Engineering and Characterization of Bacterial Nanocellulose Films as Low Cost and Flexible Sensor Material.

Antarctic microorganisms have developed extraordinary strategies for adaptation. They have also demonstrated the ability to produce various biopolymers in response to environmental stress. The demand for biopolymers is constantly increasing and is expected to grow further. Among emerging biomaterials, bacterial cellulose (BC) is generating significant interest due to its unique characteristics that distinguish it from plant-based cellulose. BC exhibits higher purity, water-holding capacity, and tensile strength compared to its plant-based counterpart. Furthermore, BC can be obtained through environmentally friendly protocols. Several bacterial strains have already been identified as cellulose producers, including Komagataeibacter xylinus. In this study, a marine bacterial strain named Pseudomonas sp. ef1, isolated from a consortium associated with the Antarctic ciliate Euplotes focardii, was tested for cellulose production. We found that this Antarctic Pseudomonas can produce BC in conditions that appear unique to this bacterial strain. Furthermore, the final BC product is structurally different from that obtained from the well-known BC producer Komagataeibacter xylinus. Additionally, a putative cellulose synthase was identified from the Pseudomonas sp. ef1 genome, exhibiting unique characteristics that may account for the unique BC production capability of this Antarctic marine Pseudomonas. The versatility of BC opens numerous applications, including in papermaking, food, pharmaceutical, and biomedical sectors.

Development and evaluation of ciprofloxacin-bacterial cellulose composites produced through in situ incorporation method

Utilization of acetate buffer to improve bacterial cellulose production by Gluconacetobacter xylinus

Bacterial cellulose (BC) is high purity and several current potential uses in industries. Liquid byproduct of sweet corn canning process (SC) contains fermentable sugars which could be utilized to get higher economic benefits. Therefore, this research aimed to produce BC from SC by Gluconacetobacter xylinus under static condition and use it to improve mechanical properties of natural rubber. The ratio of SC to coconut juice for cellulose production was studied. The result revealed that production yield, water holding capacity and tensile strength of BC produced from the medium containing coconut juice to SC at a ratio of 75:25 (w/w) supplemented with 1% acetic acid, 1% ammonium sulfate and 5% sucrose (w/w) was not significant different from BC obtained from a coconut juice medium. The FTIR spectra of BC showed the characteristics of cellulose. The morphology of BC exhibited high fibril network. BC is showed reinforcement in natural rubber composites due to enhance the stress value, whereas reduce the strain value.

The advances in bioprocess design, genetic engineering, and media optimization have enabled enhanced bacterial cellulose (BC) production and its application for diverse purposes. Following the requirements of a bioeconomy, numerous approaches were conducted to investigate alternative carbon or nitrogen sources from industrial by-products for BC biosynthesis. They can, however, not only affect the BC production but also its properties. Beet molasses, vinasse, and waste beer fermentation broth (WBFB) have thus been investigated in single and combined approaches for their BC production potential and effects on structural properties using Komagataeibacter xylinus DSM 2325. Therefore, the composition of each complex component was initially analyzed for total organic carbon (TOC), total bound nitrogen (TNb), sugars, organic acids, and alcohols. The polymer properties were characterized via gel permeation chromatography and X-ray diffraction. In dynamic shake flask cultivations, the exchange of Hestrin-Schramm (HS) medium components for a combination of all three complex substrates on a TOC- or TNb-based quantity resulted in the highest BC concentration (8.2 g L−1). Comparable concentrations were achieved when combining molasses and WBFB (8.1 g L−1). Each investigated complex component led to differing degrees of polymerization (DPn: 2751−4601) and BC crystallinities (26−58%) in comparison to HS medium. Beet molasses and vinasse were found to decrease the polymer crystallinity but induce higher DPn whereas the opposite occurred for WBFB. This study thus highlights beneficial effects of food industry by-products for BC biosynthesis and elucidates concomitantly occurring structural polymer alterations to enable further studies dealing with alternative substrates for structurally tailored BC production.

Biofilm reactors show several advantages over suspended cell reactors, especially in their biomass density, operation convenience, and production yield. The structure of biofilm matrix contributes to high resistance of microorganisms to extreme conditions of pH, temperature, toxic chemicals, and mechanical shocks. Submerged fermentation has been used for BC production due to its feasibility of large-scale production in industry. The purpose of this research topic is to improve the rate of bacterial cellulose (BC) production by exploring new culture methods with a biofilm reactor. Biofilm reactor included a plastic composite support (PCS) which was attached on agitation shaft to promote effective nutrient delivery and to control biofilm thickness. BC harvested from PCS biofilm reactor was evaluated in terms of the physical and mechanical properties, including the degree of crystallinity and crystal size by x-ray diffraction (XRD), the water content and degradation characteristics using thermogravimetric analysis (TGA), nanostructure using field emission scanning electron microscopy (FESEM), and tensile strength using a dynamic mechanical analyzer (DMA). Among thirteen types of PCS, PCS blended with dried soybean hulls, defatted soybean flour, yeast extract, dried bovine red blood cells, and mineral salts (SFYR+) yielded the highest BC (7.05 g/l) which is 2.5 fold compared to control (2.82 g/l). The XRD studies indicated that crystallinity of BC pellicle is about 90%. FESEM image showed Acetobacter xylinum grew and produced BC on the PCS. TGA results showed that BC pellicle on the PCS had 95% water content. The results clearly demonstrated that implemented with PCS in agitated bioreactor can enhance BC production.

To offset the negative effects of aeration on bacterial cellulose (BC) production by acetic acid bacteria using enmeshed cellulose microfibrils (CM) on luffa sponge matrices (LSM). The CM were enmeshed on LSM (LSM-CM). The optimal amount of LSM-CM was determined for BC production under aerated conditions. Without LSM-CM, no BC was produced in seven out of nine production cycles at the highest aeration rate (9lmin-1 ). However, with 0·5% LSM-CM and an aeration rate of 3lmin-1 , a satisfactory oxygen transfer coefficient was achieved, and also a good yield of BC (5·24gl-1 ). Moreover, the LSM-CM was able to be recycled through nine consecutive BC production cycles. The highest BC yields (from 5·8±0·4 to 6·6±0·4gl-1 ) were associated with high bacterial biomass and this was confirmed by scanning electron microscopy. We confirm that LSM-CM works well as a starter. Microenvironments low in dissolved oxygen within the matrices of LSM-CM are important for BC production under aeration conditions. The LSM-CM provides a microenvironment which offsets the negative effects of aeration on BC production. A sustainable, economic process for mass BC production is described using recycled LSM-CM with aeration.

본 연구에서는 물리적 강도가 뛰어나고 고온에서 안정하며 유연한 친환경 소재인 박테리아 셀룰로오스를 기반으로 투명 전도성막을 제조하였다. 전기전도성의 확보를 위해 은나노와이어(AgNW)와 그래핀을 도입하였다. 합성한 AgNW는 평균적으로 길이 약 <TEX>$15{\mu}m$</TEX>, 폭 약 70 nm로 종횡비 214이었다. 종횡비가 클수록 접촉저항을 낮추어 전도성을 개선시키게 된다. 총 7가지의 막을 제조하고 열적 및 전기적 물성을 조사하였다. 또 전도성막으로 제조하기 위해서 BC막을 칼로 길이 2 mm, 깊이 <TEX>$50{\mu}m$</TEX> 간격으로 홈을 파서 직교상의 그물모양을 형성한 후 이 홈에 AgNW와 그래핀을 채워 넣었다. 대표적으로 AgNW 첨가막은 두께 <TEX>$350{\mu}m$</TEX>, 전자농도 <TEX>$1.53{\times}10^{19}/cm^3$</TEX>, 전자이동도 <TEX>$6.63{\times}10^5cm^2/Vs$</TEX>, 비저항 <TEX>$0.28{\Omega}{\cdot}cm$</TEX>로 가장 우수한 전기적 특성을 지닌 것으로 평가되었다. 또한 그래핀 첨가막은 두께 <TEX>$360{\mu}m$</TEX>, 전자농도 <TEX>$7.74{\times}10^{17}/cm^3$</TEX>, 전자이동도 <TEX>$0.17cm^2/Vs$</TEX>, 비저항 <TEX>$4.78{\Omega}{\cdot}cm$</TEX>이었다. 550 nm 광투과는 AgNW 첨가막 98.1%, 그래핀 첨가막 80.9%로 투명한 전도성 막이 형성되었다. 모든 막이 평면과 휜 상태에서 LED 점등 실험에서 전구의 밝기에 차이가 있었으나 불이 켜졌다. <TEX>$150{\pm}5^{\circ}C$</TEX>의 열판에서 박테리아 셀룰로오스 막은 형태가 매우 안정하였으나 같은 두께의 PET는 형태가 심하게 변형되었다. 이러한 연구 결과를 통해 박테리아 셀룰로오스 기반의 투명전도성막을 제조할 수 있는 가능성을 확인하였다. A transparent film was fabricated based on bacterial cellulose (BC), BC has excellent physical strength and stability at high temperature and it is an environmental friendly flexible material. In order to improve the conductivity, silver nanowire (AgNW) and/or graphene were introduced to the BC membrane. The aspect ratio of the AgNW synthesized in this study was 214, with a length of <TEX>$15{\mu}m$</TEX> and width of 70 nm. The higher aspect ratio improved the conductivity by reducing the contact resistance. The thermal and electrical properties of 7 types of films prepared were investigated. Each film was fabricated with rectangular shape (<TEX>$2mm{\times}2mm{\times}50{\mu}m$</TEX>). The films were scored with a net shape by a knife, and filled with AgNW and graphene to bestow conductivity. The film filled with AgNW showed favorable electrical characteristics with a thickness of <TEX>$350{\mu}m$</TEX>, electron concentration of <TEX>$1.53{\times}10^{19}$</TEX>, electron mobility of <TEX>$6.63{\times}10^5$</TEX>, and resistivity of 0.28. The film filled with graphene had a thickness of <TEX>$360{\mu}m$</TEX>, electron concentration of <TEX>$7.74{\times}10^{17}$</TEX>, electron mobility of 0.17, and resistivity of 4.78. The transmittances at 550 nm were 98.1% and 80.9%, respectively. All the films were able to light LEDs bulbs although their brightness differed. A thermal stability test of the BC and PET films at <TEX>$150{\pm}5^{\circ}C$</TEX> showed that the BC film was more stable, whereas the PET film was quickly banded. From these results, it was confirmed that there it is possible to fabricate new transparent conductivity films based on BC.

Effect of co-culture of Komagataeibacter nataicola and selected Lactobacillus fermentum on the production and characterization of bacterial cellulose

Mannose constitutes a principal component in numerous biomass hemicelluloses; however, its utilization by the cellulose-producing bacterium Komagataeibacter xylinus is inefficient. Consequently, during biorefinery and the transformation of biomass rich in mannose for the production of the high-value biological product, bacterial cellulose (BC), the biomass components cannot be fully utilized, leading to resource wastage. Moreover, inappropriate discharge of the fermentation effluent may also result in environmental pollution. This study addressed the underutilization of mannose in spent coffee grounds (SCGs) by introducing a fusion vector expressing mannokinase and phosphomannose isomerase into K. xylinus ATCC 23770, thereby enhancing mannose utilization in this strain model. SCG was pretreated with concentrated sulfuric acid to disrupt crystalline structures, followed by enzymatic hydrolysis to extract saccharides. When culturing in SCG hydrolysate, BC pellicle-derived inoculum achieved 1.2-fold higher BC yield than broth inoculum, attributed to BC matrix protection. The engineered strain K. xylinus CGMCC 31806 demonstrated superior mannose assimilation, yielding 1.5-fold more BC than wild type in simulated SCG medium. In authentic SCG medium without extra nitrogen addition, BC production reached 3.80 g/L, a 1.2- to 2.5-fold increase. The obtained BC exhibited enhanced mechanical properties with 40-84% higher tensile strength and 20-75% increased Young's modulus. This study validates a dual strategy combining agro-waste valorization and targeted strain modification, establishing a collaborative optimization framework linking biomass feedstocks, microbial engineering, and bioprocessing for cost-effective BC production. Future research would utilize existing commercial high-yield strains to replicate the expression strategy of this fusion protein, in order to achieve truly efficient industrial production.IMPORTANCEThe inefficient utilization of mannose, a major hemicellulose component prevalent in biomass by Komagataeibacter xylinus represents a significant bottleneck in the sustainable, cost-effective bioproduction of bacterial cellulose (BC). This underutilization would lead to wasted resources and potential environmental pollution from fermentation effluents. The study directly addresses this critical challenge by pioneering a synergistic "Feedstock-Strain-Process" integration strategy in advancing BC industrialization. We demonstrate the significant impact of engineering K. xylinus for enhanced mannose assimilation coupled with optimized biorefinery of agro-industrial waste, taking mannose-rich spent coffee grounds, as the representative raw material. This integrated approach not only valorizes abundant agricultural waste streams significantly boosting BC yields under nutrient-limited conditions but also generates BC with superior mechanical properties. The study establishes an actionable blueprint for advancing BC industrialization through collaborative optimization of biomass feedstocks, targeted microbial engineering, and process innovation, aligning with the goals of the circular bioeconomy and sustainable material production.

The objective of the work is to examine the potential utilization of Palmyra palm jaggery (PPJ) for the enhancement of bacterial cellulose (BC) production byGluconacetobacter liquefaciens. To evaluate the culturing condition, the production of BC fermentation was carried out in batch mode using different carbon sources namely glucose, sucrose and PPJ. PPJ in the HS medium (PHS medium) resulted maximum concentration of BC (14.35 ± 0.18g/L) under shaking condition than other carbon sources in HS medium. The influence of different medium variables including initial pH and nitrogen sources on BC production was investigated using PHS medium under shaking condition. The maximum BC concentration of 17.79 ± 2.4g/L was obtained in shaking condition at an initial pH of 5.6 using yeast extract as nitrogen source. Stoichiometric equation for the cell growth and BC synthesis was developed using elemental balance approach. The metabolic heat of reaction (40kcal generated per liter of medium) was evaluated using electron balance approach. Based on the process economic analysis and the yield of BC during the fermentation, PHS medium without nitrogen source could be a promising cost-effective nutrient than HS medium. Thermal stability, crystallinity index and structural characterizations of produced BC using PPJ medium were evaluated using TGA, XRD and FTIR and the obtained results were compared with HS medium containing glucose and sucrose.

Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC) and a water-soluble polysaccharide called acetan in corn steep liquor-fructose medium. Acetobacter xylinum EP1, which is incapable of acetan production was derived by disrupting the aceA gene of BPR2001. The BC production by EP1 (2.88 g/L) was lower than that by BPR2001 (4.6 g/L) in baffled-flask culture. When purified acetan or agar was added to the medium from the start of cultivation, the BC production by EP1 was enhanced and the final BC yield of EP1 was almost the same as that of BPR2001. A similar improvement of BC production by EP1 by the addition of agar was also confirmed by cultivation in a 50-L airlift reactor. From these results, the role of acetan in BC production is associated with the increase in the viscosity of the culture medium which may hinder coagulation of BC and cells in the culture, thereby accelerating the growth of BPR2001 and BC production by BPR2001.

BC 합성능이 우수하며, 진탕배양에서도 BC를 생산할 수 있는 능력이 있음이 확인된 Aectobacter sp. V6로부터 BC 생산을 위한 당밀 전처리 조건을 검토하였으며, 생산된 BC의 물리화학적 특성을 검토하였다. 당밀을 배지성분으로 사용하기 위해 전처리를 실시한 결과, 1%의 TP가 BC 생산에 가장 효율적이었다. 전처리한 당밀배지를 이용하여 정치 및 진탕배양에서 생산된 BC의 물리화학적 특성을 조사한 결과, 모든 BC는 유화능이 있었으나 유화 안정능은 낮았다. 또한 모든 BC에서 높은 수분 보유능이 나타났으며, 특히 정치배양에서 생산된 BC는 <TEX>$\alpha$</TEX>-cellulose보다 14배 이상 높았다. BC의 점도는 모두 <TEX>$\alpha$</TEX>-cellulose보다 높았으며, 점도계 회전속도의 증가에 따라 급격히 감소하였다. FT-IR을 통한 조성 분석에서 BC는 식물성 셀룰로 오스와 차이가 없었으며, XRD를 통한 결정성 분석에서는 모든 BC가 결정성을 나타내었다. BC의 미세구조를 조사한 결과, 모든 BC가 미세망상구조로 이루어져 있었는데, 이로 인해 BC는 식물성 셀룰로오스와는 달리 독특한 물성을 가지는 것으로 판단되었다. 또한 정치배양에서 생산된 BC는 진탕배양에서 생산된 것보다 셀룰로오스 미세섬유가 조밀하게 얽혀있음을 알 수 있었다. The aim of this study is to investigate cane molasses pretreatments for the production of cellulose by Acetobacter sp. V6, which has excellent bacterial cellulose (BC) producing capacity in the shaking culture. Among pretreatments of cane molasses, 1% (w/v) tricalcium phosphate (TP) treatment was more efficient in BC production. The physico-chemical properties of BCs that were produced in static and shaking cultures were also investigated. Although BC had an emulsifying ability, its emulsion stability was low. Water holding capacity (WHC) of BC was high; the WHC of BC produced in static culture was 14 times higher than that of <TEX>$\alpha$</TEX>-cellulose. In addition, the viscosity of BC was higher than that of <TEX>$\alpha$</TEX>-cellulose. Composition analysis by FT-IR showed no difference in composition between BC and plant cellulose. In the crystallinity analysis by XRD, all BC samples showed crystallinity. All BC samples showed reticulated structures consisting of ultrafine cellulose fibriles. Microfibriles of cellulose from static culture were especially more compact than those of cellulose from shaking culture.

Nanocomposite Based on Bacterial Cellulose and Silver Nanoparticles Improve Wound Healing Without Exhibiting Toxic Effect

Bacterial cellulose (BC) is a non-toxic, high-purity, and biocompatible polymer that is abundant in various bacteria and does not contain lignin, hemicellulose and pectin found in plant cellulose. High concentrations of carbon sources can limit yields of BC. One potential solution to enhance BC production is the use of elicitors like plant extracts; however, the use of plant extracts such as Aloe vera leaf extract remains limited. Therefore, the current study aimed to investigate the effects of Aloe vera leaves on BC properties, glucose consumption, and synthesis rate by Komagataeibacter xylinus to increase BC volumetric production. Aloe vera extract was incorporated into the culture medium (given the conditions used), and BC was analyzed after 5 to 7 days of fermentation. The fermentation process at 30°C showed that increasing Aloe vera extract volume to 30% (v/v) improved glucose consumption, resulting in 3.35 g/L of BC accumulated in culture flasks. Adding different amounts of Aloe vera leaf extracts to the bacteria culture altered the morphology of the BC film and trapped Aloe vera extract inside the BC fibers. The treatment with 30% (v/v) Aloe vera leaf extract also resulted in a less homogeneous Aloe-BC morphological surface structure. The X-ray diffractometer (XRD) crystallinity index of control BC improved from 83.70% to 93.70% compared to the 30% Aloe-BC. According to the IR spectral analysis, the presence of amine groups in dried BC samples is confirmed by the detected absorption in the 1536-1635 cm⁻¹ range, which indicates N–H bending vibrations. In conclusion, including Aloe vera leaf increased glucose intake, enhanced BC biomass, and altered the shape of the BC.