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Development of a continuous l-lysine bioconversion system for cadaverine production
Kim, J.H.,Seo, H.M.,Sathiyanarayanan, G.,Bhatia, S.K.,Song, H.S.,Kim, J.,Jeon, J.M.,Yoon, J.J.,Kim, Y.G.,Park, K.,Yang, Y.H. Korean Society of Industrial and Engineering Chemi 2017 Journal of industrial and engineering chemistry Vol.46 No.-
<P>Cadaverine, a five carbon diamine (1,5-diaminopentane), plays a role as a building block of polyamides and it can be made by fermentation or direct bioconversion. To improve its production by increasing reusability of immobilized enzyme and avoid separation of enzyme in bioconversion, a continuous l-lysine bioconversion process for cadaverine production has been developed. Various divalent cations, alginate concentrations, cell density with alginate and flow rate of feed were examined to maximize the lysine decarboxylase activity of the whole-cell immobilized beads. Under the selected conditions, 123 h of continuous cadaverine production has been performed and 5.5 L of 819 mM cadaverine were produced with 14 mL reactor resulting in 466.5 g of cadaverine. Cadaverine production was possible with small volume reactor maintaining relatively high concentration of substrate. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.</P>
Studies on corrosion protection of Al2024 T6 alloy by electropolymerized polyaniline coating
V. Karpagam,S. Sathiyanarayanan,G. Venkatachari 한국물리학회 2008 Current Applied Physics Vol.8 No.1
Aqueous electropolymerized polymer coatings on aluminum alloys can replace the carcinogenic chromate coating. In this work, theon aluminum were formed by galvanostatic and potentiostatic methods from a bath of 0.5 M oxalic acid containing 0.1 M aniline. Thecorrosion protection ability of the coating was found out by Tafel polarization and EIS in 1% NaCl solution. It has been found thatpolyaniline coated aluminum alloy has exhibited higher corrosion activity due to the presence of pores in the coating. However, the cor-rosion resistant property of polyaniline coated aluminum has been found to be improved to 90% by post-treatment in cerium containingsolution at 60℃
Linear correlation of aliphatic diamines to response factors by number of carbons in GC-MS
Yi, D.H.,Sathiyanarayanan, G.,Seo, H.M.,Lee, J.H.,Kim, H.J.,Kim, Y.G.,Jang, K.S.,Lee, Y.K.,Park, K.,Yang, Y.H. Korean Society of Industrial and Engineering Chemi 2015 Journal of industrial and engineering chemistry Vol.30 No.-
Diamines are widely used as building blocks for the chemical synthesis of bio-based polymers such as polyamides, polyimides, and polyurea. However, the detection and quantification of diamines are still being as difficult tasks due to their high toxicity and polarity and other hazardous standards are needed to obtain the calibration curve for the diamine quantification. Hence, we have established a simple method for the analysis of aliphatic diamines using GC-MS based on the linear correlations between carbon number, retention time and response factors of diamines. The aliphatic diamines were derivatized with ethylchloroformate (ECF) by applying total ion current (TIC) and single ion monitoring (SIM) at the m/z of 102. The linear correlation of the aliphatic diamines to the retention time (RT) (R<SUP>2</SUP>=0.9949) and response factor (RF) (R<SUP>2</SUP>=0.9538) was determined by using carbon numbers from C3 to C12, via experimentation. The finding of linear correlations between aliphatic diamines are more advantageous and requires less authentic samples of using or calibrating of each diamine sample of the quantification and identification. The established method was successfully employed on a bacterium Shewanella oneidensis which is known to produce potential precursors of the biopolymer synthesis and assessed by, based on the predicted retention time and response factor of 1,4-diaminobutane for the quantification of secreted putrescine and cadaverine. By applying one or two diamines, the retention time, peak area and response factors can easily be expected depending on the concentration and this approach could be applied for the quantification of aliphatic diamines in various industrial sectors.
Kim, J.H.,Kim, J.,Kim, H.J.,Sathiyanarayanan, G.,Bhatia, S.K.,Song, H.S.,Choi, Y.K.,Kim, Y.G.,Park, K.,Yang, Y.H. IPC Science and Technology Press ; Elsevier Scienc 2017 Enzyme and microbial technology Vol.104 No.-
<P>Cadaverine, a five-carbon diamine (1,5-diaminopentane), can be made by fermentation or direct bioconversion and plays an important role as a building block of polyamides. Lysine decarboxylase (CadA) transforms L-lysine to cadaverine and pyridoxal 5'-phosphate (PLP) can increases conversion rate and yield as a cofactor. Biotransformation of cadaverine using whole Escherichia coli cells that overexpress the lysine decarboxylase has many merits, such as the rapid conversion of L-lysine to cadaverine, possible application of high concentration reactions up to the molar level, production of less byproduct and potential reuse of the enzyme by immobilization. However, the supply of PLP, which is a cofactor of lysine decarboxylase, is the major bottleneck in this system. Therefore, we initiated our study on PLP precursors and PLP-related enzymes and discovered that pyridoxal (PL) can be a viable alternative to supply PLP. Among various PLP systems examined, pyridoxal kinase (PdxY) showed the highest conversion of PL to PLP, resulting in more than 60% conversion of L-lysine to cadaverine with lysine decarboxylase. When the reaction with 0.4 M L-lysine, 0.2 mM PL and more whole cells was performed, it resulted in an 80% conversion yield. Furthermore, when barium-alginate immobilization was applied, it showed a 90% conversion yield in 1 h with PL, suggesting that it is compatible with developed whole-cell systems without a direct supply of exogenous PLP.</P>