Response surface methodology-based improvement of the yield and differentiation of properties of bacterial cellulose by metabolic enhancers

Enhancing bacterial cellulose production of Komagataeibacter nataicola through fermented coconut water by Saccharomyces cerevisiae: A metabonomics approach

Nata de coco, an edible bacterial cellulose (BC) product, is a traditional dessert fermented in coconut water. Production of Nata de coco by Komagataeibacter nataicola is enhanced by pre-fermented coconut water, but its instability is a challenge. Here, BC production by K. nataicola Y19 was significantly improved by Saccharomyces cerevisiae 84-3 through shaping the metabolite profile of the coconut water. Different fermentation time with S. cerevisiae 84-3 resulted in distinct metabolite profiles and different promoting effect on BC yield. Compared to unfermented coconut water, coconut water fermented by S. cerevisiae 84-3 for 1d and 7d enhanced BC yield by 14.1-fold and 5.63-fold, respectively. Analysis between unfermented coconut water and 1d-fermented coconut water showed 129 significantly different metabolites, including organic acids, amino acids, nucleotides, and their derivatives. Prolonged fermentation for 7d changed levels of 155 metabolites belongs to organic acids, amino acids, nucleotides and their derivatives. Spearman correlation analysis further revealed that 17 metabolites were positively correlated with BC yield and 21 metabolites were negatively correlated with BC yield. These metabolites may affect energy metabolism, cell signaling, membrane integrity, and BC production by K. nataicola Y19. The further verification experiment gave the view that BC yield was not only closely related to the types of metabolites but also the concentration of metabolites. This study provides a novel theoretical framework for a highly efficient BC fermentation system utilizing stable fermented coconut water mediums.

Enhancement of bacterial cellulose production by ethanol and lactic acid by using Gluconacetobacter kombuchae

The current study intended to analyze the impact of ethanol and lactic acid on the bacterial cellulose yield as well as physicochemical and mechanical properties, by using Gluconacetobacter kombuchae. The optimization of ethanol and lactic acid concentration has been done by using one-way ANOVA. Both the supplements significantly enhance the yield of bacterial cellulose (BC) as compared to the standard Hestrin-Schramm medium (control). Optimization leads to significant increase in BC yield as compared to the control, i.e., the addition, of optimized concentration of lactic acid (0.6%) increases the yield from (0.78 ± 0.026) g to (4.89 ± 0.020) g dry weight, and optimized concentration of ethanol (1%) increases the yield from (0.73 ± 0.057) g to (3.7 ± 0.01) g dry weight. Various physicochemical and mechanical properties of BC films produced in different media (i.e., HS, HS + Ethanol, and HS + Lactic acid), such as the crystallinity, structure, tensile strength, strain at break, Young's modulus, and water holding capacity, were also examined, by employing various techniques such as SEM, FTIR, XRD, etc. BC produced in medium supplemented with the optimum concentration of both the additives were found to possesses higher porosity. Though, slight decline in crystallinity was observed. But the tensile strength and strain at break, were upgraded 1.5-2.5 times, 2-2.5 times, respectively. This article attempted to present a method for enhancing BC yields and characteristics that may lead to more widespread and cost-effective use of this biopolymer.

Exploring the biotic and abiotic drivers influencing nata de coco production by Komagataeibacter nataicola in pre-fermented coconut water

In China and Southeast Asia, pre-fermented coconut water is commonly used for the production of nata de coco, a jelly-like fermented food that consists of bacterial cellulose (BC). The inherent natural fermentation process of coconut water introduces uncontrollable variables, which can lead to unstable yields during BC production. This study involved the collection of spontaneously pre-fermented coconut water over a five-month production cycle. The aim was to evaluate the microbiota and metabolite profile, as well as determine its impact on BC synthesis by Komagataeibacter nataicola. Significant variations in the microbial community structure and metabolite profile of pre-fermented coconut water were observed across different production months, these variations had significant effects on BC synthesis by K. nataicola. A total of 52 different bacterial genera and 32 different fungal genera were identified as potential biotic factors that can influence BC production. Additionally, several abiotic factors, including lactate (VIP = 4.92), mannitol (VIP = 4.22), ethanol (VIP = 2.67), and ascorbate (VIP = 1.61), were found to be potential driving forces affecting BC synthesis by K. nataicola. Upon further analysis, the correlation network indicated that 14 biotic factors had a significant contribution to BC production in three strains of K. nataicola. These factors included 8 bacterial genera, such as Limosilactobacillus and Lactiplantibacillus, and 6 fungal genera, such as Meyerozyma and Ogataea. The abiotic factors lactate, mannitol, and ethanol showed a positive correlation with the BC yield. This study provides significant insights into controlling the fermentation processes of pre-fermented coconut water in industrial settings.

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.

Improvement in bacterial cellulose production by co-culturing Bacillus cereus and Komagataeibacter xylinus

Bacterial cellulose (BC) is a bio-produced nanostructure material widely used in biomedical, food, and paper-manufacturing industries. However, low production efficiency and high-cost have limited its industrial applications. This study aimed to examine the level of improvement in BC production by co-culturing Bacillus cereus and Komagataeibacter xylinus. The BC yield in corn stover enzymatic hydrolysate was found to be obviously enhanced from 1.2 to 4.4 g/L after the aforementioned co-culturing. The evidence indicated that acetoin (AC) and 2,3-butanediol (2,3-BD) produced by B. cereus were the key factors dominating BC increment. The mechanism underlying BC increment was that AC and 2,3-BD increased the specific activity of AC dehydrogenase and the contents of adenosine triphosphate (ATP) and acetyl coenzyme A (acetyl-CoA), thus promoting the growth and energy level of K. xylinus. Meanwhile, the immobilization of BC could also facilitate oxygen acquisition in B. cereus under static conditions. This study was novel in reporting that the co-culture could effectively enhance BC production from the lignocellulosic enzymatic hydrolysate.

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.

Optimization of bacterial cellulose production from prickly pear peels and its ex situ impregnation with fruit byproducts for antimicrobial and strawberry packaging applications

Bacterial cellulose (BC) is currently among the most promising natural polymers. However, the production costs and biological inactivity are still challenges. The current study exploited the enzymatically hydrolyzed prickly pear peels (PPP) for BC production, which supported about 2.94 g/L as the sole production medium. The BC production was further optimized through a central composite design, where the maximum BC production was 6.01 g/L at 68 % PPPE at pH 4 after 11 days of incubation at 20 °C. The produced BC was characterized by FT-IR spectroscopy, XRD, and SEM analysis, and the results showed that PPPE is a promising carbon source for pure BC production. The BC membrane was separately loaded with several fruit byproduct extracts to enhance its biological activity for multiple applications. BC loaded with pomegranate peel extract (BC/PPE) revealed significant broad-spectrum antimicrobial activity, followed by BC loaded with pomegranate molasses (BC/PM). The BC/PPE membrane enhanced the shelf-life storage of strawberry fruits by about 5 days, with a reduction in the fruits' weight loss of 15 % compared to the uncovered group. The current study revealed the successful application of PPE for sustainable BC production with its packaging potential for enhancing strawberry shelf-life when loaded with PPE or PM.

Extraction Optimization, Preliminary Identification, and Bioactivities in Corn Silk

For thousands of years, corn silk has been widely used as an antidiabetic, antioxidant, and antihyperlipidemic and for other effects, but there is a lack of studies that correlate the extracts of flavonoid composition with their biological activities. Thus, the objectives of this study were to optimize the conditions for extracting flavonoids, identify flavonoids, and correlate the flavonoid composition with the biological activities in corn silk. The response surface experiments showed that the highest flavonoid content was predicted at 45.321 min, 57.349°C, 26.089 mL/g, and 71.269%, respectively. The verification experiment results under these optimized conditions showed an ultrasonic time of 45 min, an ultrasonic temperature of 57°C, a liquid-to-material ratio of 26, and an ethanol volume fraction of 70%. No significant differences (the relative error is 4.378%) were observed between the theoretical and experimental TFC values, indicating that the developed models were accurate. Under these optimum extraction conditions, 20 major compounds were identified and quantified by UPLC-LTQ/Orbitrap MS. Furthermore, these optimum ethanol extracts of corn silk are effective against Bacillus subtilis and hypoglycemic activity compared with the traditional heating reflux extraction method. Six corn silk components seem to be the main contributors to the inhibitory effect against Bacillus subtilis and hyperglycemia activities. These results are useful for the application of corn silk in the food or pharmaceutical industry.

Characterization of the Putative Acylated Cellulose Synthase Operon in Komagataeibacter xylinus E25

Bacterial cellulose is a natural polymer with an expanding array of applications. Because of this, the main cellulose producers of the Komagataeibacter genus have been extensively studied with the aim to increase its synthesis or to customize its physicochemical features. Up to now, the genetic studies in Komagataeibacter have focused on the first cellulose synthase operon (bcsI) encoding the main enzyme complex. However, the role of other accessory cellulose operons has been understudied. Here we aimed to fill this gap by performing a detailed analysis of the second cellulose synthase operon (bcsII), which is putatively linked with cellulose acylation. In this study we harnessed the genome sequence, gene expression and protein structure information of K. xylinus E25 and other Komagataeibacter species to discuss the probable features of bcsII and the biochemical function of its main protein products. The results of our study support the previous hypothesis that bcsII is involved in the synthesis of the acylated polymer and expand it by presenting the evidence that it may also function in the regulation of its attachment to the cell surface and to the crystalline cellulose fibers.

Comparative Analysis of Bacterial Cellulose Membranes Synthesized by Chosen Komagataeibacter Strains and Their Application Potential

This article presents a comparative analysis of bacterial cellulose membranes synthesized by several strains of the Komagataeibacter genus in terms of their specific physical, physico-chemical, and mechanical properties. Herein, the aim was to choose the most suitable microorganisms producing cellulosic materials with the greatest potential for the fabrication of bio-inspired nanocomposites. The selection was based on three main steps, starting from the evaluation of BNC biosynthetic efficiency with and without the addition of ethanol, followed by the assessment of mechanical breaking strength, and the physical parameters (compactness, structural integrity, appearance, and thickness) of the obtained biological materials. Ultimately, based on the performed screening procedure, three efficiently growing strains (K. hansenii H3 (6Et), K. rhaeticus K4 (8Et), and Komagataeibacter sp. isolated from balsamic vinegar (12Et)) were chosen for further modifications, enabling additional cellulose functionalization. Here, supplementation of the growth medium with five representative polymeric compounds (citrus/apple pectin, wheat starch, polyvinyl alcohol, polyethylene glycol) led to significant changes in BNC properties, especially dye loading abilities, mechanical strength, and water adsorption/retention capacities. The resulting nanocomposites can be potentially useful in various fields of medicine and industry, and in the future, they may become a practical and cost-effective competitor against commercial biomaterials currently available on the market.

Highly Stretchable Bacterial Cellulose Produced by Komagataeibacter hansenii SI1

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