Production of bacterial cellulose from <Emphasis Type="Italic">Enterobacter amnigenus</Emphasis> GH-1 isolated from rotten apple

Bacterial cellulose finds novel applications in biomedical, biosensor, food, textile and other industries. The optimum fermentation conditions for the production of cellulose by newly isolated Enterobacter amnigenus GH-1 were investigated. The strain was able to produce cellulose at temperature 25–35°C with a maximum at 28°C. Cellulose production occurred at pH 4.0–7.0 with a maximum at 6.5. After 14 days of incubation, the strain produced 2.5 g cellulose/l in standard medium whereas cellulose yield in the improved medium was found to be 4.1 g/l. The improved medium consisted of 4% (w/v) fructose, 0.6% (w/v) casein hydrolysate, 0.5% (w/v) yeast extract, 0.4% (w/v) disodium phosphate, and 0.115% (w/v) citrate. Addition of metal ions like zinc, magnesium, and calcium and solvents like methanol and ethanol were found to be stimulatory for cellulose production by the strain. The strain used natural carbon sources like molasses, starch hydrolysate, sugar cane juice, coconut water, coconut milk, pineapple juice, orange juice, and pomegranate juice for growth and cellulose production. Fruit juices can play important role in commercial exploitation of bacterial cellulose by lowering the cost of the production medium.     

Production of bacterial cellulose by<Emphasis Type="Italic">Gluconacetobacter hansenii</Emphasis> PJK isolated from rotten apple

A cellulose-producing strain isolated from rotten apples was identified asGluconace-tobacter hansenii based on its physiological properties and the 16S rDNA complete sequencing method, and specifically namedGluconacetobacter hansenii PJK. The amount of bacterial cellulose (BC) produced byG. hansenii PJK in a shaking incubator was 1.5 times higher than that produced in a static culture. The addition of ethanol to the medium during cultivation enhanced the productivity of bacterial cellulose, plus the supplementation of 1% ethanol into the culture medium made the produced BC aggregate into a big lump and thus protected the bacterial-cellulose-producingG. hansenii PJK cells in the shear stress field from being converted into noncellulose-producing (Cel) mutants. Cells subcultured three times in a medium containing ethanol retained their ability to produce BC without any loss in the production yield.     

Utilization of -xylose as carbon source for production of bacterial cellulose

Utilization of -xylose as carbon source for production of bacterial cellulose was studied. Seventeen strains of acetic acid bacteria were screened for their cellulose productivity in -glucose, -xylose, and -xylose/ -xylulose mixed media, respectively. -Xylose was not well metabolized by any bacterial strains that exhibited high cellulose production in -glucose medium. Consequently, bacterial cellulose production in -xylose medium was unsuccessful. -Xylose, however, became utilizable substrate for bacterial strains if xylose-isomerase was added to the medium. Acetobacter xylinus IFO 15606 was the best cellulose producer in -xylose/ -xylulose mixed medium, so cultural conditions were studied for enhanced cellulose production. With pH controlled, the strain could produce cellulose at a yield exceeding 0.3 g per 100 ml of -xylose/ -xylulose mixed medium, which was comparable to the yields in -glucose medium by excellent producers in the literature.     

Statistical optimization of bacterial cellulose production by Leifsonia soli and its physico-chemical characterization

Bacterial cellulose has multiple applications in various industries such as food, biomedical, textile due to its uniqueness of being a better bio-compatible coating agent, binding material, etc. In this study, optimization of the culture medium for producing BC from Leifsonia soli was carried out by selecting different parameters. Five significant factors such as maltose, pH, incubation days, soy whey and calcium chloride were estimated through ANOVA based response surface methodology. Maximum cellulose production (5.97 g/L) was obtained where maltose 1 % (w/v) supplemented with 0.8 % (v/v) soy whey and calcium chloride 0.8 % (w/v) at pH 6.5 for 7 days of incubation. In addition, assurance of cellulose production from bacteria was done by using High-performance liquid chromatography analysis. Further, the structure and purity of obtained cellulose were examined by SEM and elemental analysis where it was observed that the sample holds the value of carbon 44.1 ± 0.20 % and hydrogen 6.2 ± 0.3 %, respectively. This study concludes that the addition of maltose and soy whey could be used as carbon, nitrogen sources and calcium chloride was used as an additive for the bacterial cellulose production compared to the Hestrin Schramm medium. In addition, the calculated water holding capacity of the sample was found to be 73 %.     

Cellulose production from<Emphasis Type="Italic">Gluconobacter oxydans</Emphasis> TQ-B2

Gluconobacter oxydans that produces the cellulose was isolated. In order to confirm the chemical features of cellulose, various spectrophtometeric analysis were carried out using electron microscopy, X-ray diffractogram, and CP/MAS¹³C NMR. The purified cellulose was found to be identical to that ofAcetobacter xylinum. For effective production of cellulose, the various carbon and nitrogen sources, mixture of calcium and magnesium ions, and biotin concentration were investigated in flask cultures. Among the various carbon sources, glucose and sucrose were found to be best for the production of cellulose, with maximum concentration of 2.41 g/L obtained when a mixture of 10 g/L of each glucose and sucrose were used. With regard to the nitrogen sources, when 20 g/L of yeast extract was used, the maximum concentration of bacterial cellulose was reached. The concentration of cellulose was increased with mixture of 2 mM of each Ca²⁺ and Mg²⁺. The optimum biotin concentration for the production of cellulose was in the range of 15 to 20 mg/L. At higher biotin concentration (25–35 mg/L), the bacterial cellulose production was lower.     

Effect of yeast inoculation rate on the metabolism of contaminating lactobacilli during fermentation of corn mash

Two separate 4 (bacterial concentrations)×6 (yeast concentrations) full factorial experiments were conducted in an attempt to identify a novel approach to minimize the effects caused by bacterial contamination during industrial production of ethanol from corn. Lactobacillus plantarum and Lactobacillus paracasei, commonly occurring bacterial contaminants in ethanol plants, were used in separate fermentation experiments conducted in duplicate using an industrial strain of Saccharomyces cerevisiae, Allyeast Superstart. Bacterial concentrations were 0, 1×10⁶, 1×10⁷ and 1×10⁸ cells/ml mash. Yeast concentrations were 0, 1×10⁶, 1×10⁷, 2×10⁷, 3×10⁷, and 4×10⁷ cells/ml mash. An increased yeast inoculation rate of 3×10⁷ cells/ml resulted in a greater than 80% decrease (P<0.001) and a greater than 55% decrease (P<0.001) in lactic acid production by L. plantarum and L. paracasei, respectively, when mash was infected with 1×10⁸ lactobacilli/ml. No differences (P>0.25) were observed in the final ethanol concentration produced by yeast at any of the inoculation rates studied, in the absence of lactobacilli. However, when the mash was infected with 1×10⁷ or 1×10⁸ lactobacilli/ml, a reduction of 0.7–0.9% v/v (P<0.005) and a reduction of 0.4–0.6% v/v (P<0.005) in the final ethanol produced was observed in mashes inoculated with 1×10⁶ and 1×10⁷ yeast cells/ml, respectively. At higher yeast inoculation rates of 3×10⁷ or 4×10⁷ cells/ml, no differences (P>0.35) were observed in the final ethanol produced even when the mash was infected with 1×10⁸ lactobacilli/ml. The increase in ethanol corresponded to the reduction in lactic acid production by lactobacilli. This suggests that using an inoculation rate of 3×10⁷ yeast cells/ml reduces the growth and metabolism of contaminating lactic bacteria significantly, which results in reduced lactic acid production and a concomitant increase in ethanol production by yeast.     

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.     

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.     

Bacterial cellulose membrane – A new support carrier for yeast immobilization for ethanol fermentation

The aim of the work was to study the properties of the bacterial cellulose membrane (BCM) and the feasibility of using it as a new, environmentally friendly support carrier for yeast cell immobilization. It was observed that the morphology of BCM varied with different cultivation methods and the scanning electron microscopy (SEM) images confirmed that the yeast cells were entrapped in the porous network of BCM obtained from the static culture and stabilized by the cross-linked fibrils. Particularly, the research confirmed the effectiveness of yeast immobilization in BCM reflected by the high yield of alcohol (9.7% v/v, a 21.25% increase of those using free cells) and the high stability. The specific rate of ethanol production by the immobilized cells in BCM was 2.1 g g⁻¹ h⁻¹, 31.3% greater than that of the suspended cells. Results implied that applying BCM as the support carrier had little adverse effects on cell viability and proliferation. Instead, it facilitated the product leakage and nutrients transportation through the porous network.     

Temporal and spatial changes of cellulose synthesis inClosterium acerosum (Schrank) Ehrenberg during cell growth

The amount and distribution of wall microfibril synthesis were investigated in the cell-division cycle ofClosterium acerosum. Electron-microscopic examination and a methylation analysis of alkali-extracted wall fragments showed that alkali-extracted wall was mainly composed of microfibrils and that the microfibrils ofC. acerosum were 4-linked glucans, i.e., cellulose. Cellulose synthesis was measured as incorporation of¹⁴C, fed to cells as NaHCO₃, into extracted wall fragments. Extensive cellulose synthesis was coincident with septum formation, continued for more than 6 h and then ceased. It was found by microautoradiography that cellulose synthesis after cell division was essentially restricted to the expanding new semicells. Such a restricted distribution of cellulose synthesis was maintained for more than 6 h after septum formation, i.e., for more than 2 h after the cessation of expansion; afterwards, cellulose synthesis in some, but not all, cells became extended to the old semicells, and then ceased. Considerable cellulose synthesis also took place in the band-like expanding part of non-divided cells, indicating that cell division was not necessarily required for the induction of cellulose synthesis and the latter was coupled with cell expansion. Extension of cellulose synthesis to old semicells was brought about in divided cells by treatment with 3 mM colchicine, 28 M vinblastine, 50 M isopropyl-N-phenylcarbamate or 1 M isopropyl-N(3-chlorophenyl)carbamate, indicating that microtubules are involved in the limitation of cellulose synthesis to the new semicells.Abbreviations CIPC isopropyl-N(3-chlorophenyl)carbamate - DPO 2,5-diphenyloxazole - IPC isopropyl-N-phenylcarbamate     

The use of multi-parameter flow cytometry to study the impact of <Emphasis Type="Italic">n</Emphasis>-dodecane additions to marine dinoflagellate microalga <Emphasis Type="Italic">Crypthecodinium cohnii</Emphasis> batch fermentations and DHA production

The physiological response of Crypthecodinium cohnii batch cultivations and docosahexaenoic acid (DHA) production to n-dodecane additions were studied. Different n-dodecane concentrations [0, 0.5, 1, 2.5, 5, 10 and 20% (v/v)] were added to preliminary shake flask cultivations. The n-dodecane fraction that gave best results in terms of biomass and DHA production was 0.5% (v/v). The n-dodecane fractions of 2.5, 5, 10 and 20% (v/v) to C. cohnii preliminary shake flask cultures inhibited the microalgal growth and DHA production, although a high proportion of cells with intact cytoplasmic membrane was present in the end of these fermentations. After the addition of a pulse of n-dodecane (0.5% v/v) to C. cohnii exponential growing cells in a bioreactor, glucose uptake volumetric rate increased 2.5-fold, while biomass production volumetric rate increased 2.8-fold. The specific growth rate was increased 1.5-fold. The DHA % in biomass, DHA % of TFA and DHA concentration also increased (54, 22 and 58%, respectively), after the n-dodecane addition. At this n-dodecane fraction (0.5% v/v), multi-parameter flow cytometry demonstrated that C. cohnii cell membrane integrity was not affected. The results demonstrated that the addition of 0.5% of n-dodecane (v/v) to C. cohnii fermentations can be an easy and cheap way for enhancing the biomass and DHA production, avoiding the use of high speed rates (resulting in important power agitation costs) that affects the microalga proliferation and increases the bioprocess costs. A new strategy to improve the DHA production from this microalga in two-phase large-scale bioreactors is now in progress.     

Recycle of cellulases and the use of lignocellulosic residue for enzyme production after hydrolysis of steam-pretreated aspenwood

Summary Various modes of substrate and enzyme addition were used to hydrolyze a 10% concentration (w/v) of steam-exploded, water-and-alkali extracted aspenwood withTrichoderma harzianum E58 cellulases. Although cellulose conversion was high (94–100%), enzyme recovery was low in all cases. Low enzyme recovery was due to a combination of thermal inactivation and adsorption of the cellulases onto the lignocellulosic residue. Enzyme recycle was not feasible as the activity of the recovered cellulases towards crystalline cellulose was low. However, the residual material from enzyme hydrolysis was a suitable carbon source for cellulase enzyme production byT. harzianum based on enzyme yield and hydrolytic potential. These residues could only be used up to a 1% substrate concentration, since at higher substrate loadings cellulase production was reduced, likely because of lignin inhibitors.     

Simple fed-batch cultivation strategy for the enhanced production of a single-sugar glucuronic acid-based oligosaccharides by a cellulose-producing <Emphasis Type="Italic">Gluconacetobacter hansenii</Emphasis> strain

The production of water-soluble single-sugar glucuronic acid-based oligosaccharides (WSOS) by a cellulose producing strain Gluconacetobacter hansenii PJK was studied in a periodically recycled and fed-batch cultivations using glucose/ethanol or glucose only. Fermentations were carried out in a 2 L jar fermenter equipped with a turbine impeller with 6 flat blades. WSOS were produced constantly but the bacterial cellulose (BC) production stopped at 48 h of cultivation in a periodically recycled culture using the exhausted medium supplemented with glucose and ethanol. Tremendous quantities of WSOS were obtained in fed-batch cultivations using glucose/ethanol (35.6 g/L at 132 h of cultivation) or glucose only (86 g/L after 240 h of cultivation) as the nutritional source. However, the BC production yield under these nutritional conditions decreased significantly in comparison to previous studies about the BC production by the same strain. The overall results revealed that G. hansenii is capable of producing enormous quantities of WSOS compared to those reported previously for compounds of a related chemical nature. Moreover, the WSOS production was found to be dependent on the pH of the culture broth.     

Elevated 3-hydroxypropionaldehyde production from glycerol using a Citrobacter freundii mutant

A mutant strain of Citrobacter freundii capable of elevated 3-hydroxypropionaldehyde production from glycerol was isolated using chemical mutagenesis and a screening protocol. The protocol involved screening mutagenized bacterial cells on solid minimal medium containing 5 % (v/v) glycerol. Colonies were picked onto duplicate solid minimal medium plates and one plate was stained with 1 % (w/v) phloroglucinol. Those colonies staining red were further screened and a mutant, HPAO-1, was identified. The mutant strain produced a several-fold higher 3-hydroxypropionaldehyde concentration than did the parent strain when grown on 5 % (v/v) glycerol. The ratio of culture volume to flask volume influenced 3-hydroxypropionaldehyde production by the mutant cells compared to the parent cells. Aldehyde production was highest when the mutant strain was grown on 5 % (v/v) glycerol at a ratio of culture volume to flask volume of 1:3 or 1:12.5.     

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.     

Pervaporation performance of a composite bacterial cellulose membrane: dehydration of binary aqueous–organic mixtures

Summary Acetobacter xylinum (Gluconacetobacter xylinus) is a bacterium that produces extracellular cellulose under static culture conditions. The highly reticulated cellulose matrix along with the entrapped cellulose-forming bacteria is commonly referred to as a pellicle. The processed bacterial cellulose membrane/film was modified into a composite bacterial cellulose membrane (CBCM) for pervaporation separation of aqueous–organic mixtures. The CBCM was prepared by coating with alginate or alginate+polyvinylpyrrolidone and cross-linking with glutaraldehyde. The pervaporation performance was determined using aqueous–organic mixtures such as, 1:1 (v/v) water–ethanol, water–isopropanol and water–acetone. The pervaporation performance of the CBCM was more effective for zeotropic mixtures (water–acetone) in comparison to the investigated azeotropic mixtures (water–ethanol and water–isopropanol). The selectivity of CBCM was found to be 4.8, 8.8, 19.8 for water–ethanol, water–isopropanol and water–acetone mixtures, respectively. The permeation flux for the water–acetone mixture was found to be 235 ml/m²/h. The present investigation demonstrated that the CBCM could be employed to concentrate azeotropic as well as zeotrope forming binary mixtures by preferential pervaporation of water, with low energy requirements in contrast to the established method of distillation. In addition, the effects of feed composition, operating temperature, membrane thickness, and method of CBCM preparation on pervaporation performance have been evaluated. Investigations with the CBCM revealed that 94.5% ethanol, 98% acetone and 98.5% isopropanol concentrations could be attained from the initial 50% aqueous mixtures of these chemicals by way of pervaporation. In the case of the isopropanol–water mixture the resolving property of the membrane was more evident as the concentration arrived at was 98.5%, in contrast to other binary mixtures. The surface characteristics of the CBCM were revealed by scanning electron microscopy. In view of its properties the CBCM can be useful for pervaporation separation of these chemicals at moderate temperatures and pressure. The CBCM could be employed in the downstream processing of heat-labile and flavor-imparting volatile molecules in the field of food biotechnology and fabrication of membrane bioreactors for on-line product purification. Further studies are under progress to use the membrane for the immobilization of food processing enzymes.     

Production of oligosaccharides and cellobionic acid by <Emphasis Type="Italic">Fibrobacter succinogenes</Emphasis> S85 growing on sugars,cellulose and wheat straw

Extracellular culture fluid of Fibrobacter succinogenes S85 grown on glucose, cellobiose, cellulose or wheat straw was analysed by 2D-NMR spectroscopy. Cellodextrins did not accumulate in the culture medium of cells grown on cellulose or straw. Maltodextrins and maltodextrin-1P were identified in the culture medium of glucose, cellobiose and cellulose grown cells. New glucose derivatives were identified in the culture fluid under all the substrate conditions. In particular, a compound identified as cellobionic acid accumulated at high levels in the medium of F. succinogenes S85 cultures. The production of cellobionic acid (and cellobionolactone also identified) was very surprising in an anaerobic bacterium. The results suggest metabolic shifts when cells were growing on solid substrate cellulose or straw compared to soluble sugars.     

Investigation of biomass concentration,lipid production,and cellulose content in Chlorella vulgaris cultures using response surface methodology

The microalgae Chlorella vulgaris produce lipids that after extraction from cells can be converted into biodiesel. However, these lipids cannot be efficiently extracted from cells due to the presence of the microalgae cell wall, which acts as a barrier for lipid removal when traditional extraction methods are employed. Therefore, a microalgae system with high lipid productivity and thinner cell walls could be more suitable for lipid production from microalgae. This study addresses the effect of culture conditions, specifically carbon dioxide and sodium nitrate concentrations, on biomass concentration and the ratio of lipid productivity/cellulose content. Optimization of culture conditions was done by response surface methodology. The empirical model for biomass concentration (R² = 96.0%) led to a predicted maximum of 1123.2 mg dw L^?1 when carbon dioxide and sodium nitrate concentrations were 2.33% (v/v) and 5.77 mM, respectively. For lipid productivity/cellulose content ratio (R² = 95.2%) the maximum predicted value was 0.46 (mg lipid L^?1 day^?1)(mg cellulose mg biomass^?1)^?1 when carbon dioxide concentration was 4.02% (v/v) and sodium nitrate concentration was 3.21 mM. A common optimum point for both variables (biomass concentration and lipid productivity/cellulose content ratio) was also found, predicting a biomass concentration of 1119.7 mg dw L^?1 and lipid productivity/cellulose content ratio of 0.44 (mg lipid L^?1 day^?1)(mg cellulose mg biomass^?1)^?1 for culture conditions of 3.77% (v/v) carbon dioxide and 4.01 mM sodium nitrate. The models were experimentally validated and results supported their accuracy. This study shows that it is possible to improve lipid productivity/cellulose content by manipulation of culture conditions, which may be applicable to any scale of bioreactors. Biotechnol. Bioeng. 2013; 110: 2114–2122. © 2013 Wiley Periodicals, Inc.     

Molecular weight distribution of cellulose in primary cell walls

The distribution pattern of the degree of polymerization (DP) of cellulose present in the cell walls of mesophyll- and suspension-cultured cells of tobacco was compared to that of newly synthesized ¹⁴C-labeled cellulose from regenerating tobacco protoplasts and suspension-cultured cells. The cellulose was nitrated, and, after fractionation according to differences in solubility in acetone/water, the DP pattern of labeled or unlabeled cellulose nitrate was determined by viscosity measurements. A low (DP<500) and high DP-fraction (DP>2500) of cellulose were predominant in the cell walls of protoplasts, suspension — cultured cells, and mesophyll cells. The average DP of the high molecular weight fraction of cellulose in the cell walls of mesophyll was higher (DP4,000) than in protoplasts or suspension — cultured cells (DP 2,500-3,000). In all cell walls tested, minor amounts of cellulose molecules with a broad spectrum of a medium DP were present. Pulse — chase experiments with either protoplasts or suspension —cultured cells showed that a large proportion of the low and medium DP-cellulose are a separate class of structural components of the cellulose network. The results are discussed in relation to the organization of cellulose in the primary cell wall.Abbreviations DP degree of polymerisation - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid     

Silicone rubber membrane bioreactors for bacterial cellulose production

Cellulose production byAcetobacter pasteurianus was investigated in static culture using four bioreactors with silicone rubber membrane submerged in the medium. The shape of the membrane was flat sheet, flat sack, tube and cylindrical balloon. Production rate of cellulose as well as its yield on consumed glucose by the bacteria grown on the flat type membranes was approximately ten-fold greater than those on the non-flat ones in spite of the same membrane thickness. The membrane reactor using flat sacks of silicone rubber membrane as support of bacterial pellicle can supply greater ratio of surface to volume than a conventional liquid surface culture and is promising for industrial production of bacterial cellulose in large scale.