Phase transfer and biocatalyst behaviour during biotransformation of beta-ionone in a two-phase liquid system by immobilised Aspergillus niger

The biotransformation of beta-ionone by Aspergillus niger IFO 8541 entrapped in Ca-alginate beads was investigated in a two-phase liquid system, due to the low aqueous solubility of the precursor. Modelling of phase transfer processes of the substrate demonstrated that the solute was transferred from the organic droplets to the gas, giving a loss by stripping, and then from the gas to the aqueous solution where a chemical degradation occurred. The biological reaction took place after direct precursor transfer from the organic layer to the biocatalyst by surface adsorption. Studies on the biological process demonstrated the critical effect of the biomass content in the medium at the time at which beta-ionone was added. Optimum conditions involved fed-batch feedings of both precursor and carbon source (sucrose) after the biomass concentration reached a value close to 6.8g/l. The biotransformation process then took place at a constant rate of 0.046mmol/lh with a reaction yield, defined with respect to beta-ionone metabolised by the fungus, close to unity. Best results achieved in this study allowed to obtain 3.5g/l biological compounds after 400h reaction.     

Biosorption of 2,4-dichlorophenol by immobilized white-rot fungus Phanerochaete chrysosporium from aqueous solutions

The fungus Phanerochaete chrysosporium was immobilized in several polymer matrices: Ca-alginate, Ca-alginate-polyvinyl alcohol (PVA) and pectin, and was then used as a biosorbent for removing 2,4-dichlorophenol (2,4-DCP) in wastewater. Immobilization of P. chrysosporium onto pectin was less efficient than that onto other matrices because of its poor mechanical strength and low adsorption efficiency. Ca-alginate immobilized fungal beads with biocompatibility exhibited good mechanical strength and adsorption efficiency over 60%. Among the different biomass dosages in Ca-alginate immobilized fungal beads, 1.25% (w/v) was the optimum. The adsorption data of 2,4-DCP on the blank Ca-alginate beads, free, and immobilized fungal biomass could be described by the Langmuir and Freundlich isotherms very well. Desorption operation was efficiently completed by using distilled water as eluant, and the desorption efficiency reached 82.16% at an optimum solid/liquid ratio of 14.3. The consecutive adsorption/desorption cycles studies employing the Ca-alginate immobilized fungal beads demonstrated that the immobilized fungal biomass could be reused in five cycles without significant loss of adsorption efficiency and adsorbent weight.     

Headspace volatile markers for sensitivity of cocoa (<Emphasis Type="Italic">Theobroma cacao</Emphasis> L.) somatic embryos to cryopreservation

The mechanisms that reduce the viability of plant somatic embryos following cryopreservation are not known. The objective of the present study was to evaluate the sensitivity of cocoa (Theobroma cacao L.) somatic embryos at different stages of an encapsulation–dehydration protocol using stress-related volatile hydrocarbons as markers of injury and recovery. The plant stress hormone ethylene and volatile hydrocarbons derived from hydroxyl radicals (methane) and lipid peroxidation (ethane) were determined using gas chromatography headspace analysis. Ethylene and methane were the only volatiles detected, with both being produced after each step of the cryogenic protocol. Ethylene production was significantly reduced following exposure to liquid nitrogen, but then increased in parallel with embryo recovery. In contrast, the production of methane was cyclic during recovery, with the first cycle occurring earlier for embryos recovered from liquid nitrogen and desiccation than those recovered from earlier steps in the protocol. These results suggest that loss of somatic embryo viability during cryopreservation may be related to the oxidative status of the tissue, and its capacity to produce ethylene. This study has demonstrated that headspace volatile analysis provides a robust non-destructive analytical approach for assessing the survival and recovery of plant somatic embryos following cryopreservation.     

Total recovery of resources and energy from rice straw using microwave-induced pyrolysis

This article presents the application of microwave-induced pyrolysis to total recovery of resources and energy from rice straw. The microwave power and particle size of feedstock were both key parameters affecting the performance of microwave-induced pyrolysis. Under 400-500W microwave power, the reduction of fixed carbon in the biomass was significant. From the experimental results of specific surface area, zeta potential, and Cu(2+) adsorption, the applications of solid residues in the water and wastewater treatment could be expected. The major compositions in gaseous product were H(2), CO(2), CO, CH(4) of 55, 17, 13, 10vol.%, respectively. The high H(2) content might imply that microwave-induced pyrolysis of biomass waste has the potential to produce the H(2)-rich fuel gas. Alkanes, polars, and low-ringed polycyclic aromatic hydrocarbons were three primary kinds of compounds in the liquid product.     

Interactions between surfactants and biomass during liquid–liquid extraction

Fermentation systems can contain may surface‐active compounds that can interfere with downstream separation processes. This work examines the interactions that can occur between surfactants and biomass during solute mass transfer in a liquid–liquid extraction system. Adding the surfactants sodium dodecyl sulfate and dodecyl trimethyl ammonium bromide to the aqueous phase caused a substantial increase in the mass transfer of chloramphenicol between water and octanol. Further investigation of the interfacial region using an optical Schlieren apparatus revealed that these increases were due to interfacial turbulence that gave rise to a rapid surface renewal convective mass transfer mechanism. When microbial biomass was present with sodium dodecyl sulfate, an increase in the mass transfer rate was again found, however, to a lesser extent. In contrast, dodecyl trimethyl ammonium bromide did not promote mass transfer and it is postulated that electrical interactions between the surfactant and the cell surface prevented adsorption of either at the interface. The interaction between the antifoaming agent polypropylene glycol 2000 and extraction system components was also investigated, with both positive and negative effects being recorded under varying conditions. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Optimization protocol for the extraction of antioxidant components from Origanum vulgare leaves using response surface methodology

In the present work, the response surface methodology (RSM) based on a central composite rotatable design (CCRD), was used to determine optimum conditions for the extraction of antioxidant compounds from Origanum vulgare leaves. Four process variables were evaluated at three levels (31 experimental designs): methanol (70%, 80%, and 90%), the solute:solvent ratio (1:5, 1:12.5, 1:20), the extraction time (4, 10, 16 h), and the solute particle size (20, 65, 110 micron). Using RSM, a quadratic polynomial equation was obtained by multiple regression analysis for predicting optimization of the extraction protocol. Analysis of variance (ANOVA) was applied and the significant effect of the factors and their interactions were tested at 95% confidence interval. The antioxidant extract (AE) yield was significantly influenced by solvent composition, solute to solvent ratio, and time. The maximum AE was obtained at methanol (70%), liquid solid ratio (20), time (16 h), and particle size (20 micron). Predicted values thus obtained were closer to the experimental value indicating suitability of the model. Run 25 (methanol:water 70:30; solute:solvent 1:20; extraction time 16 h and solute particle size 20) showed highest TP contents (18.75 mg/g of dry material, measured as gallic acid equivalents) and DPPH radical scavenging activity (IC₅₀ 5.04 μg/mL). Results of the present study indicated good correlation between TP contents and DPPH radical scavenging activity. Results of the study indicated that phenolic compounds are powerful scavengers of free radical as demonstrated by a good correlation between TP contents and DPPH radical scavenging activity.     

Somatic embryos cultures of <Emphasis Type="Italic">Vitis amurensis</Emphasis> Rupr. in air-lift bioreactors for the production of biomass and resveratrol

Resveratrol are the most important bioactive compounds found in Vitis amurensis. In this study, a somatic embryo induction system for V. amurensis was established in air-lift bioreactors for the production of biomass and resveratrol. The somatic embryos biomass growth was low on solid medium (69.60 g L^?1) compared to in liquid medium in bioreactor (329.45 g L^?1). Bioreactor cultures were found to be superior compared with solid medium culture not only in terms of biomass but also resveratrol productivity. Various culture parameters, including culture method, inoculum density, carbon source, and organic compounds were optimized. An inoculum density of 20 g L^?1 embryogenic calli was found suitable for the accumulation of biomass and resveratrol production, whereas 10 g L^?1 embryogenic calli increased the amount of resveratrol per fresh weight in somatic embryos. For bioreactor culturing, sucrose was an optimum carbon source and 500 mg L^–1 casein hydrolysate acid was conducive to the biomass and resveratrol production. This result indicates that an efficient protocol for the large-scale production of resveratrol can be achieved by bioreactor culturing of V. amurensis somatic embryos and can be used as a source of medicinal raw materials.     

Adsorption and Distribution of Fluorescent Solutes near the Articular Surface of Mechanically Injured Cartilage

The development of cartilage-specific imaging agents supports the improvement of tissue assessment by minimally invasive means. Techniques for highlighting cartilage surface damage in clinical images could provide for sensitive indications of posttraumatic injury and early stage osteoarthritis. Previous studies in our laboratory have demonstrated that fluorescent solutes interact with cartilage surfaces strongly enough to affect measurement of their partition coefficients within the tissue bulk. In this study, these findings were extended by examining solute adsorption and distribution near the articular surface of mechanically injured cartilage. Using viable cartilage explants injured by an established protocol, solute distributions near the articular surface of three commonly used fluorophores (fluorescein isothiocyanate (FITC), tetramethylrhodamine isothiocyanate (TRITC), and carboxytetramethylrhodamine (TAMRA)) were observed after absorption and subsequent desorption to assess solute-specific matrix interactions and reversibility. Both absorption and desorption processes demonstrated a trend of significantly less solute adsorption at surfaces of fissures compared to adjacent intact surfaces of damaged explants or surfaces of uninjured explants. After adsorption, normalized mean surface intensities of fissured surfaces of injured explants were 6%, 40%, and 32% for FITC, TRITC, and TAMRA, respectively, compared to uninjured surfaces. Similar values were found for sliced explants and after a desorption process. After desorption, a trend of increased solute adsorption at the site of intact damaged surfaces was noted (316% and 238% for injured and sliced explants exposed to FITC). Surface adsorption of solute was strongest for FITC and weakest for TAMRA; no solutes negatively affected cell viability. Results support the development of imaging agents that highlight distinct differences between fissured and intact cartilage surfaces.     

Adsorption and Distribution of Fluorescent Solutes near the Articular Surface of Mechanically Injured Cartilage

The development of cartilage-specific imaging agents supports the improvement of tissue assessment by minimally invasive means. Techniques for highlighting cartilage surface damage in clinical images could provide for sensitive indications of posttraumatic injury and early stage osteoarthritis. Previous studies in our laboratory have demonstrated that fluorescent solutes interact with cartilage surfaces strongly enough to affect measurement of their partition coefficients within the tissue bulk. In this study, these findings were extended by examining solute adsorption and distribution near the articular surface of mechanically injured cartilage. Using viable cartilage explants injured by an established protocol, solute distributions near the articular surface of three commonly used fluorophores (fluorescein isothiocyanate (FITC), tetramethylrhodamine isothiocyanate (TRITC), and carboxytetramethylrhodamine (TAMRA)) were observed after absorption and subsequent desorption to assess solute-specific matrix interactions and reversibility. Both absorption and desorption processes demonstrated a trend of significantly less solute adsorption at surfaces of fissures compared to adjacent intact surfaces of damaged explants or surfaces of uninjured explants. After adsorption, normalized mean surface intensities of fissured surfaces of injured explants were 6%, 40%, and 32% for FITC, TRITC, and TAMRA, respectively, compared to uninjured surfaces. Similar values were found for sliced explants and after a desorption process. After desorption, a trend of increased solute adsorption at the site of intact damaged surfaces was noted (316% and 238% for injured and sliced explants exposed to FITC). Surface adsorption of solute was strongest for FITC and weakest for TAMRA; no solutes negatively affected cell viability. Results support the development of imaging agents that highlight distinct differences between fissured and intact cartilage surfaces.     

Human placental sialidase: partial purification and characterization

A sialidase [EC 3.2.1.18] has been partially purified from human placenta by means of procedures comprising Con A-Sepharose adsorption, ammonium sulfate precipitation, sucrose density gradient centrifugation, and high-pressure liquid chromatography on a Shim pack Diol 300 column. On high-pressure liquid chromatography, most of the beta-galactosidase that comigrated with the sialidase on sucrose density gradient centrifugation was removed. The sialidase was purified 3,600-fold from the preparation obtained by Con A-Sepharose adsorption. The enzyme liberated the sialic acid residues from (alpha 2-3) and (alpha 2-6) sialyllactose, colomic acid, fetuin, and transferrin, but not from bovine submaxillary mucin. The enzyme also hydrolyzed gangliosides GM3, GD1a, and GD1b in the presence of sodium cholate as a detergent, but GM1 and GM2 were less susceptible to the enzyme. The optimum pHs for 4-methylumbelliferyl-N-acetylneuraminate, sialyllactose, fetuin, and GM3 lay between 4.0 and 5.0.     

Solid-phase microextraction for determining twelve orange flavour compounds in a model beverage emulsion

Solid-phase microextraction (SPME) coupled to gas chromatography has been applied for the headspace analysis (HS) of 12 target flavour compounds in a model orange beverage emulsion. The main volatile flavour compounds studied were: acetaldehyde, ethyl acetate, alpha-pinene, ethyl butyrate, beta-pinene, myrcene, limonene, gamma-terpinene, octanal, decanal, linalool and citral (neral plus geranial). After screening the fibre type, the effect of other HS-SPME variables such as adsorption temperature (25-55 degrees C), extraction time (10-40 min), sample concentration (1-100% w/w), sample amount (5-10 g) and salt amount (0-30% w/w) were determined using a two-level fractional factorial design (2(5-2)) that was expanded further to a central composite design. It was found that an extraction process using a carboxen-polydimethylsiloxane fibre coating at 15 masculineC for 50 min with 5 g of diluted emulsion 1% (w/w) and 30% (w/w) of sodium chloride under stirring mode resulted in the highest HS extraction efficiency. For all volatile flavour compounds, the linearity values were accurate in the concentration ranges studied (r(2) > 0.97). Average recoveries that ranged from 90.3 to 124.8% showed a good accuracy for the optimised method. The relative standard deviation for six replicates of all volatile flavour compounds was found to be less than 15%. For all volatile flavour compounds, the limit of detection ranged from 0.20 to 1.69 mg/L.     

Microbiological investigations of high-temperature horizons of the Kongdian petroleum reservoir in connection with field trial of a biotechnology for enhancement of oil recovery

The physicochemical conditions and microbiological characteristics of the formation waters of the Kongdian bed of the Dagang oil field (China) were studied. It was demonstrated that this bed is a high-temperature ecosystem with formation waters characterized by low mineralization. The concentrations of nitrogen and phosphorus compounds, as well as of electron acceptors, are low. Oil and oil gas are the main organic matter sources. The bed is exploited with water-flooding. The oil stratum was inhabited mostly by anaerobic thermophilic microorganisms, including fermentative (10(2)-10(5) cells/ml), sulfate-reducing (0-10(2) cells/ml), and methanogenic (0-10(3) cells/ml) microorganisms. Aerobic bacteria were detected mainly in the near-bottom zone of injection wells. The rate of sulfate reduction varied from 0.002 to 18.940 microg S(2-) l(-1) day(-1) and the rate of methanogenesis from 0.012 to 16.235 microg CH4 l(-1) day(-1). Microorganisms with great biotechnological potential inhabited the bed. Aerobic thermophilic bacteria were capable of oxidizing oil with the formation of biomass, the products of partial oxidation of oil (volatile acids), and surfactants. During growth on the culture liquid of oiloxidizing bacteria, methanogenic communities produced methane and carbon dioxide, which also had oil-releasing capabilities. Using various labeled tracers, the primary filtration flows of injected solutions at the testing site were studied. Our comprehensive investigations allowed us to conclude that the tested method for microbial enhancement of oil recovery based on the activation of the stratal microflora can be applied in the Kongdian bed horizons.     

Binding of Volatile Organic Compounds to Food Biopolymers

Capillary gas chromatography was used to study the influence of the composition and structure of different food polymers (polysaccharides, vegetable fibers, and animal protein gelatin) on the binding of essential oil components. The retention of volatile organic compounds on biopolymers was shown to depend on their molecule structure and the presence, type, and position of a functional group. The maximum extent of the binding was observed for nonpolar terpene and sesquiterpene hydrocarbons, and the minimum extent was observed for alcohols. The components of essential oils were adsorbed due mostly to hydrophobic interactions. It was shown that the composition and structure of a compound, its physico-chemical state, and the presence of functional groups influence the binding. Gum arabic and guar gum were found to bind nonpolar compounds to a maximum and minimum extent, respectively. It was demonstrated the minimum adsorption ability of locust bean gum with respect to all studied compounds.     

Adsorption-desorption process using wood-based activated carbon for recovery of biosurfactant from fermented distillery wastewater

Methods used for biosurfactant recovery include solvent extraction, precipitation, crystallization, centrifugation and foam fractionation. These methods cannot be used when distillery wastewater (DW) is used as the nutrient medium for biosurfactant production by Pseudomonas aeruginosa strain BS2, because recovery of biosurfactant by any of these methods imparts color to the biosurfactant. The biosurfactant has a nonaesthetic appearance with lowered surface active properties. These methods cannot be used for continuous recovery of biosurfactant during cultivation. Hence, a new downstream technique for biosurfactant recovery from fermented DW comprised of adsorption-desorption processes using wood-based activated carbon (WAC) was developed. This study involves batch experiments to standardize the factors affecting the rate of biosurfactant adsorption onto WAC. WAC was the most efficient adsorbent among various ones tested (i.e., silica gel, activated alumina and zeolite). The WAC (1% w v(-1)), equilibrium time (90 min), pH range of 5-10 and temperature of 40 degrees C were optimum to achieve 99.5% adsorption efficiency. Adsorption kinetics and intraparticle diffusion studies revealed the involvement of both boundary layer diffusion and intraparticle diffusion. The Langmuir adsorption isotherm of WAC indicated the formation of a monolayer coverage of the biosurfactant over a homogeneous carbon surface, while the Freundlich isotherm showed high adsorption at strong solute concentrations and low adsorption at dilute solute concentrations. WAC concentration of 4% w v(-1) facilitated complete removal of the biosurfactant from collapsed foam (contained 5-fold higher concentration of biosurfactant than was present in fermented DW). Biosurfactant adsorption was of chemisorption type. Acetone (polar solvent) was a specific viable eluant screened among various ones tested because it selectively facilitated maximum recovery, i.e., 89% biosurfactant from WAC. By acetone treatment, complete regeneration of WAC was feasible and WAC can be reused for biosurfactant recovery up to 3 cycles. The recovered biosurfactant showed improved surface-active property (i.e., much lower critical micelle concentration value of 0.013 verses 0.028 mg mL(-1) for biosurfactant recovered by classical methods). The reuse potential of WAC was assessed and results suggest that the carbon can be reused for three consecutive cycles for biosurfactant adsorption from fermented wastewater without any decrease in adsorption efficiency. Thus, this process forms a basis for continuous recovery of biosurfactant from fermented DW and concentrated foam. This process reduces the use of high cost solvent, avoids end product inhibition and minimizes product degradation.     

Capillary gas chromatography of pyrimidines and purines: N,O-peralkyl and trifluoroacetyl-N,O-alkyl derivatives

Preparation and capillary gas chromatographic properties of volatile derivatives of eighteen pyrimidine and purine nucleic acid bases are described. N,O-peralkylation using methylsulfinyl carbanion, methyl or ethyl iodide reagent, and alkylation preceded by N-trifluoroacetylation produced derivatives having minimal adsorption and tailing compared with trimethylsilyl derivatives. Relative retention times and linearity of flame ionization or nitrogen—phosphorus detector response were measured using polar (Superox-FA) and apolar (SE-30) liquid phases. Application of gas chromatography—mass spectrometry to derivatives of DNA hydrolysates using mass chromatography is demonstrated.     

Membrane process for biological treatment of contaminated gas streams

A hollow fiber membrane bioreactor was investigated for control of air emissions of biodegradable volatile organic compounds (VOCs). In the membrane bioreactor, gases containing VOCs pass through the lumen of microporous hydrophobic hollow fiber membranes. Soluble compounds diffuse through the membrane pores and partition into a VOC degrading biofilm. The hollow fiber membranes serve as a support for the microbial population and provide a large surface area for VOC and oxygen mass transfer. Experiments were performed to investigate the effects of toluene loading rate, gas residence time, and liquid phase turbulence on toluene removal in a laboratory-scale membrane bioreactor. Initial acclimation of the microbial culture to toluene occurred over a period of nine days, after which a 70% removal efficiency was achieved at an inlet toluene concentration of 200 ppm and a gas residence time of 1.8 s (elimination capacity of 20 g m-3 min-1). At higher toluene loading rates, a maximum elimination capacity of 42 g m-3 min-1 was observed. In the absence of a biofilm (abiotic operation), mass transfer rates were found to increase with increasing liquid recirculation rates. Abiotic mass transfer coefficients could be estimated using a correlation of dimensionless parameters developed for heat transfer. Liquid phase recirculation rate had no effect on toluene removal when the biofilm was present, however. Three models of the reactor were created: a numeric model, a first-order flat sheet model, and a zero-order flat sheet model. Only the numeric model fit the data well, although removal predicted as a function of gas residence time disagreed slightly with that observed. A modification in the model to account for membrane phase resistance resulted in an underprediction of removal. Sensitivity analysis of the numeric model indicated that removal was a strong function of the liquid phase biomass density and biofilm diffusion coefficient, with diffusion rates below 10(-9) m2 s-1 resulting in decreased removal rates.     

Volatile allelopathy in velvet bean (Mucuna pruriens [correction of pruiens] L.) and gravity.

Allelopathy caused by volatile compounds was studied with velvet bean (Mucuna pruriens [correction of prueiens] L.). Preparatory experiment was conducted to identify the relationship between action of volatiles and gravity. The experimental protocol was defined and tested to study on volatile allelopathy of velvet bean. Root growth of lettuce (Lactuca sativa L.) seedlings was inhibited by volatile gas from velvet bean seedlings planted in Agripot. In this study, it was shown that ten-day velvet bean seedling could exhibit the volatile allelopathic ability. Growth chambers for volatile experiment were designed. Velvet bean seed can germinate in a 3-ml small vial.     

Determination of volatile organic compounds by solid-phase microextraction

The parameters of the process of isolation, concentration, and gas chromatographic analysis of volatile organic compounds by solid-phase microextraction were optimized. With different amounts of a mixture of essential oils, the conditions of reproducibility of their determination were established based on the absolute values of the squares of chromatographic peaks obtained by capillary gas chromatography. It was found that the efficiency of the extraction of volatile compounds from gas phase by sorption on mixed polymer (consisting of polydimethylsiloxane and divinylbenzene) was significantly influenced by the structure of their molecules, while the sorption time and their content in the liquid phase influenced the significance of determination.     

Enhanced biosorption of mercury(II) and cadmium(II) by cold-induced hydrophobic exobiopolymer secreted from the psychrotroph <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> BM07

The cells of psychrotrophic Pseudomonas fluorescens BM07 were found to secrete large amounts of exobiopolymer (EBP) composed of mainly hydrophobic (water insoluble) polypeptide(s) (as contain approximately 50 mol% hydrophobic amino acids, lacking cysteine residue) when grown on fructose containing limited M1 medium at the temperatures as low as 0-10 degrees C but trace amount at high (30 degrees C, optimum growth) temperature. Two types of nonliving BM07 cells (i.e., cells grown at 30 degrees C and 10 degrees C) as well as the freeze-dried EBP were compared for biosorption of mercury (Hg(II)) and cadmium (Cd(II)). The optimum adsorption pH was found 7 for Hg(II) but 6 for Cd(II), irrespective of the type of biomass. Equilibrium adsorption data well fitted the Langmuir adsorption model. The maximum adsorption (Q (max)) was 72.3, 97.4, and 286.2 mg Hg(II)/g dry biomass and 18.9, 27.0, and 61.5 mg Cd(II)/g dry biomass for cells grown at 30 degrees C and 10 degrees C and EBP, respectively, indicating major contribution of heavy metal adsorption by cold-induced EBP. Mercury(II) binding induced a significant shift of infrared (IR) amide I and II absorption of EBP whereas cadmium(II) binding showed only a very little shift. These IR shifts demonstrate that mercury(II) and cadmium(II) might have different binding sites in EBP, which was supported by X-ray diffraction and differential scanning calorimetric analysis and sorption results of chemically modified biomasses. This study implies that the psychrotrophs like BM07 strain may play an important role in the bioremediation of heavy metals in the temperate regions especially in the inactive cold season.     

A Study of the interaction of HEK-293 cells with streamline chelating adsorbent in expanded bed operation

Expanded bed adsorption (EBA) is an efficient protein purification process reducing time and steps of downstream processing (DSP) since nonclarified culture media can be processed directly without prior treatments such as filtration or centrifugation. However, cells and debris can interact with the adsorbent and affect bed stability as well as purification performance. To optimize EBA operating conditions these biomass/adsorbent interactions have to be understood and characterized. The adsorption of Human Embryonic Kidney cells (HEK 293) on unprimed and nickel-primed metal affinity adsorbent was studied in a closed loop EBA setup. With the unprimed adsorbent, the overall level of interaction observed was nonsignificant. With the nickel-primed adsorbent and an initial cell concentration ranging from 0.08 x 10(6) to 0.2 x 10(6) cells/mL, biomass/adsorbent interaction was found to be moderate and the adsorption apparent first-order kinetic rate constant was determined to be k = 0.009 to 0.011 min(-1).