Occurrence of Cellulose-Producing Gluconacetobacter spp. in Fruit Samples and Kombucha Tea, and Production of the Biopolymer

Enhancing Solanum lycopersicum Resilience: Bacterial Cellulose Alleviates Low Irrigation Stress and Boosts Nutrient Uptake

The use of natural-origin biomaterials in bioengineering has led to innovative approaches in agroforestry. Bacterial cellulose (BC), sharing the same chemical formula as plant-origin cellulose (PC), exhibits significantly different biochemical properties, including a high degree of crystallinity and superior water retention capacity. Previous research showed that natural-origin glucose-based chitin enhanced plant growth in both herbaceous and non-herbaceous plants. In this study, we produced BC in the laboratory and investigated its effects on the substrate and on Solanum lycopersicum seedlings. Soil amended with BC increased root growth compared with untreated seedlings. Additionally, under limited irrigation conditions, BC increased global developmental parameters including fresh and dry weight, as well as total carbon and nitrogen content. Under non-irrigation conditions, BC contributed substantially to plant survival. RNA sequencing (Illumina®) on BC-treated seedlings revealed that BC, despite its bacterial origin, did not stress the plants, confirming its innocuous nature, and it lightly induced genes related to root development and cell division as well as inhibition of stress responses and defense. The presence of BC in the organic substrate increased soil availability of phosphorus (P), iron (Fe), and potassium (K), correlating with enhanced nutrient uptake in plants. Our results demonstrate the potential of BC for improving soil nutrient availability and plant tolerance to low irrigation, making it valuable for agricultural and forestry purposes in the context of global warming.

Production and Characterization of Biocomposite Films of Bacterial Cellulose from Kombucha and Coated with Chitosan

The purpose of this research is to produce and characterize bacterial cellulose (BC) films coated with chitosan (BC-CH). BC films were produced in a fermentation medium based on Camellia sinensis tea and dextrose (12 days at 25 °C) and subsequently treated with coating-forming solutions (CFSs) based on chitosan (BC-CH 0.5%, BC-CH 1.0%, and BC-CH 1.5%). As a result, the FTIR spectra of BC and BC-CH 1.5% showed the main characteristic bands of cellulose and chitosan. In the physicochemical characterization of the films, it was found that the incorporation of the chitosan coatings did not affect the thickness; however, it decreased the luminosity (L*) and increased redness (a*), yellowness (b*), and opacity (75.24%). Additionally, the light absorption properties in the UV-Vis range were improved. Furthermore, the application of the CFSs increased: the solubility (64.91%), the antimicrobial activity against S. aureus (6.55 mm) and E. coli (8.25 mm), as well as the antioxidant activity (57.71% and 24.57% free radical scavenging activity), and the content of total phenols (2.45 mg GAE/g). Finally, our results suggest that the BC-CH films developed in the present study show a potential application as active packaging material for food.

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.

Oily Wastewater Treatment: Methods, Challenges, and Trends

The growing interest in innovations regarding the treatment of oily wastewater stems from the fact that the oil industry is the largest polluter of the environment. The harm caused by this industry is seen in all countries. Companies that produce such wastewater are responsible for its treatment prior to disposal or recycling into their production processes. As oil emulsions are difficult to manage and require different types of treatment or even combined methods, a range of environmental technologies have been proposed for oil-contaminated effluents, such as gravity separation, flotation, flocculation, biological treatment, advanced oxidation processes, and membranes. Natural materials, such as biopolymers, constitute a novel, sustainable solution with considerable potential for oily effluent separation. The present review offers an overview of the treatment of oily wastewater, describing current trends and the latest applications. This review also points to further research needs and major concerns, especially with regards to sustainability, and discusses potential biotechnological applications.

Research progress of the biosynthetic strains and pathways of bacterial cellulose

Bacterial cellulose is a glucose biopolymer produced by microorganisms and widely used as a natural renewable and sustainable resource in the world. However, few bacterial cellulose-producing strains and low yield of cellulose greatly limited the development of bacterial cellulose. In this review, we summarized the 30 cellulose-producing bacteria reported so far, including the physiological functions and the metabolic synthesis mechanism of bacterial cellulose, and the involved three kinds of cellulose synthases (type I, type II, and type III), which are expected to provide a reference for the exploration of new cellulose-producing microbes.

Bacterial cellulose and its potential for biomedical applications

Bacterial cellulose (BC) is an important polysaccharide synthesized by some bacterial species under specific culture conditions, which presents several remarkable features such as microporosity, high water holding capacity, good mechanical properties and good biocompatibility, making it a potential biomaterial for medical applications. Since its discovery, BC has been used for wound dressing, drug delivery, artificial blood vessels, bone tissue engineering, and so forth. Additionally, BC can be simply manipulated to form its derivatives or composites with enhanced physicochemical and functional properties. Several polymers, carbon-based nanomaterials, and metal nanoparticles (NPs) have been introduced into BC by ex situ and in situ methods to design hybrid materials with enhanced functional properties. This review provides comprehensive knowledge and highlights recent advances in BC production strategies, its structural features, various in situ and ex situ modification techniques, and its potential for biomedical applications.

Biocellulose for Treatment of Wastewaters Generated by Energy Consuming Industries: A Review

Water and energy are two of the most important resources used by humanity. Discharging highly polluting wastewater without prior treatment is known to adversely affect water potability, agriculture, aquatic life and even society. One of the greatest threats to water sources are contaminated effluents, which can be of residential or industrial origin and whose disposal in nature must comply with specific laws aimed at reducing their environmental impact. As the oil industry is closely related to energy consumption, it is among the sectors most responsible for global pollution. The damage caused by this industrial sector is present in all countries, whose legislations require companies to carry out wastewater treatment before disposal or recycling in their production process. Bacterial cellulose membranes have been shown to be efficient as filters for the removal of various contaminants, including biological and chemical agents or heavy metals. Therefore, their use could make an important contribution to bio-based technological development in the circular economy. Moreover, they can be used to produce new materials for industry, taking into consideration current environmental preservation policies aimed at a more efficient use of energy. This review aims to compare and describe the applications of cellulose membranes in the treatment of these effluents.

Atmospheric cold plasma-assisted pineapple peel waste hydrolysate detoxification for the production of bacterial cellulose

Toxic compounds in pineapple peel waste hydrolysate (PPWH), namely formic acid, 5-hydroxymethylfurfural (HMF), and furfural, are the major predicament in its utilization as a carbon source for bacterial cellulose (BC) fermentation. A rapid detoxification procedures using atmospheric cold plasma (ACP) technique were employed to reduce the toxic compounds. ACP treatment allows the breakdown of toxic compounds without causing excessive breakdown of sugars. Herein, the performance of two available laboratory ACP reactors for PPWH detoxification was being demonstrated. ACP-reactor-1 (R1) runs on plasma power of 80-200 W with argon (Ar) plasma source, while ACP-reactor-2 (R2) runs at 500-600 W with air plasma source. Treatment in R1, at 200 W for 15 min, results in 74.06%, 51.38%, and 21.81% reduction of furfural, HMF, and formic acid. Treatment in R2 at 600 W gives 45.05%, 32.59%, and 60.41% reductions of furfural, HMF, and formic acid. The BC yield from the fermentation of Komagateibacter xylinus in the R1-treated PPWH, R2-treated PPWH, and untreated-PPWH is 2.82, 3.82, and 2.97 g/L, respectively. The results show that ACP treatment provides a novel detoxified strategy in achieving agricultural waste hydrolysate reuse in fermentation. Furthermore, the results also imply that untreated PPWH can be an inexpensive and sustainable resource for fermentation media supplementation.

Production of Microbial Cellulose Films from Green Tea (Camellia Sinensis) Kombucha with Various Carbon Sources

The aim of this study was to evaluate the production of microbial cellulose films (MCFs) in culture media based on green tea and different carbon sources, using two microbial consortia (COr and CFr). During the fermentation process, there was a reduction in the total soluble solids (TSS) content and pH, as well as an increase in the acidity in all treatments. Furthermore, fluctuations in the total sugar content and proteins during the fermentation process were associated with the consumption of carbon and nitrogen sources, as well as the production of MCFs. In the color analysis, a decrease in the L* value was observed while the rest of the parameters remained stable. Production of films was observed between days 6 and 9 of fermentation; the preferred substrate for COr was glucose (wet base yields = 603.61% and dry base yields = 22.37%), whereas for CFr was dextrose (wet base yields = 601.49% and dry base yields = 28.14%). Finally, the MCFs produced by COr and CFr showed a homogeneous, thick appearance, slight flexibility, and the characteristic brown color of the fermentation medium.

Novel bacterial cellulose membrane biosynthesized by a new and highly efficient producer Komagataeibacter rhaeticus TJPU03

Bacterial cellulose(BC) is a kind of extracellular polymer synthesized by bacteria and it has very wide applications in many fields. However, the application of BC in a large commercial scale can still not be fulfilled due to the low yield and demanding for BC membranes with very different properties. To this end, a new BC-producer Komagataeibacter rhaeticus TJPU03 was isolated from rotten orange peel, which produced 8.28 ± 0.27 g/L(dry weight) in standard HS medium at the 10th day. The membrane is easier to be purified by one-step alkaline treatment and the produced BC(K-BC) membranes possess homogeneous, looser and more porous three-dimensional network composed by thinner cellulose fibrils. However, the wet K-BC possesses stronger mechanical properties and exhibits lower toxicity and higher cytocompatibility to mammalian cell. Owing to the more porous and homogeneous network, K-BC possesses high loading capacity of cell and protein drugs. Also, it exhibits sustained-controlled release ability for proteinaceous drug. The high yield of this strain and the special characteristics of K-BC predict this strain to be a very promising BC-producer and broad applications of K-BC in the fields of wound healing, scaffolds of tissue engineering, tissue repair and regeneration.

Serratia liquefaciens FG3 isolated from a metallophyte plant sheds light on the evolution and mechanisms of adaptive traits in extreme environments

Serratia liquefaciens strain FG3 (SlFG3), isolated from the flower of Stachytarpheta glabra in the Brazilian ferruginous fields, has distinctive genomic, adaptive, and biotechnological potential. Herein, using a combination of genomics and molecular approaches, we unlocked the evolution of the adaptive traits acquired by S1FG3, which exhibits the second largest chromosome containing the largest conjugative plasmids described for Serratia. Comparative analysis revealed the presence of 18 genomic islands and 311 unique protein families involved in distinct adaptive features. S1FG3 has a diversified repertoire of genes associated with Nonribosomal peptides (NRPs/PKS), a complete and functional cluster related to cellulose synthesis, and an extensive and functional repertoire of oxidative metabolism genes. In addition, S1FG3 possesses a complete pathway related to protocatecuate and chloroaromatic degradation, and a complete repertoire of genes related to DNA repair and protection that includes mechanisms related to UV light tolerance, redox process resistance, and a laterally acquired capacity to protect DNA using phosphorothioation. These findings summarize that SlFG3 is well-adapted to different biotic and abiotic stress situations imposed by extreme conditions associated with ferruginous fields, unlocking the impact of the lateral gene transfer to adjust the genome for extreme environments, and providing insight into the evolution of prokaryotes.

Kombucha from alternative raw materials - The review

Nowadays, people's awareness about the role of diet in maintaining well-being and good health has increased. Consumers expect that the products not only provide them with essential nutrients but will also be a source of biologically active substances, which are beneficial to their health. One of the "healthy trends," which has appeared among the consumers worldwide is kombucha, a tea drink with high antioxidant potential, obtained through the activity of a consortium of acetic acid bacteria and osmophilic yeast, which is also called "tea fungus." Kombucha obtained from tea is characterized by its health-promoting properties. Promising results in in vitro and in vivo studies have prompted research groups from around the world to search for alternative raw materials for tea fungus fermentation. Attempts are made to obtain functional beverages from leaves, herb infusions, vegetable pulp, fruit juices, or milk. This review focuses on describing the progress in obtaining a fermented beverage and bacterial cellulose using tea fungus on alternative raw materials.

Set-Up of Bacterial Cellulose Production From the Genus Komagataeibacter and Its Use in a Gluten-Free Bakery Product as a Case Study

The use of bacterial cellulose (BC) in food systems is still limited due to production costs. Nine clones belonging to Komagataeibacter hansenii, Komagataeibacter nataicola, Komagataeibacter rhaeticus, Komagataeibacter swingsii, and Komagataeibacter xylinus species were screened for cellulose productivity in growth tests with five different carbon sources and three nitrogen sources. The water-holding and rehydration capacities of the purified cellulose were determined. The structure of the polymer was investigated through nuclear magnetic resonance (NMR) spectroscopy, attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy and X-ray diffraction (XRD) analysis, and observed by scanning electron microscope (SEM). Natural mutants of K. rhaeticus LMG 22126T and K. swingsii LMG 22125T showed different productivity. The factors "bacterial isolate" and "nitrogen source" significantly affected the production of cellulose (p < 0.01) rather than the factor "carbon source" (p = 0.15). However, on average, the best conditions for increasing yield were found in medium containing glucose and peptone. Water-holding capacity (WHC) values ranged from 10.7 to 42.3 (g water/g cellulose) with significant differences among strains (p < 0.01), while the rehydration capacity varied from 4.2 to 9.3 (g water/g cellulose). A high crystallinity (64-80%) was detected in all samples with Iα fractions corresponding to 67-93%. The ATR-FT-IR spectra and the XRD patterns confirmed the expected structure. BC made by GVP isolate of K. rhaeticus LMG 22126T, which was the strain with the highest yield, was added to a gluten-free bread formulation. Results obtained from measurements of technological parameters in dough leavening and baking trials were promising for implementation in potential novel foods.

Kombucha Beverage from Green, Black and Rooibos Teas: A Comparative Study Looking at Microbiology, Chemistry and Antioxidant Activity

Kombucha is usually obtained from the fermentation of black or green tea by a consortium of acetic acid bacteria and yeasts. In this study, kombucha was prepared from the same starter consortium using green and black teas as well as, for the first time, an infusion of rooibos leaves (Aspalathus linearis). Microbial diversity was analysed during fermentation both in the biofilm and in the corresponding kombuchas, using culture-dependent and -independent methods. Polyphenols, flavonoids, ethanol, and acids were quantified and anti-oxidant activities were monitored. All of the Kombuchas showed similarity in bacterial composition, with the dominance of Komagataeibacter spp. Beta diversity showed that the yeast community was significantly different among all tea substrates, between 7 and 14 days of fermentation and between biofilm and kombucha, indicating the influence of the substrate on the fermenting microbiota. Kombucha from rooibos has a low ethanol concentration (1.1 mg/mL), and a glucuronic acid amount that was comparable to black tea. Although antioxidant activity was higher in black and green kombucha compared to rooibos, the latter showed an important effect on the recovery of oxidative damage on fibroblast cell lines against oxidative stress. These results make rooibos leaves interesting for the preparation of a fermented beverage with health benefits.

Alginate Production from Alternative Carbon Sources and Use of Polymer Based Adsorbent in Heavy Metal Removal

Alginate is a biopolymer composed of mannuronic and guluronic acids. It is harvested from marine brown algae; however, alginate can also be synthesized by some bacterial species, namely,AzotobacterandPseudomonas. Use of pure carbohydrate sources for bacterial alginate production increases its cost and limits the chance of the polymer in the industrial market. In order to reduce the cost of bacterial alginate production, molasses, maltose, and starch were utilized as alternative low cost carbon sources in this study. Results were promising in the case of molasses with the maximum 4.67 g/L of alginate production. Alginates were rich in mannuronic acid during early fermentation independent of the carbon sources while the highest guluronic acid content was obtained as 68% in the case of maltose. The polymer was then combined with clinoptilolite, which is a natural zeolite, to remove copper from a synthetic wastewater. Alginate-clinoptilolite beads were efficiently adsorbed copper up to 131.6 mg Cu2+/g adsorbent at pH 4.5 according to the Langmuir isotherm model.

The Phytohormone Ethylene Enhances Cellulose Production, Regulates CRP/FNRKx Transcription and Causes Differential Gene Expression within the Bacterial Cellulose Synthesis Operon of Komagataeibacter (Gluconacetobacter) xylinus ATCC 53582

Komagataeibacter (formerly Gluconacetobacter) xylinus ATCC 53582 is a plant-associated model organism for bacterial cellulose (BC) biosynthesis. This bacterium inhabits the carposphere where it interacts with fruit through the bi-directional transfer of phytohormones. The majority of research regarding K. xylinus has been focused on identifying and characterizing structural and regulatory factors that control BC biosynthesis, but its ecophysiology has been generally overlooked. Ethylene is a phytohormone that regulates plant development in a variety of ways, but is most commonly known for its positive role on fruit ripening. In this study, we utilized ethephon (2-chloroethylphosphonic acid) to produce in situ ethylene to investigate the effects of this phytohormone on BC production and the expression of genes known to be involved in K. xylinus BC biosynthesis (bcsA, bcsB, bcsC, bcsD, cmcAx, ccpAx and bglAx). Using pellicle assays and reverse transcription quantitative polymerase chain reaction (RT-qPCR), we demonstrate that ethephon-derived ethylene enhances BC directly in K. xylinus by up-regulating the expression of bcsA and bcsB, and indirectly though the up-regulation of cmcAx, ccpAx, and bglAx. We confirm that IAA directly decreases BC biosynthesis by showing that IAA down-regulates bcsA expression. Similarly, we confirm that ABA indirectly influences BC biosynthesis by showing it does not affect the expression of bcs operon genes. In addition, we are the first to report the ethylene and indole-3-acetic acid (IAA) induced differential expression of genes within the bacterial cellulose synthesis (bcs) operon. Using bioinformatics we have identified a novel phytohormone-regulated CRP/FNRKx transcription factor and provide evidence that it influences BC biosynthesis in K. xylinus. Lastly, utilizing current and previous data, we propose a model for the phytohormone-mediated fruit-bacteria interactions that K. xylinus experiences in nature.

Establishing a Role for Bacterial Cellulose in Environmental Interactions: Lessons Learned from Diverse Biofilm-Producing Proteobacteria

Bacterial cellulose (BC) serves as a molecular glue to facilitate intra- and inter-domain interactions in nature. Biosynthesis of BC-containing biofilms occurs in a variety of Proteobacteria that inhabit diverse ecological niches. The enzymatic and regulatory systems responsible for the polymerization, exportation, and regulation of BC are equally as diverse. Though the magnitude and environmental consequences of BC production are species-specific, the common role of BC-containing biofilms is to establish close contact with a preferred host to facilitate efficient host-bacteria interactions. Universally, BC aids in attachment, adherence, and subsequent colonization of a substrate. Bi-directional interactions influence host physiology, bacterial physiology, and regulation of BC biosynthesis, primarily through modulation of intracellular bis-(3'→5')-cyclic diguanylate (c-di-GMP) levels. Depending on the circumstance, BC producers exhibit a pathogenic or symbiotic relationship with plant, animal, or fungal hosts. Rhizobiaceae species colonize plant roots, Pseudomonadaceae inhabit the phyllosphere, Acetobacteriaceae associate with sugar-loving insects and inhabit the carposphere, Enterobacteriaceae use fresh produce as vehicles to infect animal hosts, and Vibrionaceae, particularly Aliivibrio fischeri, colonize the light organ of squid. This review will highlight the diversity of the biosynthesis and regulation of BC in nature by discussing various examples of Proteobacteria that use BC-containing biofilms to facilitate host-bacteria interactions. Through discussion of current data we will establish new directions for the elucidation of BC biosynthesis, its regulation and its ecophysiological roles.