Cellulose Carrier Research Articles

Development of a carrier for adhesion of nitrifying bacteria using a thermodynamic approach

Biopop, a novel modified cellulose carrier for nitrification was developed through thermodynamic analysis of carrier materials. By measuring contact angles among nitrifying bacteria, solid carrier and broth, the change in free energy of adhesion of nitrifying bacteria on carrier (δG) was calculated. Cellulose gave the most favorable free energy change for adhesion of nitrifying bacteria and all the inoculated microbes were attached on porous carrier made of cellulose within 1 day. The new carrier gave a nitrification rate (800 g N-NH /m day), which was about four times higher than other carriers made of synthetic polymers such as polyurethane or rubber.

High-rate seawater denitrification utilizing a macro-porous cellulose carrier

Continuous denitrification experiments were undertaken using marine denitrifying bacteria immobilized in a macro-porous cellulose carrier. The denitrifying capacity of this immobilized system was examined using an ejector-type bioreactor at pH 8.0, 30°C, under anaerobic conditions. In addition, the immobilized denitrifying bacteria were isolated and characterized. The results showed that complete denitrification will not occur unless (i) a phosphorus (g) per NO 3-N (g) ratio ( P NO 3-N ) of 0.029, (ii) 0.01% trace element solution (containing Fe, Mn, Mo, etc.) at 280 g/m 3 NO 3-N concentration and (iii) a methanol concentration at 30% more than the theoretical carbon concentration requirement are maintained. Copper enhanced nitrite reduction at an influent Cu (g) per influent NO 3-N (g) ratio ( Cu NO 3-N ) of 0.002. Based on these results, a feeding medium was formulated which not only reduced costs but, more importanly, allowed the maximum NO 3-N loading rate of 24.8 kg-N/m 3-carrier/d (at a NO 3-N influent concentration and hydraulic retention time of 500 g/m 3 and 5 h, respectively). This value is comparable to that of freshwater in which a macro-porous cellulose carrier was also employed, indicating the insensitivity of the immobilized denitrifying bacteria to salinity. The morphological and physiological characterisitics of the immobilized denitrifying bacteria showed similarities to Hyphomicrobium spp.

Development of bioreactors for denitrification with immobilized cells

A macro-porous cellulose carrier (AQUACEL TM) was used for immobilization of denitrifying bacteria to develop a practical, high-performance nitrogen removal system. When the immobilized cells were used for denitrification at a high nitrogen loading rate, flotation of carriers caused by the evolution of nitrogen gas occurred. For countering the problem of carrier flotation, new reactors in which hydrodynamic jet flow and centrifugal force are used. In these new reactors the floating carriers were distributed homogeneously and complete denitrification was achieved even at high loading rate of 20 kg-N/m 3-carrier/d. This AQUACEL system was used for efficient denitrification of wastewater discharged from an electroplating factory.

Improved MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay for the measurement of viable animal cell number in porous cellulose carriers

A method to measure cell concentration in porous cellulose carriers was developed. Results of the comparison of 5 colorimetric assays showed that MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay by the solubilization of the formazan with DMSO(dimethyl sulfoxide) was the most suitable method for the measurement of cell concentration in porous cellulose carriers. The growth of CHO-K1 (Chinese hamster ovary)-immobilized in different types of carrier was evaluated.

Nitrogen removal in seawater using nitrifying and denitrifying bacteria immobilized in porous cellulose carrier

Nitrogen compounds in seawater are now contributing to serious water pollution problems. In this study, continuous removal of nitrogen in seawater using nitrifiers and denitrifiers immobilized in macro-porous cellulose carrier “AQUACEL” was examined. In nitrification, the nitrite oxidation step becomes the rate limiting step unless an influent inorganic carbon (g) / influent NH4-N (g) ratio (IC/NH4-N) of 7.23 is maintained. This is equivalent to an influent alkalinity (g) / influent NH4-N (g) ratio (ALK/NH4-N) of 8.25. Nitrite oxidizers were also sensitive to change in NH4-N loading. Unlike other biological removal systems used for seawater, trace element solution (containing Mo, Cu, Mn, Co, Fe, etc.) was added only at a high NH4-N loading rate of 0.65 kg-N/m3/carrier/d (at NH4-N concentration of 40 g/m3) and acclimatizing period was short, i.e., about a week. The maximum NH4-N loading rate obtained which removed 99 to 100% of the nitrogen compounds, was 1.30 kg-N/m3/carrier/d. For completion of denitrification, an influent phosphorus (g) per influent NO3-N(g) ratio (P/NO3-N) of 0.03 was required. Trace element solution (containing Fe, Mn, Mo, etc.) was doubled to 0.02% at NO3-N concentration of 560 g/m3. In addition, methanol concentration must be maintained at 30% more of the theoretical value of carbon concentration requirements. Copper enhanced nitrite reduction at an influent Cu(g) per influent NO3-N(g) ratio (Cu/NO3-N) of 0.002. The maximum allowable NO3-N loading rate necessary to remove about 99 to 100% of the nitrogen compounds was 20.79 kg-N/m3/carrier/d. This study reveakls that the AQUACEL system has high nitrifying and denitrifying capacities. The nitrogen loading capacity of denitrification is about ten times that of nitrification and is comparable to that of freshwater which also employed the AQUACEL system. In contrast, nitrogen loading capacity of nitrification is about six times less than that of freshwater, which indicates a higher sensitivity of nitrifiers to salinity. This indficates high sensitivity of the immobilized nitrifying bacteria to salinity. Morphological observations show that the ammonia oxidizers are a mixed culture ofNitrosomonas spp . and Nitrosovibrio spp., while the nitrite oxidizer is a Nitrobacter spp. The immobilized denitrifying bacteria showed similar morphological characteristics to the Hyphomicrobium spp.

Mercury removal from wastewater using porous cellulose carrier modified with polyethyleneimine

An adsorbent for heavy metal was synthesized by introducing polyethyleneimine (PEI) into porous cellulose carriers. Evaluations of synthesis results and adsorbent properties were conducted. Elementary analysis of the adsorbent revealed extensive crosslinking of PEI with the modified matrix. Batch adsorption tests showed the ability of cell-PEI to selectively remove mercury even at acidic regions. At low concentration ranges, mercury adsorption by cell-PEI can be interpreted by the Langmuir isotherm. With this model, an adsorbent capacity and Hg-ligand stability constant of approximately 288.0 mg g −1 and 12.91 mg −1, respectively, were obtained. From adsorption rate experiments, diffusivity of Hg in the carrier was found to be approximately equal to 7.30 × 10 −14 m 2 s −1. Extensive crosslinking of PEI chains that restricts ligand mobility was cited as the foremost factor contributing to these observed properties.

The rapid determination of caesium radionuclides in water systems using composite sorbents

In the countries of the former U.S.S.R. the composite sorbent ‘Anfezh’ (ferric-potassium hexacyanoferrate on a cellulose carrier) is used for the determination of caesium radionuclides in aqueous media. The certified efficiency of Anfezh for radiocaesium extraction is 98 ± 1%. Anfezh is cheap, does not require long preparation before use and permits rapid pre-concentration of radiocaesium.

Nitrogen removal in seawater using nitrifying and denitrifying bacteria immobilized in porous cellulose carrier

Nitrogen compounds in seawater are now contributing to serious water pollution problems. In this study, continuous removal of nitrogen in seawater using nitrifiers and denitrifiers immobilized in macro-porous cellulose carrier "AQUACEL" was examined. In nitrification, the nitrite oxidation step becomes the rate limiting step unless an influent inorganic carbon (g) / influent NH4-N (g) ratio (IC/NH4-N) of 7.23 is maintained. This is equivalent to an influent alkalinity (g) / influent NH4-N (g) ratio (ALK/NH4-N) of 8.25. Nitrite oxidizers were also sensitive to change in NH4-N loading. Unlike other biological removal systems used for seawater, trace element solution (containing Mo, Cu, Mn, Co, Fe, etc.) was added only at a high NH4-N loading rate of 0.65 kg-N/m3/carrier/d (at NH4-N concentration of 40 g/m3) and acclimatizing period was short, i.e., about a week. The maximum NH4-N loading rate obtained which removed 99 to 100% of the nitrogen compounds, was 1.30 kg-N/m3/carrier/d. For completion of denitrification, an influent phosphorus (g) per influent NO3-N(g) ratio (P / NO3-N) of 0.03 was required. Trace element solution (containing Fe, Mn, Mo, etc.) was doubled to 0.02% at NO3-N concentration of 560 g/m3. In addition, methanol concentration must be maintained at 30% more of the theoretical value of carbon concentration requirements. Copper enhanced nitrite reduction at an influent Cu(g) per influent NO3-N(g) ratio (Cu/NO3-N) of 0.002. The maximum allowable NO3-N loading rate necessary to remove about 99 to 100% of the nitrogen compounds was 20.79 kg-N/m3/carrier/d. This study reveakls that the AQUACEL system has high nitrifying and denitrifying capacities. The nitrogen loading capacity of denitrification is about ten times that of nitrification and is comparable to that of freshwater which also employed the AQUACEL system. In contrast, nitrogen loading capacity of nitrification is about six times less than that of freshwater, which indicates a higher sensitivity of nitrifiers to salinity. This indficates high sensitivity of the immobilized nitrifying bacteria to salinity. Morphological observations show that the ammonia oxidizers are a mixed culture of Nitrosomonas spp. and Nitrosovibrio spp., while the nitrite oxidizer is a Nitrobacter spp. The immobilized denitrifying bacteria showed similar morphological characteristics to the Hyphomicrobium spp.

Production of human growth hormone by protein-free cultivation of anchorage-dependent cells with porous cellulose carrier

Verots S3 cells derived from Vero-317 cells which can grow in biotin-containing MEM medium were successfully cultured in a protein-free medium with a porous cellulose carrier. The growth of Verots S3 cells without a carrier was inhibited because they easily aggregated under excessive shear stress, but the cells grew very quickly when cultured with the porous cellulose carrier. This improvement in cell growth was thought to be due to the protection from fluid shear stress afforded by the porous structure of the carrier. Production of human growth hormone (hGH) by repeated batch cultivation of Verots S3 cells was much better with than without the carrier. Cultivation with a temperature shift from 39 to 33°C gave hGH production up to 400% higher in a spinner culture with the cellulose carrier. For large-scale cultivation, temperature sensitive Verots S3 cells were cultivated with the porous cellulose carrier in a rotary column bioreactor and the perfusion culture results showed that the cell density inside the carrier increased up to 7.9 × 10 8 cells·ml-carrier −1 in 2 weeks. No concentration gradient of the cells in the rotary column was observed.

Effect of volume ratio of cellulose carriers and time interval of repeated batch culture on citric acid productivity by immobilized Aspergillus niger

Abstract Citric acid production by Aspergillus niger immobilized in porous cellulose carriers, commercially known as MICROCUBE, was investigated at different volume ratios of carriers, MICROCUBE was prepared using viscose to immobilize A. niger for culture. The result showed that the acid productivity in the immobilized culture was twice that in a conventional suspension culture. In addition, it was found that the acid productivity depended on carrier volume ratio, where a maximum productivity of 8.9 g/l · d was obtained at 30% v/v. At this volume ratio, repeated batch cultures were tested at different time intervals of 5, 7 and 9 d. In all cases, the activity of immobilized A. niger was maintained for up to 40 d a maximum amount of acid was obtained at 7-d batch interval.

A general procedure for evaluation of immunological relevance of synthetic peptides: Peptides synthesized on paper in enzyme-linked immunosorbent assay

Multiple continuous-flow solid-phase peptide synthesis has been adapted for synthesis of peptides on a cellulose carrier (Whatman 3MM paper). Paper-bound synthetic peptides that represent antigenic determinants of particular proteins detected antibodies against the respective proteins in an enzyme-linked immunosorbent assay. The method is applied to the synthesis, and use in site-directed serology, of four peptides derived from the gp41 glycoprotein of HIV, the Epstein-Barr virus-determined nuclear antigen-1 and VCA proteins of the Epstein-Barr virus, and the early region of human papillomavirus type 11.

The Influence of Carrier of Gustatory Stimulation on the Cephalic Phase of Canine Pancreatic Secretion

The pancreatic secretory responses of dogs to various taste stimuli were examined in this study. Additionally, taste preferences were examined in 24-hour exposure tests to taste stimulus solutions as well as in short exposure tests to taste solutions mixed with commercial stock diet. The liquid and solid food preference tests produced quite different results. In dogs with cannulated gastric and duodenal fistulas, gustatory receptors were stimulated orally with 100 ml of taste stimulus solution (water 0.05 M monosodium glutamate (MSG), 0.05 M citric acid or 0.3 M sucrose) mixed with 25 g of a carrier (commercial stock diet, purified diet or cellulose). Pancreatic secretory responses to the taste stimuli varied with the type of carrier. Stock diet carrier was a better stimulant than the purified diet for both protein output and volume flow. Taste stimuli with a cellulose carrier did not produce any pancreatic response at all. The differences in responses to the different carriers were greater than the differences between taste stimuli when the same carrier was used. This experiment indicates that gustatory stimulation does influence the function of pancreatic secretion depending on the carriers used.

A new method of preparation of specifically purified anti-TNP antibodies

A new method of preparation of specifically purified rabbit anti-TNP antibodies is described, in which immunoadsorbents prepared from TNP-BSA and PAB-cellulose and AE-cellulose are used. To increase efficiency, TNP-BSA was reduced and alkylated in 6 M guanidine hydrochloride solution before coupling with diazotized PAB-cellulose. For coupling with AE-cellulose in the presence of cyclohexyl-morpholinyl-carbodiimide no pretreatment of TNP-BSA is necessary. In the case of PAB-cellulose 92 mg TNP-BSA were bound to 1 g of the cellulose carrier, and in case of AE-cellulose 100 mg of TNP-BSA was linked to 1 g of the cellulose. The best results were obtained with PAB-cellulose-TNP-BSA immunoadsorbent and 0.01 M picric acid as eluting agent. With low affinity rabbit anti-TNP antibodies 92% yield of 85–100% precipitable antibody was achieved reproducibly. With other methods, only 12–48% yield of 50–90% precipitable antibodies was obtained.