Enhanced production of bacterial cellulose by using a biofilm reactor and its material property analysis

Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS) were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC) production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L) that was 2.5-fold greater than the control (2.82 g/L). The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93%) and similar crystal size (5.2 nm) to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher T _max compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC. The results clearly demonstrated that implementation of PCS within agitated fermentation enhanced BC production and improved its mechanical properties and thermal stability.     

Utilization of the buffering capacity of corn steep liquor in bacterial cellulose production by Acetobacter xylinum

Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC). Using a pH sensor for the accurate control of pH, which is one of the most critical factors for efficient BC production, is difficult especially in a baffled shake-flask and an airlift reactor. The buffering capacity of corn steep liquor (CSL) was estimated by measuring (buffering capacity) values in advance and was used to maintain the pH within the optimal range during the production of BC. When CSL was added to either a shake-flask, a stirred-tank reactor or an airlift reactor, BC production was almost the same as that in cultivations where pH was controlled manually or by a pH sensor.     

Features of bacterial cellulose synthesis in a mutant generated by disruption of the diguanylate cyclase 1 gene of <Emphasis Type="Italic">Acetobacter xylinum</Emphasis> BPR 2001

The diguanylate cyclase 1 (DGC1) (dgc1) gene in Acetobacter xylinum BPR 2001—a bacterial cellulose (BC) producer—was cloned and sequenced, and a DGC1 gene-disrupted mutant, strain DD, was constructed. The production and structural characteristics of the BC formed by DD were compared with those of the parental strain BPR 2001. BC production by DD was almost the same as that by BPR 2001 in static cultivation and in shake flask cultivation. However, in a jar fermentor DD produced about 36% more BC than the parental strain. DD produced suspended particle materials that cannot aggregate owing to their random structural characteristics in static cultivation; more uniformly dispersed BC pellicles and smaller BC pellets are produced on average in a jar fermentor, as reflected by the higher BC production by DD than by the parental strain in a jar fermentor. Micrographs of BC produced by DD revealed that the width of cellulose ribbons assemblies decreased as a result of differences in the ultrastructure and mechanism of formation of BC between the two strains. These results reveal that disruption of the dgc1 gene, which catalyzes synthesis of c-di-GMP (an effector of BC synthase), is not fatal for BC synthesis, although it affects BC structure.     

Comparisons of physical properties of bacterial celluloses produced in different culture conditions using saccharified food wastes

The saccharogenic liquid (SFW) obtained by the enzymatic saccharification of food wastes was used as a medium for production of bacterial cellulose (BC). The enzymatic saccharification of food wastes was carried out by the cultivation supernatant ofTrichoderma harziaum FJ1 culture.Acetobacter xylinum KJ1 was employed for the BC production culture. The physical properties, such as polymerization, crystallinity, Young's modulus, and tensile strength, of BCs produced by three culture methods: the static cultures using HS (Hestrin-Schramm) as a reference medium (A) or the SFW medium (B), the shaking culture (C) or the air circulation culture (D) using the SFW medium, were investigated. The degrees of polymerization of BCs produced under the different culture conditions (A∼D) showed 11000, 9500, 8500, and 9200, respectively. Young's modulus was 4.15, 5.0, 4.0, and 4.6 GPa, respectively. Tensile strength was 124, 200, 80, and 184 MPa, respectively. All of the BC had a form of cellulose I representing pure cellulose. In the case of the shaking culture, the degree of crystallinity was 51.2%, the lowest degree. Under the other culturing conditions, the trend should remain in the range of 89.7–84%. Overall, the physical properties of BC produced from SFW were similar to those of BC from HS medium, a commercial complex medium, and BC production by the air circulation culture mode brought more favorable results in terms of the physical properties and its ease of scale-up. Therefore, it is expected that a new BC production method, like air circulation culture using SFW, would contribute greatly to BC-related manufacturing.     

Behavior of Freezable Bound Water in the Bacterial Cellulose Produced by Acetobacter xylinum: An Approach Using Thermoporosimetry

The aim of the study is to examine thermal behavior of water within reticulated structure of bacterial cellulose (BC) films by sub-ambient differential scanning calorimetry (DSC). BC films with different carbon source, either manitol (BC (a)) or glycerol (BC (b)), were produced by Acetobacter xylinum using Hestrin and Shramm culture medium under static condition at 30 ± 0.2°C for 3 days. BC samples were characterized by electron scanning microscopy and X-ray diffraction spectroscopy. The pore analysis was done by B.H.J. nitrogen adsorption. The pre-treated with 100% relative humidity, at 30.0 ± 0.2°C for 7 days samples were subjected to a between 25 and −150°C-cooling–heating cycle of DSC at 5.00°C/min rate. The pre-treated samples were also hydrated by adding 1 μl of water and thermally run with identical conditions. It is observed that cellulose fibrils of BC (a) were thinner and reticulated to form slightly smaller porosity than those of BC (b). They exhibited slightly but non-significantly different crystalline features. The freezable bound water behaved as a water confinement within pores rather than a solvent of polymer which is possible to use thermoporosimetry based on Gibb–Thomson equation to approach pore structure of BC. In comparison with nitrogen adsorption, it was found that thermoporosimetry underestimated the BC porosity, i.e., the mean diameters of 23.0 nm vs. 27.8 nm and 27.9 nm vs. 33.9 nm for BC (a) and BC (b), respectively, by thermoporosimetry vs. B.H.J. nitrogen adsorption. It may be due to large non-freezable water fraction interacting with cellulose, and the validity of pore range based on thermodynamic assumptions of Gibb–Thomson theory.     

Production of bacterial cellulose by Acetobacter xylinum BPR2001 using molasses medium in a jar fermentor

Bacterial cellulose (BC) production by Acetobacter xylinum subsp. sucrofermentans BPR2001 using molasses medium was carried out in a jar fermentor. When molasses was subjected to H₂SO₄-heat treatment, the maximum BC concentration increased to 76% more than that achieved using untreated molasses, and the specific growth rate increased 2-fold. When the initial sugar concentrations in the H₂SO₄-heat treated molasses were varied from 23 g/l to 72 g/l, BC concentration, production rate, and yield were maximum at sugar concentrations of 23 g/l and 37 g/l, and production of by-products, such as polysaccharides and CO₂, was lower than at sugar concentrations of 48 g/l and 72 g/l, indicating that maintaining a lower molasses concentration is essential for efficient BC production in jar fermentors, this being due mainly to the complex nature of molasses. Molasses has a clear advantage over pure sugars as a carbon source from an economic viewpoint.     

Effect of addition of sodium alginate on bacterial cellulose production by <Emphasis Type="Italic">Acetobacter xylinum</Emphasis>

Bacterial cellulose (BC) production by Acetobacter xylinum NUST4.1 was carried out in the shake flask and in a stirred-tank reactor by means of adding sodium alginate (NaAlg) into the medium. When 0.04% (w/v) NaAlg was added in the shake flask, BC production reached 6.0 g/l and the terminal yield of the cellulose was 27% of the total sugar initially added, compared with 3.7 g/l and 24% in the control, respectively. The variation between replicates in all determinations was less than 5%. During the cultivation in the stirred-tank reactor, the addition of NaAlg changed the morphology of cellulose from the irregular clumps and fibrous masses entangled in the internals to discrete masses dispersing into the broth, which indicates that NaAlg hinders formation of large clumps of BC, and enhances cellulose yield. Because the structure of cellulose is changed depending on the culture condition such as additives, structural characteristics of BC produced in the NaAlg-free and NaAlg medium are compared using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD). SEM photographs show some differences in reticulated structures and ribbon width and FT-IR spectra indicate that there is the hydrogen bonding interaction between BC and NaAlg, then X-ray diffraction (XRD) analysis reveals that BC produced with NaAlg-added has a lower crystallinity and a smaller crystalline size. The results show that enhanced yields and modification of cellulose structure occur in the presence of NaAlg.     

Effects of alcohols on bacterial cellulose production by <Emphasis Type="Italic">Acetobacter xylinum</Emphasis> 186

To improve the yield of cellulose production in bacteria, we investigated the stimulatory effects of six different alcohols during fermentation of Acetobacter xylinum 186. Our study showed that after static fermentation at 30°C for 6 days, bacterial culture with 1.0% (v/v) of methanol added in the medium produced the highest bacterial cellulose (BC) yield at 103.5 mg/100 ml, which was 21.8% higher than the control group. Addition of 0.5% of ethylene glycol in the culture yielded 105.5 mg/100 ml BC, 24.1% higher than the control group. Adding 0.5% of n-propanol yielded 96.4 mg/100 ml BC, 13.4% higher; 3.0% of glycerol yielded 108.3 mg/100 ml BC, 27.4% higher; 0.5% of n-butanol yielded 132.6 mg/100 ml BC, 56.0% higher; and 4.0% of mannitol in the culture yielded 125.2 mg/100 ml BC, 47.3% higher, respectively. The rate of bacterial cellulose production increased with the growth rate of the bacteria. The stimulatory effects of these alcohols that we observed were significant in the later stage of fermentation, which was considered to be important for the biosynthesis of bacterial cellulose.     

Efficient bioconversion from acid hydrolysate of waste oleaginous yeast biomass after microbial oil extraction to bacterial cellulose by Komagataeibacter xylinus

Biomass acid hydrolysate of oleaginous yeast Trichosporon cutaneum after microbial oil extraction was applied as substrate for bacterial cellulose (BC) production by Komagataeibacter xylinus (also named as Gluconacetobacter xylinus previously) for the first time. BC was synthesized in static culture for 10 days, and the maximum BC yield (2.9?g/L) was got at the 4th day of fermentation. Most carbon sources in the substrate (glucose, mannose, formic acid, acetic acid) can be utilized by K. xylinus. The highest chemical oxygen demand (COD) removal (40.7?±?3.0%) was obtained at the 6th day of fermentation, and then the COD increased possibly due to the degradation of BC. The highest BC yield on COD consumption was 38.7?±?4.0% (w/w), suggesting that this is one efficient bioconversion for BC production. The BC structure was affected little by the substrate by comparison with that generated in classical HS medium using field-emission scanning electron microscope (FE-SEM), Fourier transform infrared, and X-ray diffraction. Overall, this technology can both solve the issue of waste oleaginous yeast biomass and produce valuable biopolymer (BC).     

Viability and cellulose synthesizing ability of Gluconacetobacter xylinus cells under high-hydrostatic pressure

The effect of pressure on viability and the synthesis of bacterial cellulose (BC) by Gluconacetobacter xylinus ATCC53582 were investigated. G. xylinus was statically cultivated in a pressurized vessel under 0.1, 30, 60, and 100 MPa at 25°C for 6 days. G. xylinus cells remained viable and retained cellulose producing ability under all the conditions tested, though the production of cellulose decreased with increasing the pressure. The BCs produced at each pressure condition were analyzed by field emission scanning electron microscopy (FE-SEM) and Fourier Transform Infrared (FT-IR). FE-SEM revealed that the widths of BC fibers produced under high pressure decreased as compared with those produced under the atmospheric pressure. By FT-IR, all the BCs were found to be of Cellulose type I, as the same as typical native cellulose. Our findings evidently showed that G. xylinus possessed a piezotolerant (barotolerant) feature adapting to 100 MPa without losing its BC producing ability. This was the first attempt in synthesizing BC with G. xylinus under elevated pressure of 100 MPa, which corresponded to the deep sea at 10,000 m.     

Production of bacterial cellulose from Komagataeibacter saccharivorans strain BC1 isolated from rotten green grapes

Abstract

Bacterial cellulose (BC) is one of the prominent biopolymers that has been acquiring attention currently due to its distinctive properties and applications in various fields. The current work presents the isolation of Komagataeibacter saccharivorans strain BC1 isolated from rotten green grapes, followed by biochemical and genotypic characterization, which confirmed that the strain is capable of synthesizing cellulose. Further, production media was designed and certain variables such as carbon, nitrogen sources, pH, and temperature were optimized in order to obtain the maximum concentration of cellulose production. We found mannitol to be the ideal carbon source and yeast extract as the ideal nitrogen source with a highest BC dry yield of 1.81?±?0.25?g/100?mL at pH 5.76 for a week at 30?°C.The charcterization of pellicles by FTIR spectrum depicted similar functional groups present in synthesized BC as that of the commercial cellulose. X-ray diffraction revealed that BC showed 82% crystallinity. Surface morphology of the dried pellicle was studied by SEM image which showed that the BC surface was tightly packed with thin fibers with less porosity. Hence the study demonstrates that the isolates of K.saccharivorans could be used to produce a biopolymer in a short period of time using a modified production medium.     

Influence of 1‐methylcyclopropene (1‐MCP) on the production of bacterial cellulose biosynthesized by Acetobacter xylinum under the agitated culture

Aims: Bacterial cellulose is an extracellular polysaccharide secreted by Acetobacter xylinum, which has become a novel material increasingly used in food and medical industries. However, its broad application is limited by its low yield and high cost. 1‐Methylcyclopropene (1‐MCP) is a potent inhibitor to either exogenous or endogenous ethylene during the biological senescence of plants, which has been broadly applied in commercial preservation of fruits and vegetables. The purpose of this study was to investigate the effects of 1‐MCP on both the growth of Acet.  xylinum and its cellulose production to demonstrate the potential enhancement of bacterial cellulose yield. Methods and Results: Three groups of samples were fermented under agitated culture with 125 rev min^?1 rotational speed. To the culture media, 0·14 mg of 1‐MCP contained in 100 mg dextrose powder was added on assigned days or on the first culture day only. Results from the measurement of bacterial cell concentration and bacterial cellulose yield at the end of a 12‐day culture demonstrated that cultures excluding 1‐MCP displayed a higher cell concentration and a lower cellulose production, while cultures containing 1‐MCP produced 15·6% more cellulose (1‐MCP added on day 1) and 25·4% (1‐MCP added on each assigned day) with less biomass. Conclusions: 1‐MCP was able to affect the growth of Acet. xylinum cells and resulted in increasing bacterial cellulose yield up to 25·4% over controls, which did not contain 1‐MCP. Significance and Impact of the Study: This was the first study to use the growth inhibitor of plants to investigate its effects on bacterial growth and production. It also demonstrated a significant enhancement of bacterial cellulose yield by the addition of 1‐MCP during the common agitated culture of Acet. xylinum.     

Is there a relation between genetic susceptibility with cancer? A study about paraoxanase (PON1) enzyme activity in breast cancer cases

Human serum paraoxonase 1 (PON1, EC 3.1.1.2) is a high density lipoprotein (HDL)-associated antioxidant enzyme that not only decreases oxidative stress, but it is also implicated in development of many cancers. Genetic information provides a means of identifying people who have an increased risk of cancer, thus this knowledge of cancer genetics helps to identify the ability to characterize malignancies leading to the development of new therapeutic approaches. Because of this reason, in this preliminary study we aimed to investigate the role of human serum PON1 enzyme activity and phenotypic distribution in 32 breast cancer (BC) patients (age range 28–82) and 35 cancer free (CF) control group (age range 21–67). PON1 enzyme was prepared from the serum pool of BC patients using hydrophobic interaction chromatography on L-tyrosine-9-aminophenanthrene-coupled Sepharose 4Bgel. The PON1 enzyme activity towards paraoxon substrate was quantified spectrophotometrically. The basal activity of PON1 was statistically decreased in cancer cases compared to the control group. In addition, individuals were classified according to phenotyping of human PON1 Q and R types. In the cohort of BC patients, an increase in the frequency of the PON homozygote Q (AA) genotype was observed (31% in the BC group versus 14% in the CF controls). The frequency of the PON heterozygote QR (AB) genotype was 34.5% in the patients with BC and 37% in the CF group. The same trend was observed in PON homozygote R (BB) genotype frequency (BC cases 34.5% versus controls 49%). We determined that the kinetic parameters of the purified enzyme by Lineweaver–Burk method. We obtained K_m and V_max values of 0.227?mM and 62?U/mL?min for the BC enzyme, compared with 0.775?mM and 206?U/mL?min for the CF control enzyme. As a conclusion, it is clear from our results that while the PON1 AA allele frequency in BC cases is much higher, that of BB allele is much lower, in comparison with the control group. The most significant finding of this study is AA allele activity which is low in BC cases was found high. We concluded that decreased AA allele PON1 activity might have a relation with BC.     

Influence of the Interactions Between Black Carbon and Soil Constituents on the Sorption of Pyrene

Biochar (a kind of black carbon (BC)) has been advocated as a promising additive to farmland, thus it is crucial to understand the influence of BC on the fate of hydrophobic organic chemicals (HOCs) when they exist in soil. This study explored the sorption of pyrene onto a BC sample obtained by pyrolyzing pine sawdust, two soils, clay (kaolinite), and the mixtures thereof to investigate the influence of the interactions between BC and soil constituents on the sorption of HOCs and the mechanisms therein. Sorption of pyrene onto soil?BC mixtures was significantly less than that predicted by the sum of the individual soil and BC sorption, indicating that the sorption of pyrene onto soil and BC did not occur independently. The reduction of BC sorption capacity in soil seemed primarily to be caused by soil dissolved organic matter (DOM), which attenuated pyrene sorption onto BC by 18.7%?40.3% (within pyrene equilibrium concentration range of 0.05?0.5 S _w). These were likely due to the blockage of micropores, reduced accessibility of sorption sites, and binding of pyrene by DOM in aqueous solution. In addition to the DOM effect, kaolinite also diminished pyrene sorption onto BC to some extent, which suggested additional interaction between BC and soil particles. Pyrene sorption onto the soil?BC mixtures varied with water content and contact time. The influence of wet versus dry conditions and contact time on the K_oc of pyrene was more obvious when pyrene equilibrium concentrations were lower. The effect of aging also varied with soil properties. In summary, BC could not behave independently in soil, and its sorption capacity was changed by its interactions with soil constituents, which may be influenced by soil properties, environmental condition, and contact time.     

Effects of mixing conditions on the production of microbial cellulose byAcetobacter xylinum

Microbial cellulose has many potential applications due to its excellent physical properties. The production of cellulose fromAcetobacter xylinum in submerged culture is, however, beset with numerous problems. The most difficult one has been the appearance of negative mutants under shaking culture conditions, which is deficient of cellulose producing ability. Thus genetic instability ofAcetobacter xylinum under shaking culture condition made developing a stable mutant major research interest in recent years. To find a proper type of bioreactor for the production of microbial cellulose, several production systems were developed. Using a reactor system with planar type impeller with bottom sparging system, it was possible to produce 5 g/L microbial cellulose without generating cellulose minus mutants, which is comparable to that of static culture system.     

Influential factors to enhance the moving rate of Acetobacter xylinum due to its nanofiber secretion on oriented templates

Acetobacter xylinum, a bacterium which secretes a cellulose nanofiber, moves due to the inverse force of extrusion of the fiber, which accordingly correlates with the fiber production rate. To improve the production, the moving rate of the bacterium was focused to examine the influential factors on the substrates for culture and additives in the culture medium. From the real-time video analysis, the oriented template having a strong interaction with the secreted cellulose nanofibers proved to be suitable for the bacteria to move faster. Furthermore, addition of carboxymethylcellulose sodium salt (CMC) to the culture medium cause the bacteria to move faster in the culture medium. In this case, secreted cellulose nanofiber formed different from a normal cellulose nanofiber. The above result could provide an understanding how the formation of cellulose nanofibers contributes to the production rate as well as the bacterial moving rate.     

Cloning and sequencing of the cellulose synthase catalytic subunit gene of Acetobacter xylinum

The gene for the catalytic subunit of cellulose synthase from Acetobacter xylinum has been cloned by using an oligonucleotide probe designed from the N-terminal amino acid sequence of the catalytic subunit (an 83 kDa polypeptide) of the cellulose synthase purified from trypsin-treated membranes of A. xylinum. The gene was located on a 9.5 kb HindIII fragment of A. xylinum DNA that was cloned in the plasmid pUC18. DNA sequencing of approximately 3 kb of the HindIII fragment led to the identification of an open reading frame of 2169 base pairs coding for a polypeptide of 80 kDa. Fifteen amino acids in the N-terminal region (positions 6 to 20) of the amino acid sequence, deduced from the DNA sequence, match with the N-terminal amino acid sequence obtained for the 83 kDa polypeptide, confirming that the DNA sequence cloned codes for the catalytic subunit of cellulose synthase which transfers glucose from UDP-glucose to the growing glucan chain. Trypsin treatment of membranes during purification of the 83 kDa polypeptide cleaved the first 5 amino acids at the N-terminal end of this polypeptide as observed from the deduced amino acid sequence, and also from sequencing of the 83 kDa polypeptide purified from membranes that were not treated with trypsin. Sequence analysis suggests that the cellulose synthase catalytic subunit is an integral membrane protein with 6 transmembrane segments. There is no signal sequence and it is postulated that the protein is anchored in the membrane at the N-terminal end by a single hydrophobic helix. Two potential N-glycosylation sites are predicted from the sequence analysis, and this is in agreement with the earlier observations that the 83 kDa polypeptide is a glycoprotein [13]. The cloned gene is conserved among a number of A. xylinum strains, as determined by Southern hybridization.     

The effect of pH, sucrose and ammonium sulphate concentrations on the production of bacterial cellulose (Nata-de-coco) by Acetobacter xylinum

The effect of pH, sucrose and ammonium sulphate concentrations on the production of nata-de-coco, a form of bacterial cellulose, by Acetobacter xylinum was studied. Comparisons for physical properties like thickness, wet weight, water-holding capacity (WHC), moisture content and hardness, a textural parameter were done on nata-de-coco grown in tender coconut water medium supplemented with varying concentrations of sucrose and ammonium sulphate at different pH values. The results were analysed by fitting a second-order polynomial regression equation. Response surface methodology was used to study the effect of the three variables. The study showed that A. xylinum could effectively use sucrose as the sole carbon source in coconut water medium and that cellulose production was more dependent on pH than either sucrose or ammonium sulphate concentrations. Maximum thickness of nata was obtained at pH 4.0 with 10% sucrose and 0.5% ammonium sulphate concentrations. These conditions also produced good quality nata-de-coco with a smooth surface and soft chewy texture. The study will enable efficient utilization of coconut water, a hitherto wasted byproduct of coconut industry and will also provide a new product dimension to the aggrieved coconut farmers who are not getting the right price for their product.     

The interaction of blood proteins with brucine

The features of brucine (BC) binding to two blood proteins, bovine hemoglobin (BHb), and bovine serum albumin (BSA), were investigated via fluorescence, circular dichroism and UV/Vis absorption spectroscopy. The results revealed that BC caused the fluorescence quenching of blood proteins by the formation of BC–protein complex. The corresponding thermodynamic parameters were measured at different temperatures. The process of binding BC molecule on protein was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic and electrostatic interactions play a major role in stabilizing the complex. The molecular docking has been employed to explore the binding site of the BC in BHb and BSA on the Autodock 4.2. The distances r between BC and protein were calculated to be 4.93 and 5.08 nm for BHb, and BSA, respectively. The effect of BC on the conformation of blood proteins was analyzed using CD, synchronous fluorescence and three-dimensional fluorescence spectra.     

Synthesis of 20α- and 20β-Amino-3,5-pregnadiene Derivatives and Antimicrobial Activity

Cellulose production by Acetobacter strains is enhanced by the addition of a small amount of cellulose to the production culture. The effect of an endo-β-1, 4-glucanase from Bacillus subtilis on the cellulose production by Acebohacter xylinum BPR2001 was examined by adding various amounts of the purified glucanase to the culture. The addition of a small amount of this glucanase enhanced cellulose production. Furthermore, it reduced the amount of a polysaccharide called acetan produced. However, an active-site mutant enzyme of the glucanase, which showed no enzyme activity but still had cellulose-binding ability, had no effect on cellulose production. It was concluded, therefore, that the endoglucanase activity itself, but not the cellulose-binding ability, was essential for the enhancement of cellulose production. The structural properties of the cellulose produced in the presence of the endoglucanase were found to be almost identical to those of native bacterial cellulose.