The unique mechanical properties of hydrated bacterial cellulose make it suitable for biomedical applications. This study evaluates the effect of concentrated sodium hydroxide treatment on the ...structural and mechanical properties of bacterial cellulose hydrogels using rheological, tensile, and compression tests combined with mathematical modelling. Bacterial cellulose hydrogels show a concentration-dependent and irreversible reduction in shear moduli, compression, and tensile strength after alkaline treatment. Applying a poroelastic biphasic model to through-thickness compressive stress-relaxation tests showed the alkaline treatment to induce no significant change in axial compression, an effect was observed in the radial direction, potentially due to the escape of water from within the hydrogel. Scanning electron microscopy showed a more porous structure of bacterial cellulose. These results show how concentration-dependent alkaline treatment induces selective weakening of intramolecular interactions between cellulose fibres, allowing the opportunity to precisely tune the mechanical properties for specific biomedical application, e.g., faster-degradable materials.
•Concentrated alkaline treatment weakens the interaction of BC fibres.•The porosity and permeability of BC are enhanced by alkaline treatment.•The extensibility of BC is enhanced by alkaline treatment.
Abstract
Adaptive laboratory evolution through 12 rounds of culturing experiments of the nanocellulose‐producing bacterium
Komagataeibacter hansenii
ATCC 23769 in a liquid fraction from hydrothermal ...pretreatment of corn stover resulted in a strain that resists inhibition by phenolics. The original strain generated nanocellulose from glucose in standard Hestrin and Schramm (HS) medium, but not from the glucose in pretreatment liquid.
K. hansenii
cultured in pretreatment liquid treated with activated charcoal to remove inhibitors also converted glucose to bacterial nanocellulose and used xylose as carbon source for growth. The properties of this cellulose were the same as nanocellulose generated from media specifically formulated for bacterial cellulose formation. However, attempts to directly utilize glucose proved unsuccessful due to the toxic character of the lignin‐derived phenolics, and in particular, vanillan and ferulic acid. Adaptive laboratory evolution at increasing concentrations of pretreatment liquid from corn stover in HS medium resulted in a strain of
K. hansenii
that generated bacterial nanocellulose directly from pretreatment liquids of corn stover. The development of this adapted strain positions pretreatment liquid as a valuable resource since
K. hansenii
is able to convert and thereby concentrate a dilute form of glucose into an insoluble, readily recovered and value‐added product—bacterial nanocellulose.
ABSTRACT In this study, we have optimized production of bacterial cellulose (BC) by Komagataeibacter hansenii ATCC 23769 in a static cultivation using sisal juice, an agroindustrial residue, as ...substrate. Optimization of fermentation parameters has been carried out using the one-variable-at-a-time method. Effect of initial sugar concentration, pH, nitrogen supplement, and cultivation time was evaluated. The influence of nitrogen source and quantity for bacterial cellulose production was studied using a central composite rotational design (CCRD).The highest production of BC (3.38 g/L) was obtained after 10 days of cultivation, using sisal juice (pH 5) at 15 g/L of sugars and supplemented with 7.5 g/L of extract yeast. The cellulose production yield in selected sisal culture conditions was three times higher than the yield in synthetic medium, indicating that sisal juice is a suitable substrate for BC production.
Bacterial cellulose (BC) is a natural polymer renowned for its unique physicochemical and mechanical attributes, including notable water-holding capacity, crystallinity, and a pristine fiber network ...structure. While BC has broad applications spanning agriculture, industry, and medicine, its industrial utilization is hindered by production costs and yield limitations. In this study, Rhizobium sp. was isolated from bean roots and systematically assessed for BC synthesis under optimal conditions, with a comparative analysis against BC produced by Komagataeibacter hansenii. The study revealed that Rhizobium sp. exhibited optimal BC synthesis when supplied with a 1.5% glucose carbon source and a 0.15% yeast extract nitrogen source. Under static conditions at 30 °C and pH 6.5, the most favorable conditions for growth and BC production (2.5 g/L) were identified. Modifications were introduced using nisin to enhance BC properties, and the resulting BC-nisin composites were comprehensively characterized through various techniques, including FE-SEM, FTIR, porosity, swelling, filtration, and antibacterial activity assessments. The results demonstrated that BC produced by Rhizobium sp. displayed properties comparable to K. hansenii-produced BC. Furthermore, the BC-nisin composites exhibited remarkable inhibitory activity against Escherichia coli and Pseudomonas aeruginosa. This study contributes valuable insights into BC's production, modification, and characterization utilizing Rhizobium sp., highlighting the exceptional properties that render it efficacious across diverse applications.
•Bacterial cellulose production can be affected by altering medium composition.•Enhanced mechanical properties of the co-cultured BC can be maintained.•Co-culturing in bioreactor also produced BC ...with enhanced mechanical behaviors.
Bacterial cellulose (BC11Uncommon abbreviation used: BC – Bacterial Cellulose) is a biomaterial produced by various strains of microorganisms. BC has improved strength and unique structural properties as compared to plant cellulose, thus has many usages in the food and pharmaceutical industries. In our previous study, a novel co-culture agitated fermentation of Komagataeibacter hansenii, a BC producer, with Aureobasidium pullulans, a producer of pullulan polysaccharide, had been demonstrated where the BC produced exhibited improved mechanical properties. Therefore, this study is undertaken to analyze BC production under different medium composition using response surface methodology (RSM) in shake-flasks and benchtop bioreactors. A verified local high point provided 22.4% higher BC production and 4.5- to 6- folds higher elastic moduli in shake-flasks and bioreactors compared to the baseline media. Overall, the study had revealed the potential of the co-culturing method to enhance BC production while maintaining the desired mechanical properties of BC produced in shake-flasks and larger scale bioreactors.
Adaptive laboratory evolution through 12 rounds of culturing experiments of the nanocellulose‐producing bacterium Komagataeibacter hansenii ATCC 23769 in a liquid fraction from hydrothermal ...pretreatment of corn stover resulted in a strain that resists inhibition by phenolics. The original strain generated nanocellulose from glucose in standard Hestrin and Schramm (HS) medium, but not from the glucose in pretreatment liquid. K. hansenii cultured in pretreatment liquid treated with activated charcoal to remove inhibitors also converted glucose to bacterial nanocellulose and used xylose as carbon source for growth. The properties of this cellulose were the same as nanocellulose generated from media specifically formulated for bacterial cellulose formation. However, attempts to directly utilize glucose proved unsuccessful due to the toxic character of the lignin‐derived phenolics, and in particular, vanillan and ferulic acid. Adaptive laboratory evolution at increasing concentrations of pretreatment liquid from corn stover in HS medium resulted in a strain of K. hansenii that generated bacterial nanocellulose directly from pretreatment liquids of corn stover. The development of this adapted strain positions pretreatment liquid as a valuable resource since K. hansenii is able to convert and thereby concentrate a dilute form of glucose into an insoluble, readily recovered and value‐added product—bacterial nanocellulose.
Adaptive laboratory evolution through 12 rounds of culturing experiments of the nanocellulose‐producing bacterium Komagataeibacter hansenii ATCC 23769 in a liquid fraction from hydrothermal pretreatment of corn stover resulted in a strain that resists inhibition by phenolics.
Cellulose is the most common polymer in the world, formed by β-1,4 linked glucopyranose units. In this study, citrus peels (lemon, mandarin, orange and grapefruit) were used for the production of ...bacterial cellulose (BC). The peels were hydrolyzed with dilute acid and hydrolysates were used for BC production. The production of BC was carried out at 28–32 °C for 21 days under static conditions with
Komagataeibacter hansenii
GA2016. BC yields were found to be between 2.06 and 3.92%. It was found that the FTIR spectra of the BCs produced in citrus peel hydrolysates were similar to BC produced in the commercially available nutrients. The result of this study showed that all the BCs produced from citrus peels were characterized to have high water holding capacity, thin fiber diameter, high the thermal stability and high crystallinity.
Bacterial cellulose (BC) represents a renewable biomaterial with unique properties promising for biotechnology and biomedicine.
Komagataeibacter hansenii
ATCC 53,582 is a well-characterized ...high-yield producer of BC used in the industry. Its genome encodes three distinct cellulose synthases (CS),
bcsAB1
,
bcsAB2
, and
bcsAB3
, which together with genes for accessory proteins are organized in operons of different complexity. The genetic foundation of its high cellulose-producing phenotype was investigated by constructing chromosomal in-frame deletions of the CSs and of two predicted regulatory diguanylate cyclases (DGC),
dgcA
and
dgcB
. Proteomic characterization suggested that BcsAB1 was the decisive CS because of its high expression and its exclusive contribution to the formation of microcrystalline cellulose. BcsAB2 showed a lower expression level but contributes significantly to the tensile strength of BC and alters fiber diameter significantly as judged by scanning electron microscopy. Nevertheless, no distinct extracellular polymeric substance (EPS) from this operon was identified after static cultivation. Although transcription of
bcsAB3
was observed, expression of the protein was below the detection limit of proteome analysis. Alike BcsAB2, deletion of BcsAB3 resulted in a visible reduction of the cellulose fiber diameter. The high abundance of BcsD and the accessory proteins CmcAx, CcpAx, and BglxA emphasizes their importance for the proper formation of the cellulosic network. Characterization of deletion mutants lacking the DGC genes
dgcA
and
dgcB
suggests a new regulatory mechanism of cellulose synthesis and cell motility in
K. hansenii
ATCC 53,582. Our findings form the basis for rational tailoring of the characteristics of BC.
Key points
•
BcsAB1 induces formation of microcrystalline cellulose fibers.
•
Modifications by BcsAB2 and BcsAB3 alter diameter of cellulose fibers.
•
Complex regulatory network of DGCs on cellulose pellicle formation and motility.
•Bacterial cellulose was grown using two new Komagataeibacter strains.•Nanofibers and nanopaper was obtained from the bacterial cellulose.•Both materials consisted of highly crystalline ...cellulose.•Komagataeibacter rhaeticus cellulose grown in glucose–fructose media displayed the best properties.•Nanopaper showed higher mechanical properties than dried bacterial cellulose films.
Bacterial cellulose (BC) samples were obtained using two culture media (glucose and glucose+fructose) and two bacteria (Komagataeibacter rhaeticus and Komagataeibacter hansenii). Nanopaper was obtained from the BC through oxidation and both were studied to determine the impact of culture media and bacteria strain on nanofiber structure and mechanical properties. AFM and SEM were used to investigate fibre dimensions and network morphology; FTIR and XRD to determine cellulose purity and crystallinity; carboxyl content, degree of polymerisation and zeta potential were used to characterise nanofibers. Tensile testing showed that nanopaper has up to 24 times higher Young's modulus (7.39GPa) than BC (0.3GPa). BC displayed high water retention values (86–95%) and a degree of polymerisation up to 2540. Nanofibers obtained were 80–120nm wide and 600–1200nm long with up to 15% higher crystallinity than the original BC. It was concluded that BC is an excellent source for easily obtainable, highly crystalline and strong nanofibers.
A polymicrobial biofilm model of Komagataeibacter hansenii and Pseudomonas aeruginosa was developed to understand whether a pre-existing matrix affects the ability of another species to build a ...biofilm. P. aeruginosa was inoculated onto the preformed K. hansenii biofilm consisting of a cellulose matrix. P. aeruginosa PAO1 colonized and infiltrated the K. hansenii bacterial cellulose biofilm (BC), as indicated by the presence of cells at 19 μm depth in the translucent hydrogel matrix. Bacterial cell density increased along the imaged depth of the biofilm (17-19 μm). On day 5, the average bacterial count across sections was 67 ± 4 % P. aeruginosa PAO1 and 33 ± 6 % K. hansenii. Biophysical characterization of the biofilm indicated that colonization by P. aeruginosa modified the biophysical properties of the BC matrix, which inlcuded increased density, heterogeneity, degradation temperature and thermal stability, and reduced crystallinity, swelling ability and moisture content. This further indicates colonization of the biofilm by P. aeruginosa. While eDNA fibres - a key viscoelastic component of P. aeruginosa biofilm - were present on the surface of the co-cultured biofilm on day 1, their abundance decreased over time, and by day 5, no eDNA was observed, either on the surface or within the matrix. P. aeruginosa-colonized biofilm devoid of eDNA retained its mechanical properties. The observations demonstrate that a pre-existing biofilm scaffold of K. hansenii inhibits P. aeruginosa PAO1 eDNA production and suggest that eDNA production is a response by P. aeruginosa to the viscoelastic properties of its environment.
PDF
