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Dental root canal treatment is required when dental caries progress to infection of the dental pulp. A major goal of this treatment is to provide complete decontamination of the dental root canal system. However, the morphology of dental root canal systems is complex, and many human dental roots have inaccessible areas. In addition, dental reinfection is fairly common. In conventional treatment, a cotton pellet and paper point made from plant cellulose is used to dry and sterilize the dental root canal. Such sterilization requires a treatment material with high absorbency to remove any residue, the ability to improve the efficacy of intracanal medication and high biocompatibility. Bacterial cellulose (BC) is produced by certain strains of bacteria. In this study, we developed BC in a pointed form and evaluated its applicability as a novel material for dental canal treatment with regard to solution absorption, expansion, tensile strength, drug release and biocompatibility. We found that BC has excellent material and biological characteristics compared with conventional materials, such as paper points (plant cellulose). BC showed noticeably higher absorption and expansion than paper points, and maintained a high tensile strength even when wet. The cumulative release of a model drug was significantly greater from BC than from paper points, and BC showed greater compatibility than paper points. Taken together, BC has great potential for use in dental root canal treatment.

In the present investigation, several residues from agro-forestry industries such as rice straw acid hydrolysate, corn cob acid hydrolysate, tomato juice, cane molasses and orange pulp were evaluated as the economical source for the production of bacterial cellulose. The bacterial cellulose attained the significant yield of 7.8 g/L using tomato juice, followed by 3.6 g/L using cane molasses and 2.8 g/L using orange pulp after 7 days of incubation. Furthermore, the optimum pH and temperature of fermentation for maximum production of bacterial cellulose was 4.5 and 30 ± 1 °C. The identified bacterium Acetobacter pasteurianus RSV-4 has been deposited at repository under the accession number MTCC 25117. The produced bacterial cellulose was characterized through FTIR, SEM, TGA and DSC and found to be of very good quality. The bacterial cellulose produced by identified strain on these various agro-waste residues could be a cost effective technology for commercial its production.

Microbial contamination of fuels, associated with a wide variety of bacteria and fungi, leads to decreased product quality and can compromise equipment performance by biofouling and microbiologically influenced corrosion of pipelines and storage tanks. Detection and quantification of biomass are critical in monitoring fuel systems for an early detection of microbial outbreaks. The aims of this study are (i) to quantify bacterial and fungal contamination in samples from diesel storage tanks of petrol stations, using both culture dependent- and culture independent (qPCR) approaches, and (ii) to analyse the diversity of cultivable diesel-contaminating microorganisms with the purpose to create a strain collection for further use in biodeterioration experiments. Both methodological approaches revealed a high microbial contamination in all studied samples, with the bacterial load being much higher than the fungal load. The diversity of cultivable microorganisms was rather low. Based on criteria of abundance and fuel degradation potential, the most relevant microorganisms were identified as bacteria of genera Bacillus , Citrobacter , Burkholderia and Acetobacter , the filamentous fungi Paecilomyces variotii and Pseudallescheria boydii , and a Dipodascaceae yeast. Furthermore the validity and utility of qPCR-based methods are discussed.

The performance of biological phosphorus removal (BPR) in a sequencing batch reactor (SBR) with single-stage oxic process was investigated using simulated municipal wastewater. The experimental results showed that BPR could be achieved in a SBR without anaerobic phase, which was conventionally considered as a key phase for BPR. Phosphorus (P) concentration 0.22–1.79 mg L −1 in effluent can be obtained after 4 h aeration when P concentration in influent was about 15–20 mg L −1 , the dissolved oxygen (DO) was controlled at 3 ± 0.2 mg L −1 during aerobic phase and pH was maintained 7 ± 0.1, which indicated the efficiencies of P removal were achieved 90% above. Experimental results also showed that P was mainly stored in the form of intracellular storage of polyphosphate (poly-P), and about 207.235 mg phosphates have been removed by the discharge of rich-phosphorus sludge for each SBR cycle. However, the energy storage poly-β-hydroxyalkanoates (PHA) was almost kept constant at a low level (5–6 mg L −1 ) during the process. Those results showed that phosphate could be transformed to poly-P with single-stage oxic process without PHA accumulation, and BPR could be realized in net phosphate removal.

An anaerobic digestion technique was applied to azo-reactive dye aqueous solutions and cotton textile wastewater aiming at the color elimination. A batch-mode water-jacketed anaerobic reactor and acclimatized acetate-consuming bacteria initially derived from the anaerobic digester sludge of a municipal wastewater treatment plant were used for this study. Acetic acid solution and a pH-controller were utilized to maintain the pH at the desired level (6.6–7.2) while the temperature was kept constant at 37 °C using an external water-bath. Acetic acid also served as an external substrate (electron-donor) supply for the bacteria metabolism. Complete decolorization of all dye solutions was succeeded in 4–5 days of experimental run. The biodegradation ability of cotton textile wastewater was also examined without the addition of external substrate supply (acetic acid) resulting to poor decolorization results. However, anaerobic digestion of the same wastewater using the acetate-consuming bacteria and acetic acid as an external substrate supply lead to the complete decolorization of the wastewater in 4 days of experiment.

Methods of adapting micro-organisms to an inhibiting factor in an active industrial bioprocess were examined with an acetic acid fermentation as model. With the aim of automatic control, a fuzzy-logic system was developed on the basis of the collected knowledge of skilled vinegar brewers. In a first step, this fuzzy system was to assess the actual adaptation degree of the bacteria on the basis of data from robust and reasonably priced sensors. From this information an appropriate setpoint value for the inhibiting factor ‘final acid concentration’ was derived for each batch cycle. As a result a further acid tolerance was found after several batch cycles. This adaptation effect should be used to increase the product concentration to more than 20 g per 100 ml acetic acid with a high productivity. The stepwise adapted culture was productive over the aimed acetic acid concentration, a 10% improvement of the product formation rate could be found compared with the status before conditioning. High product concentration and increased productivity finally result in shorter cycle times, less transport and storage volumes, an improved utilization of energy and material resources, and, last but not least, they are an essential steps towards the fulfillment of economical and ecological demands.

With the aim of improving bacterial cellulose (BC) production in an aerated and agitated culture, the effects of the oxygen and carbon dioxide pressures were investigated. The BC production rate was dependent on the oxygen transfer rate, which declined as the broth viscosity increased, accompanied by BC accumulation. Increasing the partial pressure of oxygen by sparging with oxygen-enriched air and/or raising the operating pressure improved the oxygen supply, while the agitation power required was lowered. Although the BC production rate was not affected by higher oxygen pressure, it was reduced as the operating pressure was raised. The reduction in the production rate was considered to be due to the high carbon dioxide pressure, because carbon dioxide-enriched air also reduced the BC production rate, while the reduction was canceled out by increasing the air flow rate.

In addition to the main product l -erythrulose, altro -heptulose and l -threitol were found in medium in which meso -erythritol was undergoing oxidation by Acetobacter suboxydans . These compounds were isolated by paper chromatography and identified by their dibenzylidene derivatives. It was established that threitol had the l -configuration by measuring the optical rotation. Another compound present in the medium appeared to be heptulose phosphate by its chromatographic behavior. The formation of altro -heptulose was not detected when sorbitol ( d -glucitol), ribitol (adonitol), d -mannitol, d -ribose, or l -erythrulose were used as substrates. No heptulose formation was observed when meso -erythritol was oxidized by Acetobacter xylinium . C 14 studies revealed that the three compounds detected in the medium were derived from meso -erythritol. Some possible biochemical pathways by which these compounds might be synthesized are discussed. To the authors' knowledge this is the first report of the synthesis in vivo of this heptulose and of l -threitol by Acetobacter suboxydans .

A gas-liquid chromatographic method, based on acetylation of polyols, was applied to a study of polyols in urine and in serum. The profile of the normal urinary polyol excretion was described and the formation of additional polyols was demonstrated by treating samples with sodium borohydride prior to chromatography. In diabetes mellitus the urinary excretion of mannitol and myo-inositol was elevated. In cases of chronic renal failure the retention of polyols in serum was demonstrated and the level of myo-inositol was shown to be increased both in serum and in urine. The design of the experimental conditions eliminated the errors due to the intake of exogenous polyols. The metabolic significance of the findings is still to be determined.

Summary Bacterial cellulose can be synthesized by Acetobacter xylinum . It is a very pure cellulose, not mixed with other components as hemicelluloses or lignocelluloses. Bacterial cellulose is organized as a fibrous network. In this paper firstly the kinetics of growth and cellulose formation are described. According to increasing initial concentrations of glucose within a range of 5 to 30 g/l the rates of product formation increase and the yields at lower concentrations are optimal. With respect to the very low amounts of cell dry mass (0.4 g/l) the consumption of total nitrogen is negligable but amino acids such as tryptophane, methionine, lysine, phenylalanine and threonine are essential. The paper is introduced by an overview about structure and biochemistry of bacterial cellulose.

In order to know the kinds and forms of vitamin B 12 coenzymes which participate in the formation of glutamic acid through the pathway via citramalate, mesaconate and β-methyla spartate by Acetobacter suboxydans , isolation and identification of the compounds from the bacteria were attempted. From 500 l fermentation of A. suboxydans , 1.7 kg of the freeze-dried cells were obtained. Corrinoids were extracted from the cells with 80% ethanol with or without cyanide, purified with p -chlorophenol-chloroform, fractionated by aluminacolumn chromatography and crystallized in acetone. The paper-ionophoretic, paper-chromatographic, spectrophotometric and microbiological investigations of the cyanocorrinoid showed that the compound obtained might be 5,6-dimethylbenzimidazolyl cobamide. The investigation on the nucleoside, a Ce(III)-decomposition product of the corrinoid proved to be α-ribazole and therefore gave an additional evidence for 5,6-dimethylbenzimidazolyl cobamide. For coenzyme forms, cautions were taken to operate in every process without cyanide and in the dark. Similar physicochemical tests indicated that the coenzyme form of the compound is cobalamin coenzyme.

Since the establishment of p-aminobenzoic acid as a member of the B vitamin group, a considerable interest has been shown in methods of determination in natural materials. Since known chemical methods are not sufficiently sensitive, it became evident that microbiological tests should be the most practicable. The organism Clostridium acetobutylicum has been used (1) but no general assay procedure has been presented. Several bacterial strains which respond to p-aminobenzoic acid have been investigated in this laboratory, but satisfactory assay procedures with these organisms have not yet been devised. For the discovery of the test organism used in the procedure described in this paper, we are indebted to Dr. Beadle and Dr. Tatum who kindly furnished us with a culture of their p-aminobenzoic acid requiring a mutant strain of Neurospora crassa, designated by them as Neurospora crassa p-aminobenzoicless No. 1633 (2). This mold will grow optimally on a medium consisting of inorganic salts, ammonium tartrate, sucrose, biotin, and p-aminobenzoic acid. For purposes of assay, however, it has proved advantageous to supplement this basal medium with natural extracts which are either naturally low in p-aminobenzoic acid or have been treated to remove it. With such a complex medium, the possibility of interference by toxic substances or stimulatory substances other than p-aminobenzoic acid which might be present in samples to be assayed is reduced to a minimum. Since the completion of a considerable part of the experimental work described in this paper, microbiological assay methods for p-aminobenzoic acid have been published by Landy and Dicken (3) utilizing the organism Acetobacter suboxydans and by Lewis (4) using Lactobacillus arabinosus 17-5.

Bacterial cellulose (BC) has received substantial interest owing to its unique structural features and impressive physico-mechanical properties. BC has a variety of applications in biomedical fields, including use as biomaterial for artificial skin, artificial blood vessels, vascular grafts, scaffolds for tissue engineering, and wound dressing. However, pristine BC lacks certain properties, which limits its applications in various fields; therefore, synthesis of BC composites has been conducted to address these limitations. A variety of BC composite synthetic strategies have been developed based on the nature and relevant applications of the combined materials. BC composites are primarily synthesized through in situ addition of reinforcement materials to BC synthetic media or the ex situ penetration of such materials into BC microfibrils. Polymer blending and solution mixing are less frequently used synthetic approaches. BC composites have been synthesized using numerous materials ranging from organic polymers to inorganic nanoparticles. In medical fields, these composites are used for tissue regeneration, healing of deep wounds, enzyme immobilization, and synthesis of medical devices that could replace cardiovascular and other connective tissues. Various electrical products, including biosensors, biocatalysts, E-papers, display devices, electrical instruments, and optoelectronic devices, are prepared from BC composites with conductive materials. In this review, we compiled various synthetic approaches for BC composite synthesis, classes of BC composites, and applications of BC composites. This study will increase interest in BC composites and the development of new ideas in this field.

A bioinspired bottom-up process was developed to produce self-assembled nanocomposites of cellulose synthesized by Acetobacter bacteria and native starch. This process takes advantage of the way some bacteria extrude cellulose nanofibres and of the transport process that occurs during the gelatinization of starch. Potato and corn starch were added into the culture medium and partially gelatinized in order to allow the cellulose nanofibrils to grow in the presence of a starch phase. The bacterial cellulose (BC)–starch gels were hot pressed into sheets that had a BC volume fraction higher than 90%. During this step starch was forced to further penetrate the BC network. The self-assembled BC–starch nanocomposites showed a coherent morphology that was assessed by Atomic Force Microscopy (AFM) and Environmental Scanning Electron Microscopy (ESEM). The nanocomposites structure was studied using X-ray diffraction and ATR-FTIR spectroscopy. The degree of crystallinity of the final nanocomposites was used to estimate the volume fraction of BC. The aim of this paper is to explore a new methodology that could be used to produce nanomaterials by introducing a different phase into a cellulose nanofibre network during its assembly.

The paper deals with the question whether toxicity could be a reason for the incomplete microbial degradation of mineral oils in the laboratory and the environment, especially in soils contaminated over a long period. The luminescence test showed inhibition by the nondegradable residues as well as by the water phase from degradation experiments. This most frequently applied test reaches its limits in the case of substances with very low solubility in water. Conclusions relating to the impact on the microbial community of a contaminated ecosystem are not admissible. Neither nondegradable residues from raffinates nor extracts from long-term contaminated soils showed inhibiting effects on the dehydrogenase activity of Acetobacter methanolicus and a mineral oil-adapted consortium Inhibition of the respiration of the pure strain A. methanolicus and of the consortium growing on glucose and spindle oil respectively was not observed either. The residues evidently contain mainly highly stable compounds which withstand microbial attack. The toxicity of such compounds per se is unlikely. Moreover, toxicity investigations with aqueous phases from degradation experiments gave no indication of the formation of metabolites, which could be responsible for the stagnation of the process.

In extension of the studies on the formation of cellulose by Acetobacter acetigenum (Z-4), the action of this organism on glycerol has now been investigated; this paper records the examination of the products formed in a defined glycerol medium buffered with lactate. Preliminary observations on the action of this organism on ethylene glycol and on inositol are also reported.

When Acetobacter aceti, Acetobacter rancens, Acetobacter acidum-mucosum and Acetobacter acetosum var. nairobiense were grown in defined media containing glucose as sole source of carbon, gentiobiose (O-β- d -glucopyranosyl-(1 → 6)- d -glucopyranose) and sophorose (O-β- d -glucopyranosyl-(1 → 2)- d -glucopyranose) were the principal oligosaccharide products in all cases. These were accompanied by other disaccharides and by higher saccharides. Paper chromatograms showed that each Acetobacter species synthesized the same series of sugars.