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1.
Neelakanteshwar K. Patil T. B. Karegoudar 《World journal of microbiology & biotechnology》2005,21(8-9):1493-1498
Summary Di-n-butylphthalate (DBP) is one of the phthalate esters (PAEs) used in the manufacture of plasticizers, insect repellents and
synthetic fibres and contributes to environmental pollution. We report a novel bacterium belonging to the genus, Bacillus (NCIM 5220), which has the ability to utilize DBP as the sole source of carbon and energy. This bacterium was immobilized
in alginate. The degradation of DBP by immobilized cells was compared with free cells. The effects on the degradation of DBP
of different factors like gel (alginate) concentration, gel bead size, temperature, and pH were investigated. Oxygen uptake
in the presence of DBP by free and immobilized cells was also studied. The results showed that the degradation of DBP by immobilized
cells was more efficient than by free cells. Further, the effect of various factors tested on the degradation of DBP by alginate-immobilized
cells showed that the degradation of DBP was remarkably affected by alginate concentration between 2 and 5% and drastically
decreased between bead size 2 and 5 mm. A change of 10 °C of reaction temperature from 30 to 40 °C did not alter the degradation
of DBP, and maximum degradation was appeared to be favoured over a broad pH range of 6.5–7.5 for immobilized cells as compared
to free cells, which showed an optimum temperature of about 35 °C and pH of 7.0. The immobilized cells showed higher oxidation
of DBP than free cells. Thus more efficient degradation of DBP could be achieved by immobilizing Bacillus sp. in alginate beads. 相似文献
2.
The cells of L. mesenteroides KIBGE HA1 were immobilized for the production of dextran on acrylamide gel and gel concentration was optimized for maximum
entrapment. Sucrose at substrate concentration of 10% produced high yield of dextran at 25°C with a percent conversion of
5.82 while at 35°C it was 3.5. However, increasing levels of sucrose diminished dextran yields. The free cells stopped producing
dextran after 144 h, while immobilized cells continued to produce dextran even after 480 h. Molecular mass distribution of
dextran from free cells indicate that it is identical to that of blue dextran while the molecular mass of dextran from immobilized
cells is lower than that of free cells. 相似文献
3.
Isao Karube Shinichi Kuriyama Tadashi Matsunaga Shuichi Suzuki 《Biotechnology and bioengineering》1980,22(4):847-857
A methanogenic population was immobilized onto agar gel, polyacrylamide gel, and collagen membrane. Agar-gel-entrapped methanogenic microorganisms gave the highest activity. The optimum agar concentration was between 1.5 and 3% (w/v), and the optimum microbial content was 20 mg wet cells/g gel. The optimum conditions for methane production by immobilized whole cells were pH 7.0–7.5 and 37–45°C. The rate of methane production was initially 1.8 μmol/g gel/hr. Methane productivity was gradually increased and reached a steady state (4.5μmol/g gel/hr) after 25 days of incubation. The immobilized methanogenic microbial population continuously evolved methane over a 90 day period. No difference in methane productivity was observed after three months of storage at 5°C. Methane was also produced by immobilized whole cells under aerobic conditions. Furthermore, carbohydrates, such as glucose, in wastewater completely decomposed by immobilized whole cells. 相似文献
4.
利用基因工程菌HC01固定化细胞转化生产D-对羟基苯甘氨酸 总被引:1,自引:0,他引:1
对一菌两酶工程菌HC01转化底物DL-对羟基苯海因(DL-HPH)的最适条件及其细胞固定化进行了研究,HC01游离细胞转化DL-HPH的最适条件为40°C、pH7.5。通过对固定化细胞酶活力测定,确定细胞固定化的最优条件为海藻酸钠浓度2.5%、细胞浓度0.029g/mL、钙离子浓度3%。固定化HC01的热稳定性比游离细胞高5°C,二价金属离子Mn2+、Mg2+、Cu2+、Co2+和Ni2+在浓度为0.1mmol/L时对固定化细胞中D-海因酶(HYD)和N-氨甲酰-D-氨基酸酰胺水解酶(CAB)两酶的活力无显著影响,Mn2+和Mg2+可分别使游离细胞中CAB活力提高至原来的2.1和2.7倍。在氮气保护下,当初始pH为9.0、转化温度为40°C、转速为80r/min,利用固定化HC01转化30g/L的DL-HPH时,36h后转化率可达97%左右,产物D-HPG经纯化后光学纯度达到99.7%,得率可达85%。 相似文献
5.
Several microorganisms having higher L -histidine ammonia-lyase activity were immobilized into polyacrylamide gel lattice. The yield of enzyme activity by immobilization was highest in Achromobacter liquidum IAM 1667. As A. liquidum has urocanase activity, the cells were heat-treated at 70°C for 30 min to inactivate the urocanase. Enzymatic properties of the immobilized A. liquidum cells were investigated and compared with those of the intact cells. No difference was observed between the pH activity curve and optimal temperature for the intact and immobilized cells. The permeability of substrate or product through the cell wall was increased by immobilization of the cells. When an aqueous solution of 0.25M L -histidine (pH 9.0) containing 1mM Mg2+ was passed through a column packed with the immobilized A. liquidum cells at a flow rate of SV = 0.06 at 37°C, L -histidine was completely converted to urocanic acid. The L -histidine ammonia-lyase activity of the immobilized cell column was stable over 40 days at 37°C. From the effluent of the immobilized cell column, Urocanic acid was easily obtained in a good yield. 相似文献
6.
L. Feijoo-Siota F. Rosa-Dos-Santos T. de Miguel T. G. Villa 《Bioremediation Journal》2008,12(4):185-192
The biodegradation of naphthalene in sea water by freely suspended and alginate-entrapped cells of Pseudomonas stutzeri 19SMN4 has been investigated in batch cultures. The results showed that immobilized cells can be stored at 4°C for 1 month without loss of viability. The biodegradation was highly affected by the availability of nitrogen and phosphorous, so at 30°C a naphthalene concentration of 25 mM was almost completely degraded (93%) by free cells in 6 days in samples supplemented with these nutrients, whereas only 42% naphthalene was consumed in the nonsupplemented samples. Biodegradation was much slower at 16°C than at 30°C; after 6 days of culture at 30°C, almost all naphthalene was degradated by free and immobilized cells, whereas only 22% and 34% at 16°C, respectively. The degradation rate remained unaffected when the naphthalene concentration was reduced from 25 to 10 mM. Alginate of three different viscosities was used for immobilization of cells. After 7 days of culture, beads formed with 31.4 cP alginate were fragmented, whereas beads formed with 240 and 3600 cP did not display structural changes and afforded the same degradation rate. Beads formed with high-viscosity alginate retained cells more efficiently. 相似文献
7.
The susceptibility of targets to destruction by tumoricidal rat and mouse macrophages was studied with virus-transformed cell lines in which various elements of the transformed phenotype are only expressed at specific temperatures. BHK cells transformed by the ts3 mutant of polyoma virus, rat embryo 3Y1 cells transformed by a temperature-sensitive A cistron mutant of simian virus 40 (SV40) and the ts-H6-15 temperature-sensitive line of SV40-transformed mouse 3T3 cells were killed in vitro by macrophages at both the permissive (33 °C) or nonpermissive (39 °C) temperatures for expression of the transformed phenotype. 3T3, 3Y1 and BHK cells transformed by wild-type SV40 or polyoma virus were also destroyed by tumoricidal macrophages at both 33 and 39 °C, but untransformed 3T3, 3Y1, and BHK cells were not. Thus, transformed cells are killed by macrophages regardless of whether or not they express cell surface LETS protein or Forssman antigen, display surface changes which permit agglutination by low doses of plant lectins, express SV40 T antigen, have a low saturation density, or exhibit density-dependent inhibition of DNA synthesis. 相似文献
8.
Regulatory mutants of simian virus 40: constructed mutants with base substitutions at the origin of DNA replication. 总被引:43,自引:0,他引:43
Mutants of simian virus 40 (SV40) with base substitutions at or near the origin of replication of the viral genome have been constructed by bisulfite mutagenesis at the BglI restriction site of SV40 DNA, followed by transfection of cells with the BglI-resistant (BglIr) DNA so generated. Based on plaque morphology at different temperatures, the resulting BglIr mutants could be classified into four-groups. Class I mutants (designated ar for “altered restriction”) were indistinguishable from wild-type SV40; class II mutants (designated shp for “sharp plaque”) produced small, sharp-edged plaques; class III mutants (designated sp for “small plaque”) produced small plaques at 32 °C, 37 °C and 40 °C; and class IV mutants (designated cs for “cold sensitive”) produced small plaques at 32 °C and wild-type plaques at 37 °C and 40 °C. That the altered plaque morphology of sp and cs mutants was related to mutation at the BglI restriction site was demonstrated by co-reversion to wild-type of the plaque phenotype and BglI sensitivity. The nucleotide sequence around the original BglI site was determined in the DNA from one mutant of each class. In each case a different base-pair substitution was found, at a site outside sequences coding for SV40 proteins. When rates of replication of mutant DNAs were measured during productive infection, ar mutant DNA was synthesized at a rate comparable to that of wild-type SV40 DNA, shp mutant DNA was made at a rate exceeding that of wild-type, sp mutant DNA was synthesized at a lower rate than that of wild type. and cs mutant DNA synthesis was reduced at 32 °C, but about the same as the wild-type rate at 40 °C. These patterns of mutant DNA synthesis were unaltered in cells co-infected with mutant and wild-type virus, i.e. the defects in DNA synthesis were not trans-complementable. We conclude that the defective mutants have single base-pair changes in a cis element that determines the rate of viral DNA replication, presumably within the origin signal itself. 相似文献
9.
Jung Soo Lim Seung Won Park Seung Wook Kim 《World journal of microbiology & biotechnology》2006,22(1):39-44
Summary In this study, an investigation was performed into the thermal and operational characteristics of glutaryl-7-aminocephalosporanic
acid (GL-7-ACA) acylase (EC 3.5.1.-) immobilized on silica gel that had been modified by epoxide silanization. The pH values
for the optimum activity of free and immobilized GL-7-ACA acylase were almost the same. However, the pH-dependent activity
profile for the immobilized GL-7-ACA acylase is considerably expanded. Both free and immobilized enzymes generally had the
highest activity at 50 °C. In thermodynamic studies, it was found that immobilization using epoxide silanization made GL-7-ACA
acylase thermodynamically stable. In the results of repeated batch production of 7-ACA, 89.0 and 83.5% of the 7-ACA produced
at the initial cycle were maintained after 20 times of recycle at 25 °C and 30 °C, respectively. Hence it was suggested that
mass production of 7-ACA at 25 °C using immobilized GL-7-ACA acylase by epoxide silanization would be possible on a large
scale. 相似文献
10.
Cotton fabric was first oxidized with sodium periodate, and then employed to immobilize catalase. Optimization studies for oxidation of the fabric and immobilization of the enzyme were performed. The properties of the immobilized catalase were examined and compared with those of the free enzyme. A high activity of the immobilized enzyme was obtained when the fabric was oxidized at 40°C and pH 6.0 for 8h in a bath containing 0.20 mol L?1 sodium periodate and the enzyme was immobilized at 4°C for 24h with a catalase dosage of 120.0 U mL?1. The immobilized enzyme exhibited optimum activity at 40°C, while the free enzyme had optimal temperature of 30°C, suggesting that the immobilized catalase could be used in a broader temperature range. Both the immobilized and free enzyme had pH optima of 7.0. The staining test and reusability showed that the catalase was fixed covalently on the oxidized cotton fabric. 相似文献
11.
《Enzyme and microbial technology》1987,9(9):538-541
Arthrobacter simplex cells have been covalently immobilized to granules of microcrystallized regenerated cellulose by means of N-hydroxymethyl, N′-glucosylurea groups at pH 8.5, 18°C and cell suspension concentration of 60 mg/ml. The immobilization yield was found to exceed 100%. The maximum initial rate of Cortisol transformation to Prednisolone remained almost constant after 20-fold transformation in a nutrient medium containing 0.5% peptone at pH 8.0, 32°C and aeration with oxygen. The effect of the substrate concentration on the activity of the immobilized cells, as well as of the ratio between substrate and immobilized cells on the degree of transformation, was investigated. The immobilized cells were characterized by means of electronmicroscopic studies. Microbiological observations have shown that immobilized cells can proliferate and the free cells obtained are accumulated in the nutrient medium. The immobilized cells preserve their viability for a long time when they are stored at 4°C. 相似文献
12.
The production of agar-oligosaccharides from agarose by free and immobilized agarase, obtained from a Pseudomonas aeruginosa AG LSL-11 was investigated and the activity, longevity and the operational stability of immobilized enzyme was compared with that of the free enzyme. The agar hydrolyzed products of free enzyme and immobilized enzyme were neoagarobiose, neoagarotetraose and neoagarohexaose as evidenced by LC-MS analysis. The immobilization of agarase was confirmed by SEM and also by the enzymatic transformation of agarose into agaroligosaccharides. The free agarase showed maximum activity at 40°C, whereas it’s immobilized counterpart showed maximum activity at 45oC, however, the optimum pH for both systems remained unchanged (pH 8.0). The relative activities of free agarase at pH 9.0 and 10.0 were 90 and 74%, respectively, whereas, the corresponding activities of the immobilized system were determined to be 97 and 90%. The stabilities of free agarase at pH 9.0 and 10.0 were 80 and 60% respectively, but for the immobilized system the respective residual activities were estimated to be 97 and 85%. Immobilized agarase appears to be more tolerant to high temperatures in terms of its activity and stability as it is compared to that of the free enzyme which retained 74 and 50.84% of relative activity at 55 and 60°C while, free agarase retained only 40 and 16.79% of its original activity. Furthermore, the immobilized agarase could be reused in batches efficiently for eight cycles, and could be stored for 3 months at 4°C as wet beads and for more than 6 months as dry beads. 相似文献
13.
Kousaku Murata Keiko Tani Jyoji Kato Ichiro Chibata 《Enzyme and microbial technology》1981,3(3):233-242
Efficient ATP generation is required to produce glutathione and NADP. Hence, the generation of ATP was investigated using the glycolytic pathway of yeast. Saccharomyces cerevisiae cells immobilized using polyacrylamide gel generated ATP from adenosine, consuming glucose and converting it to ethanol and carbon dioxide. Under optimal conditions, the ATP-generating activity of immobilized yeast cells was 7.0 μmol h?1 ml?1 gel. A column packed with these immobilized yeast cells was used for continuous ATP generation. The half-life of the column was 19 days at a space velocity of (SV) 0.3 h?1 at 30°C. The properties of glutathione- and NADP-producing reactions coupled with the ATP-generating reaction were investigated. Escherichia coli cells with glutathione synthesizing activity and Brevibacterium ammoniagenes cells with NAD kinase activity were immobilized in a polyacrylamide gel lattice. Under optimal conditions, the immobilized E. coli cells and immobilized B. ammoniagenes cells produced glutathione and NADP at the rates of 2.1 and 0.65 μmol h?1 ml?1 gel, respectively, adding ATP to the reaction mixture. In order to produce glutathione and NADP economically and efficiently, the glutathione- and NADP-producing reactions were finally coupled with the ATP-generating reaction catalysed by immobilized S. cerevisiae cells. To compare the productivities of glutathione and NADP, and to compare the efficiency of ATP utilization for the production of these two compounds, the two reactor systems, co-immobilized cell system and mixed immobilized cell system, were designed. As a result, these two compounds were also found to be produced by these two kinds of reactor systems. Using the data obtained, the feasibility and properties of ATP generation by immobilized yeast cells are discussed in terms of the production of glutathione and NADP. 相似文献
14.
Firefly (Luciola mingrelica) luciferase [Photinus luciferin 4-monooxygenase (ATP-hydrolysing); Photinus luciferin: oxygen 4-oxidoreductase (decarboxylating, ATP-hydrolysing), EC 1.13.12.7] has been immobilized on albumin and polyacrylamide gel, on AH-, CH- and CNBr-Sepharose 4B as well as on Ultragel, Ultradex and cellophane film activated by cyanogen bromide. Only immobilization on cyanogen bromide-activated polysaccharide carriers resulted in highly active immobilized luciferase. Kinetic properties of immobilized luciferase hardly differed from those of the soluble enzyme. The inactivation rate constants of soluble and immobilized luciferase were measured at pH 5.5–9.0 and 25°C as well as at pH 7.8 and 20–40°C. The ΔH≠ and ΔS≠ values for inactivation of soluble and immobilized luciferases were obtained. A 1000-fold stabilization effect was noted for the luciferase immobilized on CNBr-Sepharose 4B at pH 7.5 and 25°C. A stabilization mechanism for the immobilized luciferase is discussed. 相似文献
15.
Retransformation of ts SV40 Transformants by Murine Sarcoma Virus at Non-permissive Temperature 总被引:6,自引:0,他引:6
HARTMUT C. RENGER 《Nature: New biology》1972,240(96):19-21
Temperature sensitive (ts) SV40 transformed mouse fibroblasts (tsSV3T3) express their transformed phenotype in vitro when growing at 32° C but not when growing at 39° C1. Viral mRNA is, however, apparently transcribed at 39° C, for SV40 specific T-antigen can be demonstrated and viral mRNA can be found by nucleic acid hybridization: Fusion-rescue experiments show that the transforming virus is wild type but tsSV3T3 cells cannot be re-transformed at 39° C with high multiplicity SV40. This suggests that the temperature sensitive behaviour stems from a cellular rather than a viral mutation. The question then arises of the stringency with which these ts transformants control the expression of viral transformation functions at 39° C. 相似文献
16.
The isolation of a temperature sensitive cell line from the Chinese hamster line CCL39 of the American Type Culture Collection is described. At the nonpermissive temperature (39°C) the cells become attached to the surface of tissue culture dishes, but no microscopically observable colonies are formed upon prolonged incubation. Exposure to the high temperature for more than 24 hours leads to an almost complete loss in viability. A karyotypic analysis showed that this new line has lost one of the medium-sized metacentric chromosomes, although no proof is available so far to show that this loss is not simply coincidental. In nonsynchronized cultures transferred to 39°C DNA synthesis stops first, RNA synthesis shortly thereafter, while protein synthesis (turnover) continues for a longer time. After such a shift the cell number increases by less than 15% as measured with the Coulter counter. Studies with synchronized cultures give the following results: (1) one round of DNA synthesis can occur at 39°C when the cells are released from serum starvation or a hydroxyurea block, or when mitotic cells are placed at 39°C; (2) the entry of cells into metaphase of mitosis at 39°C is almost normal when the preceding time interval at 39°C is only eight hours (release of cells from G1/S boundary), but considerably reduced when the cells spend an additional 12 to 15 hours at 39°C in G1 (release from serum starvation). Infection by SV40 virus temporarily induces DNA synthesis after it has come to a stop at the nonpermissive temperature, but cells permanently transformed by SV40 still exhibit the temperature-sensitive phenotype. 相似文献
17.
Glucansucrase from Leuconostoc mesenteroides was immobilized in 1?% (w/v) with sodium alginate to produce oligosaccharides. Glucansucrase gave three activity bands of approx. 240, 178, and 165?kDa after periodic acid-Schiff staining with sucrose. The immobilized enzyme had 40?% activity after ten batch reactions at 30?°C and 75?% activity after a month of storage at 4?°C, which is six times more stable than the free enzyme. Immobilized enzyme was more stable at lower (3.5?4.5) and higher (6.5?7.0) pH ranges and higher temperatures (35?40?°C) compared with the free enzyme. Immobilized and free glucansucrase were employed in the acceptor reaction with maltose and each produced gluco-oligosaccharide ranging from trisaccharides to homologous pentasaccharides. 相似文献
18.
《Enzyme and microbial technology》1987,9(2):112-116
Cells and partially purified α-amylase (EC 3.2.1.1) of the producer strain, Lactobacillus cellobiosus D-39 were immobilized on acrylamide gel. The enzyme showed marked improvement in operational stability. Both immobilized cells and enzyme were stable for a long period and no appreciable loss activity was detected on keeping at 4°C for 4 months. The amylase activity of immobilized cells and enzyme attained maximum at pH 6.0 and 7.6 respectively and at temperature 60°C for both cases. The effects of various solvents, detergent and metal ions were tested; Triton X-100 gave maximum stimulation of the enzyme activity of immobilized cells whereas metal ions exhibited no such enhancement for either of immobilized cells or enzyme. 相似文献
19.
Jun Huang Le-he Mei Hong Wu Dong-qiang Lin 《World journal of microbiology & biotechnology》2007,23(6):865-871
On an industrial scale, the production of γ-aminobutyric acid (GABA) from the cheaper sodium L-glutamate (L-MSG) is a valuable
process. By entrapping Lactobacillus brevis cells with higher glutamate decarboxylase (GAD) activity into Ca-alginate gel beads, the biotransformation conditions of
L-MSG to GABA were optimized with the immobilized cells. The cells obtained from a 60-h culture broth showed the highest biotransformation
efficiency from L-MSG to GABA. The optimal cell density in gel beads, reaction pH and temperature were 11.2 g dry cell weight
(DCW) l−1, 4.4 and 40°C respectively. The thermal stability of immobilized cells was significantly higher than free cells. Under the
optimized reaction conditions, the yield of GABA reached above 90% during the initial five batches and the yield still remained
56% in the tenth batch. Continuous production of GABA was realized with a higher yield by incorporating cell re-cultivation
using the packed bed reactor. 相似文献
20.
《Biochimica et Biophysica Acta (BBA) - Nucleic Acids and Protein Synthesis》1976,418(3):257-265
A method is described for the preparation of 1 2 5I-labelled SV40 DNA. Using this method, SV40 DNA can be routinely labelled to 15 · 106 dpm per μg; much higher specific activities are easily obtained by minor modifications of the method. Once incorporated, the radioactive label dissociates from DNA exceedingly slowly at 4°C or at 68°C. Iodinated SV40 DNA is shown to be useful in the quantitation of viral nucleic acid sequences in SV40-transformed 3T3 cells by DNA · DNA reassociation kinetics. 相似文献