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Biochemical Engineering Journal (v.36, #1)
Mechanistic understanding and performance enhancement of biosorption of reactive dyestuffs by the waste biomass generated from amino acid fermentation process by Min Hee Han; Yeoung-Sang Yun (pp. 2-7).
Biosorption has been demonstrated as a useful alternative to conventional treatment systems for the removal of dyes from dilute aqueous solution. This study dealt with a renewable, low cost biosorbent derived from the waste biomass of Corynebacterium glutamicum which are generated from full-scale amino acid fermentation industry. The biosorbent has been proved to have a higher (or comparable) dye uptake capacity than conventional sorbents, such as activated carbons and ion-exchange resins. This study focused on the underlying mechanisms of dye binding to the biosorbent. The binding sites were identified to be primary amine groups present in the biomass. Chemical modification of the biomass, FT-IR and potentiometric titration studies revealed that carboxyl and phosphate groups played a role in repulsion of dye molecules, inhibiting the dye binding to the biosorbent. With the help of elucidated biosorption mechanisms, the performance of biosorbent for practical application could be enhanced by removal of the inhibitory carboxyl groups.
Keywords: Biosorption; Corynebacterium glutamicum; Chemical modification; Biosorbent; Binding sites; Binding mechanisms
Kinetic study for the extraction of succinic acid with TOA in fermentation broth; effects of pH, salt and contaminated acid by Young-Si Jun; Eun Zoo Lee; Yun Suk Huh; Yeon Ki Hong; Won Hi Hong; Sang Yup Lee (pp. 8-13).
Reactive extraction can be used for the recovery of carboxylic acids from fermentation broth. Through the formation of complex with extractants at the two-phase interface, the carboxylic acids are partitioned into organic solvents. However, the recovery of carboxylic acids is interrupted by the conditions of fermentation broth. In this study, the effects of conditions of fermentation broth on the extraction kinetics were investigated using a microporous membrane-based stirred cell for the extraction of succinic acid with tri- n-octylamine. The interfacial concentrations of species in various systems were correlated and thus the effects of pH, salts and contaminated acid on the intrinsic reaction kinetics were discovered. The reaction rate constants were determined from the forward reaction rate equation reported in our previous work. It was found that the extraction rates were steeply decreased at pH values larger than 3 due to the dissociation of carboxylic group. Competitive extraction of salts, which were HPO42− (or PO43−), CO32− and SO42−, and contaminated acid, which was pyruvic acid, had negative influence on the extraction process of succinic acid and thus the extraction rates were decreased. The interfacial concentrations of succinic acid and TOA in fermentation broth had no difference with those in artificial single acid systems. Therefore, the decrease of extraction rates can be explained by the change of ionic strength in fermentation broth.
Keywords: Liquid–liquid extraction; Extraction kinetics; Succinic acid; Tri-; n; -octylamine; Fermentation; Stirred cell; Microporous membrane; Diffusion-reaction; Salts
Batch kinetics and modelling of Pleuromutilin production by Pleurotus mutilis by Othmane Benkortbi; Salah Hanini; Fatiha Bentahar (pp. 14-18).
The kinetics of Pleuromutilin production was studied in batch cultivation process at pH 7.5 and temperature 27°C. An unstructured mathematical model was proposed to describe the batch culture kinetics. The Luedeking–Piret equation was proposed for Pleuromutilin production. The model parameters were evaluated by means of batch cultivation data. The proposed model describe well the observed experimental kinetics with respect to substrate, biomass and product formation. The model may be useful for optimization of Pleuromutilin production.
Keywords: Pleurotus mutilis; Pleuromutilin; Fermentation; Kinetic; Modelling
A discrete multi states model for the biological production of hydrogen by phototrophic microalga by Wonjun Park; Il Moon (pp. 19-27).
This paper focuses on the development of discrete based multi states model of producing molecular hydrogen by microalga. Even though the biological process in nature has discrete behaviors, considering discrete variable has difficulties in model construction and solutions as well. We developed discrete multi states model to describe the discrete event of sulfur deprivation using kinetic dynamic modeling of the photosynthetic process for the biological production of hydrogen. Suggested model includes not only continuous variables describing the concentration of metabolites and the intensity of light, but also discrete variables describing the behavior of the manual operation such as removing specific nutrient. Modeling provided the methods to show discrete event and biological discrete process as well. The parameters for the dynamic simulation were estimated using the function implemented neural network. The optimal light intensity was identified at 238μEm−2s−1 for the maximum production of hydrogen under the given experimental condition. The result of dynamic simulation showed the rapid decrease of algae growth rate due to the production of hydrogen. The dynamic growth patterns to condition of light intensity were investigated. The discrete based multi states model suggests a practical approach to understand the photosynthetic process of the hydrogen production in microalga. This model can be used for the design and operation of photobioreactor to product hydrogen by microalga.
Keywords: Discrete multi states; Hydrogen production; Dynamic modeling; Dynamic simulation; Optimization; Algae
Metabolic pathway recruiting through genomic data analysis for industrial application of Saccharomyces cerevisiae by Suteaki Shioya; Hiroshi Shimizu; Takashi Hirasawa; Keisuke Nagahisa; Chikara Furusawa; Gaurav Pandey; Yoshio Katakura (pp. 28-37).
This paper aims to establish the methodology for building object-oriented metabolic pathway models which describe metabolic flux change due to the cultivation conditions change such as from normal one to high osmotic pressure (sugar concentration) based on the genomic data analysis, and also to apply the method for metabolic pathway recruiting in an improved strain producing useful compounds which can play important roles for green chemistry. The model will be developed using the data of transcriptome, proteome and metabolites, including metabolic flux analysis. Practically, profiling data of transcriptome and proteome have been taken at high osmolarity condition. And a better-improved strain based on the analysis was obtained.
Keywords: DNA; Modelling; Osmotic stress; Protein; Yeast; Transcriptome
Enrichment of triglyceride docosahexanoic acid by lipase used as a hydrolysis medium in lecithin-based nano-scale molecular assemblage by Hideaki Koike; Masanao Imai; Isao Suzuki (pp. 38-42).
Docosahexanoic acid (DHA) in triglyceride from marine bioresources was successfully enriched with the aid of lipase used for hydrolysis reaction in a water in oil (W/O) microemulsion formed by soybean lecithin. Ester-bonded DHA was hardly hydrolyzed by Candida rugosa lipase, due to their steric hindrance. In contrast, mono-unsaturated fatty acid in triglyceride was easily hydrolyzed by lipase specificity, and then it was removed. W/O microemulsion formed by soybean lecithin was used as an appropriate reaction medium for hydrophobic enzyme reaction. Soybean lecithin, well-known as a biocompatible amphiphile, was employed to prepare the W/O microemulsion. Phosphate buffer (6.0≦pH≦7.5) was used as an aqueous phase, and 2,2,4-trimethylpentane was employed as an organic solvent. The initial reaction rate obviously depended on the water–lecithin molar ratio, which was maximum at 10. The optimal lecithin concentration was 12mM, which was almost the same level as the critical micelle concentration in the organic solvent. Soybean lecithin was superior to AOT in obtaining a higher initial reaction rate, due to moderate electrostatic interaction. The molar fraction of DHA in triglyceride was enriched up to 97%.
Keywords: Lecithin; Candida rugosa; lipase; DHA; Water in oil microemulsion; Nano-scale molecular assemblage
Water permeability of chitosan membrane involved in deacetylation degree control by Tomoki Takahashi; Masanao Imai; Isao Suzuki (pp. 43-48).
Chitosan membrane was prepared by the casting method in combination with N-acetylation reaction. Deacetylation degree decreased linearly with increasing added amounts of acetic anhydride. The stoichiometric control of the deacetylation degree to the desired level was successfully performed. The maximum stress and strain were measured and were linearly depended on the deacetylation degree. The chitosan membrane produced by the casting method had an asymmetric cross-section in the thickness direction based on scanning electron microscope. The solubility of the chitosan membrane changed with pH. Ranging over pH 6.6, the chitosan membrane was still stable and had elasticity. The volumetric permeated water flux through the chitosan membrane increased linearly with operational pressure. It was exponentially dependent on the deacetylation degree and was satisfactory at a constant level after repeated use. The deacetylation degree was anticipated as a parameter for production of chitosan membrane for practical applications.
Keywords: Abbreviations; DD; deacetylation degree; M; w; molecular weight; M-x; the membrane code in this paper as “M-x” refers to the solution prepared by adding acetic anhydride; x; μl into the chitosan solution; PVS-K; potassium polyvinyl sulfate; PEG; polyethylene glycol; SEM; scanning electron microscopeChitosan; Membrane; Deacetylation degree; Water permeability
Comparisons of isoflavones from Korean and Chinese soybean and processed products by Youn-Woo Lee; Jae-Duck Kim; Jinzhu Zheng; Kyung Ho Row (pp. 49-53).
Soybeans and soy products are the main source of isoflavones. Several methods and different kinds of soybeans have been published to quantify soy isoflavones, but the amount of isoflavones was variable each other. In order to investigate the contents of isoflavone with pure and processed soybean (the name of soybean is Dae du soybean) from different area (Korea and China), some isoflavones (7- o-glucosides, acetyl daidzin, malonyl genistin and aglycones) from Korean soybean, Chinese soybean and their processed products of soybeans were extracted by 60% EtOH, and analyzed using reversed-phase high performance liquid chromatography (RP-HPLC). The malonyl genistin was found the most content in soybean, but it was very small in chungkukjang. For the aglycones, glycitein was extracted more than daidzein from chungkukjang, contrary to the trend in pure soybean. The small amounts of isoflavones were extracted from doenjang, and the main isoflavone was daidzein.
Keywords: Isoflavone; Soybean; Processed product; HPLC
Biosorption of Cr(III) and Cr(VI) onto the cell surface of Pseudomonas aeruginosa by So-Young Kang; Jong-Un Lee; Kyoung-Woong Kim (pp. 54-58).
Biosorption of the chromium ions Cr(III) and Cr(VI) onto the cell surface of Pseudomonas aeruginosa was investigated. Batch experiments were conducted with various initial concentrations of chromium ions to obtain the sorption capacity and isotherms. It was found that the sorption isotherms of P. aeruginosa for Cr(III) were described well by Langmuir isotherm models, while Cr(VI) appeared to fit Freundlich models. The results of FT-IR analysis suggested that the chromium binding sites on the bacterial cell surface were most likely carboxyl and amine groups. The bacterial surface of P. aeruginosa seemed to engage in reductive and adsorptive reactions with respect to Cr(VI) biosorption.
Keywords: Biosorption; Pseudomonas aeruginosa; Chromium; FT-IR spectroscopy; Bioremediation; Wastewater treatment
Biodegradation and biosorption for decolorization of synthetic dyes by Funalia trogii by Chulhwan Park; Myunggu Lee; Byunghwan Lee; Seung-Wook Kim; Howard A. Chase; Jinwon Lee; Sangyong Kim (pp. 59-65).
The objective of this study was to investigate two major mechanisms for decolorization of dyes by cultivation of fungi on either a solid or in a liquid phase and to confirm the possibility of practical application via repeated-batch cultivation. The decolorization of six commercial dyes with 10 fungal strains was studied. Enzyme activity, decolorization trends and decolorization mechanisms were monitored. Under the experimental conditions, extracellular laccase and manganese peroxidase (MnP), but not lignin peroxidase (LiP), were detected. The decolorization mechanisms by F. trogii ATCC 200800 involved a complex interaction of enzyme activity and biosorption. This study suggests that it is possible to decolorize a high concentration of commercial dyes, which would be a great advance in the treatment of dye containing wastewater. These methods may have a potential application for dye decolorization and for textile effluent treatment.
Keywords: Dye; Decolorization; Enzyme; Laccase; Manganese peroxidase; Funalia trogii
Effects of EDTA and Tween60 on biodegradation of n-hexadecane with two strains of Pseudomonas aeruginosa by Zhaozhe Hua; Ruohai Song; Guocheng Du; Huazhong Li; Jian Chen (pp. 66-71).
Two Pseudomonas aeruginosa strains with different hydrocarbon uptake modes were observed in the previous research. One strain produces biosurfactant during the process of hydrocarbon uptake, and was named as P. aeruginosa S. The other one utilizes hydrocarbon directly and was named as P. aeruginosa Y. For comparison of the characteristics of the two strains, the effects of EDTA and Tween60 on alkane biodegradation and cell surface characteristics were investigated in this paper. The results showed that the bacteria with different hydrocarbon uptake mode also have different response to the addition of EDTA and Tween60. As a result, in the case of P. aeruginosa S, the addition of EDTA inhibited the cell growth and hexadecane biodegradation, but enhanced the lipopolysaccharide (LPS) release and increased the cell surface potential, while the influence of the addition of Tween60 was smaller than that of EDTA. On the other hand, in the case of P. aeruginosa Y, the addition of EDTA or Tween60 not only inhibited the cell growth and hexadecane biodegradation, but also decreased the cell surface hydrophobicity (CSH) dramatically.
Keywords: Biodegradation; Fermentation; Waste treatment; Bioremediation; Biosurfactant; Pseudomonas aeruginosa