present review summarizes the strategies for the cost-effective production of such important biomacromolecules as xanthan and BC and demonstrates for the first time common approaches to their efficient production and to obtaining new functional materials for a wide range of applications, including wound healing, drug delivery, tissue engineering, environmental remediation, nanoelectronics, and 3D bioprinting. In the end, we discuss present limitations of xanthan and BC production and the line of future research.

Acetic acid bacteria in agro-wastes: from cheese whey and olive mill wastewater to cellulose

In this study, cheese whey and olive mill wastewater were investigated as potential feedstocks for producing bacterial cellulose by using acetic acid bacteria strains. Organic acids and phenolic compounds composition were assayed by high-pressure liquid chromatography. Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction were used to investigate modifications in bacterial cellulose chemical and morphological structure. Cheese whey was the most efficient feedstock in terms of bacterial cellulose yield (0.300 g of bacterial cellulose/gram of carbon source consumed). Bacterial cellulose produced in olive mill wastewater presented a more well-defined network compared to pellicles produced in cheese whey, resulting in a smaller fiber diameter in most cases. The analysis of bacterial cellulose chemical structure highlighted the presence of different chemical bonds likely to be caused by the adsorption of olive mill wastewater and cheese whey components. The crystallinity ranged from 45.72 to 80.82%. The acetic acid bacteria strains used in this study were characterized by 16S rRNA gene sequencing, allowing to assign them to Komagataeibacter xylinus and Komagataeibacter rhaeticus species. This study proves the suitability to perform sustainable bioprocesses for producing bacterial cellulose, combining the valorisation of agro-wastes with microbial conversions carried out by acetic acid bacteria. The high versatility in terms of yield, morphology, and fiber diameters obtained in cheese whey and olive mill wastewater contribute to set up fundamental criteria for developing customized bioprocesses depending on the final use of the bacterial cellulose. KEY POINTS: • Cheese whey and olive mill wastewater can be used for bacterial cellulose production. • Bacterial cellulose structure is dependent on the culture medium. • Komagataeibacter strains support the agro-waste conversion in bacterial cellulose.

Superabsorbent bacterial cellulose film produced from industrial residue of cashew apple juice processing

The industrial residue of cashew apple juice processing (MRC) was evaluated as an alternative medium for bacterial cellulose (BC) production by Komagataeibacter xylinus ATCC 53582 and Komagataeibacter xylinus ARS B42. The synthetic Hestrin-Schramm medium (MHS) was used as a control for growing and BC production. First, BC production was assessed after 4, 6, 8, 10, and 12 days under static culture. After 12 days of cultivation, K. xylinus ATCC 53582 produced the highest BC titer in MHS (3.1 g·L^-1) and MRC (3 g·L^-1), while significant productivity was attained at 6 days of fermentation. To understand the effect of culture medium and fermentation time on the properties of the obtained films, BC produced at 4, 6, or 8 days were submitted to infrared spectroscopy with Fourier transform, thermogravimetry, mechanical tests, water absorption capacity, scanning electron microscopy, degree of polymerization and X-ray diffraction. The properties of BC synthesized in MRC were identical to those of BC from MHS, according to structural, physical, and thermal studies. MRC, on the other hand, allows the production of BC with a high water absorption capacity when compared to MHS. Despite the lower titer (0.88 g·L^-1) achieved in MRC, the BC from K. xylinus ARS B42 presented a high thermal resistance and a remarkable absorption capacity (14664 %), suggesting that it might be used as a superabsorbent biomaterial.

Opportunities for bacterial nanocellulose in biomedical applications: Review on biosynthesis, modification and challenges

Bacterial nanocellulose (BNC) is a natural polysaccharide produced as extracellular material by bacterial strains and has favorable intrinsic properties for primary use in biomedical applications. In this review, an update on state-of-the art and challenges in BNC production, surface modification and biomedical application is given. Recent insights in biosynthesis allowed for better understanding of governing parameters improving production efficiency. In particular, introduction of different carbon/nitrogen sources from alternative feedstock and industrial upscaling of various production methods is challenging. It is important to have control on the morphology, porosity and forms of BNC depending on biosynthesis conditions, depending on selection of bacterial strains, reactor design, additives and culture conditions. The BNC is intrinsically characterized by high water absorption capacity, good thermal and mechanical stability, biocompatibility and biodegradability to certain extent. However, additional chemical and/or physical surface modifications are required to improve cell compatibility, protein interaction and antimicrobial properties. The novel trends in synthesis include the in-situ culturing of hybrid BNC nanocomposites in combination with organic material, inorganic material or extracellular components. In parallel with toxicity studies, the applications of BNC in wound care, tissue engineering, medical implants, drug delivery systems or carriers for bioactive compounds, and platforms for biosensors are highlighted.

Production and Characterization of Active Bacterial Cellulose Films Obtained from the Fermentation of Wine Bagasse and Discarded Potatoes by Komagateibacter xylinus

Potato waste, such as peels, broken or spoiled potatoes and grape bagasse residues from the winery industry, can be used for the biotechnological production of high-value products. In this study, green, sustainable and highly productive technology was developed for the production of antioxidant bacterial cellulose (BC). The aim of this work was to evaluate the feasibility of a low-cost culture medium based on wine bagasse and potato waste to synthesize BC. Results show that the production of BC by Komagateibacter xylinus in the GP culture medium was five-fold higher than that in the control culture medium, reaching 4.0 g/L BC in 6 days. The compounds of the GP culture medium improved BC production yield. The mechanical, permeability, swelling capacity, antioxidant capacity and optical properties of the BC films from the GP medium were determined. The values obtained for the tensile and puncture properties were 22.77 MPa for tensile strength, 1.65% for elongation at break, 910.46 MPa for Young's modulus, 159.31 g for burst strength and 0.70 mm for distance to burst. The obtained films showed lower permeability values (3.40 × 10^-12 g/m·s·Pa) than those of other polysaccharide-based films. The BC samples showed an outstanding antioxidant capacity (0.31-1.32 mg GAE/g dried film for total phenolic content, %DPPH^• 57.24-78.00% and %ABTS^•+ 89.49-86.94%) and excellent UV-barrier capacity with a transmittance range of 0.02-0.38%. Therefore, a new process for the production of BC films with antioxidant properties was successfully developed.

Characterization, genome analysis and genetic tractability studies of a new nanocellulose producing Komagataeibacter intermedius isolate

Bacterial nanocellulose (BC) is a highly versatile biopolymer currently pursued as a material of choice in varied themes of biomedical and material science research fields. With the aim to extend the biotechnological applications, the genetic tractability of the BC producers within the Komagataeibacter genus and its potential as an alternative host chassis in synthetic biology have been extensively studied. However, such studies have been largely focused on the model Komagataeibacter spp. Here, we present a novel K. intermedius strain capable of utilizing glucose, and glycerol sources for biomass and BC synthesis. Genome assembly identified one bacterial cellulose synthetase (bcs) operon containing the complete gene set encoding the BC biogenesis machinery (bcsI) and three additional copies (bcsII-IV). Investigations on the genetic tractability confirmed plasmid transformation, propagation of vectors with pBBR1 and p15A origin of replications and constitutive and inducible induction of recombinant protein in K. intermedius ENS15. This study provides the first report on the genetic tractability of K. intermedius, serving as starting point towards future genetic engineering of this strain.

Bacterial Cellulose-Based Polymer Nanocomposites: A Review

Bacterial cellulose (BC) is currently one of the most popular environmentally friendly materials with unique structural and physicochemical properties for obtaining various functional materials for a wide range of applications. In this regard, the literature reporting on bacterial nanocellulose has increased exponentially in the past decade. Currently, extensive investigations aim at promoting the manufacturing of BC-based nanocomposites with other components such as nanoparticles, polymers, and biomolecules, and that will enable to develop of a wide range of materials with advanced and novel functionalities. However, the commercial production of such materials is limited by the high cost and low yield of BC, and the lack of highly efficient industrial production technologies as well. Therefore, the present review aimed at studying the current literature data in the field of highly efficient BC production for the purpose of its further usage to obtain polymer nanocomposites. The review highlights the progress in synthesizing BC-based nanocomposites and their applications in biomedical fields, such as wound healing, drug delivery, tissue engineering. Bacterial nanocellulose-based biosensors and adsorbents were introduced herein.

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.

Contributions of Women in Recent Research on Biopolymer Science

Nowadays, biopolymers are playing a fundamental role in our society because of the environmental issues and concerns associated with synthetic polymers. The aim of this Special Issue entitled ‘Women in Polymer Science and Technology: Biopolymers’ is highlighting the work designed and developed by women on biopolymer science and technology. In this context, this short review aims to provide an introduction to this Special Issue by highlighting some recent contributions of women around the world on the particular topic of biopolymer science and technology during the last 20 years. In the first place, it highlights a selection of important works performed on a number of well-studied natural polymers, namely, agar, chitin, chitosan, cellulose, and collagen. Secondly, it gives an insight into the discovery of new polysaccharides and enzymes that have a role in their synthesis and in their degradation. These contributions will be paving the way for the next generation of female and male scientists on this topic.

Low-cost and highly efficient production of bacterial cellulose from sweet potato residues: Optimization, characterization, and application

Bacterial cellulose (BC) is an emerging biological material with unique properties and structure, which has attracted more and more attention. In this study, Gluconacetobacter xylinus was used to convert sweet potato residues (SPR) hydrolysate to BC. SPR was directly used without pretreatment, and almost no inhibitors were generated, which was beneficial to subsequent glucan conversion and SPR-BC synthesis. SPR-BC production was 11.35 g/L under the optimized condition. The comprehensive structural characterization and mechanical analysis demonstrated that the crystallinity, maximum thermal degradation temperature, and tensile strength of SPR-BC were 87.39%, 263 °C, and 6.87 MPa, respectively, which were superior to those of BC produced with the synthetic medium. SPR-BC was added to rice straw pulp to enhance the bonding force between fibers and the indices of tensile, burst, and tear of rice straw paper. The indices were increased by 83.18%, 301.27%, and 169.58%, respectively. This research not only expanded the carbon source of BC synthesis, reduced BC production cost, but also improved the quality of rice straw paper.

Natural Polymers-Based Materials: A Contribution to a Greener Future

Natural polymers have emerged as promising candidates for the sustainable development of materials in areas ranging from food packaging and biomedicine to energy storage and electronics. In tandem, there is a growing interest in the design of advanced materials devised from naturally abundant and renewable feedstocks, in alignment with the principles of Green Chemistry and the 2030 Agenda for Sustainable Development. This review aims to highlight some examples of the research efforts conducted at the Research Team BioPol4fun, Innovation in BioPolymer-based Functional Materials and Bioactive Compounds, from the Portuguese Associate Laboratory CICECO–Aveiro Institute of Materials at the University of Aveiro, regarding the exploitation of natural polymers (and derivatives thereof) for the development of distinct sustainable biobased materials. In particular, focus will be given to the use of polysaccharides (cellulose, chitosan, pullulan, hyaluronic acid, fucoidan, alginate, and agar) and proteins (lysozyme and gelatin) for the assembly of composites, coatings, films, membranes, patches, nanosystems, and microneedles using environmentally friendly strategies, and to address their main domains of application.

Superabsorbent bacterial cellulose spheres biosynthesized from winery by-products as natural carriers for fertilizers

Soil contamination, sustainable management of water resources and controlled release of agrochemicals are the main challenges of modern agriculture. In this work, the synthesis of sphere-like bacterial cellulose (BC) using agitated culture conditions and Komagateibacter medellinensis bacterial strain ID13488 was optimized and characterized from grape pomace (GP). First, a comparative study was carried out between agitated and static cultures using different nitrogen sources and applying alternative GP treatments. Agitation of the cultures resulted in higher BC production yield compared to static culture conditions. Additionally, Water holding capacity (WHC) assays evidenced the superabsorbent nature of the BC biopolymer, being positively influenced by the spherical shape as it was observed an increase of 60% in contrast to the results obtained for the BC membranes under static culture conditions. Moreover, it was found that sphere-like BCs were capable of retaining urea up to 375% of their dry weight, rapidly releasing the fertilizer in the presence of water. According to our findings, sphere-like BCs represent suitable systems with great potential for actual agricultural hazards and grape pomace valorisation.

Evaluation of carbon sources from sugar industry to bacterial nanocellulose produced by Komagataeibacter xylinus

Nanocellulose derived from microorganism is crucial bio-based products due to its unique physicochemical and mechanical properties for material science. Thus, optimizing bacterial cellulose (BNC) production is essential to widen applications and reduce production cost. Using various carbon sources derive from fruits as alternatives for synthesizing BNC could produce a low-cost BNC with comparable properties. Although Komagataeibacter xylinus grown in different natural juices, including clarified juice (CJ), sugarcane juice (SC) and coconut juice (CN) demonstrated a lower yield than that of control medium (HS), FTIR confirmed no change in chemical functional groups of BNCs. Similarly, different sugar sources have slightly effects on mechanical and thermal properties of BNC. However, the internal morphology illustrated the pore structure in oval shape for HS and CN while CJ and SC resulted in irregular pores which could lead to the highest crystallinity index value for BNC from HS compared to that from alternative media.

Cellulose biosynthesis using simple sugars available in residual cacao mucilage exudate

Worldwide only 8% of the biomass from harvested cacao fruits is used, as cacao beans, in chocolate-based products. Cacao mucilage exudate (CME), a nutrient-rich fluid, is usually lost during cacao beans fermentation. CME's composition and availability suggest a potential carbon source for cellulose production. CME and the Hestrin and Schramm medium were used, and compared, as growth media for bacterial cellulose (BC) production with Gluconacetobacter xylinus. CME can be used to produce BC. However, the high sugar content, low pH, and limited nitrogen sources in CME hinder G. xylinus growth affecting cellulose yields. BC production increased from 0.55 ± 0.16 g L^-1 up to 13.13 ± 1.09 g L^-1 after CME dilution and addition of a nitrogen source. BC production was scaled up from 30 mL to 15 L, using lab-scale experiments conditions, with no significant changes in yields and production rates, suggesting a robust process with industrial possibilities.

Novel use of Kombucha consortium to reduce Escherichia coli in dairy shed effluent

BACKGROUND

Faecal contamination from dairy farm effluent is a major risk to water quality in New Zealand. In this experiment we have tested the efficacy of Kombucha SCOBY (symbiotic culture of bacteria and yeast), to reduce the concentration of Escherichia coli in dairy shed effluent (DSE).

RESULTS

Kombucha SCOBY was highly effective in lowering the number of E. coli colony forming units (CFUs) to levels that were undetectable. The decrease in CFUs occurred rapidly within 48 h of Kombucha SCOBY being inoculated to the effluent matrix and was accompanied by a corresponding decline in pH.

CONCLUSION

We conclude that Kombucha SCOBY was effective in reducing the abundance of E. coli in DSE due to its effect on solution pH. Further work is required to assess the practicality of treating DSE with Kombucha SCOBY within a farm environment where effluent management and climatic complexities are important. © 2021 Society of Chemical Industry.

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.

A Comprehensive Bioprocessing Approach to Foster Cheese Whey Valorization: On-Site β-Galactosidase Secretion for Lactose Hydrolysis and Sequential Bacterial Cellulose Production

Cheese whey (CW) constitutes a dairy industry by-product, with considerable polluting impact, related mostly with lactose. Numerous bioprocessing approaches have been suggested for lactose utilization, however, full exploitation is hindered by strain specificity for lactose consumption, entailing a confined range of end-products. Thus, we developed a CW valorization process generating high added-value products (crude enzymes, nutrient supplements, biopolymers). First, the ability of Aspergillus awamori to secrete β-galactosidase was studied under several conditions during solid-state fermentation (SSF). Maximum enzyme activity (148 U/g) was obtained at 70% initial moisture content after three days. Crude enzymatic extracts were further implemented to hydrolyze CW lactose, assessing the effect of hydrolysis time, temperature and initial enzymatic activity. Complete lactose hydrolysis was obtained after 36 h, using 15 U/mL initial enzymatic activity. Subsequently, submerged fermentations were performed with the produced hydrolysates as onset feedstocks to produce bacterial cellulose (5.6–7 g/L). Our findings indicate a novel approach to valorize CW via the production of crude enzymes and lactose hydrolysis, aiming to unfold the output potential of intermediate product formation and end-product applications. Likewise, this study generated a bio-based material to be further introduced in novel food formulations, elaborating and conforming with the basic pillars of circular economy.

Coproduction of bacterial cellulose and pear vinegar by fermentation of pear peel and pomace

Bacterial cellulose (BC)-derived materials are given significant attention due to their porous fibrous texture, high crystallinity and extraordinary physico-mechanical properties. The main reason for the restricted use of BC is its high production cost. To reduce the production cost, the suitability of pear residue for the production of BC and pear vinegar was investigated. Komagataeibacter rhaeticus and Komagataeibacter intermedius with high fermentation ability screened from the surface of vinegar film of millet fermentation were used to produce BC and pear vinegar simultaneously. Through response surface optimization, the maximum yield of BC from pear residue medium was 10.94 ± 0.42 g/L, which was higher than the synthesis medium generally used for Acetobacter strains. When pear residue medium was incubated at 30 °C for 7 days, the contents of total acid and soluble solids were greater than 0.3 g/100 mL and 3%, respectively, which met the standard requirements for fruit vinegar. The flavour components of pear vinegar were determined using gas chromatography-mass spectrometry. The pear vinegar showed similar flavour characteristics to conventional fruit vinegar. This research not only solved the utilization of agricultural resources but also avoided the discharge of waste liquid when producing BC. In addition, a more environmentally friendly and less expensive way to produce BC and pear vinegar was achieved.

Properties of Bacterial Cellulose Produced Using White and Red Grape Bagasse as a Nutrient Source

The purpose of the study is to investigate the possibility of using wine industry wastes, such as red and white grape bagasse, to produce bacterial cellulose (BC) instead of using a costly commercial medium. BC was produced using grape bagasse as a carbon source replacement and the sole nutrient in the medium. The BC films were evaluated for their productivity and water-holding capacity. The BC films were also investigated for their morphology using scanning electron microscopy (SEM), their viscoelastic properties using dynamic mechanical analysis (DMA), and their chemical composition using Fourier-transform infrared spectroscopy (FTIR). Although the use of grape bagasse as the sole nutrient was successful in the preparation of BC, the BC films had inferior viscoelastic properties to other produced BC films. White grape bagasse proved to be an excellent carbon substitute as the production of BC and its water-holding capacity were five times higher and the produced BC films were up to 72% more flexible than the bacterial cellulose produced using standard HS medium.

Efficient utilization of date palm waste for the bioethanol production through Saccharomyces cerevisiae strain

Dates (Phoenix dactylifera L.) are rich in nutritional compounds, particularly in sugars. Sugars offer anaerobic fermentation, used for bioethanol production. Recently, researchers and industrialists finding ways to produce low-cost bioethanol on large scale using agricultural wastes. Date palm residual is the largest agricultural waste in Pakistan, which can be the cheapest source for bioethanol production, whereas the current study was designed to explore the possible utilization and the potential of date palm waste for bioethanol production through Saccharomyces cerevisiae grown in yeast extract, Bacto peptone, and d-glucose medium. The fermentation process resulted in the production of 15% (v/v) ethanol under the optimum condition of an incubation period of 72 hr and three sugars (glucose, fructose, and sucrose) were found in date waste. The functional group of ethanol (C2H5OH) was also found via Fourier-transform infrared spectroscopy (FTIR) analysis. Therefore, S. cerevisiae could be recommended for ethanol production due to short fermentation time at 25% inoculum in 30°C and reduced the processing cost. Common date varieties of low market value are a preferred substrate for the process of producing industrial ethanol. Additionally, proximate analysis of date fruit by near-infrared spectroscopy revealed moisture contents (16.84%), crude protein (0.3%), ash (9.8%), crude fat (2.6%), and neutral detergent fibers (13.4%). So, date fruit contains various nutrients for microbial growth for ethanol production.

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 review of functionalised bacterial cellulose for targeted biomedical fields

Bacterial cellulose (BC), which can be produced by microorganisms, is an ideal biomaterial especially for tissue engineering and drug delivery systems thanks to its properties of high purity, biocompatibility, high mechanical strength, high crystallinity, 3 D nanofiber structure, porosity and high-water holding capacity. Therefore, wide ranges of researches have been done on the BC production process and its structural and physical modifications to make it more suitable for certain targeted biomedical applications thoroughly. BC's properties such as mechanical strength, pore diameter and porosity can be tuned in situ or ex situ processes by using various polymer and compounds. Besides, different organic or inorganic compounds that support cell attachment, proliferation and differentiation or provide functions such as antimicrobial effectiveness can be gained to its structure for targeted application. These processes not only increase the usage options of BC but also provide success for mimicking the natural tissue microenvironment, especially in tissue engineering applications. In this review article, the studies on optimisation of BC production in the last decade and the BC modification and functionalisation studies conducted for the three main perspectives as tissue engineering, drug delivery and wound dressing with diverse approaches are summarized.

Bacterial Nanocellulose-A Biobased Polymer for Active and Intelligent Food Packaging Applications: Recent Advances and Developments

The aim of this review is to provide an overview of recent findings related to bacterial cellulose application in bio-packaging industry. This constantly growing sector fulfils a major role by the maintenance of product safety and quality, protection against environmental impacts that affect the shelf life. Conventional petroleum-based plastic packaging are still rarely recyclable and have a number of harmful environmental effects. Herein, we discuss the most recent studies on potential good alternative to plastic packaging-bacterial nanocellulose (BNC), known as an ecological, safe, biodegradable, and chemically pure biopolymer. The limitations of this bio-based packaging material, including relatively poor mechanical properties or lack of antimicrobial and antioxidant activity, can be successfully overcome by its modification with a wide variety of bioactive and reinforcing compounds. BNC active and intelligent food packaging offer a new and innovative approach to extend the shelf life and maintain, improve, or monitor product quality and safety. Incorporation of different agents BNC matrices allows to obtain e.g., antioxidant-releasing films, moisture absorbers, antimicrobial membranes or pH, freshness and damage indicators, humidity, and other biosensors. However, further development and implementation of this kind of bio-packaging will highly depend on the final performance and cost-effectiveness for the industry and consumers.

Preparation and characterization of bacterial cellulose produced from fruit and vegetable peels by Komagataeibacter hansenii GA2016

This study focused on the investigation of bacterial cellulose production potency of some fruit and vegetable peels (cucumber, melon, kiwifruit, tomato, apple, quince and pomegranate) with Komagataeibacter hansenii GA2016. Fruit and vegetable peels were hydrolyzed, used for bacterial cellulose (BC) production and their chemical, physical, thermal and structural features were compared to BC from Hestrin-Schramm medium (HSBC) and plant cellulose (CP). Except for pomegranate peel hydrolysate, all the fruit and vegetable peel hydrolysates supplied to K. hansenii GA2016 supported the BC production. Among the fruit and vegetable peel hydrolysates, the highest BC production was observed in kiwifruit peel hydrolysate (11.53%), while the lowest production was observed in apple peel hydrolysate (1.54%). Water-holding capacities of the BCs were ranged from 627.50% to 928.79% and higher than HSBC (609.30%), average fiber diameters were ranged from 47.64 nm to 61.11 nm and thinner than HSBC (74.29) and CP (10,420 nm), crystallinities were ranged from 80.27% to 92.96%, thermal capacities BCs were higher than HSBC and CP. For the BC productions, utilization of the fruit and vegetable peels as the sole nutrient source could reduce the production costs and among the polysaccharides, increase the use of BC in industry.

Production of bacterial cellulose from whey-current state and prospects

Bacterial cellulose (BC) is a biopolymer with a wide range of potential applications starting from the food industry and biomedicine to electronics and cosmetics. Despite that, BC industrial production to date still is associated with certain difficulties. One of them is the high cost of growth media, which can reach up to 30% of production costs. To decrease production costs, use of industrial and agricultural by-products, including whey, as alternative growth media has been reported. Whey, as the main high-volume by-product of dairy industry, which is known for its low valorisation opportunities and negative environmental impact, can nevertheless be considered as an alternative growth medium for BC production. To date, several studies aimed at evaluating BC production on whey and lactose substrates have been reported, but they are still insufficient. Reviews of them showed that, in general, BC production on untreated whey- and lactose-containing media was lower than that on the standard medium. However, some wild and recombinant strains have been reported to produce BC on whey as good as the standard medium. Enzymatic and acidic pre-treatment of whey significantly enhanced BC yield. Changes in the microstructure of BC obtained from whey were also recognised, which should be considered regarding the impact on physical properties of the desired BC product. This mini-review indicates that currently whey can be recognised as quite a problematic alternative growth substrate for industrial BC production; however, further extensive studies may improve the prospects in both the search for a cheap alternative growth substrate for industrial BC production and valorisation of whey. KEY POINTS: • Whey is a by-product in which valorisation is still challenging. • Whey can be used for bacterial cellulose (BC) production. • BC yield and properties vary upon cultivation conditions and producer strains.

Production and characterization of Gluconacetobacter xylinus bacterial cellulose using cashew apple juice and soybean molasses

Bacterial cellulose (BC) has been largely used in biomedical and technological fields. The use of agro-industrial byproducts as alternative source of carbon and nitrogen in culture media reduces the BC cost production, adds value to the byproducts and minimizes the environmental impact. In this study, the use of cashew apple juice and soybean molasses were evaluated to produce BC by Gluconacetobacter xylinus in comparison to the usual Hestrin and Schramm medium (HS). BC produced in static cultivation was characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The BC production (4.50 g L-1) obtained from the medium using cashew apple juice as carbon source (20 g L-1) with soybean molasses as nitrogen source (10 g L-1) was superior than HS medium (4.03 g L-1). Morphological analysis showed that bacterial celluloses produced with agro-industrial byproducts combined were similar to those found for the pellicle obtained from HS medium.

Optimization of bacterial cellulose production by Komagataeibacter xylinus PTCC 1734 in a low-cost medium using optimal combined design

This study was aimed to optimize the production of bacterial cellulose (BC) by Komagataeibacter xylinus PTCC 1734 using mixture of date syrup and cheese whey as carbon sources as well as ascorbic acid as a supplementary agent and to characterize the properties of produced BC. The results showed the highest BC production on the 10th day. The 50:50 ratio of date syrup and cheese whey lead to the highest BC production. Three samples were selected in optimal cultivation conditions until the 10th day, with different ascorbic acid concentrations (0, 0.1 and 0.4%). SEM results showed no difference in the morphology of BC product in the optimal samples, where the average diameter of cellulose nanofibers produced was in the range of nanometer. The FTIR test results showed no difference in the chemical structure of cellulose product in different ascorbic acid concentrations. According to XRD and TGA analyses, the highest degree of BC crystallinity and thermal resistance was obtained at maximum ascorbic acid concentration (0.04%). Consequently, the 50:50 ratio of date syrup and cheese whey and 10th day of fermentation time were selected as the best conditions for BC production. Though ascorbic acid reduced production efficiency, it improved the physical properties of the BC product.

Waste paper: An underutilized but promising source for nanocellulose mining

Nanocellulose has achieved an inimitable place and value in nano-materials research sector. Promising and exclusive physical, chemical and biological properties of nanocellulose make it an attractive and ideal material for various high end-user applications. Conventionally, the base material for nanocellulose i.e. cellulose is being extracted from various lignocellulosic raw materials (like wood, agro-industrial-residues, etc.) using pulping followed by bleaching sequences. As an alternate to lignocellulosic raw materials, waste paper also showed potential as a competent raw material due to its abundant availability and high cellulosic content (60-70%) with comparatively less hemicelluloses (10-20%) and lignin (5-10%) without any harsh treatments. The production yields of nanocellulose were reported to vary from 1.5% to 64% depending upon the waste papers and treatments given. The diameters of these nanocelluloses were reported in the range of 2-100 nm and crystallinity range around 54-95%. Thermal degradation of waste paper nanocellulose was varied from 187 °C to 371 °C. Although these properties are comparable with the nanocellulose obtained from lignocellulosic raw materials, yet waste paper is an underutilized source for nanocellulose preparation due to its ordinary fate of recycling, dumping and incineration. In the sight of necessity and possibility of waste paper utilization, this article reviews the outcomes of research carried out for preparation of nanocellulose using waste paper as a source of cellulose. There is a need of sincere investigation to convert this valuable waste to wealth i.e. waste papers to nanocellulose, which will be helpful in solid waste management to protect environment in economical way.

Cheese Whey Processing: Integrated Biorefinery Concepts and Emerging Food Applications

Cheese whey constitutes one of the most polluting by-products of the food industry, due to its high organic load. Thus, in order to mitigate the environmental concerns, a large number of valorization approaches have been reported; mainly targeting the recovery of whey proteins and whey lactose from cheese whey for further exploitation as renewable resources. Most studies are predominantly focused on the separate implementation, either of whey protein or lactose, to configure processes that will formulate value-added products. Likewise, approaches for cheese whey valorization, so far, do not exploit the full potential of cheese whey, particularly with respect to food applications. Nonetheless, within the concept of integrated biorefinery design and the transition to circular economy, it is imperative to develop consolidated bioprocesses that will foster a holistic exploitation of cheese whey. Therefore, the aim of this article is to elaborate on the recent advances regarding the conversion of whey to high value-added products, focusing on food applications. Moreover, novel integrated biorefining concepts are proposed, to inaugurate the complete exploitation of cheese whey to formulate novel products with diversified end applications. Within the context of circular economy, it is envisaged that high value-added products will be reintroduced in the food supply chain, thereby enhancing sustainability and creating "zero waste" processes.

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.

Cost-effective production of bacterial cellulose using acidic food industry by-products

To reduce the cost of obtaining bacterial cellulose, acidic by-products of the alcohol and dairy industries were used without any pretreatment or addition of other nitrogen sources. Studies have shown that the greatest accumulation of bacterial cellulose (6.19 g/L) occurs on wheat thin stillage for 3 days of cultivation under dynamic conditions, which is almost 3 times higher than on standard Hestrin and Schramm medium (2.14 g/L). The use of whey as a nutrient medium makes it possible to obtain 5.45 g/L bacterial cellulose under similar conditions of cultivation. It is established that the pH of the medium during the growth of Gluconacetobacter sucrofermentans B-11267 depends on the feedstock used and its initial value. By culturing the bacterium on thin stillage and whey, there is a decrease in the acidity of the waste. It is shown that the infrared spectra of bacterial cellulose obtained in a variety of environments have a similar character, but we found differences in the micromorphology and crystallinity of the resulting biopolymer.