Optimization and physicochemical characterization of enhanced microbial cellulose production with a new Kombucha consortium

Recent advances review in tea waste: High-value applications, processing technology, and value-added products

Tea waste (TW) includes pruned tea tree branches, discarded summer and fall teas, buds and wastes from the tea making process, as well as residues remaining after tea preparation. Effective utilization and proper management of TW is essential to increase the economic value of the tea industry. Through effective utilization of tea waste, products such as activated carbon, biochar, composite membranes, and metal nanoparticle composites can be produced and successfully applied in the fields of fuel production, composting, preservation, and heavy metal adsorption. Comprehensive utilization of tea waste is an effective and sustainable strategy to improve the economic efficiency of the tea industry and can be applied in various fields such as energy production, energy storage and pharmaceuticals. This study reviews recent advances in the strategic utilization of TW, including its processing, conversion technologies and high value products obtained, provides insights into the potential applications of tea waste in the plant, animal and environmental sectors, summarizes the effective applications of tea waste for energy and environmental sustainability, and discusses the effectiveness, variability, advantages and disadvantages of different processing and thermochemical conversion technologies. In addition, the advantages and disadvantages of producing new products from tea wastes and their derivatives are analyzed, and recommendations for future development of high-value products to improve the efficiency and economic value of tea by-products are presented.

Enhanced bacterial cellulose production by Komagataeibacter species and Hibiscus sabdariffa herbal tea

This study proposed Hibiscus sabdariffa as a novel substrate for BC production with Komagataeibacter species and their consortia. K. intermedius is found as the most efficient producer (5.98 g/L BC, 3.56 × 10-2 g-1 h-1 productivity rate) following K. maltaceti (4.44 g/L BC, 2.64 × 10-2 g-1 h-1 productivity rate) and K. nataicola (3.67 g/L BC, 2.18 × 10-2 g-1 h-1 productivity rate). Whereas agitation increased BC production with K. nataicola (1.22-fold, 4.49 g/L BC), K. maltaceti (1.24-fold, 5.52 g/L BC) and K. intermedius (1.27-fold, 7.63 g/L BC), irregular shaped BC was obtained. This could be a novel result as Komagataeibacter consortia increased BC production by 1.17-2.01-fold compared to monocultures resulting as 8.11 g/L BC through the co-cultivation of K. maltaceti-K. intermedius. Maximum increase was found to be 1.75-fold (1.79-fold WHC), occurring with monoculture of K. maltaceti, while 1.94-fold (1.26-fold WHC) with K. maltaceti-K. intermedius consortium when H. sabdariffa-based media compared Hestrin-Schramm media. Based on these results, this could be a novel result as H. sabdariffa-based media may replace the use of HS media in BC production by means of a bioactive content-rich plant and obtaining 3-D ultrafine porous structure with high thermal resistant (∼460-500 °C) BC with mono and co-cultivation of Komagataeibacter species to be used in industrial area.

Techno-functional aspects of kombucha analogs formulated from mulberry coproducts

This study investigated the techno-functional conditions for producing fermented beverages using the kombucha artisanal consortium (kAC) while implementing sustainable strategies. According to the circular economy principles, the study focused on mulberry coproducts (MC) generated as agro-industrial waste during mulberry fruit production. The presence of target microorganisms in the beverage and biofilm was recorded to determine the MC content necessary for establishing kAC. Additionally, the physicochemical characteristics, carbohydrate and polyphenol profiles were analyzed to understand their impact on antioxidant activity and sensory responses in the soft drink. Notably, a concentration of 0.25% MC was found to yield fermented soft drinks rich in probiotic populations and displaying nutraceutical qualities that enhance antioxidant activity and sensory acceptability. This study offers valuable technical guidance for repurposing mulberry pruning coproducts in the creation of novel products.

Antimicrobial assay and controlled drug release studies with novel eugenol imprinted p(HEMA)-bacterial cellulose nanocomposite, designed for biomedical applications

In this study, a novel bio-composite material that allow sustained release of plant derived antimicrobial compound was developed for the biomedical applications to prevent the infections caused by microorganisms resistant to commercial antimicrobials agents. With this aim, bacterial cellulose (BC)-p(HEMA) nanocomposite film that imprinted with eugenol (EU) via metal chelated monomer, MAH was prepared. Firstly, characterization studies were utilized by FTIR, SEM and BET analysis. Then antimicrobial assays, drug release studies and in vitro cytotoxicity test were performed. A significant antimicrobial effect against both Gram (+) Staphylococcus aureus and Gram (-) Escherichia coli bacteria and a yeast Candida albicans were observed even in low exposure time periods. When antimicrobial effect of EU compared with commercially used agents, both antifungal and antibacterial activity of EU were found to be higher. Then, sustained drug release studies showed that approximately 55% of EU was released up to 50 h. This result proved the achievement of the molecular imprinting for an immobilization of molecules that desired to release on an area in a long-time interval. Finally, the in vitro cytotoxicity experiment performed with the mouse L929 cell line determined that the synthesized EU-imprinted BC nanocomposite was biocompatible.

Bacterial cellulose microfilament biochar-architectured chitosan/polyethyleneimine beads for enhanced tetracycline and metronidazole adsorption

This study investigates the potential applications of incorporating 2D bacterial cellulose microfibers (BCM) biochar into chitosan/polyethyleneimine beads as a semi-natural sorbent for the efficient removal of tetracycline (TET) and metronidazole (MET) antibiotics. Batch adsorption experiments and characterization techniques evaluate removal performance and synthesized adsorbent properties. The adsorbent eliminated 99.13 % and 90 % of TET and MET at a 10 mg.L-1 concentration with optimal pH values of 8 and 6, respectively, for 90 min. Under optimum conditions and a 400 mg.L-1 concentration, MET and TET have possessed the maximum adsorption capacities of 691.325 and 960.778 mg.g-1, respectively. According to the isothermal analysis, the adsorption of TET fundamentally follows the Temkin (R2 = 0.997), Redlich-Peterson (R2 = 0.996), and Langmuir (R2 = 0.996) models. In contrast, the MET adsorption can be described by the Langmuir (R2 = 0.997), and Toth (R2 = 0.991) models. The pseudo-second-order (R2 = 0.998, 0.992) and Avrami (R2 = 0.999, 0.999) kinetic models were well-fitted with the kinetic results for MET and TET respectively. Diffusion models recommend that pore, liquid-film, and intraparticle diffusion govern the rate of the adsorption process. The developed semi-natural sorbent demonstrated exceptional adsorption capacity over eleven cycles due to its porous bead structure, making it a potential candidate for wastewater remediation.

Microorganisms and bacterial cellulose stability of Kombucha under different manufacture and storage conditions

It is crucial to clarify the stability of Kombucha in the manufacture and storage stages due to the extensive study on the fermented products of Kombucha and the increase in the use of bacterial cellulose (BC). This study aimed to evaluate the stability of Kombucha in different manufacturing and storage temperatures within a certain time period. The stability of microorganisms and BC in Kombucha was investigated through regular replacement with the tea media at 28 and 25°C for manufacture, and the storage temperature of Kombucha was at 25, 4, and -20°C. Morphological observations of the BC in Kombucha ended at 28 and 25°C for manufacture and storage were performed using atomic force microscopy (AFM) before inoculation. The viable cell counts and AFM results showed that the stability of Kombucha during manufacture was better at 28°C than at 25°C, with higher microbial viability and BC productivity in the former at the time of manufacture, whereas 25°C was more favorable for the stability of Kombucha during storage. At the same temperature of 25°C, the manufacturing practice improved the microbial viability and BC stability compared with storage; the pH value of Kombucha was lower, and the dry weight of BC was higher during storage compared with manufacture. The maximum BC water holding capacity (97.16%) was maintained by storage at 4°C on day 63, and the maximum BC swelling rate (56.92%) was observed after storage at -20°C on day 7. The research was conducted to provide reference information for applying Kombucha and its BC in food and development in other industries.

Investigation of anti-adherence and antimicrobial properties of prodigiosin-functionalized bacterial cellulose membrane for biomedical applications

In this study, novel biomaterial that consisted entirely of bacterial products was developed with the approach of designing cost effective material for biomedical applications. With this aim, bacterial cellulose membranes (BCMs) which synthesized by Komagataeibacter intermedius were produced. Moreover, to impart antimicrobial properties to enhance the capacity of BCMs for biomedical usage, prodigiosin (PG) pigment of Serratia marcescens which presents wide range of antimicrobial activities was loaded to BCMs. Firstly, high yield of PG production was achieved, and then crude pigment was purified with silica gel column. The purified PG was characterized with thin layer chromatography and UV-visible spectrometry. The antimicrobial effect of the produced pigment on Gram-positive and negative bacteria and a yeast was investigated. The success of modification in PG-modified BCMs has been demonstrated by FTIR and SEM. Moreover, antimicrobial and antiadhesive ability of novel PG-BCMs were examined with disc diffusion and plate counting methods. As a result, it was established that PG-BCMs were able to inhibit the growth of all tested microorganisms. Furthermore, excellent antiadhesive effect was observed for the tested microorganisms with the inhibition rates of 82.05-96.25 %. Finally, cytotoxicity test with L929 cell line demonstrated that PG-BCM is biocompatible at a level that can be applied in in vivo studies.

Bioconversion of underutilized brewing by-products into bacterial cellulose by a newly isolated Komagataeibacter rhaeticus strain: A preliminary evaluation of the bioprocess environmental impact

A novel Komagataeibacter rhaeticus UNIWA AAK2 strain was used to produce bacterial cellulose (BC), valorizing brewers' spent grain (BSG) and brewer's spent yeast (BSY). Under optimal conditions (controlled pH = 6 and 30 g/L sugars), a maximum BC of 4.0 g/L was achieved when BSG aqueous extract (BSGE) was used. The substitution of yeast extract and peptone with BSY autolyzates did not show significant differences on BC concentration and productivity. The FTIR, SEM, and TGA analyses showed that the use of brewing by-products had no effect on the structure and thermal stability of the produced BC, compared to highly-pure and commercial substrates. The LCA of the developed bioprocess revealed that BSGE- and BSY-based media can reduce the carbon footprint of 1 kg dry BC by 76% compared to commercial-based-media. Beer by-products could serve as cost-effective resources to produce value-added and sustainable biopolymers such as BC, while minimizing waste and restructuring the brewing-industry.

Microbiological and Physico-Chemical Characteristics of Black Tea Kombucha Fermented with a New Zealand Starter Culture

Kombucha is a popular sparkling sugared tea, fermented by a symbiotic culture of acetic acid bacteria (AAB) and yeast. The demand for kombucha continues to increase worldwide, mainly due to its perceived health benefits and appealing sensory properties. This study isolated and characterised the dominant AAB and yeast from a starter culture and kombucha broth after 0, 1, 3, 5, 7, 9, 11, and 14 days of fermentation at ambient temperature (22 °C). Yeast and AAB were isolated from the Kombucha samples using glucose yeast extract mannitol ethanol acetic acid (GYMEA) and yeast extract glucose chloramphenicol (YGC) media, respectively. The phenotypic and taxonomic identification of AAB and yeast were determined by morphological and biochemical characterisation, followed by a sequence analysis of the ribosomal RNA gene (16S rRNA for AAB and ITS for yeast). The changes in the microbial composition were associated with variations in the physico-chemical characteristics of kombucha tea, such as pH, titratable acidity, and total soluble solids (TSS). During fermentation, the acidity increased and the TSS decreased. The yield, moisture content, and water activity of the cellulosic pellicles which had developed at the end of fermentation were attributed to the presence of AAB. The dominant AAB species in the cellulosic pellicles and kombucha broth were identified as Komagataeibacter rhaeticus. The yeast isolates belonged to Debaryomyces prosopidis and Zygosaccharomyces lentus.

Advances in the Production of Biomaterials through Kombucha Using Food Waste: Concepts, Challenges, and Potential

In recent years, several researchers have focused their studies on the development of sustainable biomaterials using renewable sources, including the incorporation of living biological systems. One of the best biomaterials is bacterial cellulose (BC). There are several ways to produce BC, from using a pure strain to producing the fermented drink kombucha, which has a symbiotic culture of bacteria and yeasts (SCOBY). Studies have shown that the use of agricultural waste can be a low-cost and sustainable way to create BC. This article conducts a literature review to analyze issues related to the creation of BC through kombucha production. The databases used were ScienceDirect, Scopus, Web of Science, and SpringerLink. A total of 42 articles, dated from 2018 to 2022, were referenced to write this review. The findings contributed to the discussion of three topics: (1) The production of BC through food waste (including patents in addition to the scientific literature); (2) Areas of research, sectors, and products that use BC (including research that did not use the kombucha drink, but used food waste as a source of carbon and nitrogen); and (3) Production, sustainability, and circular economy: perspectives, challenges, and trends in the use of BC (including some advantages and disadvantages of BC production through the kombucha drink).

Nanobacterial Cellulose from Kombucha Fermentation as a Potential Protective Carrier of Lactobacillus plantarum under Simulated Gastrointestinal Tract Conditions

Kombucha bacterial cellulose (KBC), a by-product of kombucha fermentation, can be used as a biomaterial for microbial immobilization. In this study, we investigated the properties of KBC produced from green tea kombucha fermentation on days 7, 14, and 30 and its potential as a protective carrier of Lactobacillus plantarum, a representative beneficial bacteria. The highest KBC yield (6.5%) was obtained on day 30. Scanning electron microscopy showed the development and changes in the fibrous structure of the KBC over time. They had crystallinity indices of 90-95%, crystallite sizes of 5.36-5.98 nm, and are identified as type I cellulose according to X-ray diffraction analysis. The 30-day KBC had the highest surface area of 19.91 m²/g, which was measured using the Brunauer-Emmett-Teller method. This was used to immobilize L. plantarum TISTR 541 cells using the adsorption-incubation method, by which 16.20 log CFU/g of immobilized cells was achieved. The amount of immobilized L. plantarum decreased to 7.98 log CFU/g after freeze-drying and to 2.94 log CFU/g after being exposed to simulated gastrointestinal tract conditions (HCl pH 2.0 and 0.3% bile salt), whereas the non-immobilized culture was not detected. This indicated its potential as a protective carrier to deliver beneficial bacteria to the gastrointestinal tract.

The Effect of Dekkera bruxellensis Concentration and Inoculation Time on Biochemical Changes and Cellulose Biosynthesis by Komagataeibacter intermedius

Bacterial Cellulose (BC) is a biopolymer with numerous applications. The growth of BC-producing bacteria, Komagataeibacter intermedius, could be stimulated by Dekkera bruxellensis, however, the effect on BC yield needs further investigation. This study investigates BC production and biochemical changes in the K. intermedius-D. bruxellensis co-culture system. D. bruxellensis was introduced at various concentrations (103 and 106 CFU/mL) and inoculation times (days 0 and 3). BC yield was ~24% lower when D. bruxellensis was added at 103 CFU/mL compared to K. intermedius alone (0.63 ± 0.11 g/L). The lowest BC yield was observed when 103 CFU/mL yeast was added on day 0, which could be compromised by higher gluconic acid production (10.08 g/L). In contrast, BC yields increased by ~88% when 106 CFU/mL D. bruxellensis was added, regardless of inoculation time. High BC yield might correlate with faster sugar consumption or increased ethanol production when 106 CFU/mL D. bruxellensis was added on day 0. These results suggest that cell concentration and inoculation time have crucial impacts on species interactions in the co-culture system and product yield.

Biocatalysts in Synthesis of Microbial Polysaccharides: Properties and Development Trends

Polysaccharides synthesized by microorganisms (bacterial cellulose, dextran, pullulan, xanthan, etc.) have a set of valuable properties, such as being antioxidants, detoxifying, structuring, being biodegradable, etc., which makes them suitable for a variety of applications. Biocatalysts are the key substances used in producing such polysaccharides; therefore, modern research is focused on the composition and properties of biocatalysts. Biocatalysts determine the possible range of renewable raw materials which can be used as substrates for such synthesis, as well as the biochemistry of the process and the rate of molecular transformations. New biocatalysts are being developed for participating in a widening range of stages of raw material processing. The functioning of biocatalysts can be optimized using the following main approaches of synthetic biology: the use of recombinant biocatalysts, the creation of artificial consortia, the combination of nano- and microbiocatalysts, and their immobilization. New biocatalysts can help expand the variety of the polysaccharides’ useful properties. This review presents recent results and achievements in this field of biocatalysis.

Exploration of a novel and efficient source for production of bacterial nanocellulose, bioprocess optimization and characterization

The demand for bacterial nanocellulose is expected to rise in the coming years due to its wide usability in many applications. Hence, there is a continuing need to screen soil samples from various sources to isolate a strain with a high capacity for bacterial nanocellulose production. Bacillus sp. strain SEE-12, which was isolated from a soil sample collected from Barhiem, Menoufia governorate, Egypt, displayed high BNC production under submerged fermentation. Bacillus sp. strain SEE-12 was identified as Bacillus tequilensis strain SEE-12. In static cultures, BNC was obtained as a layer grown in the air liquid interface of the fermentation medium. The response surface methodology was used to optimise the process parameters. The highest BNC production (22.8 g/L) was obtained using 5 g/L peptone, 5 g/L yeast extract, 50%, v/v Cantaloupe juice, 5 g/L Na₂HPO₄, 1.5 g/L citric acid, pH 5, medium volume of 100 mL/250 mL conical flask, inoculum size 5%, v/v, temperature 37 °C and incubation time 6 days. The BNC was purified and characterized by scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM).

Optimization and physicochemical characterization of bacterial cellulose by Komagataeibacter nataicola and Komagataeibacter maltaceti strains isolated from grape, thorn apple and apple vinegars

Bacterial cellulose (BC) is a valuable biopolymer that is increasingly used in medical, pharmaceutical and food industries with its excellent physicochemical properties as high water-holding capacity, nanofibrillar structure, large surface area, porosity, mechanical strength and biocompatibility. Accordingly, the isolation, identification and characterization of potent BC producers from grape, thorn apple and apple vinegars were performed in this study. The strains isolated from grape and apple vinegars were identified as Komagataeibacter maltaceti and the strain isolated from thorn apple vinegar was identified as Komagataeibacter nataicola with 16S rRNA analysis. Optimized conditions were found as 8% dextrin, 1.5% (peptone + yeast extract) and 10% inoculation amount at pH 6.0 with a productivity rate of 1.15 g/d/L, a yield of 8.06% and a dry weight of 6.45 g/L for K. maltaceti, and 10% maltose, 1% (peptone + yeast extract) and 10% inoculation amount at pH 6.0 with a productivity rate of 0.96 g/L/d, a yield of 5.35% and a dry weight of 5.35 g/L for K. nataicola. Obtained BC from K. maltaceti and K. nataicola strains was more than 2.56- and 1.86-fold when compared with BC obtained from HS media and exhibited 95.1% and 92.5% WHC, respectively. Based on the characterization results, BC pellicles show characteristic FT-IR bands and have ultrafine 3D structures with high thermal stability. By means of having ability to assimilate monosaccharides, disaccharides and polysaccharide used in this study, it is predicted that both isolated Komagataeibacter species can be used in the production of biopolymers from wastes containing complex carbon sources in the future.

Techno-economic feasibility assessment of bacterial cellulose biofilm production during the Kombucha fermentation process

Bacterial cellulose produced during Kombucha fermentation has recently received lots of attention owing to its desirable mechanical and physicochemical properties and is exploited for different food, textiles and environmental applications. However, lack of information on process feasibility often hinders large-scale manufacturing of Kombucha-based cellulose. Therefore, the current study assesses techno-economic feasibility of a 60-ton annual capacity Kombucha-based cellulose production facility using SuperPro designer. Economic feasibility analysis showed an estimation of 13.72 million US$ as total investment and 3.8 million US$ as operating costs with 89% expenses associated with facility dependent and labour costs. The process feasibility is revealed with a payback time of 4.23 years, 23.64% return on investment and 16.48% internal rate of return. Sensitivity analysis presented that increased volume of fermentation units and automating the process can significantly reduce input costs. Such research is necessary to aid policymakers in facilitating the commercialization of Kombucha-based cellulose at field scale.