Feasibility study of degradation of phenol in a fluidized bed bioreactor with a cyclodextrin polymer as biofilm carrier

This work is focused on the evaluation of a beta-cyclodextrin polymer as a carrier medium in a fluidized bed bioreactor treating aqueous phenol as a model pollutant. The insoluble polymer support was obtained in the shape of spherical beads by crosslinking beta-cyclodextrin with epichlorohydrin. A batch of swollen polymer particles was loaded into the reactor and inoculated with a mixed bacterial culture. Bacterial growth on the polymer beads was initially stimulated by glucose addition to the medium, and then gradually replaced with phenol. The operational variables studied after the acclimation period included phenol load, hydraulic residence time and recirculation flow rate. Low hydraulic residence times and moderate phenol loads were applied. The elimination capacity was usually about 1.0 kg-phenol/m(3)d, although a maximum of 2.8 kg-phenol/m(3)d was achieved with a retention time of only 0.55 h. The depuration efficiency was not affected by the recirculation flow rate in the range studied. Neither operational nor support stability problems were detected during the operation. A high degree of expansion was achieved in the bioreactor due to the hydrogel nature of the cyclodextrin polymer and, consequently, a low energy requirement was necessary to fluidize the bed.     

Biofilm Growth and Bed Fluidization in a Fluidized Bed Reactor Packed with Support Materials of Low Density

Support materials of low‐density for fluidized bed reactors provide several operational advantages, including lower energy requirements and proper biofilm growth balance. The aim of this investigation was to study the extent of biofilm growth and bed fluidization in an experimental reactor, using polyester resin (ρ_pr = 1220 kg/m³) and vitrified expanded perlite (ρ_vep = 1710 kg/m³) as alternative support materials to conventional silica sand. A noteworthy amount of biofilm was observed to be attached to both support materials from the very beginning of the bioreactor operation. Nevertheless, there were significant variations in biofilm growth and activity over the course of the experimental trials. For both perlite and polyester beds, the highest biofilm mass and the highest total number of mesophilic bacteria were observed between the 7^th and the 10^th day, showing a steady state trend at the end of the experimental runs. The chemical oxygen demand (COD) removal levels were concomitant with biofilm mass and total mesophilic bacteria changes, although the polyester bed efficiency was slightly higher than that for the perlite bed. As expected, the polyester bed was fluidized at a lower re‐circulation flow compared to the perlite bed. Reactor back‐washing was not required for these support materials since biomass excess was adequately separated by means of a special internal device. The efficiencies of removal of organic matter achieved were acceptable (up to 78 %) despite the low volume of the support material (25 %) and the low hydraulic retention time (30 min).     

扩张柱床吸附层析回收纯化灌流培养生产的单克隆抗体

用扩张柱床吸附层析技术,一步回收纯化连续灌流培养的单克隆抗体。用Streamline SP阳离子交换介质在固定床柱XK16/20上进行条件摸索,扩张床柱Streamline25和50分别用于小规模条件优化和中试规模放大。培养液中的低浓度单抗经此步处理,浓缩10倍以上,纯度提高5～7倍,回收率＞90%,制备周期比固定柱床层析缩短一半以上。 根据培养液中单抗浓度的不同,一次处理量为18～50L,纯化规模由实验室水平（400mg）扩大至中试水平（2g）,生产成本和工艺复杂性大为降低。应用扩张柱床吸附层析技术,建立单克隆抗体回收纯化工艺,具有经济、简便、高效实用和良好的可放大性。     

Development of anaerobic sludge bed (ASB) reactor technologies for domestic wastewater treatment: motives and perspectives

During the treatment of raw domestic wastewater in the upflow anaerobic sludge blanket (UASB) reactor, the suspended solids (SS) present in the wastewater tend to influence negatively the methanogenic activity and the chemical oxygen demand (COD) conversion efficiency. These problems led to the emergence of various anaerobic sludge bed systems such as the expanded granular sludge bed (EGSB), the upflow anaerobic sludge blanket (UASB)-septic tank, the hydrolysis upflow sludge bed (HUSB), the two-stage reactor and the anaerobic hybrid (AH) reactor. However, these systems have, like the UASB reactor, limited performance with regard to complete treatment (e.g., removal of pathogens). In this respect, a new integrated approach for the anaerobic treatment of domestic wastewater is suggested. This approach combines a UASB reactor and a conventional completely stirred tank reactor (CSTR) for the treatment of the wastewater low in SS and sedimented primary sludge, respectively. The principal advantages of the proposed system are energy recovery from organic waste in an environmentally friendly way; lowering the negative effect of suspended solids in the UASB reactor; production of a high quality effluent for irrigation; and prevention of odour problems.     

Occurrence of sulfated galactans in marine angiosperms: evolutionary implications

We report for the first time that marine angiosperms (seagrasses) possess sulfated polysaccharides, which are absent in terrestrial and freshwater plants. The structure of the sulfated polysaccharide from the seagrass Ruppia maritima was determined. It is a sulfated D-galactan composed of the following regular tetrasaccharide repeating unit: [3-beta-D-Gal-2(OSO3)-1-->4-alpha-D-Gal-1-->4-alpha-D-Gal-1-->3-beta-D-Gal-4(OSO3)-1-->]. Sulfated galactans have been described previously in red algae and in marine invertebrates (ascidians and sea urchins). The sulfated galactan from the marine angiosperm has an intermediate structure when compared with the polysaccharides from these two other groups of organisms. Like marine invertebrate galactan, it expresses a regular repeating unit with a homogenous sulfation pattern. However, seagrass galactan contains the D-enantiomer of galactose instead of the L-isomer found in marine invertebrates. Like red algae, the marine angiosperm polysaccharide contains both alpha and beta units of D-galactose; however, these units are not distributed in an alternating order, as in algal galactan. Sulfated galactan is localized in the plant cell walls, mostly in rhizomes and roots, indicative of a relationship with the absorption of nutrients and of a possible structural function. The occurrence of sulfated galactans in marine organisms may be the result of physiological adaptations, which are not correlated with phylogenetic proximity. We suggest that convergent adaptation, due to environment pressure, may explain the occurrence of sulfated galactans in many marine organisms.     

A novel system for continuous protein refolding and on-line capture by expanded bed adsorption

A novel two-step protein refolding strategy has been developed, where continuous renaturation-bydilution is followed by direct capture on an expanded bed adsorption (EBA) column. The performance of the overall process was tested on a N-terminally tagged version of human beta2-microglobulin (HAT-hbeta2m) both at analytical, small, and preparative scale. In a single scalable operation, extracted and denatured inclusion body proteins from Escherichia coli were continuously diluted into refolding buffer, using a short pipe reactor, allowing for a defined retention and refolding time, and then fed directly to an EBA column, where the protein was captured, washed, and finally eluted as soluble folded protein. Not only was the eluted protein in a correctly folded state, the purity of the HAThbeta2m was increased from 34% to 94%, and the product was concentrated sevenfold. The yield of the overall process was 45%, and the product loss was primarily a consequence of the refolding reaction rather than the EBA step. Full biological activity of HAT-hbeta2m was demonstrated after removal of the HAT-tag. In contrast to batch refolding, a continuous refolding strategy allows the conditions to be controlled and maintained throughout the process, irrespective of the batch size; i.e., it is readily scalable. Furthermore, the procedure is fast and tolerant toward aggregate formation, a common complication of in vitro protein refolding. In conclusion, this system represents a novel approach to small and preparative scale protein refolding, which should be applicable to many other proteins.     

Operational intensification by direct product sequestration from cell disruptates: application of a pellicular adsorbent in a mechanically integrated disruption-fluidised bed adsorption process

A novel prototype adsorbent, designed for intensified fluidised bed adsorption processes, was assembled by the emulsification coating of 4% (w/v) porous agarose upon a zirconia-silica solid core. The adsorbent, designated ZSA (particle density 1.75 g/ml, maximum pellicle depth 40 microm), was subjected to physical and biochemical comparison with the performance of two commercial adsorbents (Streamline and Macrosorb K4AX). Bed expansion qualities and hydrodynamic characteristics (N, D(axl) and B(o)) of ZSA demonstrated a marked robustness in the face of elevated velocities (up to 550 cm/h) and biomass loading (up to 30% (ww/v)) disrupted yeast cells. Cibracron Blue derivatives of the pellicular prototype (ZSA-CB), evaluated in the batch and fluidised bed recovery of glyceraldehyde 3-phosphate dehydrogenase (G3PDH) from unclarified yeast disruptates, exhibited superior capacities and adsorption/desorption performance to the commercial derivatives. These advanced physical and biochemical properties facilitated a demonstration of the direct, mechanical coupling of bead-milling and fluidised bed adsorption in a fully integrated process for the accelerated recovery of G3PDH from yeast. The generic application of such pellicular adsorbents and integrated processes to the recovery of labile, intracellular products is discussed.     

Evaluation of a high temperature immobilised enzyme reactor for production of non-reducing oligosaccharides

There is interest in the production of non-reducing carbohydrates due to their potential application in various industrial fields, particularly the food industry. In this paper, we describe the development of an immobilised cell bioprocess for the synthesis of non-reducing maltodextrins at high temperatures. The trehalosyl-dextrins-forming enzyme (TDFE) isolated from the thermoacidophilic archaeon Sulfolobus solfataricus (strain MT4), was recently expressed at high yields in Escherichia coli (strain Rb-791). Here, we evaluate different matrices, such as polyacrylamide gel, crude egg white, chitosan and calcium alginate for their effectiveness in immobilising whole recombinant E. coli cells subjected to prior thermal permeabilisation. Calcium-alginate based gels formed a solid biocatalyst with a good activity yield and the best enzymatic stability at the operating temperature (75°C). Therefore, these beads were used to pack a glass column reactor to perform the bioconversion of interest. Optimal operating parameters were defined in relation to the substrate stream flow-rate and the substrate-to-biocatalyst ratio. The production of trehalosylmaltotetraose from maltohexaose reached equilibrium with a constant of about 2.6 at 75°C. The bioreactor was exploited for production of trehalosylmaltodextrins from a commercial mixture of maltodextrins, achieving a productivity of 106.5 mg ml⁻¹ h⁻¹ (g biocatalyst)⁻¹ with ~40% conversion when using a 30% (w/v) solution.     

Lipase-mediated acidolysis of butteroil with free conjugated linoleic acid in a packed bed reactor

Acidolysis of butteroil with free conjugated linoleic acid (CLA) was studied in a packed bed reactor containing an immobilized Candida antarctica (fraction B) lipase. Kinetic data were used to develop quantitative reversible rate expressions of the general Michaelis-Menten form that also incorporate a term for first-order deactivation of the enzyme. The extent of incorporation of CLA in the triacylglycerols of butteroil was characterized for reactions carried out at several temperatures (namely 45 degrees, 50 degrees, and 55 degrees C) with different weight ratios of butteroil to CLA (namely 10:1 and 2:1). At the optimum operating temperature of 50 degrees C, similar levels of incorporation of CLA (60% to 85%) were achieved at low space times (<3 h) for both 10:1 and 2:1 (w/w) ratios of butteroil to CLA.     

区域性血管床对局部注射植物雌激素三羟异黄酮的反应

在72只麻醉大鼠,分别采用后肢、肾脏和肠系膜动脉在体恒流灌注法,观察了向灌流环路中直接注射植物雌激素三羟异黄酮(genistein,GST)的血管效应,以所引起的灌流压增减反映血管的收缩和舒张。结果如下：(1)不同剂量的GST(0．4、0．8、1．2mg／k8)注射于股部灌注环路时,剂量依赖性地降低股动脉的灌流压。GST的这一效应可被L-硝基精氨酸甲酯(L-NAME)部分阻断,预先注射蛋白酪氨酸磷酸酶抑制剂正钒酸钠(50μg/kg),可部分抑制GST(0．8mg／kg)引起的效应;(2)向肾血管灌注环路中直接注射GST也可剂量依赖性地降低肾动脉的灌流压,预先注射正钒酸钠可完全抑制GST引起的效应,而L-NAME对此效应没有影响;(3)肠系膜血管灌流环路中注射GST可剂量依赖性地降低其灌流压,这一效应可被正钒酸钠部分抑制,而L-NAME对此无影响。根据上述结果得出的结论是：GST降低后肢、肾脏和肠系膜血管床的血管张力,其机制与酪氨酸激酶抑制有关,而在股动脉则与NO释放有部分关系。