Impact of Electrospun Piezoelectric Core–Shell PVDFhfp/PDMS Mesh on Tenogenic and Inflammatory Gene Expression in Human Adipose-Derived Stem Cells: Comparison of Static Cultivation with Uniaxial Cyclic Tensile Stretching

Specific microenvironments can trigger stem cell tenogenic differentiation, such as specific substrates or dynamic cell cultivation. Electrospun meshes composed by core–shell fibers (random or aligned; PDMS core; piezoelectric PVDFhfp shell) were fabricated by coaxial electrospinning. Elastic modulus and residual strain were assessed. Human ASCs were seeded on such scaffolds either under static conditions for 1 week or with subsequent 10% dynamic stretching for 10,800 cycles (1 Hz, 3 h), assessing load elongation curves in a Bose® bioreactor system. Gene expression for tenogenic expression, extracellular matrix, remodeling, pro-fibrotic and inflammatory marker genes were assessed (PCR). For cell-seeded meshes, the E modulus increased from 14 ± 3.8 MPa to 31 ± 17 MPa within 3 h, which was not observed for cell-free meshes. Random fibers resulted in higher tenogenic commitment than aligned fibers. Dynamic cultivation significantly enhanced pro-inflammatory markers. Compared to ASCs in culture flasks, ASCs on random meshes under static cultivation showed a significant upregulation of Mohawk, Tenascin-C and Tenomodulin. The tenogenic commitment expressed by human ASCs in contact with random PVDFhfp/PDMS paves the way for using this novel highly elastic material as an implant to be wrapped around a lacerated tendon, envisioned as a functional anti-adhesion membrane.

Green environment: Effects of acetate buffer on cellulose production by Acetobacter xylinum 0416 in fermented static cultivation

Bacterial cellulose (BC) white leathery pellicle produced from fermentation process of Acetobacter xylinum has many advantages such as high-water holding capacity, high porosity and high purity compared to plant cellulose. However, one of the BC application problems in industry is its low bio-cellulose productivity. The significant decrease of BC production can be effected by the reduction of pH culture due to production of by-product, gluconic acid during the static fermentation process. Therefore, the production of BC pellicle would be improved efficiently by controlling the pH of BC static cultivation. Bio-cellulose dry weight was at the greatest in acetates of 5.66 g/L while the dry weight derived from BC is 2.72 and 2.56 g/L in Control and Hestrin and Schramm (HS). The acetate buffered medium can be completed in a static fermentation method which can improve BC film production effectively.

Bacterial Cellulose Production from Acerola Industrial Waste Using Isolated Kombucha Strain

Bacterial Cellulose (BC) production is still considered expensive and challenging for industries. Herein, BC was produced through an acetic acid bacteria isolated from the kombucha consortium and an extract from acerola juice-industrial waste. The isolated bacterium was characterized through different assays (biochemical characterization and 16S rRNA gene) being identified as Komagataeibacter rhaeticus. BC production with static cultivation mode by the isolated strain was compared using traditional Hestrin-Schramm (HS) medium and acerola waste (AC) (5% w/v). The kinetic behavior of BC production was slightly higher in the HS medium reaching 2.9 g/L after 12 days of fermentation, while 2.3 g/L in the AC medium. Minor differences were observed between crystallite size and d-spacing, highlighting BC produced by the AC medium with higher crystallinity of 93.9% and two-fold breaking stress resistance in comparison with the conventional medium, with high-temperature stability and economically feasible, promissory results for further application of this synthetized cellulose obtained from industrial residues.

Bacterial Cellulose: Production, Characterization and Application as Antimicrobial Agent

Bacterial cellulose (BC) is recognized as a multifaceted, versatile biomaterial with abundant applications. Groups of microorganisms such as bacteria are accountable for BC synthesis through static or agitated fermentation processes in the presence of competent media. In comparison to static cultivation, agitated cultivation provides the maximum yield of the BC. A pure cellulose BC can positively interact with hydrophilic or hydrophobic biopolymers while being used in the biomedical domain. From the last two decades, the reinforcement of biopolymer-based biocomposites and its applicability with BC have increased in the research field. The harmony of hydrophobic biopolymers can be reduced due to the high moisture content of BC in comparison to hydrophilic biopolymers. Mechanical properties are the important parameters not only in producing green composite but also in dealing with tissue engineering, medical implants, and biofilm. The wide requisition of BC in medical as well as industrial fields has warranted the scaling up of the production of BC with added economy. This review provides a detailed overview of the production and properties of BC and several parameters affecting the production of BC and its biocomposites, elucidating their antimicrobial and antibiofilm efficacy with an insight to highlight their therapeutic potential.

Degeneration of Aortic Valves in a Bioreactor System with Pulsatile Flow

Calcific aortic valve disease is the most common valvular heart disease in industrialized countries. Pulsatile pressure, sheer and bending stress promote initiation and progression of aortic valve degeneration. The aim of this work is to establish an ex vivo model to study the therein involved processes. Ovine aortic roots bearing aortic valve leaflets were cultivated in an elaborated bioreactor system with pulsatile flow, physiological temperature, and controlled pressure and pH values. Standard and pro-degenerative treatment were studied regarding the impact on morphology, calcification, and gene expression. In particular, differentiation, matrix remodeling, and degeneration were also compared to a static cultivation model. Bioreactor cultivation led to shrinking and thickening of the valve leaflets compared to native leaflets while gross morphology and the presence of valvular interstitial cells were preserved. Degenerative conditions induced considerable leaflet calcification. In comparison to static cultivation, collagen gene expression was stable under bioreactor cultivation, whereas expression of hypoxia-related markers was increased. Osteopontin gene expression was differentially altered compared to protein expression, indicating an enhanced protein turnover. The present ex vivo model is an adequate and effective system to analyze aortic valve degeneration under controlled physiological conditions without the need of additional growth factors.

The structure of Gluconacetobacter hansenii GH 1/2008 population cultivated in static conditions on various sources of carbon

Bacterial cellulose (BC) is a natural polymer that has a number of unique properties that determine the need to synthesize large amounts of it and to search the ways to increase the productivity of strains and to optimize the nutritive media. It is known that the choice of the producer for BC synthesis has an impact on its final properties and on the productivity of this polymer production. Under static liquid phase cultivation conditions, all cellulose-producing bacteria form a uniform film on the medium surface that serves as a scaffold for cells immobilization, thus providing them with the access to the air/liquid interface, where the access to oxygen is not limited. Meanwhile, when cultivation goes under agitating conditions, most of Gluconacetobacter xylinus strains produce less cellulose in form of globules of various sizes, despite the better oxygen access. Several authors explain the lower cellulose outcome when cultivated under agitated conditions by the appearance of spontaneous mutants that do not produce cellulose in the population. It was revealed that when grown on agarized media, cellulosenon- producing mutants form colonies of a specific mucoid type, while non-mucoid phenotype cells form smooth colonies of non-mucoid type. To our knowledge, there is no published research on the impact of cultivation conditions and nutritive medium composition on the appearance of spontaneous phenotype mutations in the population of Gluconacetobacter hansenii representatives. The aim of the present research is to elucidate the impact of the carbon source on the productivity of G. hansenii strain and the appearance of cellulose-negative mutants under static cultivation conditions. We studied the strain G. hansenii GH 1/2008 (VKPM В-10547) as a BC source. Liquid phase static cultivation of G. hansenii GH 1/2008 was carried out using the modified Hestrin-Schramm (HS) medium, containing 4% of monosaccharides (glucose, fructose and galactose) or disaccharides (sucrose, maltose, lactose) as carbon sources. The occurrence of mutants was calculated considering phenotypes of colonies obtained by seeding the samples of cultural liquid and wash-offs of cells from films produced by the cultivation of the producer on modified agarized HS media. The polymer outcome was expressed as the film absolute dry weight (a.d.w.) per cultivation medium volume unit. We studied the morphology of the producer’s wild type and mutant cells by means of atomic force microscopy (AFM) (See Fig. 8). The structural organization of the produced films and gel was revealed by means of scanning electron microscopy (SEM) performed after freeze-drying. The composition of the fibers was checked acquiring FTIR Spectroscopy. We established that G. hansenii GH 1/2008 produces a dense film on media containing fructose, glucose and sucrose, while the polymer has gel consistence when grown on maltose, galactose and lactose (See Fig. 1). The maximal quantity (a.d.w.) of polymer was produced on fructose- and sucrose-containing media. The overall number of immobilized producer cells was considerably higher when grown on media with glucose, fructose and sucrose than on gels grown on those containing maltose, galactose and lactose (See Table 1). SEM imaging revealed considerable difference in the microscale organization of films and gels produced by G. hansenii GH 1/2008 on various carbon sources (See Fig. 2). Fructose-containing medium yields the densest structure with dense layers separated by 2μm thick areas filled with non-ordered BC fibrils. The microscale organization of sucrose- and glucose-based films were very similar and had a cell-like structure. In cases where the synthesized polymer had squeezable gel consistence, its microstructure was not layered but close to isotropic. The studies of gels by means of FTIR spectroscopy showed that the gels are also formed of BC molecules; the spectra were almost identical (See Fig. 4). The only difference, i.e. the intensity of the 1638 см-1 peak, can be explained by the presence of a higher amount of bound water in the latter. It is known that some strains of this species may produce glucuronic acid oligomers under unfavorable conditions, but peaks corresponding to carboxyl or carbonyl groups were not revealed in the spectra. This is the evidence that no detectable amounts of glucuronic acid were produced under conditions studied. The analysis of colonies of G. hansenii GH 1/2008 cultivated under static conditions on media containing various carbon sources revealed colonies with two dominating phenotypes: non-mucoid smooth convex colonies and mucoid flat ones (See Fig. 5). The number of cells forming smooth non-mucoid colonies on agarized media was maximal in the inoculations of cultural liquids after the cultivation on media containing fructose and sucrose, i.e. those carbon sources that demonstrated high productivity per 1L of cultural liquid (See Fig. 6). In the inoculations of the cultural liquid and wash-offs of cells immobilized on gels obtained by the cultivation on media containing galactose and lactose, the number of mucoid colonies was considerably higher (See Table 2). The clones forming mucoid type colonies did not produce BC films when reinoculated in liquid media, while those forming colonies of mucoid (smooth) type produce films on the 3rd day of cultivation (See Fig. 7). The analysis of cells shape and sizes by means of AFM did not reveal any statistically valid difference between the mutants and the wild type. The present research shows that the source of carbon is a selective factor in the formation of the inner composition of the population of clones of the bacterial cellulose producer Gluconacetobacter hansenii GH 1/2008. The proliferation of cellulosenegative cells arouses competition for the substrate with cellulose-positive cells of G. hansenii GH 1/2008 that reduces the number of the latter and the production of the exopolymer.

Aspergillus niger Decreases Bioavailability of Arsenic(V) via Biotransformation of Manganese Oxide into Biogenic Oxalate Minerals

The aim of this work was to evaluate the transformation of manganese oxide (hausmannite) by microscopic filamentous fungus Aspergillus niger and the effects of the transformation on mobility and bioavailability of arsenic. Our results showed that the A. niger strain CBS 140837 greatly affected the stability of hausmannite and induced its transformation into biogenic crystals of manganese oxalates—falottaite and lindbergite. The transformation was enabled by fungal acidolysis of hausmannite and subsequent release of manganese ions into the culture medium. While almost 45% of manganese was bioextracted, the arsenic content in manganese precipitates increased throughout the 25-day static cultivation of fungus. This significantly decreased the bioavailability of arsenic for the fungus. These results highlight the unique A. niger strain’s ability to act as an active geochemical factor via its ability to acidify its environment and to induce formation of biogenic minerals. This affects not only the manganese speciation, but also bioaccumulation of potentially toxic metals and metalloids associated with manganese oxides, including arsenic.

Silver Nanoparticles Impregnated Biocellulose Produced by Sweet Glutinous Rice Fermentation with the Genus Acetobacter

Bacterial cellulose (BC) is a natural renewable and biodegradable polymer and mostly synthesized from the bacteria genus, Acetobacter. More recent studies on effective biopolymer in various applications have been conducted due to its uniform structure and morphology superior to those of plant cellulose. In this study, the researchers have observed the effectiveness on antimicrobial activity of BC produced by sweet glutinous rice as a raw material instead of cellulosic materials. In the process, sweet glutinous rice fermented by Loog-pang was fermented for alcohol before further making rice vinegar product by inoculating with Gluconacetobacter xylinum TISTR 086, or mixed with indigenous vinegar producers, isolated Acetobacter spp. from our laboratory. Both these two samples gave comparable BC yields and the antimicrobial activity after impregnating with silver nanoparticles and also comparable to the control coconut vinegar medium (2.20 vs 2.00 g/L within 3 days). The optimum conditions for high BC production were pH 4 to 7, temperature approximately 25-30°C, slow agitation (50 to 90 rpm) as well as static cultivation. The remarkable antimicrobial activities of silver nanoparticles impregnated BC products (Ag-BC) showed high tentative in vitro inhibition on common pathogens in contaminated wounds; Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa by agar diffusion test. From this study, Ag-BC produced by fermented sweet glutinous rice (FSR) will therefore be one attractive affordable choice for being biomaterials applied in medical interests, especially skin disinfectant.