Production of optically pure L-alanine by immobilized Pseudomonas sp. BA2 cells

The conditions for immobilizing the new L -aminoacylase-producing bacterial strain, Pseudomonas sp. BA2, by entrapment in κ-carrageenan gel, were investigated. The optimal gel concentration and cell load were determined. The addition of CoCl₂ and N-acetyl-L -alanine to the immobilizing matrix enhanced L -aminoacylase activity. The enzymatic properties of immobilized Pseudomonas sp. BA2 were investigated. Enzyme activity in immobilized cells was optimal at a pH of 6·5 using 0·15 mol dm⁻³ Tris–maleate buffer at 45°C. The presence of 0·7 mmol dm⁻³ CoCl₂ in the enzymatic reaction mixture improved L -aminoacylase activity. The immobilized cell preparation was used for the production of L -alanine from N-acetyl-DL -alanine in a batch reactor. Conversions of 100% were obtained using substrate concentrations ranging from 20 to 200 mmol dm⁻³. The reactor production was 0·74 mol h⁻¹ g cell⁻¹ dm⁻³ which is noticeably higher than that previously reported in the literature. © 1998 Society of Chemical Industry     

Anaerobic and aerobic treatment of a simulated textile effluent

A simulated textile effluent (STE) was generated for use in laboratory biotreatment studies; this effluent contained one reactive azo dye, PROCION Red H‐E7B (1.5 g dm⁻³); sizing agent, Tissalys 150 (1.9 g dm⁻³); sodium chloride (1.5 g dm⁻³) and acetic acid (0.53 g dm⁻³) together with nutrients and trace elements, giving a mean COD of 3480 mg dm⁻³. An inclined tubular anaerobic digester (ITD) was operated for 9 months on the STE and a UASB reactor for 3 months. For a 57 day period anaerobic effluent from two reactors, a UASB and an ITD, was mixed and treated in an aerobic stage. In days 77–247 68% of the true colour of PROCION Red H‐E7B was removed by anaerobic treatment with no colour removal aerobically and up to 37% COD was removed anaerobically, with a corresponding BOD removal of 71%. For combined anaerobic and aerobic treatment a mean COD removal of 57% and BOD removal of 86% was achieved. Operation of the ITD at a 2.8 day HRT (volumetric loading rate (B _v) 1.24 g COD dm⁻³day⁻¹) and the UASB at a 2 day HRT (B _v 1.74 g COD dm⁻³day⁻¹) gave comparable COD removals but the UASB gave better true colour removal. Effluent from the combined process operating on this simulated waste still contained an average 1500 mg COD dm⁻³, and further treatment would be required to meet consent standards. © 1999 Society of Chemical Industry     

Batch and Continuous Production of Lactic Acid from Beet Molasses by Lactobacillus delbrueckii IFO 3202

Process variables were optimized for the production of lactic acid from pretreated beet molasses by Lactobacillus delbrueckii IFO 3202 for batch and continuous fermentations. In the batch fermentation, maximum yields (95·4% conversion, 77·1% effective) and maximum lactic acid volumetric productivity (4·83 g dm⁻³ h⁻¹) was achieved at 45°C, pH 6·0, 78·2 g dm⁻³ sugar concentration with 10 g dm⁻³ yeast extract. Various cheaper nitrogen sources were replaced with yeast extract on equal nitrogen bases in batch fermentation. Of all the nitrogen sources tested, yeast extract yielded the highest and malt sprouts yielded the second highest level of lactic acid. In the continuous fermentation, maximum lactic acid (4·15%) was obtained at a dilution rate of 0·1 h⁻¹. Maximum volumetric lactic acid productivity (11·20 g dm⁻³ h⁻¹) occurred at D = 0·5 h⁻¹ dilution rate. © 1997 SCI.     

Liquid Membrane Transport of Hg(II) by an Azocalix[4]arene Derivative

Abstract

A kinetic study of Hg(II) transport from an aqueous donor solution into an aqueous acceptor solution through a liquid membrane containing 25,26,27–tribenzoyloxy‐28‐hydroxy‐5,11,17,23‐tetra‐(4‐n‐butylphenylazo)calix[4]arene 1 as a carrier was studied. The kinetic parameters (k ₁, k ₂, R _m ^max, t _max, J _d ^max, J _a ^max) for the transport were investigated in terms of the effect of temperature, the stirring rate, the carrier concentration, and the type of solvent. The kinetics of transport was analyzed in the formalism of two consecutive irreversible first‐order reactions. The membrane entrance rate, and exit rate constants were increased with increasing of temperature stirring rate, and carrier concentration. The membrane entrance rate and exit rate constants depended on the type of solvent and was found to be in order of CH₂Cl₂> CHCl₃> CCl₄. The activation energy values are calculated as 30.67±2.64 and 57.33±4.90 kj mol^?1 for extraction and reextraction, respectively. The values of calculated activation energy indicate that the process is diffusionally controlled by species.     

Optimization of lactic acid production from whey by L casei NRRL B‐441 immobilized in chitosan stabilized Ca‐alginate beads

The production of lactic acid from whey by Lactobacillus casei NRRL B‐441 immobilized in chitosan‐stabilized Ca‐alginate beads was investigated. Higher lactic acid production and lower cell leakage were observed with alginate–chitosan beads compared with Ca‐alginate beads. The highest lactic acid concentration (131.2 g dm^?3) was obtained with cells entrapped in 1.3–1.7 mm alginate–chitosan beads prepared from 2% (w/v) Na‐alginate. The gel beads produced lactic acid for five consecutive batch fermentations without marked activity loss and deformation. Response surface methodology was used to investigate the effects of three fermentation parameters (initial sugar, yeast extract and calcium carbonate concentrations) on the concentration of lactic acid. Results of the statistical analysis showed that the fit of the model was good in all cases. Initial sugar, yeast extract and calcium carbonate concentrations had a strong linear effect on lactic acid production. The maximum lactic acid concentration of 136.3 g dm^?3 was obtained at the optimum concentrations of process variables (initial sugar 147.35 g dm^?3, yeast extract 28.81 g dm^?3, CaCO₃ 97.55 g dm^?3). These values were obtained by fitting of the experimental data to the model equation. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in lactic acid production using alginate–chitosan‐immobilized cells. Copyright © 2005 Society of Chemical Industry     

Biocatalysis of Chlorophyllase in Ternary Micellar Systems Using Pheophytins as Substrates

The partially purified chlorophyllase, obtained from the alga Phaeodactylum tricornutum, was assayed for its hydrolytic activity towards the pheophytin in ternary micellar systems of hexane/Tris–HCl/surfactant. A wide range of surfactants, sorbitans (Span 20, 40, 60, 80 and 85) and polysorbates (Tween 20, 40, 60, 80 and 85), was used. The use of either 50 μmol dm⁻³ of Span 85 or 1 μmol dm⁻³ of Tween 80 increased the hydrolytic activity of chlorophyllase by 110 and 23%, respectively. The optimum values of pH, enzyme content, incubation time and temperature for the hydrolytic activity of chlorophyllase were determined as 8·25, 8·00 μg protein cm⁻³, 60 min and 27·5°C, respectively. The V_max and K_m values were 6·91 nmole hydrolyzed pheophytin mg⁻¹ protein min⁻¹ and 47·2 nmole pheophytin dm⁻³, respectively, in the Span 85 medium and 10·04 and 121·00, respectively, in the Tween 80 medium. The addition of optimized amounts of individual membrane lipids, L -α-phosphatidylcholine, L -α-phosphatidyl-DL -glycerol and β-carotene increased the hydrolytic activity of chlorophyllase by 50, 36 and 10%, respectively, for Span 85 and 30, 48 and 15%, respectively, for Tween 80. Phytol showed a competitive inhibitory effect on chlorophyllase activity in both Span and Tween systems with a K_i value of 15·5 and 14·3 μmol dm⁻³, respectively. High-performance liquid chromatography and spectrophotometry analyses were used to characterize the end-products of chlorophyllase hydrolytic reaction. © 1997 SCI.     

The influence of ammonium and methods for removal during the anaerobic treatment of poultry manure

The addition of exogenous NH₄Cl to poultry manure and synthetic medium was used to study the effect of ammonia-nitrogen on the activity and composition of a methanogenic consortium. Results indicated that the production of biogas and methane was not affected by the variation in NH₄Cl concentration within the range 2–10 g dm⁻³ (0·5–2·6 g N-NH₄ dm⁻³). At higher values of ammonium (10–30 g dm⁻³ or 2–8 g N-NH₄ dm⁻³) a significant decline in both parameters (by 50–60% for biogas and 80–90% for methane) was observed. A significant decrease in the numbers of bacteria of all physiological groups (especially proteolytic and methanogenic) was observed when more than 30 g NH₄Cl dm⁻³ (7·8 g N-NH₄ dm⁻³) was added to the fermentation medium. The addition of 10% (w/v) of powdered phosphorite ore enhanced the production of biogas and methane at NH₄Cl concentrations up to 30 g dm⁻³, and also changed the composition of the methanogenic consortium. A partial recovery in the numbers of proteolytic and methanogenic bacteria coupled with the decrease in the density of sulphate-reducers was observed. High concentrations (more than 50 g dm⁻³) of NH₄Cl seemed to cause irreversible inhibition of methanogenesis which could not be eliminated by the addition of phosphorites. ©1997 SCI     

Homogeneous liquid–liquid extraction using perfluorooctanesulfonic acid and calcium and its application to the separation and recovery of vitamin B12

A new phase separation phenomenon was observed in which the perfluorooctanesulfonate ion (PFOS⁻) and calcium ion form an ion‐pair associator and the sedimented liquid phase occurs from the homogeneous aqueous solution. This phenomenon was observed in the neutral pH region at room temperature (25 °C). The optimum concentration conditions for the reagents were [PFOS⁻]_T = 7 × 10⁻³ mol dm^‐3 and [Ca²⁺]_T = 1.1 mol dm^‐3. When these findings were applied to the homogeneous liquid–liquid extraction of vitamin B₁₂, the extraction percentage (E) was 83% and the concentration ratio (ie V_a/V_s, where V_a is the volume of the aqueous phase and V_s is the volume of the sedimented liquid phase) was a maximum of 149. The recovery of vitamin B₁₂ was achieved by adding the propanol–acetone (20 : 80 v/v%) mixed solvent to the sedimented liquid phase; the vitamin B₁₂ precipitated and was filtered. Both the PFOS⁻ and Ca²⁺ were removed by dissolution in the mixed solvent. The recovery percentage of vitamin B₁₂ was 78%. © 1999 Society of Chemical Industry     

A trimethylamine–carbon dioxide draw solution for osmotic engines

This study evaluates the pressure retarded osmosis performance of TMA–CO₂ for potential use in osmotic heat engines. Power densities up to 18.6 W m^?2 were achievable at relatively low pressure (10 bar) using 5 M TMA–CO₂ draw solutions. Compared to NaCl control tests, the TMA–CO₂ exhibited 20% lower water flux due in large part to its larger molecular size and associated higher solution viscosity and lower diffusion coefficient. Compared to the ammonia‐carbon dioxide draw solution, water flux was comparable but reverse solute flux of TMA–CO₂ was nearly one order of magnitude lower. Larger solute size was found to create a performance tradeoff as reduced reverse solute flux improved water flux while higher viscosity and lower diffusion coefficient worsened water flux. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3369–3375, 2018     

Production of lactic acid from beet molasses by calcium alginate immobilized Lactobacillus delbrueckii IFO 3202

Lactic acid was produced from pretreated beet molasses by the homofermentative organism Lactobacillus delbrueckii subsp delbrueckii IFO 3202 entrapped in calcium alginate gel using batch, repeated batch and continuous fermentation systems. In batch fermentation studies successful results were obtained with 2.0–2.4 mm diameter beads prepared from 2% sodium alginate solution. The highest effective yield (82.0%) and conversion yield (90.0%) were obtained from substrate concentrations of 52.1 and 78.2 g dm⁻³ respectively. The gel beads produced lactic acid for 14 consecutive batch fermentations without marked activity loss and deformation. In the continuous fermentation, the highest lactic acid (4.22%) was obtained at a dilution rate of 0.1 h⁻¹ while the highest productivity (13.92 g dm⁻³ h⁻¹) was obtained at a dilution rate of 0.4 h⁻¹. © 1999 Society of Chemical Industry     

Removal of linuron from water by natural and activated bentonite

The sorption of linuron on bentonite desiccated at 110°C untreated, and acid‐treated with H₂SO₄ solutions over a concentration range between 0.25 M and 1.00 M from aqueous solution at 25°C has been studied by using batch experiments. In addition, column experiments were carried out with the bentonite sample treated with the 1.00 M H ₂SO₄ solution [B‐A(1.00)] by using two aqueous solutions of linuron of different concentrations (C=4.97 mg dm⁻³ and C=7.63 mg dm⁻³ ). The experimental data points have been fitted to the Langmuir equation in order to calculate the sorption capacities (X_m) of the samples; X_m values range from 0.02 g kg⁻¹ for the untreated bentonite [B‐N] up to 0.20 g kg⁻¹ for the sample acid‐treated with the 1.00 M H₂ SO₄ solution. The removal efficiency (R ) has also been calculated; R values ranging from 15.86% for the [B‐N] sample up to 41.54% for [B‐A(1.00)]. The batch experiments show that the acid‐treated bentonite is more effective than the natural bentonite in relation to sorption of linuron. The column experiments show that the B‐A(1.00) sample might be reasonably used in removing linuron, the column efficiency increasing from 61.8% for the C=7.63 mg dm⁻³ aqueous solution of linuron up to 77.6% for the C=4.97 mg dm⁻³ one. © 1999 Society of Chemical Industry     

Production of GST–SOD fusion protein by recombinant E coli XL1 Blue

A recombinant plasmid was constructed by inserting a DNA fragment with the coding region of Cu/Zn–superoxide dismutase (Cu/Zn–SOD) cDNA from sweet potato, Ipomoea batatas (l) Lam cv Tainong 57, into the 3′ end of the open reading frame of the glutathione S‐transferase (GST) gene in an expression vector, pGEX‐2T. The constructed plasmid was transformed into E coli XL1 Blue. Fusion proteins of Cu/Zn–SOD and GST (GST–SOD) were produced from the recombinant E coli. About 6 mg of GST–SOD fusion proteins could be obtained from 1 dm³ of cultural broth after induction with 0.075 mmol dm⁻³ Isopropyl‐β‐D ‐thiogalactoside (IPTG). Lactose was not an efficient inducer. High cell density culture was performed by fed‐batch fermentation using a glucose analyzer to control glucose concentration at 1 g dm⁻³. The cell density of the fed‐batch culture reached an OD₆₀₀ of 30, the total amount of GST–SOD fusion protein was 100 mg dm⁻³ which is about 14 times more than that of the batch culture. Most of the fusion proteins were shown to be in an active monomeric form, and the molecular weight was estimated to be 45 kDa by SDS–PAGE and 47 kDa by gel filtration. The specific activity of the purified fusion proteins was about 1200 mg⁻¹ and equal to 3200 unit per mg of SOD domain only. © 2000 Society of Chemical Industry     

Solvent extraction of silver(I) from nitrate media using thiourea derivatives

Liquid–liquid extraction of Ag(I) from nitrate solutions using N‐(N′,N′‐diethyl thiocarbamoyl)‐N″‐phenylbenzamidine (TCBA) and 1‐6,‐diethylcarbamoyl imino‐1,6‐diphenyl‐2,5 dithiahexane (TCTH) dissolved in cumene has been studied. The extraction of Ag(I) from 1 mol dm⁻³ NO₃⁻ solutions by TCTH and TCBA was investigated as a function of several variables: equilibration time, organic phase diluent, pH of aqueous phase, Ag(I) and NO₃⁻ concentration in aqueous phase as well as TCBA and TCTH concentrations. Experimental equilibrium data were analysed numerically using the programs LETAGROP‐DISTR and LETAPL and the results showed that Ag(I) extraction could be explained assuming the formation of AgL and AgNO₃HL with TCBA (HL) and AgNO₃S with TCTH (S). The metal extraction was not influenced significantly by the structures of the thiourea derivatives used as extractants. The back extraction of Ag(I) from loaded organic phase was performed using different strippants and 0.5 mol dm⁻³ NaSCN was found to be efficient for this purpose. © 2000 Society of Chemical Industry     

Organosolv delignification of white‐ and brown‐rotted Eucalyptus grandis hardwood

Sound (undecayed control) and fungally‐pretreated wood samples were submitted to organosolv delignification. The cooking liquor used was methanol/water (78:22 v/v) containing CaCl₂ and MgSO₄ each at a concentration of 25 mmol dm⁻³. The cooking process was performed at 180 °C for reaction times varying from 5 to 100 min. Despite some differences in the lignin removal pattern, pseudo‐first order kinetic models permitted a prediction of delignification rate constants for all experiments. All biodegraded samples provided higher delignification rate constants than the undecayed control (2.0 × 10⁻²min⁻¹ for the undecayed control and, for example, 14.2 × 10⁻²min⁻¹ for the sample decayed by Trametes versicolor for 2.5 months). Biodegraded samples also presented significantly increased xylan removal rates. The type of biodegradation affected the behavior of wood samples under organosolv pulping. The highest delignification and xylan removal rate constants were observed in the sample decayed by T versicolor for 2.5 months (17% weight loss). However, high delignification and xylan removal rate constants were also observed in the sample decayed by Punctularia artropurpurascens for only 0.5 months (1.2% weight loss). Data obtained from a single fungal species pretreatment or data from all fungal pretreatments indicated that there is no clear correlation between the delignification constants and the wood weight or component losses. This lack of correlation suggested that the structure of residual polymers in decayed wood affects the delignification process in the organosolv pulping more than the removal extent of each individual component. © 2000 Society of Chemical Industry     

Effect of zeolite addition on ethanol production from glucose by Saccharomyces bayanus

Zeolite NaY at 5 g dm⁻³ concentration, was selected to improve the production of ethanol fermentation by Saccharomyces bayanus from high glucose concentration media. The highest ethanol productivity (3·07 g dm⁻³ h⁻¹) was obtained from a 220 g dm⁻³ initial glucose concentration, while the highest ethanol concentration (130 g dm⁻³) was obtained from a 350 g dm⁻³ glucose medium. The zeolite is believed to have acted as a pH regulator, maintaining the pH value around 3·7–3·8. Under these conditions cellular viability was preserved and metabolic activity was maintained. Thus all the glucose was consumed, and high ethanol productivity and concentration were obtained. Therefore, the addition of zeolite improved ethanol production from high concentrations of glucose by Saccharomyces bayanus. © 1998 Society of Chemical Industry     

Cell recycle and broth reuse fermentation with cross-flow filtration and ion-exchange resin

A novel integrated fermentation system in which cross-flow filtration was coupled to an anion-exchange resin column was developed to achieve biomass recycle and broth reuse for lactic acid fermentation. An anion-exchange resin column was employed to recover lactic acid from the spent broth. The effluent was diluted with fresh medium, supplemented with glucose and nutrients. Spent broth was reused for three consecutive biomass recycle fermentations with no significant decrease in fermentation performance. The fermentation system enabled simultaneously high productivity of lactic acid (average value 7·75 g dm⁻³ h⁻¹ and total amount of lactic acid produced 85·21 g dm⁻³ after 11 h fermentation), high productivity of cells (average value 2·00 g dm⁻³ h⁻¹) and efficient utilization of medium (about 75% of the spent broth was reutilized). The system described may be applied to other organic fermentations subject to end-product inhibition.     

Biotechnological production of lactic acid integrated with potato wastewater treatment by Rhizopus arrhizus

This paper describes a feasibility study of a for lactic acid production integrated with are treatment of wastewater from an industrial starch plant. Rhizopus oryzae two strains, Rhizopus arrhizus and Rhizopus oligosporus were tested with respect to their capability to carry out simultaneous saccharification and fermentation to lactic acid using potato wastewater. Rhizopus arrhizus DAR 36017 was identified as a suitable strain that demonstrated a high capacity for starch saccharification and lactic acid synthesis. The optimal conditions, in terms of pH, temperature and starch concentration, for lactic acid production were determined. The selected fungal strain grew well in a pH range from 3.0 to 7.0. The addition of CaCO₃10 g dm^?3 maintained the pH at 5.0–6.0 and significantly enhanced lactic acid production. Kinetic study revealed that almost complete starch saccharification and a lactic acid yield of 450g kg^?1 could be achieved in 20 h and 28 h cultivation, respectively. The maximum lactic acid production 21 g dm^?3 and mycelial biomass (1.7 g dm^?3) were obtained at 30 °C. Besides the multiple bioproducts, total removal of suspended solids and 90% reduction of COD were achieved in a single no‐aseptic operation. Copyright © 2003 Society of Chemical Industry     

Poly(L‐lactide): v. effects of storage in swelling solvents on physical properties and structure of poly(L‐lactide)

The effects of storage at 25°C in swelling solvents having different solubility parameter (δ_s) values of 16.8–26.0 J^0.5 cm^−1.5 on the physical properties and structure of as‐cast poly(L ‐lactide) (PLLA) films was investigated by the degree of swelling (DS), differential scanning calorimetry (DSC), and tensile tests. It was found that PLLA film shows durabity to swelling solvents having δ_s values much lower or higher than the value range of 19–20.5 J^0.5 cm^−1.5 and that the polymer solubility parameter (δ_p) for PLLA is in the value range of 19–20.5 J^0.5 cm^−1.5. The decrease in the glass transition temperature (T_g) and tensile properties and the increase in melting temperature (T_m) and crystallinity (x_c) were larger for PLLA films swollen in solvents having a high DS at 7 days (DS_7days). The slight increase in T_m and x_c for PLLA films after swelling in solvents with high DS_7days values was due to the crystallization of PLLA that occurred during swelling, while the small increase in T_g and elongation at break (ε_B) for PLLA films after immersion in the solvents having low DS_7days values was ascribed to stabilized chain packing in the amorphous region. The T_g, ε_B, and Young's modulus of the PLLA films after swelling in the solvents varied in the ranges of 47–57°C, 4–8%, and 55–77 kg/mm², depending on their DS_7days or δ_s values. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1582–1589, 2001     

Immobilization of invertase onto dimer acid‐co‐alkyl polyamine

Invertase was immobilized onto the dimer acid‐co‐alkyl polyamine after activation with 1,2‐diamine ethane and 1,3‐diamine propane. The effects of pH, temperature, substrate concentration, and storage stability on free and immobilized invertase were investigated. Kinetic parameters were calculated as 18.2 mM for K_m and 6.43 × 10^?5 mol dm^?3 min^?1 for V_max of free enzyme and in the range of 23.8–35.3 mM for K_m and 7.97–11.71 × 10^?5 mol dm^?3 min^?1 for V_max of immobilized enzyme. After storage at 4°C for 1 month, the enzyme activities were 21.0 and 60.0–70.0% of the initial activity for free and immobilized enzyme, respectively. The optimum pH values for free and immobilized enzymes were determined as 4.5. The optimum temperatures for free and immobilized enzymes were 45 and 50°C, respectively. After using immobilized enzyme in 3 days for 43 times, it showed 76–80% of its original activity. As a result of immobilization, thermal and storage stabilities were increased. The aim of this study was to increase the storage stability and reuse number of the immobilized enzyme and also to compare this immobilization method with others with respect to storage stability and reuse number. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1526–1530, 2004     

Kinetics of syntrophic acetogenesis in a saline medium

BACKGROUND: The anaerobic degradation kinetics of volatile fatty acids (VFA) in a saline (24 g NaCl dm^?3) and mesophilic (37 °C) medium was studied under batch test conditions. The acetate production kinetics without inhibition by propionic, butyric and valeric acids was determined. The inhibition of acetate production during syntrophic acetogenesis by VFA and pH was studied. The acetogenesis without inhibition was modelled using a Monod equation. The pH inhibition was represented by a Michaelis pH function, while the inhibition by acetic acid (HAc) was represented by a non‐competitive model. RESULTS: The specific maximum degradation rate and saturation constant (k_{max, VFA}, K_{S, max}) values were (5.89, 15.95), (7.97, 25.99) and (7.75 g VFA g^?1 volatile suspended solids day^?1, 11.52 mg VFA dm^?3) for propionic, butyric and valeric acids respectively, with maximum velocity at pH 7. The inhibition constants (K_{I, HAc}) were 1295, 671 and 572 mg HAc dm^?3 for propionic, butyric and valeric acids respectively. CONCLUSION: VFA and pH can be inhibitory for acetogenesis under these conditions. Copyright © 2008 Society of Chemical Industry