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Biochemical Engineering Journal (v.63, #)

BEJ Keywords (pp. ii).
Editorial Board (pp. co2).

Sono-assisted enzymatic saccharification of sugarcane bagasse for bioethanol production by Rajendran Velmurugan; Karuppan Muthukumar (pp. 1-9).
Display Omitted► Sono-assisted alkaline pretreatment was carried out for effective lignin removal. ► C. flavigena was utilized for saccharification which is intensified using ultrasound. ► Optimization of sono-assisted saccharification was carried out. ► The data obtained at different conditions were analyzed using two fraction model. ► The suitability of the hydrolyzate obtained for fermentation was evaluated.This study presents the sono-assisted pretreatment and enzymatic saccharification of sugarcane bagasse (SCB) for the production of bioethanol. The effect of sono-assisted alkali (NaOH) pretreatment on the removal of hemicellulose and lignin from SCB was studied and the results showed 80.8% of hemicellulose and 90.6% of lignin removal. Sono-assisted enzymatic saccharification was performed with Cellulomonas flavigena (MTCC 7450) and the yield was found to be affected by liquid-to-solid ratio (LSR), cell mass and pH. The optimum reaction time, LSR, cell mass and pH were found to be 360min, 15:1, 15g/L and 6.0 respectively. At optimum conditions, the maximum glucose yield obtained was 91.28% of the theoretical yield and the maximum amount of glucose obtained was 38.4g/L. The enhancement in performance may be correlated with the swelling of cellulose and accelerated enzymatic saccharification due to the application of ultrasound. The hydrolyzate obtained was fermented using Zymomonas mobilis (MTCC 89) and about 91.22% of the theoretical ethanol yield was observed in 36h of fermentation.

Keywords: Ethanol; Bioconversion; Cellulase; Sono-assisted saccharification; Fermentation


Biodiesel production catalyzed by Rhizomucor miehei lipase-displaying Pichia pastoris whole cells in an isooctane system by Dengfeng Huang; Shuangyan Han; Zhenlin Han; Ying Lin (pp. 10-14).
A recombinant Pichia pastoris displaying Rhizomucor miehei Lipase (RML) on the cell surface was shown to be an efficient biocatalyst in biodiesel production from soybean oil. Various reaction parameters affecting the transesterification catalyzed by RML-displaying P. pastoris whole cells were studied. The optimal reaction conditions were: temperature 55°C, water activity 0.66, the ratio of isooctane to oil 2:1 (v/v) and the whole-cell biocatalyst 40% (w/w, soybean oil). To reduce the inactivation of displaying lipases by methanol, each 1.5 molar equivalent of methanol (mol/mol, soybean oil) were added in a three-step procedure at the reaction time of 0h, 24h and 48h, respectively. Under these optimized conditions, a methyl esters (ME) yield reached 83.14% after 72h, which significantly enhanced the ME yield catalyzed by the displaying lipase reported previously. The RML-displaying P. pastoris whole-cell biocatalyst exhibited quite a good operational stability with more than 80.46% of its original activity remained even after 10 batches reaction as well as storage stability. Thus, it showed promising potential in biodiesel production.

Keywords: Biodiesel; Pichia pastoris; Rhizomucor miehei; Lipase; Three-step methanolysis; Whole-cell biocatalyst; Yeast-displaying


l-Phenylalanine synthesis catalyzed by immobilized aspartate aminotransferase by Max Cárdenas-Fernández; Carmen López; Gregorio Álvaro; Josep López-Santín (pp. 15-21).
► We studied the enzymatic synthesis of phenylalanine by aspartate aminotransferase. ► The enzyme was successfully immobilized by covalent and entrapment techniques. ► The derivatives catalyzed the reaction with the same rate that the soluble enzyme. ► Immobilization improved the enzymatic stability.The essential amino acidl-phenylalanine (Phe), extensively applied in the manufacture of food and drink products, is usually produced by chemoenzymatic or fermentative processes. In this work, an enzymatic alternative based on the application of the enzymel-aspartate aminotransferase (AAT; EC 2.6.1.1) from porcine heart, which catalyzes the transamination between phenylpyruvate andl-aspartate, was developed. Aiming to improve its stability and enable the reuse, the enzyme AAT was immobilized via different techniques such as by covalent attachment on Eupergit® C (epoxy support) and MANA-agarose (amino support), and by entrapment in polyvinyl alcohol hydrogel particles (LentiKats®). For low enzymatic loads, retained activities of 40, 70 and 40% and immobilization yields of 95, 98 and 40% were obtained using Eupergit® C, MANA-agarose and LentiKats®, respectively. Free and highly loaded immobilized enzymes were used to synthesizel-phenylalanine. The high conversions, reaction yields and initial rates obtained for free enzyme were similar to those obtained when using Eupergit® C and LentiKats® immobilized catalysts. Moreover, the AAT stability under reaction conditions was moderately enhanced for Eupergit® C and LentiKats® immobilized enzymes related to that of the free enzyme.

Keywords: l; -Phenylalanine synthesis; l; -Aspartate aminotransferase; AAT immobilization; Eupergit; ®; C; LentiKats; ®; MANA-agarose; Diffusional limitations


Biochemical properties and thermal behavior of pectate lyase produced by Pectobacterium carotovorum subsp. carotovorum BR1 with industrial potentials by V.B. Maisuria; A.S. Nerurkar (pp. 22-30).
► Kinetics and thermodynamics parameters of the pectate lyase (PL) were determined. ► Thermal inactivation curves of PL fitted three-fraction first-order kinetic model. ► Alkaline pH and Ca2+ ions favor the thermostability of purified PL at 60 and 70°C. ► Thermoactive PL has an alkaline pH optimum, low Ea and broad substrate specificity. ► PL could be utilized efficiently as a novel source for industrial applications.An extracellular pectate lyase (PL, EC 4.2.2.2) produced by Pectobacterium carotovorum subsp. carotovorum BR1 was purified and characterized with respect to its biochemical properties including the thermodynamic parameters of substrates hydrolysis and thermal behavior. The PL showed higher affinity for polygalacturonic acid ( Km, 0.4gl−1) as compared to 70% methylated pectin ( Km, 0.77gl−1). Nonlinear thermal inactivation curves of PL at 50 and 60°C, fitted to a three-fraction first-order kinetic model. Furthermore, the thermodynamic parameters of thermal deactivation of purified PL viz. Δ H*, Δ S*, Ed and Δ G* were determined over pH range 6–10 and in presence of different cations. Alkaline pH and Ca2+ ions individually influenced the thermostability of PL at elevated temperatures 60 and 70°C, based on the thermodynamic parameters. The studies suggested that this alkaline PL can be considered as potential candidate for various applications like pectic waste management, degumming of fibers, food, paper and textile industries.

Keywords: Abbreviations; PL; pectate lyase; PG; polygalacturonase; PNL; pectin lyase; Pcc; Pectobacterium carotovorum; subsp.; carotovorum; Ecc; Erwinia carotovora; subsp.; carotovora; Eca; E. carotovora; subsp.; atroseptica; Ech; E. chrysanthemi; w/v; weight per volume; Δ; H; #; enthalpy of substrate hydrolysis; Δ; S; #; entropy of substrate hydrolysis; Δ; G; #; free energy changes during substrate hydrolysis; Δ; G; E; –; S; #; free energy changes of enzyme–substrate complex; Δ; G; E; –; T; #; free energy changes of transition state formation; E; a; activation energy; Q; 10; temperature quotient; K; d; deactivation rate constant; t; 1/2; half-life time; Δ; H*; enthalpy of thermal inactivation; Δ; S*; entropy of thermal inactivation; Δ; G*; free energy change during thermal inactivation; E; d; thermal inactivation energyPectate lyase; Enzyme biocatalysis; Kinetic parameters; Enzyme deactivation; Thermodynamic parameters; Enzyme technology


An anaerobic reactor packed with a pair of Fe-graphite plate electrodes for bioaugmentation of azo dye wastewater treatment by Jingxin Zhang; Yaobin Zhang; Xie Quan; Yang Li; Shuo Chen; Huimin Zhao; Dong Wang (pp. 31-37).
► Azo dye wastewater treatment was improved in an anaerobic reactor when packed with a pair of Fe-graphite electrodes. ► The removal efficiencies in this electric-anaerobic reactor were increased as dosing NaCl. ► As voltage for the electrodes was cut off, the performance of this hybrid reactor was still higher. ► The reason for the enhanced performances was ascribed to the richer and more diverse microbial communities.An anaerobic reactor packed with a pair of Fe-graphite plate electrodes (supplied with 1.2V) was developed to enhance azo dye wastewater treatment. The results showed that decolorization and COD removal of the azo dye wastewater in this hybrid reactor (R1) reached 83.4% and 84.7% at a dye concentration of 1200mg/L, respectively. These values were significantly higher than the sum of the same values in a single anaerobic reactor (R2) and a single electrode reactor (R3). Salinity enhanced the performance of R1 to a certain extent, but weakened that of R2. After a long period of operation, reactor R1 still performed better than the control, even when the voltage supplied to the electrode was off. Taken together, these results indicate that there was a coupling effect between the electrode reaction and biodegradation. 16S rDNA analysis revealed that anaerobic microorganisms in R1 were richer and more diverse. This increased richness and diversity was partially related to the Fe2+ leaching induced by the electrochemical reaction and increased production of extracellular polymeric substances, which benefited microbial growth and function.

Keywords: Azo dye; Anaerobic sludge; Up-flow anaerobic sludge blanket reactor; Electrode; Decolorization; Microbial community


Effect of (−)-epigallocatechin-3-gallate on human insulin fibrillation/aggregation kinetics by Shi-Hui Wang; Xiao-Yan Dong; Yan Sun (pp. 38-49).
Display Omitted► A natural occurring polyphenol was found to inhibit the fibrillation of insulin. ► EGCG reduces the length and width of insulin fibrils at pH 2.0 and 60°C. ► EGCG redirects insulin into globular aggregates at pH 7.4 and 37°C. ► EGCG blocks the changes of the secondary structures of insulin in the aggregation. ► EGCG suppresses the exposure of hydrophobic groups of insulin in the aggregation.(−)-Epigallocatechin-3-gallate (EGCG), a food additive derived from green tea, has been reported to effectively inhibit the fibrillation of many amyloid proteins, but not insulin. So herein, the influences of EGCG on the fibrillation kinetics of human insulin at two conditions (pH 2.0, 60°C and pH 7.4, 37°C) were extensively studied. It was found that at pH 2.0 and 60°C the inhibitory effect increased with increasing EGCG concentration from 0.35 to 3.5mmol/L but kept almost unchanged from 3.5 to 5mmol/L EGCG. The addition of EGCG reduced the length and width of fibrils and kept part of insulin from fibrillation at this condition. At pH 7.4 and 37°C, however, EGCG altered the fibrillation pathway of insulin and redirected it into globular aggregates, and the inhibitory effect of EGCG on the aggregation reached maximum at about 0.1–0.2mmol/L. In this case, part of insulin molecules were prevented from aggregation and existed as a mixture of monomer, dimer, tetramer, and hexamer in the solution. Circular dichroism spectroscopy indicated that EGCG slowed down the changes of the secondary structures of insulin in the aggregation. Finally, two physical models were proposed to explain the molecular interactions between insulin and EGCG at the two conditions. The research has clarified the kinetic mechanism of the inhibitory effect of EGCG on insulin fibrillation/aggregation.

Keywords: Biophysical chemistry; Protein; Aggregation; Kinetic parameters; (−)-Epigallocatechin-3-gallate; Inhibition


Paclitaxel uptake and transport in Taxus cell suspension cultures by Michael C. Naill; Martin E. Kolewe; Susan C. Roberts (pp. 50-56).
► Paclitaxel transport was studied via a fluorescent analog Flutax-2®. ► Flutax-2® is stable in suspension culture and cell-free media. ► Flutax-2® uptake was inhibited by paclitaxel but not similar taxanes. ► Saturation kinetics of Flutax-2® uptake was demonstrated. ► Methyl jasmonate increases uptake by 60%.The transport of paclitaxel in Taxus suspension cultures was studied with a fluorescence analog of paclitaxel (Flutax-2®) in combination with flow cytometry detection. Experiments were carried out using both isolated protoplasts and aggregated suspension cell cultures. Flutax-2® was shown to be greater than 90% stable in Taxus suspension cultures over the required incubation time (24h). Unlabeled paclitaxel was shown to inhibit the cellular uptake of Flutax-2®, although structurally similar taxanes such as cephalomannine, baccatin III, and 10-deacetylbaccatin III did not inhibit Flutax-2® uptake. Saturation kinetics of Flutax-2® uptake was demonstrated. These results indicate the presence of a specific transport system for paclitaxel. Suspension cells elicited with methyl jasmonate accumulated 60% more Flutax-2® than unelicited cells, possibly due to an increased cellular storage capacity following methyl jasmonate elicitation. The presence of a specific mechanism for paclitaxel transport is an important first result that will provide the basis of more detailed studies as well as the development of targeted strategies for increased paclitaxel secretion to the extracellular medium.

Keywords: Paclitaxel; Plant cell culture; Methyl jasmonate; Metabolite transport; Diffusion; Product inhibition


Mini-scaffoldin enhanced mini-cellulosome hydrolysis performance on low-accessibility cellulose (Avicel) more than on high-accessibility amorphous cellulose by Chun You; Xiao-Zhou Zhang; Y.-H. Percival Zhang (pp. 57-65).
► The synergistic effect of cellulosome was more significant on Avicel than on RAC. ► The synergistic effect of cellulosome increased when enzyme usage decreased. ► Construction of cellulosome would increase cellulose conversion at low enzyme usage.A glycoside hydrolase family 5 Bacillus subtilis endoglucanase, a family 9 Clostridium thermocellum processive endoglucanase, and a family 48 Clostridium phytofermentans ISDg cellobiohydrolase were assembled together by the high-affinity interaction between three cohesins in a mini-scaffoldin (mini-CipA) and dockerins in three cellulases, forming the mini-cellulosome. This mini-cellulosome exhibited enhanced hydrolytic activity on low-accessibility cellulose (microcrystalline cellulose, Avicel) and high accessibility cellulose (regenerated amorphous cellulose, RAC) as compared to the non-complexed cellulase mixture at the same enzyme amount. The stimulation factors (SF, i.e., activity ratios of the mini-cellulosome to the non-complexed cellulase mixture) were larger on Avicel than on RAC regardless of substrate/enzyme ratios. Also, SF increased when substrate/enzyme ratio increased. The different hydrolysis patterns of the mini-cellulosome and cellulase mixture on Avicel and RAC suggested that the construction of synthetic cellulosomes would be an efficient way to significantly enhance cellulose hydrolysis rate and digestibility, especially in the case of low-accessibility recalcitrant cellulose at low enzyme usage.

Keywords: Biofuels; Cellulase engineering; Enzymatic cellulose hydrolysis; Synthetic cellulosome; Synergy


Application of genetic algorithms and response surface analysis for the optimization of batch chromatographic systems by Katrin Treier; Philip Lester; Jürgen Hubbuch (pp. 66-75).
► A genetic algorithm was used to optimize a chromatographic process step. ► Experimental batch mode optimization was successful transferred to packed bed mode. ► Procedure for automated pH adjustment on liquid handling station was developed. ► Applicability of genetic algorithms and design of experiments were investigated. ► Genetic algorithm preferable for systems with several optima.A trend to scientifically sound, robust and especially accelerated downstream process development in the biopharmaceutical industry is encouraged by the FDA . The underlying methodology – high throughput process development – is an interplay of high throughput experimentation, usage of adequate analytics and model based experimentation or process development. In this study, high-throughput batch chromatographic methods were combined with design of experiments, genetic algorithm and response surface analysis to optimize a cation exchange step. The optimization was successful in batch mode and validated in packed bed column mode. Full automation was achieved by establishing a method to automate pH and salt concentration adjustment on liquid handling stations. Several process optima were identified by the genetic algorithm. It was demonstrated that the initial population design influenced the number of optima found during a genetic algorithm optimization procedure. The mere application of response surface analysis on the experimental results showed that for systems with several optima no distinct statements on parameter dependency are achieved. A combination of genetic algorithm, design of experiments and response surface analysis showed to be the most efficient data usage during process optimization if no information on the process landscape investigated is available.

Keywords: Abbreviations; CCI; central composite inscribed design; CV; column volume; DoE; design of experiments; E; ij; elution step; i; fraction; j; GA; genetic algorithm; HTS; high-throughput screening; HTE; high-throughput experiments; L; load step; lhs; liquid handling station; LHS; latin hypercube sample design; OV; objective value; P; purity; R; ij; regeneration step; i; fraction; j; RMSE; root mean square error; RSA; response surface analysis; VR; volume range; W; wash step; Y; yieldHigh throughput screening; Genetic algorithms; Chromatography; Downstream processing; Optimisation; Scale-up


Improved performance of a packed-bed reactor for biodiesel production through whole-cell biocatalysis employing a high-lipase-expression system by Ayumi Yoshida; Shinji Hama; Naoki Tamadani; Hideki Fukuda; Akihiko Kondo (pp. 76-80).
► A packed-bed reactor system was developed using recombinant fungal whole-cells. ► We used immobilized Aspergillus oryzae employing a high-lipase-expression system. ► Optimization enabled the achievement of a methyl ester content above 96%. ► The batch methanolysis could be repeated for 5 cycles.To improve enzymatic biodiesel production, we developed a packed-bed reactor (PBR) system using recombinant cells, into which a strong enolase promoter and 5′ untranslated region were introduced. Aspergillus oryzae expressing Fusarium heterosporum lipase was immobilized within biomass support particles (BSPs) during cultivation and used directly as a whole-cell biocatalyst. BSP-immobilized A. oryzae carrying three copies of the expression cassette showed a higher performance than previously developed cell systems, resulting in 87.5% conversion after 10 passes in PBR. The performance was also affected by operational factors including residence time and methanol feeding. After optimization, the PBR system attained a final methyl ester content of 96.1% with a residence time of 140min per pass and stepwise addition of 4.25molar equivalents of methanol to oil for 6 passes. Moreover, lipase activity was maintained for 5 batch cycles. Therefore, the developed PBR employing a high-lipase-expression system is considered useful for improving enzymatic biodiesel production.

Keywords: Biodiesel fuel; Methanolysis; Filamentous fungi; Immobilized cells; Lipase; Packed-bed reactor


Techno-economic analysis of a membrane-integrated bioreactor system for production of lactic acid from sugarcane juice by Jaya Sikder; Mousumi Roy; Pinaki Dey; Parimal Pal (pp. 81-87).
► Experimental investigation on lactic acid production in membrane-integrated reactor. ► Economic evaluation of lactic acid production in the new system for scale up. ► Only 1% of the fixed capital investment is due to the pumps and membrane. ► 46% of the fixed capital investment is attributed to fermentation unit. ► Raw material and nutrient contribute 96% to the total operating cost. ► Product cost computed to 3.15 US $/kg of 95% (w/w) lactic acid.Economic evaluation of a membrane-integrated bioreactor system for lactic acid production from sugarcane juice was performed. The production process consisted of sterilization, fermentation, microfiltration, nanofiltration and final concentration by vacuum evaporation. Membrane recycle fermentor operating at a cell concentration of 22g/L resulted in a productivity of 53g/Lh with a lactic acid concentration of 106g/L and a yield of 0.96. The membrane units (cross-flow microfiltration and nanofiltration) and pump contribute about 2% to the total fixed capital cost whereas fermentation unit along with holding tank contribute about 36% to the total fixed capital cost. The two largest cost components were raw material and yeast extract costs contributing about 6% and 87% respectively to the total operating cost. Total product cost stood at 3.15 US $/kg of 80% (w/w) concentrated and 95% pure lactic acid. The study reveals that operating cost could be reduced further by using a cheaper nitrogen source like silk worm larvae or yeast autolysate and installing the lactic acid plant in the sugarcane-growing areas or by optimizing the recycle of nanofiltration retentate to the fermentor.

Keywords: Lactic acid; Sugarcane juice; Membrane bioreactor; Downstream processing; Scale-up; Economics


Use of cross-linked tyrosinase aggregates as catalyst for synthesis ofl-DOPA by Da-You Xu; Ju-Yu Chen; Zhen Yang (pp. 88-94).
Display Omitted► Mushroom tyrosinase can be immobilized as cross-linked enzyme aggregates (CLEAs). ► Tyrosinase CLEAs efficiently catalyze the production ofl-DOPA froml-tyrosine. ► High productivity can be obtained in both batch and continuous flow processes. ► Operability of CLEAs is remarkably enhanced by entrapment into Ca alginate gels.Mushroom tyrosinase immobilized as cross-linked enzyme aggregates (CLEAs) was used as the catalyst for production ofl-3,4-dihydroxyphenylalanine (l-DOPA) froml-tyrosine. The synthetic reaction catalyzed by this immobilized enzyme was investigated in different processes. In the batch process, a conversion of 53.0% was obtained during 2h with a productivity of 209.0mgl−1h−1, much superior to other batch processes catalyzed by the same enzyme immobilized with traditional carrier-bound immobilization methods. The effects of pH, temperature, andl-ascorbic acid (as the reducing agent) on thel-DOPA production were examined. Reactions can be tracked by determining thel-DOPA concentration with the spectrophotometric and HPLC methods, both giving consistent results as long as the reducing agent is in sufficient supply. In the continuous synthetic processes carried out in a continuous stirred-tank reactor and a packed bed reactor, a productivity of 103.0 and 48.9mgl−1h−1 was obtained, respectively. The operational stability of the tyrosinase CLEAs can be dramatically improved by entrapment into calcium alginate gels. The CLEA/alginate beads in the continuous stirred-tank reactor achieved a long life time of >104h, producingl-DOPA with a productivity of 57.4mgl−1h−1.

Keywords: l; -DOPA; Cross-linked enzyme aggregates (CLEAs); Enzyme activity; Biocatalysis; Biotranstransformations; Immobilization


Sequential modular simulation of ethanol production in a three-phase fluidized bed bioreactor by Amir Sheikhi; Rahmat Sotudeh-Gharebagh; Ali Eslami; Abolhasan Hashemi Sohi (pp. 95-103).
Display Omitted► Ethanol production by means of biological processes is of the high demand of industries. ► Newly-introduced SMS approach can predict the conversion of non-ideal bioreactors reliably. ► “ ASh” dimensionless number provides the optimum number of required simulation stages. ► SMS coupled with “ ASh” can be embedded in the industrial process simulators for advanced purposes.A state-of-the-art sequential modular approach towards the modeling of a complex three-phase fluidized bed bioreactor has been introduced. The aim was to simulate the fermentation process of glucose for ethanol production using immobilized yeast in a gas–liquid–solid three-phase bioreactor. According to the newly-introduced dimensionless number ( ASh number), a fluidized bed bioreactor was divided into several sections in which the three phases of emulsion, wake, and bubble were modeled parallel to each other. In the proposed model, two sub-models, namely, hydrodynamic and chemical reaction sub-models, were integrated to take the governing physical and chemical phenomena into account. Emulsion, wake, and bubble phases were considered as CSTR (continuous stirred-tank reactor), PFR (plug flow reactor), and bypass flow, respectively. Afterwards, mass transfer was taken into account right at the outlet of each section. The simulation results were compared with the experimental data derived from the literature in a wide range of gas velocity, liquid flow rate, biocatalyst particle size, and the concentration of glucose in the feed stream, which showed a great consistency. The simulation approach proposed in this study proved to be applicable in predicting the behavior of industrial three-phase fluidized bed reactors successfully.

Keywords: Three-phase fluidized bed; Sequential modular simulation; Bioreactors; Ethanol production; Glucose


Evaluating the industrial potential of biodiesel from a microalgae heterotrophic culture: Scale-up and economics by Antonio Tabernero; Eva M. Martín del Valle; Miguel A. Galán (pp. 104-115).
► A scaling-up of a biodiesel plant from microalgae was performed. ► A sensibility study reveals the feasibility of the plant if the residues are sold. ► Two different options were considered for the residuals. ► These results highlight the energetic potential of a plant with these characteristics.An attempt to scale-up a biodiesel production plant from a heterotrophic culture of microalgae, together with an evaluation of feasibility is performed in this article. The plant employs the microalgae Chlorella protothecoides to obtain biomass. The subsequent oil extraction is done with supercritical carbon dioxide. Based on previous studies, it was possible to determine the mass and energy balances and to design the equipment of the main process. A non-conservative study reveals the no feasibility of the production plant unless the residues are sold (two different and real prices were chosen), providing with an investment recovery in both cases. On the other hand, the estimations from a conservative study, showed the non-viability of the process even if the residues are sold. This is mainly due to the big quantity of bioreactors required by the plant and the oil extraction yield. An alternative process with a complete extraction was also applied, which became viable in a conservative study only if the residues are sold at the highest price. All these results highlight the future potential of a plant with these characteristics in the current energetic context.

Keywords: Abbreviations; C; Production costs; C; -; xx; Condenser; C; T; -; xx; Condenser of the distillation tower; CF; Centrifuge; CL; T; -; xx; Boiler of the tower; CSTR; Continous stirred tank reactor; DG; Diglycerides; DR-xx; Dryer; f; Manufaturing cycle; FAME; Fatty acid methyl esters; Gp; Gross profit per year; Gpp; Percentual gross profit per year; HE; -; xx; Heat exchanger; HETP; Height equivalent plate theoretical; i; Interest rate; M; -; xx; Mixing device; MG; Monoglycerides; M; 1; Raw material cost for product unit; M; 2; Manufacturing cost for ton of product; n; Year; NFW; Net future worth; NFWa; Accumulated net future worth; Np; Net profit per year; Npp; Percentual net profit per year; NPW; Net present worth; NPWa; Accumulated net present worth; q; Final biodiesel production; R; -; xx; Reactor; S; Liquid–vapour separator; SCF; Supercritical fluid; SF; Flash liquid–vapour separator; SFE; Supercritical fluid extraction; T; -; xx; Distillation tower; TEC; Total equipment cost; TG; Triglycerides; TI; Total investment; TMAC; Total manufacturing costs; TMGC; Total management costs; U; Society tax; V; Sales income; VAT; Value added taxBioreactors; Transesterification; Microalgae; Large scale cultivation; Biodiesel; Microalgal oil


On the Lambert W function and its utility in biochemical kinetics by Marko Goličnik (pp. 116-123).
► This review describes the Lambert W function, and its use in biochemical kinetics. ► Numerical evaluations of W, together with analytical approximations, are presented. ► Three illustrative problems that are solvable by the use of W are demonstrated. ► The utility of W in various engineering sciences are also cited but not described.This article presents closed-form analytic solutions to three illustrative problems in biochemical kinetics that have usually been considered solvable only by various numerical methods. The problems solved concern two enzyme-catalyzed reaction systems that obey diversely modified Michaelis–Menten rate equations, and biomolecule surface binding that is limited by mass transport. These problems involve the solutions of transcendental equations that include products of variables and their logarithms. Such equations are solvable by the use of the Lambert W( x) function. Thus, these standard kinetics examples are solved in terms of W( x) to show the applicability of this commonly unknown function to the biochemical community. Hence, this review first of all describes the mathematical definition and properties of the W( x) function and its numerical evaluations, together with analytical approximations, and then it describes the use of the W( x) function in biochemical kinetics. Other applications of the function in various engineering sciences are also cited, although not described.

Keywords: Biokinetics; Biosensors; Enzymes; Integrated rate equation; Kinetic parameters; Lambert; W; function


Biodegradation of n-alkanes at high concentration and correlation to the accumulation of H+ ions in Rhodococcus erythropolis NTU-1 by Chih-Wen Liu; Mao-Shih Liang; Yun-Chi Chen; Luis A. Sayavedra-Soto; Hwai-Shen Liu (pp. 124-128).
► We devised a simple method to estimate the n-alkane consumption via pH monitoring. ► The method was validated in a fed-batch bioreactor operation. ► The linear relation between H+ ions accumulated and n-alkane degraded was found. ► Rhodococcus eryrthpolis NTU-1 fast degraded n-hexadecane at high concentration. Rhodococcus erythropolis strain NTU-1 was isolated from oil-contaminated aqueous sludge and can grow at relatively high concentration of n-hexadecane as the only carbon source. The higher concentration of n-hexadecane, the faster degradation rate by NTU-1. Approximately 20,000ppmv (2%) of n-hexadecane were degraded in a treatment with 100,000ppmv (10%) within 4days of incubation. The amount of H+ ions released corresponded well to the carbon-chain length of the n-alkanes (either n-tetradecane, n-hexadecane or n-octadecane). The correspondence was 0.634mmol H+ ions accumulated per mole of n-hexadecane biodegraded. Using this correspondence, n-alkanes consumption can be closely estimated by monitoring pH changes in the medium. This procedure presents an alternative to other complex procedures that use organic solvent extractions and gas chromatography analysis. The procedure following the H+ ions accumulation was validated in a fed-batch bioreactor operation.

Keywords: Batch Processing; Biodegradation; Bioremediation; Bioprocess Monitoring; Rhodococcus erythropolis; strain NTU-1; Hydrogen-ions accumulation


Recovery of indium from aqueous solutions by the Gram-negative bacterium Shewanella algae by Takashi Ogi; Koshiro Tamaoki; Norizoh Saitoh; Arumi Higashi; Yasuhiro Konishi (pp. 129-133).
► The bacterium Shewanella algae was able to absorb indium(III) from aqueous solutions. ► The pH of the solution and the bacterial concentration affected the recovery fraction. ► Indium concentrates were prepared by drying or burning the microbial biomass. ► These methods represent an economical and efficient bioprocess for recovery of indium.This is the first report of an environmentally friendly microbial method to recover soluble indium(III) from aqueous solutions. Microbial uptake of soluble indium(III) was successfully achieved at room temperature over a pH range of 2.4–3.9 using the Gram-negative bacterium Shewanella algae. The microbial uptake of indium by the resting cells of S. algae was very rapid: 0.1mol/m3 (11.4ppm) indium(III) ions were completely collected by bacterial cells within 10min. The pH value and the concentration of bacterial cells in the aqueous indium(III) solutions significantly affected the recovery fraction of soluble indium(III). After drying the indium-adsorbed bacterium at 50°C for 12h, the indium concentration in the dried biomass was approximately 5.4% (w/w), 474-times the concentration of indium(III) in the initial solution (0.94mol/m3). Heating the bacterial cells at approximately 800°C for 2h yielded a solid condensate containing 40% indium (w/w), 4300-times the concentration of indium(III) in the initial solution. These methods represent an efficient and cost-effective method for recovery of indium(III) from wastewaters.

Keywords: Indium; Microbial recovery; Biosorption; Shewanella algae; Adsorption; Bioseparations
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