Influence of readily metabolizable carbon on pentachlorophenol metabolism by a pentachlorophenol-degrading Flavobacterium sp.

The influence of high concentrations of pentachlorophenol (PCP) and readily metabolizable carbon on the activity and viability of a PCP-degrading Flavobacterium sp. was examined in a mineral salts medium. Lags preceding PCP removal by glutamate-grown Flavobacterium cells were greatly attenuated by the addition of glutamate, aspartate, succinate, acetate, glucose, or cellobiose. The effect of these supplementary carbon sources on the apparent lag was not mediated entirely through the stimulation of growth since PCP metabolism accompanied the onset of growth. The specific activity of PCP-degrading cells in the absence of supplementary carbon was 1.51 x 10(-13) +/- 0.08 x 10(-13) g of PCP per cell per h and in the presence of supplementary carbon was 0.92 x 10(-13) +/- 0.09 x 10(-13) g of PCP per cell per h. Glutamate in combination with glucose or cellobiose partially repressed PCP metabolism. PCP removal by PCP-induced, glutamate-grown cells suspended in the presence of 4 g of sodium glutamate per liter was sensitive to shock loads of PCP, with a Ki of about 86.8 micrograms/ml. Subsequent removal rates, however, were more resistant to PCP. Optimal stimulation of PCP removal by sodium glutamate required 3.0 g/liter, about the same concentration as that which saturated growth in the absence of PCP. PCP removal rates decayed within minutes following the transfer of PCP-induced, glutamate-grown cells to media containing PCP without supplementary carbon, and increasing PCP concentrations accelerated the decay.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of readily metabolizable carbon on pentachlorophenol metabolism by a pentachlorophenol-degrading Flavobacterium sp

The influence of high concentrations of pentachlorophenol (PCP) and readily metabolizable carbon on the activity and viability of a PCP-degrading Flavobacterium sp. was examined in a mineral salts medium. Lags preceding PCP removal by glutamate-grown Flavobacterium cells were greatly attenuated by the addition of glutamate, aspartate, succinate, acetate, glucose, or cellobiose. The effect of these supplementary carbon sources on the apparent lag was not mediated entirely through the stimulation of growth since PCP metabolism accompanied the onset of growth. The specific activity of PCP-degrading cells in the absence of supplementary carbon was 1.51 x 10(-13) +/- 0.08 x 10(-13) g of PCP per cell per h and in the presence of supplementary carbon was 0.92 x 10(-13) +/- 0.09 x 10(-13) g of PCP per cell per h. Glutamate in combination with glucose or cellobiose partially repressed PCP metabolism. PCP removal by PCP-induced, glutamate-grown cells suspended in the presence of 4 g of sodium glutamate per liter was sensitive to shock loads of PCP, with a Ki of about 86.8 micrograms/ml. Subsequent removal rates, however, were more resistant to PCP. Optimal stimulation of PCP removal by sodium glutamate required 3.0 g/liter, about the same concentration as that which saturated growth in the absence of PCP. PCP removal rates decayed within minutes following the transfer of PCP-induced, glutamate-grown cells to media containing PCP without supplementary carbon, and increasing PCP concentrations accelerated the decay.(ABSTRACT TRUNCATED AT 250 WORDS)     

高产莪术细胞悬浮系建立及产物前体对挥发油合成的调控研究

研究了高产莪术细胞悬浮系培养的条件及前体物质添加对挥发油合成的调控。结果表明：淡黄色颗粒状愈伤组织是建立高产细胞悬浮系的最佳供试愈伤组织;最佳培养基成分是MS培养基添加葡萄糖与蔗糖各15—30g／L(1：1),氮源为NH4^ 和NO3^-,比例为1：3,总量为80mmol／L;激素组合为6-BA3．0—5．0mg／L、2,4-D1．0mg／L;光下培养10—15天再转入优化条件下的暗培养,可形成稳定的高产细胞悬浮系;其细胞周期中的最大细胞生长量及挥发油含量分别是248g／L和2．28％;前体物质泛酸钙、乙酸铵、乙酸钾的添加均可有效提高培养细胞合成挥发油的百分含量,其中乙酸铵最有效,在指数生长中期添加0．5mmol／L乙酸铵,挥发油的最高含量可达3．11％,产量为8．27g/L,分别是添加前的1.25倍及1.2倍。     

黄孢原毛平革菌产絮凝剂营养条件优化

微生物絮凝剂与传统化学絮凝剂相比,安全无毒、无二次污染,具有开发潜力.黄孢原毛平革菌(Phanerochaete chrysosporium)能产生微生物絮凝剂,但目前缺少对其产絮凝剂营养条件的优化.使用高岭土并利用单因素法研究碳源、氮源、碳氮比、接种量对Phanerochaete chrysosporium产絮凝剂的...     

Production of nattokinase by high cell density fed-batch culture of Bacillus subtilis

Bacillus subtilis was cultivated to high cell density for nattokinase production by pH-stat fed-batch culture. A concentrated mixture solution of glucose and peptone was automatically added by acid-supplying pump when culture pH rose above high limit. Effect of the ratio of glucose to peptone in feeding solution was investigated on cell growth and nattokinase production by changing the ratio from 0.2 to 5 g glucose/g peptone. The highest cell concentration was 77 g/L when the ratio was 0.2 g glucose/g peptone. Cell concentration decreased with increasing the ratio of glucose to peptone in feeding solution, while the optimum condition existed for nattokinase production. The highest nattokinase activity was 14,500 unit/mL at a ratio of 0.33 g glucose/g peptone, which was 4.3 times higher than that in batch culture.     

Zeta potential as a measure of polyelectrolyte flocculation and the effect of polymer dosing conditions on cell removal from fermentation broth

Characterization of flocculation for cell removal from fermentation broth via polyelectrolyte addition is commonly based on qualitative methods such as physical appearance of the floc. The use of zeta potential as a quantitative measure of floc character was evaluated as an indicator of optimal polymer addition. Zeta potential was found to increase with increasing cationic polyelectrolyte dosage, but never reached zero regardless of the total amount of polymer added, indicating flocculation occurs at least partially through a bridging type mechanism. Experiments were conducted using various polymer concentrations (25-75 g/L) and dosing methods (batch, incremental and continuous addition) that resulted in variable overall polymer requirements to achieve optimum flocculation. Zeta potential was found to be constant at optimal floc character regardless of the total amount of polymer added, polymer concentration, or method of polymer addition. Experiments with two additional types of fermentation broth also showed characteristic zeta potentials at optimal flocculation. Polymer requirements to achieve a particular floc character can vary greatly, depending on polymer dosing conditions and fermentation batch. The effect of polymer dosing conditions on the polymer requirement to obtain optimal floc character was evaluated. Polymer dosing method and calcium concentration were both found to have a significant effect (P < 0.0001) with continuous polymer addition and high calcium concentration requiring less polymer than did batch polymer addition and low calcium concentration, respectively. Polymer dosing concentration did not significantly affect polymer requirement for optimal flocculation.     

Preparation and performance of immobilized yeast cells in columns containing no inert carrier

Schizosaccharomyces pombe was cultivated in a medium of glucose (10 g/L) malt extract (3 g/L), yeast extract (3 g/L), and bactopeptone (5 g/L) to form flocs. More than 95% of the cell population were flocculated. Variation in glucose concentration (from 10 to 100 g/L) did not affect flocculation. Yeast extract helped induce flocculation. Application of the immobilized yeast for the continuous production of ethanol was tested in a column reactor. Soft yeast flocs (50-200 mesh) underwent morphological changes to heavy particles (0.1-0.3 cm diameter) after continuously being fed with fresh substrates in the column. Productivity as high as 87 g EtOH L(-1) h(-1) was obtained when a 150 g/L glucose medium was fed. The performance of this yeast reactor was stable over a two-month period. The ethanol yield was 97% of the theoretical maximum based upon glucose consumed.     

Flocculation performance of a cationic biopolymer derived from a cellulosic source in mild aqueous solution

The flocculation behavior of cationic, quaternary ammonium groups containing cellulosic biopolymers, CDACs, synthesized by cationizing dialdehyde cellulose in mild aqueous solution was studied in a kaolin suspension. In particular, the role of CDAC dosage and solution pH, NaCl concentration, and temperature were clarified. In addition, the initial apparent charge densities (CDs), particle sizes, ζ-potential, and stability of CDs were determined. CDACs possessed a high flocculation activity in neutral and acidic solutions, but a significant decrease was observed in alkaline solutions (pH >9). This was also seen as a decline in the apparent CD and particle size of the CDACs in alkaline conditions. The measurements also indicated that the apparent CD decreased to a constant level of 3 mmol/g in aqueous solutions. However, no notable decrease in flocculation performance was obtained after several days of storage. Moreover, the variation of NaCl concentration and temperature did not affect the flocculation activity.     

红豆杉细胞培养产物提取策略及其对紫杉醇的影响

研究了硫酸铈铵及原位提取对红豆杉细胞悬浮培养过程中细胞生长、紫杉醇合成及释放的影响。红豆杉细胞悬浮培养过程中培养第12d添加2mg/L硫酸铈铵能获得最大紫杉醇产量8．3mg/L,其中2．4mg/L释放到细胞外,分别为对照组的4倍及12倍。同时添加2mg/L硫酸铈铵、5％油酸(v/v)时胞外紫杉醇产量达到9mg/L,为对照组的45倍。将硫酸铈铵及原位提取与补料培养相结合,最高紫杉醇产量可达24．5mg/L,其中60％释放到胞外。     

Flocculation behavior and mechanism of an exopolysaccharide from the deep-sea psychrophilic bacterium Pseudoalteromonas sp. SM9913

Flocculation behavior and mechanism of the exopolysaccharide secreted by Pseudoalteromonas sp. SM9913 (EPS SM9913), a psychrophilic bacterium isolated from 1855m deep-sea sediment, has been studied in this paper. EPS SM9913 showed a peak flocculating activity of 49.3 in 1g/L kaolin suspension with 4.55mmol/L CaCl2 and the optimum pH range of 5-8. It appears that the flocculating activity of EPS SM9913 was stimulated by Ca2+ and Fe2+. This study found that EPS SM9913 showed a better flocculation performance than Al2(SO4)3 at salinity of 5-100 per thousand or temperatures of 5-15 degrees C. In addition, this EPS was effective to flocculate several other suspended solids. The measured zeta-potentials, the size of flocs formed during the flocculation process and the surface profile of flocs revealed by scan electron micrograph suggest that bridging is the main flocculation mechanism of the studied EPS. Deacetylation of EPS SM9913 resulted in a significant decrease in its flocculating activity indicating that the large number of acetyl groups in EPS SM9913 played an important role in its flocculation performance.     

Polymer–Magnesium Aluminum Silicate Composite Dispersions for Improved Physical Stability of Acetaminophen Suspensions

The aims of this study were to characterize the morphology and size of flocculates and the zeta potential and rheological properties of polymer–magnesium aluminum silicate (MAS) composite dispersions and to investigate the physical properties of acetaminophen (ACT) suspensions prepared using the composite dispersions as a flocculating/suspending agent. The polymers used were sodium alginate (SA), sodium carboxymethylcellulose (SCMC), and methylcellulose (MC). The results showed that SA, SCMC, and MC could induce flocculation of MAS by a polymer-bridging mechanism, leading to the changes in the zeta potential of MAS and the flow properties of the polymer dispersions. The microscopic morphology and size of the flocculates was dependent on the molecular structure of the polymer, especially ether groups on the polymer side chain. The residual MAS from the flocculation could create a three-dimensional structure in the SA–MAS and SCMC–MAS dispersions, which brought about not only an enhancement of viscosity and thixotropic properties but also an improvement in the ACT flocculating efficiency of polymers. The use of polymer–MAS dispersions provided a higher degree of flocculation and a lower redispersibility value of ACT suspensions compared with the pure polymer dispersions. This led to a low tendency for caking of the suspensions. The SCMC–MAS dispersions provided the highest ACT flocculating efficiency, whereas the lowest ACT flocculating efficiency was found in the MC–MAS dispersions. Moreover, the added MAS did not affect ACT dissolution from the suspensions in an acidic medium. These findings suggest that the polymer–MAS dispersions show good potential for use as a flocculating/suspending agent for improving the rheological properties and physical stability of the suspensions.     

不同种类无机盐对灰毡毛忍冬“渝蕾1号”悬浮培养体系中细胞生长和绿原酸含量的影响

为提高灰毡毛忍冬"渝蕾1号"悬浮培养体系中绿原酸的含量,该研究探讨了B_5培养基中不同浓度的无机盐对灰毡毛忍冬"渝蕾1号"悬浮培养细胞生物量及绿原酸含量的影响,通过在悬浮培养体系中添加不同浓度的无机盐,采用重量法测定灰毡毛忍冬"渝蕾1号"悬浮培养细胞的生物量及采用高效液相色谱法测定绿原酸的含量。结果表明:当硝态氮和铵态氮配比与B_5培养基中硝态氮和铵态氮配比一致时,即NO_3~-/NH_4~+摩尔比值为13∶1时,培养体系有利于细胞的生长和绿原酸的积累。当KNO_3浓度为3.5 g·L~(-1)时,细胞生物量达到最大,为19.26 g·L~(-1);当KNO_3在较低浓度(0.5 g·L~(-1)和1.5 g·L~(-1))时,积累较多的绿原酸。NO_3~-的两项研究结果均与对照浓度(2.5g·L~(-1))有一定的差异。另外,对(NH_4)_2SO_4来说,在高于对照浓度0.134 g·L~(-1),即浓度为0.268 g·L~(-1)时,生物量和绿原酸含量都达到了最大。P、Ca、Mg三种矿质元素的研究结果表明,当Na H_2PO_4·2H_2O浓度为0.10 g·L~(-1)、Ca Cl_2的浓度为0.20 g·L~(-1)时,细胞的生长和绿原酸的积累均可达到最大值;而对Mg~(2+)来说,低浓度促进细胞的生长,高浓度促进绿原酸的积累。兼顾细胞生物量和绿原酸含量两个指标,需选择适中的浓度。这些结果均与对照浓度有一定的差异。这说明灰毡毛忍冬"渝蕾1号"悬浮细胞所需无机盐的浓度与B_5培养基无机盐的浓度有一定的差异,选择适宜的浓度可促进其悬浮细胞的生长及次生代谢产物绿原酸的积累。该研究结果为绿原酸的工业化生产打下了基础。     

Bacillus mojavensis strain 32A, a bioflocculant-producing bacterium isolated from an Egyptian salt production pond

Bacillus mojavensis strain 32A that exhibited 96.11% flocculation efficiency for clay suspensions was selected from other 15 comparative strains. Under growth condition, strain 32A was able to produce 5.2 g/L of purified biopolymer. Its constituent was mainly polysaccharide and protein with proportional of 98.4-1.6% respectively. FTIR spectrum was confirming its chemical analysis. This biopolymer attain very fast sedimentation rate. The cost-effective biopolymer and CaCl₂ dosages were 3 mg/L and 5 ml/L respectively that posed 89.7% flocculation efficiency. These dosages were suitable only for clay concentrations ?5 g/L. The maximum flocculation efficiency of the biopolymer recorded at pH 1.0 of clay suspension. The too high (>75 °C) or too low (<25 °C) clay suspension temperature was unfavorable for the biopolymer flocculation performance. The biopolymer solution utilized high thermal stability over the temperature range of 5-60 °C. Furthermore, its pH stability recorded at pH range of 5-9.     

条件培养液对红豆杉细胞Paclitaxel生产的促进作用

在两步法红豆杉（Taxus chinensis)细胞悬浮培养体系的生产阶段,加入从生长阶段悬浮培养物中制得的条件培养液（conditioned Medium,CM)既能促进细胞的生长,又能提高紫杉醇（paclitaxel)的产率,解决了生产培养时,细胞生长受抑制的问题,特别是,取自生长12天的细胞悬浮培养物的CM按体积分数为25％添加到新鲜生产培养基中时,可使细胞紫杉醇最高产量达28．5mg/L,细胞干重达32．3g/L,分别是对照的2．4倍和2．2倍,对CM中的蔗糖,果糖,NO3－和PO4－3等的含量的进行了分析。     

Production of butanol from glucose and xylose with immobilized cells of Clostridium acetobutylicum

Pretreated cotton towels were used as carriers to immobilize Clostridium acetobutylicum CGMCC 5234 cells for butanol or ABE production from glucose and xylose. Results showed that cell immobilization was a promising method to increase butanol concentration, yield and productivity regardless of the sugar sources compared with cell suspension. In this study, a high butanol concentration of 10.02 g/L with a yield of 0.20 g/g was obtained from 60 g/L xylose with 9.9 g/L residual xylose using immobilized cells compared with 8.48 g/L butanol and a yield of 0.141 g/g with 20.2 g/L residual xylose from 60 g/L xylose using suspended cells. In mixed-sugar fermentation (30 g/L glucose plus 30 g/L xylose), the immobilized cultures produced 11.1 g/L butanol with a yield of 0.190 g/g, which were 28.3% higher than with suspended cells (8.65 g/L) during which 30 g/L glucose was utilized completely using both immobilized and suspended cells while 3.46 and 13.1 g/L xylose maintained untilized for immobilized and suspended cells, respectively. Based on the results, we speculated that immobilized cells showed enhanced tolerance to butanol toxicity and the cultures preferred glucose to xylose during ABE fermentation. Moreover, the cultures showed obvious difference when grown between high initial concentrations of glucose and those of xylose. Repeated-batch fermentations from glucose with immobilized cells showed better long-term stability than from xylose. At last, the morphologies of free and immobilized cells adsorbed on pretreated cotton towels during the growth cycle were examined by SEM.     

Biostimulation and Bioaugmentation of Anaerobic Pentachlorophenol Degradation in Contaminated Soils

The effects of bioaugmentation with a pentachlorophenol (PCP)-adapted consortium and biostimulation with glucose as a carbon source on anaerobic bioremediation of PCP-contaminated soil were investigated in terms of the initial PCP removal rate and the extent of PCP dechlorination and mineralization. Samples from two PCP-contaminated sites were prepared, put into a series of Hungate tubes, inoculated, and fed under different conditions. Chlorophenols in the tubes were monitored over a 4-month period to measure PCP transformation in the soil. In less contaminated soil (10 mg PCP/kg soil), it was found that biostimulation with glucose at 1 g/kg soil or bioaugmentation at 0.14 g volatile suspended solids (VSS)/kg soil could greatly improve PCP degradation. The best PCP degradation was obtained when both bioaugmentation and biostimulation were applied, but higher levels of glucose (2 g/kg soil) or inoculum (0.56 g VSS/kg soil) had little additional effect. The highest initial PCP-removal rate reached 8.1 μmol/kg soil-d, which is almost 20 times greater than in the unamended controls. PCP was dechlorinated to lesser chlorinated phenols with 0.6 chlorine remaining on average, and the extent of mineralization approached 70% in 4 months. In highly PCP-contaminated soil (90 mg PCP/kg soil), PCP degradation was partially inhibited, but the relative effects of augmentation, stimulation, and combined treatments were the same as in the less contaminated soil.     

Recovery of insect cells using hollow fiber microfiltration

An efficient method was developed for media separation and cell collection for eukaryotic cells growing in suspension. The method is based on tangential flow microfiltration using an open channel arrangement in a hollow fiber configuration. Best results (highest processing flux rate) for polysulfone hollow fibers were obtained using fibers with internal diameter of 0.75 mm, 0.45 mum pore size, and a cell suspension flow at a shear rate of 14000 s(-1) (0.032 L/min per fiber). A flux rate of 500 L/m(2) h can be obtained by maintaining the surface area/cell ratio at 0.05 m(2)/10 L of cells at a concentration of 2.5 x 10(6) cells/mL. Forty liters of infected insect cells can be concentrated 10 times in 20 min without affecting cell viability. (c) 1995 John Wiley & Sons, Inc.     

Degradation of pentachlorophenol by a Flavobacterium species grown in continuous culture under various nutrient limitations

A Flavobacterium sp. was grown in continuous culture limited for growth with ammonium, phosphate, sulfate, glucose, glucose + pentachlorophenol (PCP) (0.065 h -1), or PCP. Cells ere harvested, washed, and suspended to 3 x 10(7) cells ml (-1) in shake flasks containing a complete mineral salts medium without added carbon or supplemented with 50 mg of PCP ml(-1) or 50 mg of PCP ml(-1) + 100 mg of glucose ml(-1). The PCP concentration and the viable cell density were determined periodically. Cells that were grown under phosphate, glucose, or glucose + PCP limitation were more sensitive to PCP and took longer to degrade 50 mg of PCP ml(-1) than did cells that very were grown under ammonium, sulfate, or PCP limitation. Glucose stimulated viability and PCP degradation in all cases except when the cells were grown under carbon limitation with glucose and PCP added together as the carbon source. These results indicate that there is a relationship between nutrient limitation, phenotypic variation, and the sensitivity to and degradation of PCP by this organism.     

Degradation of pentachlorophenol by a Flavobacterium species grown in continuous culture under various nutrient limitations.

A Flavobacterium sp. was grown in continuous culture limited for growth with ammonium, phosphate, sulfate, glucose, glucose + pentachlorophenol (PCP) (0.065 h -1), or PCP. Cells ere harvested, washed, and suspended to 3 x 10(7) cells ml (-1) in shake flasks containing a complete mineral salts medium without added carbon or supplemented with 50 mg of PCP ml(-1) or 50 mg of PCP ml(-1) + 100 mg of glucose ml(-1). The PCP concentration and the viable cell density were determined periodically. Cells that were grown under phosphate, glucose, or glucose + PCP limitation were more sensitive to PCP and took longer to degrade 50 mg of PCP ml(-1) than did cells that very were grown under ammonium, sulfate, or PCP limitation. Glucose stimulated viability and PCP degradation in all cases except when the cells were grown under carbon limitation with glucose and PCP added together as the carbon source. These results indicate that there is a relationship between nutrient limitation, phenotypic variation, and the sensitivity to and degradation of PCP by this organism.     

Modification by glucose of the flocculent phenotype of a <Emphasis Type="Italic">Kloeckera apiculata</Emphasis> wine strain

We have evaluated the induction of the flocculent phenotype of Kloeckera apiculata by glucose mc1 and propose a pathway involved in carbohydrate flocculation induction. Pulses of glucose were given to cells growing in glucose-poor medium (2 g l(-1)) and the flocculation percentage was measured. To elucidate the mechanism involved in flocculation induction, cycloheximide was injected into the cultures 120 min before the glucose pulse. 2,4-Dinitrophenol or cAMP was added to the media instead, or simultaneously with glucose, while a protein kinase A (PKA) inhibitor was added 30 min before the glucose pulse. With 20 and 50 g l(-1) glucose pulse, the yeast flocculation percentage arises to 55 and 65%, respectively. The quantity of proteins and the reflocculating capacity of a lectinic protein extract from the yeast cell wall increase as the concentration of glucose pulse was higher. Cycloheximide prevented the glucose-induced flocculation, while cAMP or 2,4-dinitrophenol increased it 4- and 5-fold, respectively. PKA inhibitor completely prevented the glucose induction flocculation. The flocculent phenotype of K. apiculata mc1 was induced by glucose and the mechanism seems to imply de novo protein (lectin) synthesis via the PKA transduction pathway. This work contributes to the elucidation of the mechanism involved in flocculation induction by glucose of a non-Saccharomyces wine yeast, K. apiculata, which has not been reported. The induction of flocculation by glucose could be a biotechnological tool for the early removal of the indigenous microorganisms from the grape must before the inoculation of a selected starter strain to conduct the alcohol fermentation.