Establishment of willow cuttings grown in porous membrane root envelopes

Small diameter fine, fibrous roots of willow are exceedingly difficult to remove from most soils. Where field retrieval of entire plants including clean roots may be important, porous membrane rooting envelopes are a method of choice.Purple osier willow (Salix purpurea L.) stem cuttings (clone SP3) were field rooted in buried porous membrane envelopes permeable to water and nutrients. Ramets were grown for two and four months, then separated into component parts for dry weight analysis.At two months, cuttings grown in rooting envelopes were no different in shoot dry weight than plants grown in clay pots or in soil. Tests indicated that rooting envelopes may be reused at least once without affecting shoot or total plant dry weight. Likewise, membrane pore sizes of 0.45, 1.2 and 3 m did not affect SP3 dry weight in four month tests. The importance of matching plant material and experiment duration to envelope size was illustrated by the limitation of growth by envelope edges at four months compared to two months.     

Cultural and physiological factors affecting expression of recombinant proteins

The variability in expression of recombinant proteins has been analyzed with regard to (a) comparison of clones from the same transfection experiment; (b) comparison of the same genetic construct in different cell lines; (c) the effect of the culture system used (free suspension, aggregate suspension, and microcarrier); and (d) physicochemical parameters in long-term (100d) culture in a macroporous fixed bed bioreactor (FBR).Differences in product expression between clones were accompanied by differences in growth rates, metabolic kinetics, and ability to grow in suspension as opposed to attached culture. The single most important factor affecting product expression when comparing constructs (for SEAP and IgG), cell lines (BHK 21 and myeloma), and culture systems was whether cells were grown in an attached or suspension mode. Thus key factors could be related to cell morphology (suspension versus monolayer), the presence of microenvironments and physiological stress to control growth rate.The relationship of key process parameters to volumetric and specific rAb productivity of the FBR was investigated in a partial factorial experiment with a rBHK cell line. The highest productivity levels are associated with a combination of the highest values tested for re-cycle (195 ml min^–1) and dilution rates (1 d^–1) and glutamine concentration (2.5 mmol l^–1), plus the lowest values for bead size (2 mm) and inoculum density (10⁷ ml^–1). Together with data from fluidised bed cultures, these results suggest that higher productivity is not primarily the result of greater cell numbers within the system but more the physicochemical definition of the system.Abbreviations FIBR fluidised bed bioreactor - FBR fixed bed reactor - STR stirred tank reactor - SEAP secreted alkaline phosphatase - rAb recombinant antibody     

Grazing in a porous environment: 1. The effect of soil pore structure on C and N mineralization

The porous soil environment constrains grazing of microorganisms by microbivorous nematodes. In particular, at matric potentials at which water-filled pore spaces have capillary diameters less than nematode body diameters the effect of grazing, e.g. enhanced mineralization, should be reduced ('exclusion hypothesis') because nematodes cannot access their microbial forage. We examined C and N mineralization, microbial biomass C (by fumigation-extraction), the metabolic quotient (C mineralization per unit biomass C), nematode abundance, and soil water content in intact soil cores from an old field as a function of soil matric potential (−3 to −50 kPa). We expected, in accordance with the exclusion hypothesis, that nematode abundance, N and C mineralization would be reduced as matric potential decreased, i.e. as soils became drier. N mineralization was significantly greater than zero for −3 kPa but not for −10, −20 and −50 kPa. Microbial biomass C was less at −50 kPa than at −10 kPa, but not significantly different from biomass C at −3 and −20 kPa. The metabolic quotient was greatest at −50 kPa than any of the other matric potentials. From the exclusion hypothesis we expected significantly fewer nematodes to be present at −50 and −20 kPa representing water-filled capillary pore sizes less than 6 and 15 μm, respectively, than at −3 and −10 kPa. Microbivorous (fungivorous+bacterivorous) nematode abundance per unit mass of soil was not significantly different among matric potentials. Body diameters of nematodes ranged from 9 μm to 40 μm. We discuss several alternatives to the exclusion hypothesis, such as the 'enclosure hypothesis' which states that nematodes may become trapped in large water-filled pore spaces even when capillary pore diameters (as computed from matric potential) are smaller than body diameters. One of the expected outcomes of grazing in enclosures is the acceleration of nutrient cycling. This revised version was published online in June 2006 with corrections to the Cover Date.     

Spatial development of the cultivation of a bone marrow stromal cell line in porous carriers

The spatial development of the cultivation of a bone marrow stromal cell line (SR-4987) in porous carriers was investigated in order to construct a three-dimensional hematopoietic culture system. Low-rate continuous agitation, 20 rpm, was an appropriate method to achieve initial adhesion of cells onto a cellulose porous beads (CPB, 100 μm pore diameter) in a spinner bottle, compared with other methods such as centrifugation and intermittent agitation. Cell growth with continuous agitation at 70 rpm after initial cell adhesion was not inferior to that at 20 rpm. A 2- and 10-fold increase in the inoculum cell concentration for CPB and another type of porous cellulose beads (Micro-cube (MC), 500 μm pore diameter) resulted in a 1.2- and 2-fold increase in final cell concentrationm, respectively. Cells attached to the MC beads and a polyester nonwoven dic (Fibra-cell (FC)) could grow and spread well on the carriers and a fibroblast-like shape was observed under scanning electron microscopy while the cells on CPB were globular. The flatness and inner surface area of these carriers may be the reason for the differences in cell morphology. This revised version was published online in July 2006 with corrections to the Cover Date.     

Use of 1H NMR to study transport processes in porous biosystems

The operation of bioreactors and the metabolism of microorganisms in biofilms or soil/sediment systems are strongly dictated by the transport processes therein. Nuclear magnetic resonance (NMR) spectroscopy or magnetic resonance imaging (MRI) allow nondestructive and noninvasive quantification and visualisation (in case of MRI) of both static and dynamic water transport phenomena. Flow, mass transfer and transport processes can be measured by mapping the (proton) displacement in a defined time interval directly in a so-called pulsed field gradient (PFG) experiment. Other methods follow the local intensity in time-controlled sequential images of water or labelled molecules, or map the effect of contrast agents. Combining transport measurements with relaxation-time information allows the discrimination of transport processes in different environments or of different fluids, even within a single picture element in an image of the porous biosystem under study. By proper choice of the applied NMR method, a time window ranging from milliseconds to weeks (or longer) can be covered. In this paper, we present an overview of the principles of NMR and MRI techniques to visualise and unravel complex, heterogeneous transport processes in porous biological systems. Applications and limitations will be discussed, based on results obtained in (model) biofilms, bioreactors, microbial mats and sediments. Journal of Industrial Microbiology & Biotechnology (2001) 26, 43–52. Received 20 April 2000/ Accepted in revised form 14 August 2000     

多孔微载体无血清培养rCHO细胞生产u-PA

在30L搅拌式反应器中无血清培养分泌尿激酶型纤溶酶原激活剂(u-PA)的DNA重组CHO细胞,定期部分更换Cytopore多孔微载体,使生长在多孔微载体中的细胞不断更新繁殖,解决大规模细胞培养中的细胞凋亡问题。在91d连接换液培养过程中,细胞密度可维持在(1.3～2.6)×107/mL,活细胞比率维持在90%以上。在7.5L搅拌罐中培养细胞,利用外部周期性压力振荡刺激并结合载体更新技术,可减轻密度效应对细胞生长和表达的影响,在一定程度上提高细胞在高密度培养条件下的表达水平。在67d连续换液培养中,细胞最高密度为2.64×10⁷/mL,活细胞比率维持在95%以上。与稳压操作相比,利用周期变压刺激技术可提高产量10%～20%,且可降低葡萄糖厌氧代谢生成乳酸的转化率,利用4步纯化工艺,从含u-PA约135g的2100 L上清中获得约80guPA(单链比例约为90%)。     

Vitamin addition: an option for sustainable activated sludge process effluent quality

The process performance and metabolic rates of samples of activated sludge dosed with vitamin supplements have been compared. After initial screening, four vitamins and two metals as single supplements and in pairs, were dosed continuously into the mixed liquor of an activated sludge simulation. Toxicity, oxygen demand removal, respiration rates and suspended solids were measured to monitor the effect on process efficiency. It was confirmed experimentally that an industrial wastewater stream did not contain a sufficient supply of micronutrients for efficient biological treatment. This was concluded from the observation that control sludge batches (receiving no supplements) averaged chemical oxygen demand removal efficiency of 58%. Dosing micronutrients into the mixed liquor produced removal efficiencies of up to 69%. Some of the supplements increased the respiration rate of the sludge while some decreased it, indicating a range of stimulatory and inhibitory effects. Complex interactions between micronutrients that were dosed simultaneously were evident. Several positive effects led to the conclusion that micronutrients have the potential to optimise process performance of activated sludge plants treating industrial wastewater. The addition of phosphorus/niacin and molybdenum/lactoflavin removed wastewater components that were toxic to nitrifiers as indicated through toxicity testing, thus protecting downstream nitrification/denitrification treatment processes. Journal of Industrial Microbiology & Biotechnology (2000) 24, 267–274. Received 24 August 1999/ Accepted in revised form 06 January 2000     

Size‐dependent interaction of cells and hemoglobin–albumin based oxygen carriers prepared using the SPG membrane emulsification technique

Hemoglobin‐based oxygen carriers (HBOCs) of various sizes have been developed so far, but their optimum size has not been clarified yet. Here, we examined the effect of HBOCs size on their interaction with cells using Shirasu porous glass (SPG) membrane emulsification technique, which enables precise tuning of particle size. Microspheres composed of bovine hemoglobin (bHb) and bovine serum albumin (BSA) was fabricated with the average diameters of 1.2–18.3 μm and the coefficient of variation of below 13%. Cellular uptake of the microspheres by RAW264.7 was observed at a diameter below 5 μm; however, uptake of the microspheres by HepG2 and HUVEC were not observed at any diameter. No enhancement of the generation of reactive oxygen species in the cytoplasm was detected at diameters above 9.8 μm in the three cell lines, due to their low cellular uptake. In addition, cytotoxicity of the microspheres decreased with increasing microsphere diameter in the three cell lines and microspheres of 18.3 μm showed good cellular compatibility regardless of the oxyhemoglobin percentage. Since cytotoxicity is a crucial factor in their applications, our systemic investigation would provide a new insight into the design of HBOCs. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1676–1684, 2015     

多孔淀粉固化杜香精油的制备及缓释性能研究

我国东北地区拥有丰富的杜香植物资源。该植物带有独特香气,带叶嫩枝含油量较高。然而,杜香精油挥发性强,稳定性差,香气不持久和携带不便等缺点限制了杜香精油及其相关产品的开发和利用。本文将主要探究了多孔淀粉固化杜香精油的制备工艺及其缓释性能。利用精油粉末化技术,采用研磨吸附的方法,制备了固化杜香精油粉末。利用DSC和TG探究了固化精油粉末的热学稳定性能并探究了其在不同温度下的缓释持香效果结果表明:多孔淀粉的最大吸油量为1.42 g·g^-1。多孔淀粉与杜香精油的质量比为1∶0.75(g·g^-1)时,固化精油粉末的气味较好,呈现出淡黄色粉末状态;固化精油粉末的保留率为杜香精油的3.57倍体现出其良好的热学稳定性;在同一温度下,相同时间内固化精油粉末比未固化精油的缓释持香效果更显著。多孔淀粉固化杜香精油的制备工艺简单,样品缓释持香效果明显,具有一定的应用推广价值。     

TiO2 Nanocrystals Synthesized by Laser Pyrolysis for the Up‐Scaling of Efficient Solid‐State Dye‐Sensitized Solar Cells

A crucial issue regarding emerging nanotechnologies remains the up‐scaling of new functional nanostructured materials towards their implementation in high performance applications on a large scale. In this context, we demonstrate high efficiency solid‐state dye‐sensitized solar cells prepared from new porous TiO₂ photoanodes based on laser pyrolysis nanocrystals. This strategy exploits a reduced number of processing steps as well as non‐toxic chemical compounds to demonstrate highly porous TiO₂ films. The possibility to easily tune the TiO₂ nanocrystal physical properties allows us to demonstrate all solid‐state dye‐sensitized devices based on a commercial benchmark materials (organic indoline dye and molecular hole transporter) presenting state‐of‐the‐art performance comparable with reference devices based on a commercial TiO₂ paste. In particular, a drastic improvement in pore infiltration, which is found to balance a relatively lower surface area compared to the reference electrode, is evidenced using laser‐synthesized nanocrystals resulting in an improved short‐circuit current density under full sunlight. Transient photovoltage decay measurements suggest that charge recombination kinetics still limit device performance. However, the proposed strategy emphasizes the potentialities of the laser pyrolysis technique for up‐scaling nanoporous TiO₂ electrodes for various applications, especially for solar energy conversion.