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Biochemical Engineering Journal (v.38, #2)

Editorial Board (pp. co2).

BEJ Keywords (pp. iv).

Publisher's note (pp. 123-123).

Periodic and chaotic solutions for a model of a bioreactor with cell recycle by G. Ibrahim; H. Habib; O. Saleh (pp. 124-137).

A heterogenous model of bioreactor with cell recycle is proposed to predict complex dynamic behavior of such system. The model is based on interactive kinetics between substrate and dissolved oxygen and takes into account the external mass transfer resistance around the biological floc. The investigation of the static and dynamic bifurcation of the model shows that periodic and chaotic behavior occur for some range of feed conditions and dissolved oxygen levels as confirmed by several experimental studies which have been reported in the literature. The ability of the proposed model to predict periodic and/or chaotic behavior is investigated over a wide range of model parameters.

Keywords: Bioreactor with cell recycling; Autonomous system; Bifurcation; Periodic attractor; Chaotic attractor; Lyapunov exponents

Integrated model of the production of soluble microbial products (SMP) and extracellular polymeric substances (EPS) in anaerobic chemostats during transient conditions by Sérgio F. Aquino; David C. Stuckey (pp. 138-146).

A model to predict the accumulation of soluble microbial products (SMP) in anaerobic chemostats during steady-state and transient conditions is presented in this paper. The model incorporates the concept of production and degradation of extracellular polymeric substances (EPS or ECP) as part of SMP, and was used to predict SMP production during hydraulic and organic shock load experiments in anaerobic continuously stirred tank reactors (CSTRs). For most variables the model predicted reasonably well the shock loads, and the best-fit values of the main parameters provided valuable information on the types of SMP that predominate under particular culture conditions. According to the model, during steady-state conditions ∼58% of the SMP are utilization-associated products (UAP) whilst ∼42% are biomass-associated products (BAP) of which ∼7% are soluble EPS (sEPS). During the hydraulic and organic shock loads the importance of BAP and sEPS decreases and the UAP accounts for up to 95% of the SMP.

Keywords: Anaerobic digestion; Modelling; Shock loads; Soluble microbial products; Extracellular polymeric substances; Extracellular polymers

Phenol and4-chlorophenol biodegradation by yeast Candida tropicalis in a fluidized bed reactor by J. Galíndez-Mayer; J. Ramón-Gallegos; N. Ruiz-Ordaz; C. Juárez-Ramírez; A. Salmerón-Alcocer; H.M. Poggi-Varaldo (pp. 147-157).

The objective of this work was to evaluate (i) the hydrodynamics and oxygen transfer characteristics of a fluidized bed reactor (FBR) and (ii) their performance in the continuous biodegradation of a phenol (Phe) and 4-chlorophenol (4-CP)-containing influent when the FBR was loaded with Candida tropicalis yeast immobilized onto granular activated carbon (GAC) particles. The first part was carried out in terms of the behavior of mixing time ( t_m95), bubble diameter ( d_B), gas hold-up ( ɛ_G), gas–liquid interfacial area ( a′) and oxygen transfer coefficient ( k_L a) in biphasic (gas–liquid) and triphasic (gas–liquid–carbon) systems, both batch-wise operated in pseudohomogeneous regime at superficial gas flow rates U_G below 1.72cms⁻¹. Mixing time was determined using a tracer technique, ɛ_G was measured by the volume expansion method; ( d_B) was determined by the procedure reported by Poulsen and Iversen and k_L a was determined by a transient gassing-in technique. It was found that hydrodynamic variables were severely influenced by GAC particles. The d_B values were smaller in triphasic than in biphasic system, with the consequent increase in the ɛ_G, a′ and k_L a values.The removal efficiencies of both Phe and 4-CP in the bioreactor challenged at increasing volumetric loading rate of pollutants were determined in the second part of the study. Phe and 4-CP was determined by HPLC. Immobilized biomass on GAC was estimated from their total nitrogen content. Regarding continuous biodegradation experiments, the FBR was capable of efficiently removing Phe at volumetric loading rates as high as 60mgPheL⁻¹h⁻¹ when it was fed as the sole carbon source. Beyond this point, removal efficiencies drastically decreased. When operated with a feed consisting of a mixture of Phe and 4-CP, the FBR was able to remove more than 98% of 4-CP in the range of volumetric loading rates of 4.1mg 4-CPL⁻¹h⁻¹ and 55mgPheL⁻¹h⁻¹ with no apparent deterioration of bioreactor performance.

Keywords: Bubble column; Candida tropicalis; Chlorophenol biodegradation; Fluidized bed reactor; Immobilized yeast; Phenol biodegradation

An efficient DPB utilization process: The modified A₂N process by Liu Hongbo; Sun Liping; Xia Siqing (pp. 158-163).

The modified A₂N process was proposed on basis of the A₂N process. There are two waste sludge lines in the modified A₂N process: an AN (anaerobic-anoxic) waste sludge line and an AO (anaerobic–aerobic) waste sludge line. Denitrifying phosphorus removing bacteria (DPB) and common phosphorus accumulation organisms (PAOs) coexisted in the modified A₂N process but was relatively separated. Two streams of mixed liquor suspended solid (MLSS) were out of the anaerobic tank with one entering the anoxic tank, where DPB was the dominant microorganism, and the other the nitrification tank, where the aerobic PAOs dominated. The effects of pH and DO on process performance were investigated. Results showed that DPB might be more pH tolerable than aerobic PAOs while DPB and aerobic PAOs shared similar responses to DO. Parameters optimization was conducted and the following optimized parameters obtained: DO in nitrification tank was 2–3mgL⁻¹; nominal HRT for each unit (anaerobic, anoxic and aerobic units) was 3h; SRT was 15d. When the influent nutrient mass ratio (C/N/P) was 26.6/7.67/1 to 26.6/3/1, the average effluent COD, TN, and TP concentrations of the optimized process were 45, 10.5 and 0.7mgL⁻¹, respectively, with average removal efficiency 89%, 95.3% and 76.7% for COD, TN and TP.

Keywords: Modified A; ₂; N process; Denitrifying phosphorus removing bacteria (DPB); Two waste sludge lines; Biological nutrient removal (BNR)

Towards oriented assembly of proteins onto magnetic nanoparticles by Chi-Wei Hung; Tracey R.P. Holoman; Peter Kofinas; William E. Bentley (pp. 164-170).

Magnetic particles, functionalized with transition metal ions, possess the ability to specifically bind recombinant proteins engineered to contain C- or N-terminal histidine residues (e.g., a hexahistidine tag). We have surface-functionalized these particles and developed a simple orientational model that predicts the spatial arrangement of a model histidine tagged protein, green fluorescent protein (GFP), adsorbed to the surface of Fe₃O₄ magnetite nanoparticle agglomerates. A Langmuir isotherm model can describe well the specific, monolayer adsorption onto the particle surface, and the maximum adsorption capacity was 0.865μg-GFP/μg particle. We have also determined the net available surface area of these nanoparticles (97m²/g) and our results suggest a vertical alignment of 88 GFP molecules in a nearly closest packed configuration per “average” nanoparticle. This approach may be useful for characterizing the assembly of other proteins with known shape onto magnetic nanoparticles.

Keywords: Adsorption; Affinity; Bioseparation; Immobilized Enzymes; Magnetic Nanoparticles; Protein Purification

Field determination of phenolic compounds in olive oil mill wastewater by artificial neural network by José S. Torrecilla; Maria L. Mena; Paloma Yáñez-Sedeño; Julián García (pp. 171-179).

In this paper, a new computerised approach to the determination of concentrations of phenolic compounds (catechol) is considered. In this approach an integrated artificial neural network (ANN)/laccase biosensor is designed. The data collected (current signals) from amperometric detection of the laccase biosensor were transferred into an ANN trained computer for modelling and prediction of output. Such an integrated ANN/laccase biosensor system is capable of prediction of cathecol concentration of olive oil mill wastewater, based on the created models and patterns, without any previous phenomenological knowledge. The predicted results using the ANN were compared with the amperometric detection of phenolic compounds obtained at a laccase biosensor in olive oil wastewater during the 2004–05 harvest season. The difference between the real and the predicted values was less than 1%.

Keywords: Biosensor; Modelling; Optimization; Integrated processing; Phenolic compounds; Artificial neural network

Covalent immobilization of chloroperoxidase onto magnetic beads: Catalytic properties and stability by Gülay Bayramoğlu; Senem Kiralp; Meltem Yilmaz; Levent Toppare; M. Yakup Arıca (pp. 180-188).

Amino groups containing magnetic beads were used in covalent immobilization of the enzyme “chloroperoxidase (CPO)” which is one of a few enzymes that can catalyse the peroxide dependent oxidation of a wide spectrum of organic and inorganic compounds. The magnetic poly(glycidylmethacrylate-methylmethacrylate-ethyleneglycol dimethacrylate), magnetic p(GMA-MMA-EGDMA) beads were prepared via suspension polymerization in the presence of ferric ions. The magnetic beads were characterized with scanning electron microscope (SEM), Fourier transform infrared (FTIR), Mössbauer spectroscopy and vibrating sample magnetometer (VSM). The magnetic beads were derivatized sequentially with ammonia and glutaraldehyde, and CPO was covalently immobilized on the support via reaction of the amino groups of the enzyme under mild conditions. The effect of various parameters including pH, temperature and enzyme concentration on the immobilization efficiency of CPO onto glutaric dialdhyde activated magnetic beads was evaluated. Magnetic measurement revealed that the resultant CPO-immobilized magnetic beads were superparamagnetic with a saturation magnetization of 18.2emu/g. The analysis of FTIR spectra confirmed the binding of CPO on the magnetic beads. The maximum amount of immobilized CPO on the magnetic beads was 2.94mg/g support. The values of Michaelis constants K_m for immobilized CPO was significantly larger, indicating decreased affinity by the enzyme for its substrate, whereas V_max values were smaller for the immobilized CPO. However, the CPO immobilized on the magnetic beads resulted in an increase in enzyme stability with time.

Keywords: Magnetic beads; Enzyme immobilization; Chloroperoxidase; Kinetic parameters; Enzyme stability

Effects of vitamins on the lactic acid biosynthesis of Lactobacillus paracasei NERCB 0401 by Guo-Qian Xu; Ju Chu; Ying-Ping Zhuang; Yong-Hong Wang; Si-Liang Zhang (pp. 189-197).

The effects of various vitamin supplements, vitamin B₁, B₂, B₅, B₆, and H on the fermentation of Lactobacillus paracasei NERCB 0401 for production of lactic acid were investigated. Vitamin B₁ and H were found to be the determinant supplements for the fermentation process. The optimal addition of vitamin supplements in defined medium were experimentally studied and found be 0.053mg/L vitamin B₁, 0.01mg/L vitamin B₂, 4.0mg/L vitamin B₅, 0.2mg/L vitamin B₆, and 0.075mg/L vitamin H. The concentration of lactic acid was 92% greater under the optimal addition of the vitamin components than that without vitamins addition. Compared to the fermentation without vitamins supplement addition, the death rate of L. paracasei under the optimal vitamin addition decreased remarkably, with maximum extent by 53.5% at 24h. The possible mechanism of enhancement of lactic acid production was elucidated by the time course analysis of the specific activities of phosphofructokinase, lactate dehydrogenase, pyruvate dehydrogenase complex and pyruvate carboxylase during fermentation processes.

Keywords: l; (+)-Lactic acid; Steepest ascent method; Response surface analysis; Vitamin; Cell viability

Effect of plant oil and surfactant on the production of mycelial biomass and polysaccharides in submerged culture of Grifola frondosa by Chienyan Hsieh; Hui-Liang Wang; Chien-Cheng Chen; Tai-Hao Hsu; Mei-Hua Tseng (pp. 198-205).

Effects of various plant oil addition and surfactant addition at different stages of cell growth phase on the cell growth and production of bioactive metabolites, such as exopolysaccharide (EPS) and intracellular polysaccharide (IPS) in the submerged culture of Grifola frondosa were studied with 2% glucose medium. Olive, safflower seed, soy and sunflower oil were favorable plant oil sources to the mycelial growth of G. frondosa. The highest cell growth (∼12.64±0.47g/l cell dry weight) can be obtained on day 13 of cultivation in the medium containing 1% all the plant oil sources. EPS production was slightly enhanced by olive oil but significantly inhibited by safflower seed oil and sunflower oil after 13 days of cultivation. With 4% glucose, 0.5% plant oils were selected to add on 0-, 3-, 7-, and 9-day of cultivation to exam the effect on the cell growth at different stages. Amongst four plant oil sources examined, cell growth yielded relatively high mycelial biomass (11.22±1.14g/l) and that was achieved in 4% glucose medium with 0.5% soybean oil. The higher EPS production and slightly lower cell growth were found in 4% glucose media; the maximum EPS production was 2.248±0.107g/l found in 4% glucose media with olive oil addition.Tween 80 and Span 80 addition had shown to increase cell growth and the maximal cell concentration of 9.10±0.80g/l was obtained with 1% Span 80 addition. Both EPS and IPS production were found to decrease with all the tested concentrations of Tween 80 and Span 80 addition. Span 80 added at the vegetative growth phase in 4% glucose media yielded the highest mycelial biomass of G. frondosa (8.95±0.57g/l); meanwhile Tween 80 added at the beginning cultivation had resulted in the highest EPS production (1.451±0.098g/l). Tween 20 and Span 20 addition were shown to have serious inhibition on cell growth of G. frondosa and also on polysaccharides production. The results obtained were useful in better understanding the regulation and optimization of G. frondosa culture for efficient production of cell mass and polysaccharides in the submerged culture.

Keywords: Grifola frondosa; Plant oil; Tween 80; Span 80; Polysaccharides

Characterization of two-step direct somatic embryogenesis in carrot by Toshiya Takeda; Miki Mizukami; Hiroshi Matsuoka (pp. 206-211).

Direct somatic embryogenesis has been used to induce intact regenerated plantlets. We applied two-step direct somatic embryogenesis to the mass propagation of carrots and characterized this method. Morphological observation revealed that somatic embryos were generated from whole segments except for the callus part. Secondarily formed collenchyma-like structures were observed in the segments after the induction culture. The somatic embryos were generated from the collenchyma-like structure. When the longer-grown hypocotyls which had less potential to generate somatic embryos were used, the collenchyma-like structure did not develop. RAPD-PCR investigation showed that the regenerated plantlets had genetic stability. These results indicated that two-step direct somatic embryogenesis was a useful method for the mass propagation of plants without losing the quality of the donor plants.

Keywords: Direct somatic embryo; Carrot; Plant cell culture; Tissue cell culture; Genetic stability; DNA

Synthesis of ion-imprinted chitosan-TiO₂ adsorbent and its multi-functional performances by Qiang Li; Haijia Su; Tianwei Tan (pp. 212-218).

During the preparation of a novel adsorbent, molecular imprinting technology and photo degradation technology were coupled through the immobilization of nanometer titanium dioxide on molecular imprinted chitosan matrixes. This novel adsorbent can not only degrade organic compound but also adsorb the heavy metal ions. The compound adsorbent was characterized by using scanning electron microscope (SEM) and FI-IR spectrum. As can be deduced from the FI-IR spectrum, hydrogen bond was one of the combination strengths between chitosan and TiO₂. The effects of amount of TiO₂, chitosan concentration, solidifying solutions and imprinting ions on the degradation of methyl orange and adsorption for Ni²⁺ ions were investigated. The adsorptive capacity and degradability of the adsorbent were assessed in this work too.

Keywords: Nanometer titanium dioxide; Chitosan; Molecular imprinting; Metal ions; Methyl orange

Bioavailability of PCBs in biphasic bioreactors by Lars Rehmann; Andrew J. Daugulis (pp. 219-225).

Polychlorinated biphenyls (PCBs) are xenobiotic and toxic contaminants of soil and sediment. A possible remediation scheme involves solvent extraction followed by microbial biodegradation in biphasic bioreactors. This study examined the effect of two water immiscible liquid phases on the extent and rate of aerobic Aroclor^® 1242 biodegradation by Burkholderia xenovorans LB400 under controlled conditions. The immiscible phases were neither toxic nor biodegradable by the employed organism and it was found that reduced aqueous phase availability, caused by the immiscible phases, had a negative effect on the extent and rate of degradation. The initial PCB concentration in the immiscible phase and the nature of the immiscible phase was shown to influence biodegradation. It was further found that under the employed conditions, providing intensive mixing, the microbial degradation rate and not the mass transfer of PCBs from the immiscible phase into the aqueous phase was limiting the degradation process. Despite reduced specific microbial degradation rates in the presence of a water immiscible phase a maximum volumetric degradation rate of 0.44mgl⁻¹h⁻¹ in the presence of 0.1% silicone oil could be achieved. The findings in the study show that microbial degradation of PCBs in biphasic bioreactors might be a suitable technology for the treatment of solvent extracts of contaminated soils.

Keywords: Aroclor; ^®; 1242; Availability; Burkholderia xenovorans; LB400; Sequestration; Equilibrium partitioning

Removal of suspended solids from tuna spleen extract by microfiltration: A batch process design and improvement by Zhenyu Li; Aran H-Kittikun; Wirote Youravong (pp. 226-233).

In order to reduce the fouling load during separation of trypsin and chymotrypsin from yellowfin tuna spleen extract by ultrafiltration, a batch concentration microfiltration was designed as a pretreatment process to remove suspended solids from this extract. The design process included both dead-end and crossflow microfiltration (CFMF) to select optimal conditions for operation. The optimal membrane pore size of 0.10μm was selected by a preliminary test using dead-end microfiltration. And then based on total recycle and single-batch concentration CFMF, a continuous-batch concentration CFMF (CBC-CFMF) with 0.10μm hollow fiber membrane, crossflow velocity of 0.2ms⁻¹, transmembrane pressure of 0.15bar and gas injection factor of 0.38 was designed and applied successfully to remove suspended solids from tuna spleen extract while transmissions of about 1 for both trypsin and chymotrypsin were attained in this study. The negative effects of shear stress, high concentration of feed and long holding time in batch operation process were minimized by CBC-CFMF combined with gas bubbling technique. The optimal gas injection factor ( r) of 0.38 resulted in a 300% improvement in flux comparing to the process without gas injection. Higher gas injection factor caused damage on both transmission and activity of expected enzymes. A clear permeate with slight yellow colour was obtained after CBC-CFMF.

Keywords: Enzyme production; Pretreatment; Suspended particles; Filtration; Microporous membranes; Optimization

Screening, purification, and characterization of a leather-degrading protease by Hiroyasu Ogino; Toshihiko Otsubo; Haruo Ishikawa (pp. 234-240).

A bacterium which secreted natural leather powder-degrading protease was obtained by successive screening using media containing white meal, gelatin, and leather powder. The selected and isolated strain (PN-13) belongs to the family of Bacillus. A protease (PN-13 protease) secreted by the Bacillus sp. PN-13 was purified from culture supernatant. The protease was homogeneously purified and the molecular mass was estimated as 30kDa. The protease hydrolyzed casein, gelatin, and especially leather powder effectively under alkaline conditions.

Keywords: Protease; Bacillus; Leather-degrading; Screening; Purification; Characterization

Partitioning of Ciprofloxacin in aqueous two-phase system of poly(ethylene glycol) and sodium sulphate by Babak Mokhtarani; Ramin Karimzadeh; Mohammad Hassan Amini; Siavash Darvish Manesh (pp. 241-247).

Extraction by an aqueous two-phase system is a powerful technique for separation, concentration, and purification of biomolecules and pharmaceutical products. In the present study, the partitioning of Ciprofloxacin in aqueous two-phase system of PEG–Na₂SO₄–water has been investigated. The influences of temperature, salt concentration, polymer concentration and polymer molecular weight on the partitioning of Ciprofloxacin were studied. The experiments were designed using an orthogonal central composite design (orthogonal CCD) based on 2³ full factorial and a second-order model was used to determine the effects of different factors on Ciprofloxacin partitioning. The results of the model indicate that the Ciprofloxacin partitioning is highly dependent on salt concentration. Temperature and PEG concentration have moderate effects on partitioning but PEG molecular weight has no significant effect on the antibiotic partitioning.

Keywords: Aqueous two-phase system; ATPS; Partitioning; Ciprofloxacin; Experimental design

Correlation of reactor performance and bacterial community composition during the removal of trimethylamine in three-stage biofilters by Ding Ying; Wu Weixiang; Han Zhiying; Chen Yingxu (pp. 248-258).

Two three-stage biofilters packed with compost (BFC) or sludge (BFS), respectively, were prepared for removing trimethylamine (TMA) from waste gases. The correlation between reactor performance and bacterial community composition was investigated. Although TMA could be successfully removed by both biofilters, TMA removal efficiency in the bottom stage of the BFC was considerably higher than that of the BFS. Moreover, NH₃ generated by the degradation of TMA could be removed in the BFC, while it accumulated in the BFS. Spatial and temporal shifts of bacterial community composition in both biofilters developed differently as assessed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) followed by clone library analysis. Results showed that the lack of ammonia-oxidizing bacteria (AOB) may have contributed to the accumulation of NH₃ in the BFS. Therefore, AOB may play a decisive role in a complete degradation of TMA. It is necessary for the sludge packing material to be inoculated with AOB in order to initiate ammonia oxidation in the bioreactor. Understanding of microbial community compositions in biofilters plays an important role in seeking biological limiting factors related to the removal efficiencies of TMA and other compounds from waste gas and further enhancing the performance of biofilters.

Keywords: Biofiltration; Trimethylamine; Three-stage biofilters; PCR-DGGE; Bacterial community composition

Application of two anaerobic digestion models to biofilm systems by Mauren Fuentes; Nicolás J. Scenna; Pío A. Aguirre; Miguel C. Mussati (pp. 259-269).

This work deals with a comparative analysis of two alternative anaerobic digestion models proposed by Batstone et al. [D.J. Batstone, J. Keller, I. Angelidaki, S.V. Kalyuzhnyi, S.G. Pavlostathis, A. Rozzi, W.T.M. Sanders, H. Siegrist, V.A. Vavilin, Anaerobic Digestion Model No. 1 (ADM1) IWA Task Group for Mathematical Modelling of Anaerobic Digestion Processes, IWA Publishing, London, UK, 2002] and Angelidaki et al. [I. Angelidaki, L. Ellegaard, B.K. Ahring, A comprehensive model of anaerobic bioconversion of complex substrates to biogas, Biotechnol. Bioeng. 63 (5) (1999) 363–372], and their application to biofilm systems. Bioreactors are modeled as dynamic (gas–solid–liquid) three-phase systems. The experimental set-up consists of two mesophilic (36±1°C) lab-scale anaerobic fluidized bed reactors, which were loaded with sand as inert support for biofilm development. The experimental protocol is based on step-type disturbances applied on the inlet substrate concentration (glucose and acetate-based feeding) and on the feed flow rate considering the criterion of maximum efficiency. The predicted and measured responses of total and soluble chemical oxygen demand (COD), volatile fatty acid concentrations, biogas production rate and pH are investigated. Under the operating conditions evaluated in this investigation, the anaerobic digestion model proposed by Angelidaki et al. [I. Angelidaki, L. Ellegaard, B.K. Ahring, A comprehensive model of anaerobic bioconversion of complex substrates to biogas, Biotechnol. Bioeng. 63 (5) (1999) 363–372] ensures the best prediction. Parameters related to non-active biomass composition, disintegration and hydrolysis should be revised to achieve a good agreement between experimental and predicted values using the model proposed by Batstone et al. [D.J. Batstone, J. Keller, I. Angelidaki, S.V. Kalyuzhnyi, S.G. Pavlostathis, A. Rozzi, W.T.M. Sanders, H. Siegrist, V.A. Vavilin, Anaerobic Digestion Model No. 1 (ADM1) IWA Task Group for Mathematical Modelling of Anaerobic Digestion Processes, IWA Publishing, London, UK, 2002].

Keywords: Anaerobic digestion model; Biofilms; Fluidized bed bioreactor; Three-phase system; Dynamic modeling and simulation

Increased eleutheroside production in Eleutherococcus sessiliflorus embryogenic suspension cultures with methyl jasmonate treatment by Abdullah Mohammad Shohael; Hosakatte Niranjana Murthy; Eun Joo Hahn; Hyung Lae Lee; Kee Yoeup Paek (pp. 270-273).

The effects of methyl jasmonate elicitation were investigated in embryogenic suspension cultures of Eleutherococcus sessiliflorus in bioreactors for the production of eleutherosides and chlorogenic acid. Eleutherosides and chlorogenic acid increased with methyl jasmonate elicitation (in the range 50–400μM); however, fresh weight, dry weight and growth ratio of the cells were inhibited by increasing methyl jasmonate concentration. There were 3.5-, 2.6-, 2.5- and 3.2-fold increments in eleutherosides B, E, E1 and chlorogenic acids were evident, respectively, with 200μM methyl jasmonate treatment. These results suggest that methyl jasmonate elicitation is beneficial for eleutheroside accumulation in the embryogenic suspension cultures.

Keywords: Eleutherococcus sessiliflorous; Eleutherosides; Elicitation; Methyl jasmonate

Reactivity of Candida rugosa lipase in cetyltrimethylammonium bromide microemulsion–gelatin complex organogels by Kazuhito Nagayama; Ryo Katakura; Takashi Hata; Kazumitsu Naoe; Masanao Imai (pp. 274-276).

Esterification activity of Candida rugosa lipase in cetyltrimethylammonium bromide (CTAB) microemulsion-based organogels (MBGs) containing gelatin as natural resource polymer was investigated. The lipase activity reached maximum at a water content of 48–50% (v/v) and at a CTAB concentration of 60mM. During batch repeated reactions, the lipase activity gradually decreased and the MBGs were swollen in appearance.

Keywords: CTAB; Microemulsion; Gelatin; Organogel; Lipase; Esterification

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Biochemical Engineering Journal (v.38, #2)