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1.
Rhodococcus opacus B-4, which has recently been isolated as an organic solvent-tolerant bacterium, stabilized water-in-oil (w/o) emulsions by inhibition of droplet coalescence when the cells were dispersed in 90% (v/v) organic solvents. Confocal microscopy revealed that many bacterial cells assembled at the interface between oil and water droplets, though free cells were also detectable at the inside of water droplets. Bacterial cells in the w/o emulsion were capable of utilizing both a water-soluble (glucose) and an oil-soluble substrate (oleic acid) as an energy source. Availability of the w/o emulsion as an immobilized cell system in organic solvents was demonstrated using production of indigo from indole and production of o-cresol from toluene as model conversions. When glucose and oleic acid were simultaneously supplied as energy sources, the w/o emulsion culture of R. opacus B-4 produced indigo and o-cresol at levels of 0.217 and 2.12 mg ml−1, respectively, by 12 h.  相似文献   

2.
Permeabilization is known to overcome cell membrane barriers of whole cell biocatalysts. The use of organic solvents is advantageous in terms of cost, simplicity, and efficiency. In this study,Ochrobactrum anthropi SY509 was permeabilized with various organic solvents. Treatment with organic solvents resulted in lower permeability barriers due to falling out lipids of the cell membrane. Therefore, permeabilized cells showed higher enzyme activity with no cell viability. Among various organic solvents, 0.5% (v/v) chloroform was selected as the most efficient permeabilizing reagent. Changes in the cell membrane structure were observed and the residual amounts of phospholipids of the cell membrane were measured to investigate the mechanism of the improved permeability.  相似文献   

3.
Rhodococcus opacus strain B-4, which has recently been isolated as an organic solvent-tolerant bacterium, has a high hydrophobicity and exhibits a high affinity for hydrocarbons. This bacterium was able to survive for at least 5 days in organic solvents, including n-tetradecane, oleyl alcohol, and bis(2-ethylhexyl) phthalate (BEHP), which contained water less than 1% (w/v). The biocatalytic ability of R. opacus B-4 was demonstrated in the essentially nonaqueous BEHP using indigo production from indole as a model conversion. By the catabolism of oleic acid for NADH regeneration, indigo production increased up to 71.6 μg ml−1 by 24 h.  相似文献   

4.
Taxus chinensis var. mairei was grown in two-liquid-phase culture in a 2.5 l airlift external loop reactor for production of Taxol. A mixture of oleic acid and dibutyl phthalate (1:1, v/v) in a volume ratio of 8:92 to the culture medium gave higher production of Taxol (up to 12 mg l–1) with an aeration rate of 1 vvm. By combination of the in situ extraction, precursor feeding and additional sugar introduction, Taxol production (16.7 mg l–1) was 5 times higher than that in the case without any additives (3.4 mg l–1) and 1.4 times of that in the case with only thein situ extraction (12 mg l–1). Taxol was extracted from the organic solvents with water and methanol (1:1:1.4, by vol.) and lyophilized giving a total yield of ca. 90%.  相似文献   

5.
To extract the microalgal lipid in situ, biocompatible solvents were screened for lipid milking of Nannochloropsis sp. in an aqueous–organic system. The effects of organic solvents on the microalgal growth, the lipid extractability, the dehydrogenases activity and the cell membrane integrity were investigated by UV–visible spectrophotometer, FT-IR spectroscopy, 2,3,5-triphenyltetrazolium chloride (TTC) and Evans Blue stain method, respectively. The results showed that alkane solvents with log P > 5.5 were biocompatible while the hydrophilic solvents with log P < 5.5 were toxic to Nannochloropsis sp. due to the deactivated dehydrogenase and increased cell membrane permeability. As 10% (v/v) hexadecane was used to establish biphasic system, the total lipid production of Nannochloropsis sp. was increased by 28.9% compared to the control. The screened biocompatible solvent hexadecane enhanced not only the algal growth but also the lipid accumulation, showing an effective way to facilitate the process for in situ lipid milking from Nannochloropsis sp.  相似文献   

6.
周旭  胡亚萍  葛晓敏  陈水飞  马方舟  丁晖 《广西植物》2020,40(12):1740-1754
为探讨南美天胡荽对其他植物种子萌发的影响以及筛选影响其他植物的主要化合物,该文采用种子萌发试验、气相色谱-质谱联用以及液相色谱-质谱联用的方法,分析了南美天胡荽不同溶剂浸提液对种子萌发的影响、南美天胡荽植株及其根际土壤浸提液成分。结果表明:(1)南美天胡荽不同溶剂浸提物均具有一定程度的抑制种子萌发作用。(2)气相色谱-质谱分析下,南美天胡荽植株水浸提液中共分离鉴定了35种化合物,其中,邻苯二甲酸二丁酯(15.2%)、10,15-十八烷二元酸(8.58%)、2,4-二叔丁基苯酚(6.81%)相对含量最高; 根际土壤水浸提液中共分离鉴定了17种化合物,其中,油酸酰胺(26.47%)、正二十七烷(9.63%)、十六酸乙酯(4.83%)相对含量最高。(3)液相色谱-质谱分析下,南美天胡荽植株水浸提液共分离鉴定了109种化合物,ESI+模式下,L-苯丙氨酸(3 483.99 ng·mg-1)、木犀草素(2 306.64 ng·mg-1)含量最多,ESI-模式下,右旋奎宁酸(21 827.71 ng·mg-1)、绿原酸(12 589.25 ng·mg-1)含量最多; 根际土壤水浸提液中共分离鉴定了93种化合物,ESI+模式下,丁酸(7 660.53 ng·mg-1)、棕榈酰胺(3 200.36 ng·mg-1)含量最多,ESI-模式下,正二十八酸(18 605.35 ng·mg-1)、蔗糖(12 183.23 ng·mg-1)含量最多。(4)南美天胡荽的潜在化感物质主要为脂肪酸类、酰胺类、酯类、芳香酸类化合物,而土壤中直接起化感作用的物质可能为丁酸、正二十八酸、羟基乙酸、油酸酰胺、棕榈酰胺、十六酸乙酯、苯甲酸,其中脂肪酸类化合物输入可能来源于南美天胡荽、土壤微生物和土壤动物,酰胺类、酯类、芳香类化合物则更可能来源于南美天胡荽植株。  相似文献   

7.
Aspergillus niger with mycelium-bound tannase activity was employed to investigate the synthesis of propyl gallate from gallic acid and 1-propanol in organic solvents. The effects of various organic solvents (log P: −1.0 to 6.6) on the enzymatic reactions showed that benzene (log P: 2.0) was the most suitable solvent. The water content and protonation state of mycelium-bound enzyme both had significant effects on the activity of tannase. The maximum molar conversion (65%) was achieved with 7.3% (v/v) 1-propanol and 5.56 mM gallic acid at stirring speeds of 200 rev/min, 40 °C in presence of anhydrous sodium sulfate and PEG-10,000. Enzyme specificity for the alcohol portion (C1–C8) of the ester showed that the optimum synthesis was observed with alcohols ranging from C3 to C5.  相似文献   

8.
The alcohol dehydrogenase from Thermus sp. ATN1 (TADH) was characterized biochemically with respect to its potential as a biocatalyst for organic synthesis. TADH is a NAD(H)-dependent enzyme and shows a very broad substrate spectrum producing exclusively the (S)-enantiomer in high enantiomeric excess (>99%) during asymmetric reduction of ketones. TADH is active in the presence of 10% (v/v) water-miscible solvents like 2-propanol or acetone, which permits the use of these solvents as sacrificial substrates in substrate-coupled cofactor regeneration approaches. Furthermore, the presence of a second phase of a water-insoluble solvent like hexane or octane had only minor effects on the enzyme, which retained 80% of its activity, allowing the use of these solvents in aqueous/organic mixtures to increase the availability of low-water soluble substrates. A further activity of TADH, the production of carboxylic acids by dismutation of aldehydes, was investigated. This reaction usually proceeds without net change of the NAD+/NADH concentration, leading to equimolar amounts of alcohol and carboxylic acid. When applying cofactor regeneration at high pH, however, the ratio of acid to alcohol could be changed, and full conversion to the carboxylic acid was achieved.  相似文献   

9.
The toxicity to adults of the American house dust mite, Dermatophagoides farinae, and the European house dust mite, Dermatophagoides pteronyssinus, of cassia bark and cassia and cinnamon oil compounds was examined using residual contact and vapour-phase toxicity bioassays. Results were compared with those of the currently used acaricides: benzyl benzoate and dibutyl phthalate. The acaricidal principles of cassia bark were identified as (E)-cinnamaldehyde and salicylaldehyde. In fabric-circle residual contact bioassays with adult D. farinae, salicylaldehyde (17.3 mg/m2) and (E)-cinnamaldehyde (25.8 mg/m2) were 2.5 and 1.7 times more toxic than benzyl benzoate (43.7 mg/m2), respectively, based on 24-h LD50 values. The acaricidal activity was more pronounced in benzaldehyde, menthol, α-terpineol, and thymol (70.8–234.3 mg/m2) than in dibutyl phthalate (281.0 mg/m2). Against adult D. pteronyssinus, salicylaldehyde (17.3 mg/m2) and (E)-cinnamaldehyde (19.3 mg/m2) were 2.4- and 2.2-fold more active than benzyl benzoate (41.9 mg/m2). The toxicity of benzaldehyde, menthol, α-terpineol, and thymol (75.3–179.2 mg/m2) was higher than that of dibutyl phthalate (285.1 mg/m2). In vapour-phase toxicity tests with adult D. farinae, the test compounds described were much more effective in closed—but not in open—containers, indicating that the effect of these compounds was largely a result of action in the vapour phase.  相似文献   

10.
The organic solvent dimethylsulphoxide (DMSO) and 1,1,1,3,3,3-hexafluoro-2-isopropanol (HFIP) have been widely used as a pre-treating agent of amyloid peptides and as a vehicle for water-insoluble inhibitors. These solvents are left in many cases as a trace quantity in bulk and membrane environments with treated amyloid peptides or inhibitors. In the present work, we studied the effects of the two organic solvents on the aggregation behaviors of human islet amyloid polypeptide (hIAPP) and the performances of an all-D-amino-acid inhibitor D-NFGAIL in preventing hIAPP fibrillation both in bulk solution and at phospholipid membrane. We showed that the presence of 1% v/v DMSO or HFIP decreases the rate of fibril formation of hIAPP at the lipid membrane rather than accelerates the fibril formation as what happened in bulk solution. We also showed that the presence of 1% v/v DMSO or HFIP impairs the activity of the inhibitor at the lipid membrane surface dramatically, while it affects the efficiency of the inhibitor in bulk solution slightly. We found that the inhibitor inserts into the lipid membrane more deeply or with more proportion in the presence of the organic solvents than it does in the absence of the organic solvents, which may hinder the binding of the inhibitor to hIAPP at the lipid membrane. Our results suggest that the organic solvents should be used with caution in studying membrane-induced fibrillogenesis of amyloid peptides and in testing amyloid inhibitors under membrane environments to avoid incorrect evaluation to the fibrillation process of amyloid peptides and the activity of inhibitors.  相似文献   

11.
Summary A wild-type strain of Cryptococcus neoformans and Pseudomonas aeruginosa were used to convert n-pentadecane to the corresponding dioic acid, tridecane 1,13-dicarboxylic acid (DC-15). Altering the cell permeability by treating C. neoformans with 1% (v/v) toluene or 7% (v/v) Triton X-100 stimulated production of DC-15 by 1.5-fold and fourfold, respectively. Furthermore, DC-15 productivity was increased from 2.5 mg/l per hour to 18 or 30 mg/l per hour, respectively. If 10% (v/v) hexane was used to treat the yeast culture, stimulation of DC-15 production could reach 200% and more viable cells remained compared to the toluene-treated culture. Data from the organic solvent treatment experiment indicated that the solvent with a higher polarity showed a more adverse effect on DC-15 production. P. aeruginosa was vulnerable to most organic solvents; however, Tween 80 could greatly stimulate the conversion of n-pentadecane to DC-15. Although organic solvents and non-ionic detergents could enhance DC-15 formation by microbial conversion, it was inhibited by elevated levels of DC-15.Offprint requests to: E.-C. Chan  相似文献   

12.
An antibiotic-resistant strain of Saccharomyces cerevisiae was isolated from shochu yeast. Three mutants were used for shochu brewing and gave higher ethanol productivities than the parent. The mutants were resistant to cycloheximide, cerulenin, trichothecin and other organic compounds such as lauric acid. In the presence of 20% (v/v) ethanol, the viability of the mutants was 87–96%, but that of the parent was 77%. Zymolyase treatment for 3 h, decreased the viability of the parent by 44% but that of the mutants only by 11–32%. Thus the higher ethanol productivity of these mutants is related to their high ethanol tolerance and resistance to various organic compounds.  相似文献   

13.
Monoterpenes are a diverse class of compounds with applications as flavors and fragrances, pharmaceuticals and more recently, jet fuels. Engineering biosynthetic pathways for monoterpene production in microbial hosts has received increasing attention. However, monoterpenes are highly toxic to many microorganisms including Saccharomyces cerevisiae, a widely used industrial biocatalyst. In this work, the minimum inhibitory concentration (MIC) for S. cerevisiae was determined for five monoterpenes: β‐pinene, limonene, myrcene, γ‐terpinene, and terpinolene (1.52, 0.44, 2.12, 0.70, 0.53 mM, respectively). Given the low MIC for all compounds tested, a liquid two‐phase solvent extraction system to alleviate toxicity during fermentation was evaluated. Ten solvents were tested for biocompatibility, monoterpene distribution, phase separation, and price. The solvents dioctyl phthalate, dibutyl phthalate, isopropyl myristate, and farnesene showed greater than 100‐fold increase in the MIC compared to the monoterpenes in a solvent‐free system. In particular, the MIC for limonene in dibutyl phthalate showed a 702‐fold (308 mM, 42.1 g L?1 of limonene) improvement while cell viability was maintained above 90%, demonstrating that extractive fermentation is a suitable tool for the reduction of monoterpene toxicity. Finally, we estimated that a limonane to farnesane ratio of 1:9 has physicochemical properties similar to traditional Jet‐A aviation fuel. Since farnesene is currently produced in S. cerevisiae, its use as a co‐product and extractant for microbial terpene‐based jet fuel production in a two‐phase system offers an attractive bioprocessing option. Biotechnol. Bioeng. 2012; 109: 2513–2522. © 2012 Wiley Periodicals, Inc.  相似文献   

14.
Hou SW  Jia JF 《Plant cell reports》2004,22(10):741-746
An efficient and reproducible protocol is described for the regeneration of Astragalus melilotoides protoplasts isolated from hypocotyl-derived embryogenic calli. Maximum protoplast yield (11.74±0.6×105/g FW) and viability (87.07±2.8%) were achieved using a mixture of 2% (w/v) Cellulase Onozuka R10, 0.5% (w/v) Cellulase Onozuka RS, 0.5% (w/v) Macerozyme R10, 0.5% (w/v) Hemicellulase, and 1% (w/v) Pectinase, all dissolved in a cell protoplast wash (CPW) salt solution with 13% (w/v) sorbitol. First divisions occurred 3–7 days following culture initiation. The highest division frequency (9.86±0.68%) and plating efficiency (1.68±0.05%) were obtained in solid-liquid medium (KM8P) supplemented with 1.0 mg/l 2,4-dichlorophenoxyacetic acid, 0.5 mg/l 6-benzylaminopurine (BA), 0.2 mg/l kinetin, 0.2 M glucose, 0.3 M mannitol and 500 mg/l casein hydrolysate. Upon transfer to MS medium with 0.5 mg/l -naphthaleneacetic acid and 1-2 mg/l BA, the protoplast-derived calli produced plantlets via somatic embryogenesis (56.3±4.1%) and organogenesis (21.6±0.6%). Somatic embryos or adventitious shoots developed into well-rooted plantlets on MS medium without any plant growth regulators or supplemented with 3.0 mg/l indole-3-butyric acid, respectively. About 81% of the regenerants survived in soil, and all were normal with respect to morphology and growth characters.Abbreviations BA: 6-Benzylaminopurine - CH: Casein hydrolysate - CPW: Cell protoplast wash - 2,4-D: 2,4-Dichlorophenoxyacetic acid - FDA: Fluorescein diacetate - IBA: Indole-3-butyric acid - KIN: Kinetin - MES: 2-(N-morpholino) Ethanesulphonic acid - NAA: -Naphthaleneacetic acidCommunicated by A. Altman  相似文献   

15.
Apoptotic cell death in suspension cultures of Taxus cuspidata induced by exogenous salicylic acid and/or H2O2 was investigated. H2O2 (0.012% v/v) alone changed the permeability of cell membrane while salicylic acid (0.375 mM) not only altered the permeability but also caused nuclei condensation and a small amount of nuclei fragments. The combined use of salicylic acid (0.375 mM) and H2O2 (0.012% v/v) changed the cell membrane permeability more significantly and nuclei fragments occurred in ca. 30% of the cells at 48 h. DNA ladders of 180 bp and oligopolymers, characteristics of the apoptotic cleavage of nuclei DNA, were observed by agar electrophoresis. These results show that exogenous salicylic acid and H2O2 could synergistically induce the apoptotic cell death of suspension cultures of Taxus cuspidata.  相似文献   

16.
The synthesis of optically active (R)-2-trimethylsilyl-2-hydroxyl-ethylcyanide by asymmetric trans-cyanation of acetyltrimethylsilane with acetone cyanohydrin in a biphasic system was achieved using (R)-oxynitrilase from loquat seed meal. Diisopropyl ether was the most suitable organic phase among the organic solvents examined. The optimal concentration of acetyltrimethylsilane, concentration of crude enzyme, volume ratio of the aqueous to the organic phase, temperature and the buffer pH value were 14 mM, 61.4 U ml-1, 13% (v/v), 30 °C and 4, respectively. The substrate conversion and the product enantiomeric excess were 95% and 98% under the optimized conditions. Acetyltrimethylsilane was a better substrate of the enzyme than its carbon counterpart. Revisions requested 24 August 2004; Revisions received 12 November 2004  相似文献   

17.
Dibutyl phthalate, oleic acid and terpineol were used to extract paclitaxel in situ fromTaxus chinensis suspension cultures. Oleic acid/terpineol (1:1, v/v) added to the cultures gave a higher paclitaxel concentration, compared with either of them alone. Oleic acid/terpineol (1:1, v/v) incorporated into the cultures at 3:50 (v/v) 4 days after elicitation, which was carried out by adding 50 mg chitosan l–1, 60 M methyl jasmonate and 30 M Ag+ to 10-day-old cultures, resulted in the greatest paclitaxel production of 48 mg l–1 at day 10 after elicitation. This was double that of the culture by elicitation, and 7-fold higher than that of the culture by in situ extraction.  相似文献   

18.
Yarrowia lipolytica is able to secrete large amounts of citric acid (CA), which is greatly affected by the dissolved oxygen concentration (DOC) in the fermentation medium. In this study, oleic acid was selected as oxygen‐vector to improve DOC during CA fermentation. When 2% (v/v) of oleic acid was added to the culture broth, higher DOC (>42.1%) was determined throughout the CA synthesis phase. The yield of CA reached a maximum of 32.1 g/L (25.4% higher than the control) and the biomass was 8.8 g/L. The substrate uptake rate, products formation rate and key enzyme activities were also determined, and the results indicated that CA synthesis was strengthened with oleic acid addition. Furthermore, it was detected that oleic acid could be assimilated by the cells, which means that oleic acid could be served both as oxygen‐vector and co‐substrate for CA synthesis by Y. lipolytica. In a bioreactor with working volume of 3 L, the highest concentration of CA reached to 36. 4 g/L in the presence of 2% (v/v) oleic acid after 192 h of fermentation. These results confirmed that oleic acid could be applied in the large‐scale production of CA by Y. lipolytica.  相似文献   

19.
Plant genebanks often use cryopreservation to securely conserve clonally propagated collections. Shoot tip cryopreservation procedures may employ vitrification techniques whereby highly concentrated solutions remove cellular water and prevent ice crystallization, ensuring survival after liquid nitrogen exposure. Vitrification solutions can be comprised of a combination of components that are either membrane permeable or membrane impermeable within the timeframe and conditions of cryoprotectant exposure. In this study, the osmotic responses of sweet potato [Ipomoea batatas (L.) Lam.] suspension cell cultures were observed after treatment with plant vitrification solution 2 [PVS2; 15% (v/v) dimethyl sulfoxide (DMSO), 15% (v/v) ethylene glycol, 30% (v/v) glycerol, 0.4 M sucrose], plant vitrification solution 3 (PVS3; 50% (v/v) glycerol, 50% (w/v) sucrose), and their components at 25 and 0°C, as well as cryoprotectant solution, PGD (10% (w/v) PEG 8000, 10% (w/v) glucose, 10% (v/v) DMSO) at 25°C. At either 25 or 0°C, sweet potato cells plasmolyzed after exposure to PVS2, PVS3, and PGD solutions as well as the PVS2 and PVS3 solution components. Cells deplasmolyzed when the plasma membrane was permeable to the solutes and when water re-entered to maintain the chemical potential. Sweet potato suspension cells deplasmolyzed in the presence of 15% (v/v) DMSO or 15% (v/v) ethylene glycol. Sweet potato plasma membranes were more permeable to DMSO and ethylene glycol at 25°C than at 0°C. Neither sucrose nor glycerol solutions showed evidence of deplasmolysis after 3 h, suggesting low to no membrane permeability of these components in the timeframes studied. Thus, vitrification solution PVS2 includes components that are more membrane permeable than PVS3, suggesting that the two vitrification solutions may have different cryoprotectant functions. PGD includes DMSO, a permeable component, and likely has a different mode of action due to its use in two-step cooling procedures.  相似文献   

20.
Single cells isolated from aggregated Taxus cuspidata cultures via enzymatic digestion were grown in suspension culture. High seeding density (4×105 cells/ml) and the addition of cell-free conditioned medium were essential for growth. Doubling the concentration of the nutrients [ascorbic acid (150 g/l), glutamine (6.25 mm), and citric acid (150 g/l)] had no effect on single cell growth or viability. A specific growth rate of 0.11 days−1 was achieved, which is similar to the observed growth rate of aggregated Taxus suspensions. The biocide, Plant Preservative Mixture, added at 0.2% (v/v) to all single cell cultures to prevent microbial contamination, had no significant effect on growth or viability. Following cell sorting, single cell cultures can be used to establish new cell lines for biotechnology applications or provide cells for further study.  相似文献   

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