Production of bacterial cellulose byGluconacetobacter hansenii PJK isolated from rotten apple

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.

Functionalization of bacterial cellulose: Exploring diverse applications and biomedical innovations: A review

The demand for the functionalization of additive materials based on bacterial cellulose (BC) is currently high due to their potential applications across various sectors. The preparation of BC-based additive materials typically involves two approaches: in situ and ex situ. In situ modifications entail the incorporation of additive materials, such as soluble and dispersed substances, which are non-toxic and not essential for bacterial cell growth during the production process. However, these materials can impact the yield and self-assembly of BC. In contrast, ex situ modification occurs subsequent to the formation of BC, where the additive materials are not only adsorbed on the surface but also impregnated into the BC pellicle, while the BC slurry was homogenized with other additive materials and gelling agents to create composite films using the casting method. This review will primarily focus on the in situ and ex situ functionalization of BC then sheds light on the pivotal role of functionalized BC in advancing biomedical technologies, wound healing, tissue engineering, drug delivery, bone regeneration, and biosensors.

Tannin Removal of Cashew Apple Juice by Powdered Gelatin Treatment and Its Utilization in Bacterial Cellulose Production

In this study, cashew apple juice was treated with different levels of powdered gelatin (2%, 5%, and 10%) to remove tannins. The results showed that the addition of 5% gelatin removed 99.2% of condensed tannins while did not affect reducing sugars of juice. Subsequently, tannin-free cashew apple juice (CA) was aerobically fermented for 14 days with Komagataeibacter saccharivorans strain 1.1 (KS) and Gluconacetobacter entanii HWW100 (GE) in comparison with Hestrin-Schramm (HS) medium as control. The dry weight of bacterial cellulose (BC) obtained from the KS strain (2.12 and 1.48 g/L for CA and HS media, respectively) was higher than that from the GE strain (0.69 and 1.21 g/L for CA and HS media, respectively). Although GE showed low BC production yield, its viability in both media after 14-day fermentation was notable (6.06-7.21 log CFU/mL) compared to KS strain (1.90-3.30 log CFU/mL). In addition, the XRD and FT-IR analysis showed that there was no significant difference in the crystallinity and functional groups of BC films when cultured on CA and HS medium, while the morphology by SEM exhibited the phenolic molecules on the film surface. Cashew apple juice has been shown to be a viable and cost-effective medium for the BC production.

Enhanced bacterial cellulose production in Komagataeibacter sucrofermentans: impact of different PQQ-dependent dehydrogenase knockouts and ethanol supplementation

BACKGROUND

Bacterial cellulose (BC) is a biocompatible material with unique mechanical properties, thus holding a significant industrial potential. Despite many acetic acid bacteria (AAB) being BC overproducers, cost-effective production remains a challenge. The role of pyrroloquinoline quinone (PQQ)-dependent membrane dehydrogenases (mDH) is crucial in the metabolism of AAB since it links substrate incomplete oxidation in the periplasm to energy generation. Specifically, glucose oxidation to gluconic acid substantially lowers environmental pH and hinders BC production. Conversely, ethanol supplementation is known to enhance BC yields in Komagataeibacter spp. by promoting efficient glucose utilization.

RESULTS

K. sucrofermentans ATCC 700178 was engineered, knocking out the four PQQ-mDHs, to assess their impact on BC production. The strain KS003, lacking PQQ-dependent glucose dehydrogenase (PQQ-GDH), did not produce gluconic acid and exhibited a 5.77-fold increase in BC production with glucose as the sole carbon source, and a 2.26-fold increase under optimal ethanol supplementation conditions. In contrast, the strain KS004, deficient in the PQQ-dependent alcohol dehydrogenase (PQQ-ADH), showed no significant change in BC yield in the single carbon source experiment but showed a restrained benefit from ethanol supplementation.

CONCLUSIONS

The results underscore the critical influence of PQQ-GDH and PQQ-ADH and clarify the effect of ethanol supplementation on BC production in K. sucrofermentans ATCC 700178. This study provides a foundation for further metabolic pathway optimization, emphasizing the importance of diauxic ethanol metabolism for high BC production.

Biosynthesis of bacterial cellulose nanofibrils in black tea media by a symbiotic culture of bacteria and yeast isolated from commercial kombucha beverage

Bacterial cellulose has drawn the attention for its unique properties and applications including; medicine, pharmacy, food, agricultural, textile and electronics. The present study focused on the production of bacterial cellulose nanofibrils (BCNF) from black tea as cost effective alternative medium in addition to study the effect of gamma radiation on BCNF properties. A symbiotic culture of bacteria and yeast (SCOBY) were isolated from commercial Kombucha beverage and were identified as Acinetobacter lowffii and Candida krusei, respectively. The symbiotic culture was used for production of BCNF on Hestrin-Schramm (HS), black tea (BT) and modified BT media. BCNF was purified (0.5 N NaOH) and quantified by dry weight, yield and productivity determination. Characterization and effect of gamma radiation (5-25 kGy) on BCNF were studied using Scanning Electron Microscope (SEM), Fourier transform infrared (FTIR) and X-Ray Diffraction (XRD). The highest BCNF production was achieved using BT medium with 0.2% tea and 6.0% commercial sugar (with dry weight 4.77-4.61 g/l and productivity 68.14% and 65.85%, respectively). Supplementation of BT medium with 1% ethanol, 0.27% Na₂HPO₄ and 0.5% yeast extract individually, enhanced the BCNF production (7.85, 6.84 and 5.73 g/l), respectively. FTIR spectrum of BCNF from sugared water (SW), HS and BT showed similar structure with high purity. As a conclusion, gamma irradiation has no effect on the BCNF structure while showed different effects on its crystallinity index and size with the different doses. The changes in CrI were ranged between (17 and 23.5%), while the crystallinity size (Cs) was affected by gamma irradiation in a positive relationship where the crystalline size was decreased (33%) by exposure to 5 kGy then increased by increasing the dose of radiation reaching 25.7% at 25 kGy. SEM graphs showed the morphology of microbial culture and its symbiotic relationship in addition to the ultrafine structure of non-irradiated and irradiated BCNF.

Liquid-crystalline ordering in bacterial cellulose produced by Gluconacetobaсter hansenii on glucose-containing media

This research is dedicated to the studies of the microscale morphology of bacterial cellulose (BC) obtained by means of static cultivation of Gluconacetobacter hansenii GH-1/2008. We found that the microscale morphology depended on the BC production rate that was varied by using different glucose concentrations in the cultivation medium. It was revealed that at higher production rates, BC fibrils were aligned in a liquid-crystalline-like (LC-like) order. The observed helical alignment was always left-handed. The half-periods of the helix varied from 50 μm to 150 μm depending on the cultivation conditions. The mechanical and water absorption properties of the obtained BC pellicles were measured. The former correlated mainly with the density of the samples; the latter were the best for films with layered structure, where the BC had segregated into fleece sheets separated by gaps with low density of fibrils.

Bacterial cellulose: A promising biopolymer with interesting properties and applications

The ever-increasing demands for materials with desirable properties led to the development of materials that impose unfavorable influences on the environment and the ecosystem. Developing a low-cost, durable, and eco-friendly functional material with biological origins has become necessary to avoid these consequences. Bacterial cellulose generated by bacteria dispenses excellent structural and functional properties and satisfies these requirements. BC and BC-derived materials are essential in developing pure and environmentally safe functional materials. This review offers a detailed understanding of the biosynthesis of BC, properties, various functionalization methods, and applicability in biomedical, water treatment, food storage, energy conversion, and energy storage applications.

Bacterial cellulose as a potential biopolymer in biomedical applications: a state-of-the-art review

Throughout history, natural biomaterials have benefited society. Nevertheless, in recent years, tailoring natural materials for diverse biomedical applications accompanied with sustainability has become the focus. With the progress in the field of materials science, novel approaches for the production, processing, and functionalization of biomaterials to obtain specific architectures have become achievable. This review highlights an immensely adaptable natural biomaterial, bacterial cellulose (BC). BC is an emerging sustainable biopolymer with immense potential in the biomedical field due to its unique physical properties such as flexibility, high porosity, good water holding capacity, and small size; chemical properties such as high crystallinity, foldability, high purity, high polymerization degree, and easy modification; and biological characteristics such as biodegradability, biocompatibility, excellent biological affinity, and non-biotoxicity. The structure of BC consists of glucose monomer units polymerized via cellulose synthase in β-1-4 glucan chains, creating BC nano fibrillar bundles with a uniaxial orientation. BC-based composites have been extensively investigated for diverse biomedical applications due to their similarity to the extracellular matrix structure. The recent progress in nanotechnology allows the further modification of BC, producing novel BC-based biomaterials for various applications. In this review, we strengthen the existing knowledge on the production of BC and BC composites and their unique properties, and highlight the most recent advances, focusing mainly on the delivery of active pharmaceutical compounds, tissue engineering, and wound healing. Further, we endeavor to present the challenges and prospects for BC-associated composites for their application in the biomedical field.

Effect of Culture Conditions on Cellulose Production by a Komagataeibacter Xylinus Strain

Different fermentation conditions cause different shear forces, which have a great influence on BC synthesis. The shearing force activates the conversion of microbial cells to Cel^- mutants, and the accumulation of water-soluble exopolysaccharides is also observed. A substrate competitive relationship between these two polysaccharides is found, which is significant in terms of the optimization of cellulose production in commercial processes. This article is protected by copyright. All rights reserved.

Bioprocess development for bacterial cellulose biosynthesis by novel Lactiplantibacillus plantarum isolate along with characterization and antimicrobial assessment of fabricated membrane

Bacterial cellulose (BC) is an ecofriendly biopolymer with diverse commercial applications. Its use is limited by the capacity of bacterial production strains and cost of the medium. Mining for novel organisms with well-optimized growth conditions will be important for the adoption of BC. In this study, a novel BC-producing strain was isolated from rotten fruit samples and identified as Lactiplantibacillus plantarum from 16S rRNA sequencing. Culture conditions were optimized for supporting maximal BC production using one variable at a time, Plackett–Burman design, and Box Behnken design approaches. Results indicated that a modified Yamanaka medium supported the highest BC yield (2.7 g/l), and that yeast extract, MgSO₄, and pH were the most significant variables influencing BC production. After optimizing the levels of these variables through Box Behnken design, BC yield was increased to 4.51 g/l. The drug delivery capacity of the produced BC membrane was evaluated through fabrication with sodium alginate and gentamycin antibiotic at four different concentrations. All membranes (normal and fabricated) were characterized by scanning electron microscope, Fourier transform-infrared spectroscopy, X-ray diffraction, and mechanical properties. The antimicrobial activity of prepared composites was evaluated by using six human pathogens and revealed potent antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Streptococcus mutans, with no detected activity against Pseudomonas aeruginosa and Candida albicans.

Improved water dispersion and bioavailability of coenzyme Q10 by bacterial cellulose nanofibers

The purpose of this study was to investigate the potential of bacterial cellulose nanofiber suspension (BCNs) as stabilizer in anti-solvent precipitation and its effect on improving bioavailability of coenzyme Q10. Bacterial cellulose (BC) was hydrolyzed by sulfuric acid followed by the oxidation with hydrogen peroxide to prepare BCNs. The suspension of BCNs-loaded CoQ10 (CoQ10-BCNs) were prepared by antisolvent precipitation. The zeta potential of CoQ10-BCNs was about -36.01 mV. The properties of CoQ10, BCNs and CoQ10-BCNs were studied by scanning electron microscopy, transmission electron microscope, Fourier-transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermo gravimetric analysis. The crystallinity of CoQ10 decreased in CoQ10-BCNs compared with the raw CoQ10, and CoQ10-BCNs have good physicochemical stability. In oral bioavailability studies, the area under curve (AUC) of CoQ10-BCNs was about 3.62 times higher than the raw CoQ10 in rats.

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

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

TEMPO-oxidized cellulose nanofibril film from nano-structured bacterial cellulose derived from the recently developed thermotolerant Komagataeibacter xylinus C30 and Komagataeibacter oboediens R37-9 strains

Bacterial cellulose (BC), prepared from two recently developed thermotolerant bacterial strains (Komagataeibacter xylinus C30 and Komagataeibacter oboediens R37-9), were used as a raw material to synthesize nanofibril films. Field-emission scanning electron microscope (FE-SEM) observations confirmed the ultrafine nano-structure of BC pellicle (BCP) with average fibril widths between 50 and 60 nm. The BC was directly oxidized in a TEMPO/NaBr/NaClO system at pH of 10 for 2 h. TEMPO-oxidized bacterial cellulose nanofibrils (TOBCN) were obtained by a mild mechanical treatment and the TOBCN films were prepared through heat-drying. The oxidation yielded a recovery ratio between 70 and 80% by weight with an increase in the carboxylate content of 0.9-1.0 mmol g ^-1. Nanofibrillation yields were more than 90% and the resulting high aspect ratio TOBCNs were ~6 nm in average width with >800 nm in lengths, when observed under transmission electron microscope (TEM). TOBCN film of K. xylinus C30 exhibited high transparency (79%), tensile strength (142 MPa), Young's modulus (7.13 GPa), elongation around failure (3.89%), and work of fracture (2.29 MJ m^-3), when compared to the TOBCN films of K. oboediens R37-9 at 23 °C and 50% RH. Coefficients of thermal expansion of both the TOBCN films were low at around 6 ppm K^-1.

Bacterial cellulose in food industry: Current research and future prospects

Bacterial cellulose, a pure exocellular polysaccharide produced by microorganisms, has many excellent properties as compared with plant-derived cellulose, including high water holding capability, high surface area, rheological properties, biocompatibility. Due to its suspending, thickening, water holding, stabilizing, bulking and fluid properties, BC has been demonstrated as a promising low calorie bulking ingredient for the development of novel rich functional foods of different forms such as powder gelatinous or shred foams, which facilitate its application in food industry. In this review, the recent reports on the biosynthesis, structure and general application of bacterial cellulose in food industry have been summarized and discussed. The main application of bacterial cellulose in current food industry includes raw food materials, additive ingredients, packing materials, delivery system, enzyme and cell immobilizers. In addition, we also propose the potential challenges and explore the solution of expanding the application of BC in various fields.

Use of Anionic Polysaccharides in the Development of 3D Bioprinting Technology

Three-dimensional (3D) bioprinting technology is now one of the best ways to generate new biomaterial for potential biomedical applications. Significant progress in this field since two decades ago has pointed the way toward use of natural biopolymers such as polysaccharides. Generally, these biopolymers such as alginate possess specific reactive groups such as carboxylate able to be chemically or enzymatically functionalized to generate very interesting hydrogel structures with biomedical applications in cell generation. This present review gives an overview of the main natural anionic polysaccharides and focuses on the description of the 3D bioprinting concept with the recent development of bioprinting processes using alginate as polysaccharide.

Production of high crystallinity type-I cellulose from Komagataeibacter hansenii JR-02 isolated from Kombucha tea

In this study, a bacterial cellulose (BC) producing strain was isolated from Kombucha tea and identified as Komagataeibacter hansenii JR-02 by morphological, physiological, and biochemical characterization and 16S rRNA sequence. Then, the media components and culture conditions for BC production were optimized. Result showed that the highest BC yield was 3.14 ± 0.22 and 8.36 ± 0.19 g/L after fermentation for 7 days under shaking and static cultivation, respectively. Moreover, it was interesting that JR-02 could produce BC in nitrogen-free medium with the highest yield of 0.76 ± 0.06 g/L/7days, and the possible nitrogen fixation gene nifH was cloned from its genomic DNA. The BC produced by JR-02 was type-I cellulose with high crystallinity and thermodynamic stability, which was revealed from Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis methods. The crystallinity of static and shaking cultured BC were 91.76% and 90.69%, respectively. The maximum rate of weight loss of static and shaking BC occurred at temperature of approximately 373.1 °C and 369.1 °C, respectively. Overall, these results indicated that K. hansenii JR-02 had great potential to produce high crystallinity type-I BC in manufacture.

Isolation and identification of a bacterial cellulose synthesizing strain from kombucha in different conditions: Gluconacetobacter xylinus ZHCJ618

A bacterial cellulose (BC) synthesizing strain (Gluconacetobacter xylinus ZHCJ618) was isolated from kombucha and selected as the species for commercial applications owing to its high phenotypic stability and sustainable production capacity of 7.56 ± 0.57 g/L under static culturing conditions and 8.31 ± 0.79 g/L under shaking conditions. The morphological, physiological and biochemical characteristics of the strain were similar to those of Gluconacetobacter genus. The 16S rDNA sequence homologies with G. xylinus NCIB 11664 reached 99%, showing that the isolated strain can be identified as G. xylinus. The material properties of BC were studied by fourier transform infrared spectroscopy, scanning electronic microscopy, X-ray diffraction, thermogravimetric analysis, and tensile test. The results showed that BC synthesized under static conditions exhibited stronger tear strength, higher crystallinity, superior waterhold and rehydration rate than BC synthesized under shaking conditions.

Recent advances in polysaccharide bio-based flocculants

Natural polysaccharides, derived from biomass feedstocks, marine resources, and microorganisms, have been attracting considerable attention as benign and environmentally friendly substitutes for synthetic polymeric products. Besides many other applications, these biopolymers are rapidly emerging as viable alternatives to harmful synthetic flocculating agents for the removal of contaminants from water and wastewater. In recent years, a great deal of effort has been devoted to improve the production and performance of polysaccharide bio-based flocculants. In this review, current trends in preparation and chemical modification of polysaccharide bio-based flocculants and their flocculation performance are discussed. Aspects including mechanisms of flocculation, biosynthesis, classification, purification and characterization, chemical modification, the effect of physicochemical factors on flocculating activity, and recent applications of polysaccharide bio-based flocculants are summarized and presented.

Physicochemical characterization of high-quality bacterial cellulose produced by Komagataeibacter sp. strain W1 and identification of the associated genes in bacterial cellulose production

Komagataeibacter sp. W1 produced high-quality BC, the properties and synthesis mechanisms of which were analyzed by SEM, XRD and FTIR, and genome sequencing, respectively.

Effect of carbon sources on physicochemical properties of bacterial cellulose produced from Gluconacetobacter xylinus MTCC 7795

In this study, the effect of modified Hestrin Schramm (HS) medium supplemented with different carbon sources viz., glucose, fructose, galactose and lactic acid on the yield and physicochemical properties of bacterial cellulose (BC) produced from Gluconacetobacter xylinus strain MTCC 7795 in shake flask culture conditions was investigated. Growth studies indicated that all carbon sources supported the growth of bacteria, though specific growth rate and doubling time differs. Fructose gave the highest cellulose yield of 7.72 mg/ml after 130 h of fermentation, while yield in glucose and galactose supplemented medium were 4.49 mg/ml and 3.38 mg/ml, respectively. X-ray powder diffraction (XRD) analysis revealed that all BC samples were amorphous in comparison to commercial cellulose. Fourier transform infrared (FTIR) spectroscopic investigations of bacterial cellulose (BC) samples affirm the purity of the cellulose produced. No significant variations in physicochemical properties of cellulose samples produced with different carbon sources were observed. This study for the first time has investigated the effect of carbon sources on physicochemical properties of bacterial cellulose produced by G. xylinus MTCC 7795 and provides a strategy for economical production of BC with anticipated application in therapeutics and tissue engineering.

Preparation of an inoculum of Gluconacetobacter xylinus without mutants in shaken culture

AIMS

A high-quality inoculum of Gluconacetobacter xylinus is important to produce bacterial cellulose (BC), a versatile biomaterial. This work aims to develop a method of preparing an inoculum of this bacterium with high cell density and without mutants.

METHODS AND RESULTS

Inocula of G. xylinus ACCC 10220 without and with cellulase or carboxymethyl cellulose (CMC) were prepared in shaken culture. BC pellets and BC-negative mutants were present in the inoculum without additives but absent in the inoculum with additives. Based on BC weights statically produced in fresh BC-producing media initiated by different seed culture, the 24-h-shaken inoculum with 1·50% (w/v) CMC was the best because of high biomass and absence of mutants. The BC weights in fresh media inoculated by the 96-h-static inoculum and 24-h-shaken CMC inoculum at 7% (v/v) were 0·70 and 1·05 g l(-1) , respectively, implying significant difference (P < 0·01) in BC weights. However, structure properties of the two BC samples, including the crystallinity index, mass fraction of cellulose Iα , degree of polymerization (DP) and micromorphology were slightly different.

CONCLUSIONS

The 24-h-shaken CMC inoculum was the most suitable for a starter culture of BC.

SIGNIFICANCE AND IMPACT OF THE STUDY

A novel method of preparing G. xylinus inoculum in shaken culture was developed, featuring high biomass, absence of mutants and no BC entanglements. Cellulase or CMC added into the medium completely suppressed mutation of G. xylinus, and CMC facilitated to form colloidal BC with the low DP in shaken culture, indicating less BC stress to cells. These findings suggested the mutation could be induced by BC stress, and not by shear stress commonly accepted.

Isolation and identification of biocellulose-producing bacterial strains from Malaysian acidic fruits

Biocellulose (BC) is pure extracellular cellulose produced by several species of micro-organisms that has numerous applications in the food, biomedical and paper industries. However, the existing biocellulose-producing bacterial strain with high yield was limited. The aim of this study was to isolate and identify the potential biocellulose-producing bacterial isolates from Malaysian acidic fruits. One hundred and ninety-three bacterial isolates were obtained from 19 local acidic fruits collected in Malaysia and screened for their ability to produce BC. A total of 15 potential bacterial isolates were then cultured in standard Hestrin-Schramm (HS) medium statically at 30°C for 2 weeks to determine the BC production. The most potent bacterial isolates were identified using 16S rRNA gene sequence analysis, morphological and biochemical characteristics. Three new and potent biocellulose-producing bacterial strains were isolated from soursop fruit and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. Stenotrophomonas maltophilia WAUPM42 was the most potent biocellulose-producing bacterial strain that produced the highest amount of BC 0·58 g l(-1) in standard HS medium. Whereas, the isolates P. vagans WAUPM45 and B. fluminensis WAUPM53 showed 0·50 and 0·52 g l(-1) of BC production, respectively.

SIGNIFICANCE AND IMPACT OF THE STUDY

Biocellulose (BC) is pure extracellular cellulose that is formed by many micro-organisms in the presence of carbon source and acidic condition. It can replace plant-based cellulose in multifarious applications due to its unique characteristics. In this study, three potential biocellulose-producing bacterial strains were obtained from Malaysian acidic fruits and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. This study reports for the first time the new biocellulose-producing bacterial strains isolated from Malaysian acidic fruits.

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.

Evaluating the possibility of using acetone-butanol-ethanol (ABE) fermentation wastewater for bacterial cellulose production by Gluconacetobacter xylinus

To reduce the cost of bacterial cellulose (BC) production, the possibility of using acetone-butanol-ethanol (ABE) fermentation wastewater with high COD value (18 050 mg l(-1) ) for BC production by Gluconacetobacter xylinus was evaluated. After 7 days of fermentation, the highest BC yield (1·34 g l(-1) ) was obtained. The carbon sources including sugars (glucose and xylose), organic acids (acetic acid and butyric acid) and alcohol compounds (ethanol and butanol) were utilized by G. xylinus simultaneously during fermentation. Although the COD decrease ratio (about 14·7%) was low, the highest BC yield on COD consumption (56·2%, g g(-1) ) was relatively high and the remaining wastewater could be used for further BC fermentation. Besides, the environment of ABE fermentation wastewater showed small influence on the BC structure by comparison with the BC products obtained in traditional HS medium using field emission scanning electron microscope (FE-SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Overall, ABE fermentation wastewater is one promising substrate for BC production.

SIGNIFICANCE AND IMPACT OF THE STUDY

The possibility of using acetone-butanol-ethanol (ABE) fermentation wastewater for bacterial cellulose (BC) production by Gluconacetobacter xylinus was evaluated in this study. This is the first time that ABE fermentation wastewater was used as substrate for BC fermentation. The results provide detail information of metabolism of G. xylinus in ABE fermentation wastewater and the influence of wastewater environment on the structure of BC samples. Overall, this bioconversion could reduce the cost of BC production greatly.

Microbial Cellulose Production from Bacteria Isolated from Rotten Fruit

Microbial cellulose, an exopolysaccharide produced by bacteria, has unique structural and mechanical properties and is highly pure compared to plant cellulose. Present study represents isolation, identification, and screening of cellulose producing bacteria and further process optimization. Isolation of thirty cellulose producers was carried out from natural sources like rotten fruits and rotten vegetables. The bacterial isolates obtained from rotten pomegranate, rotten sweet potato, and rotten potato were identified asGluconacetobactersp. RV28,Enterobactersp. RV11, andPseudomonassp. RV14 through morphological and biochemical analysis. Optimization studies were conducted for process parameters like inoculum density, temperature, pH, agitation, and carbon and nitrogen sources usingGluconacetobactersp. RV28. The strain produced 4.7 g/L of cellulose at optimum growth conditions of temperature (30°C), pH (6.0), sucrose (2%), peptone (0.5%), and inoculum density (5%). Characterization of microbial cellulose was done by scanning electron microscopy (SEM).

Isolation and characterization of an efficient bacterial cellulose producer strain in agitated culture: Gluconacetobacter hansenii P2A

In this study, typical niches of acetic acid bacteria were screened for isolation of cellulose producer strains. Hestrin Schramm broth was used as enrichment and production media. Only nine out of 329 isolates formed thick biofilms on liquid surface and were identified as potential cellulose producers. Physiological and biochemical tests proved that all cellulose producers belonged to Gluconacetobacter genus. Most productive and mutation-resistant strain was subjected to 16S rRNA sequence analysis and identified as Gluconacetobacter hansenii P2A due to 99.8 % sequence similarity. X-ray diffraction analysis proved that the biofilm conformed to Cellulose I crystal structure, rich in Iα mass fraction. Static cultivation of G. hansenii P2A in HS medium resulted with 1.89 ± 0.08 g/l of bacterial cellulose production corresponding to 12.0 ± 0.3 % yield in terms of substrate consumption. Shaking and agitation at 120 rpm aided in enhancement of the amount and yield of produced cellulose. Productivity and yield reached up to 3.25 ± 0.11 g/l and 17.20 ± 0.14 % in agitated culture while a slight decrease from 78.7 % to 77.3 % was observed in the crystallinity index.

Improvement of bacterial cellulose production by manipulating the metabolic pathways in which ethanol and sodium citrate involved

Nowadays, bacterial cellulose has played more and more important role as new biological material for food industry and medical and industrial products based on its unique properties. However, it is still a difficult task to improve the production of bacterial cellulose, especially a large number of byproducts are produced in the metabolic biosynthesis processes. To improve bacterial cellulose production, ethanol and sodium citrate are added into the medium during the fermentation, and the activities of key enzymes and concentration of extracellular metabolites are measured to assess the changes of the metabolic flux of the hexose monophosphate pathway (HMP), the Embden-Meyerhof-Parnas pathway (EMP), and the tricarboxylic acid cycle (TCA). Our results indicate that ethanol functions as energy source for ATP generation at the early stage of the fermentation in the HMP pathway and the supplementation of ethanol significantly reduces glycerol generation (a major byproduct). While in the EMP pathway, sodium citrate plays a key role, and its supplementation results in the byproducts (mainly acetic acid and pyruvic acid) entering the gluconeogenesis pathway for cellulose synthesis. Furthermore, by adding ethanol and sodium citrate, the main byproduct citric acid in the TCA cycle is also reduced significantly. It is concluded that bacterial cellulose production can be improved by increasing energy metabolism and reducing the formation of metabolic byproducts through the metabolic regulations of the bypasses.

Production of microbial cellulose by a bacterium isolated from fruit

This study presents the production of bacterial cellulose (BC) by a bacterium isolated from a rotten fruit and its process optimization. Here, isolation and screening of potent cellulose producers were carried out from different natural sources, viz., soil, rotten fruits, and vegetables and vinegar. A total of 200 bacterial isolates were obtained, which were screened for cellulose production using Hestrin-Schramm medium. A novel and potent cellulose-producing bacterium was newly isolated from a rotten fruit and identified as Gluconacetobacter sp. F6 through 16S ribosomal DNA sequencing and morphological, cultural, and biochemical characteristics. After optimization of culture conditions, including pH, temperature, agitation, carbon/nitrogen sources, and inducers, the BC production was greatly increased from 0.52 to 4.5 g/l (8.65-fold increase). The optimal culture medium contained 1% (w/v) glucose, 1.5% (w/v) yeast extract, 0.5% (w/v) peptone, 0.27% (w/v) disodium hydrogen phosphate, 0.115% (w/v) citric acid, and 0.4% (w/v) ethanol. BC produced was analyzed for the presence of cellulose fibrils by epiflourescent microscopy using Calcofluor white stain and scanning electron microscopy and confirmed by NMR. There are very scanty reports about the optimization of BC production by bacteria isolated from rotten fruits.