المؤلفون: Kumar, Vinod, Sankaranarayanan, Mugesh, Durgapal, Meetu, Zhou, Shengfang, Ko, Yeounjoo, Ashok, Somasundar, Sarkar, Ritam, Park, Sunghoon

مصطلحات موضوعية: K. pneumoniae J2B KGSADH, K. pneumoniae J2B ??ldhA KGSADH, 3-Hydroxypropionic acid, 1,3-Propanediol, Lactate dehydrogenase

الوصف: In the present study, the lactate dehydrogenase-deficient (ldhA(-)) recombinant Klebsiella pneumoniae overexpressing an ALDH (KGSADH) was developed and the co-production of 3-HP and PDO from glycerol by this recombinant under resting cell conditions was examined. The new recombinant did not produce any appreciable lactate, which seriously inhibits the production of 3-HP and PDO. The final titers of 3-HP and PDO by the ldhA(-) recombinant strain at 60 h were 252.2 mM and 308.7 mM, respectively, which were improved by approximately 30% and 50%, respectively, compared to those by the counterpart recombinant strain, which was the wild type for ldhA. In addition, after deleting ldhA, the cumulative yield on glycerol and specific production rate of these two metabolites (3-HP and PDO) were enhanced by 41.4% and 52%, respectively.

العلاقة: BIORESOURCE TECHNOLOGY, v.135, no., pp.555 - 563; http://www.sciencedirect.com/science/article/pii/S0960852412016914Test; https://scholarworks.unist.ac.kr/handle/201301/25328Test; 3392; 27927; 2-s2.0-84876490011; 000319181000076

الإتاحة: https://doi.org/10.1016/j.biortech.2012.11.018Test
https://scholarworks.unist.ac.kr/handle/201301/25328Test
http://www.sciencedirect.com/science/article/pii/S0960852412016914Test

المؤلفون: Zhang, Yan, Ashok, Somasundar, Seol, Eunhee, Ainala, Satish Kumar, Lee, Sun-Gu, Madan, Bharat, Xu, Jian-He, Park, Sunghoon

مصطلحات موضوعية: adipic acid, 2-Oxoadipate, 2-Oxoadipate reductase, 2-Oxoglutarate, Alcaligenes eutrophus H16, lactate dehydrogenase

الوصف: Adipic acid is an important monomer for the production of nylon-6,6 polyamide. One novel biological route for the synthesis of adipic acid, which combines the lysine synthetic pathway and glutaconic acid production pathway, has been suggested, but this route has suffered from the lack of an efficient 2-oxoadipate reductase connecting the two pathways or converting 2-oxoadipate to 2-hydroxyadipate. In this study, we report that the lactate dehydrogenase of Alcaligenes eutrophus H16 is a promising catalyst for this reaction. The lactate dehydrogenase gene (Ae-ldhO) was cloned, expressed in Escherichia coli, purified, and characterized. The recombinant enzyme, having a molecular weight of 36.7 kDa, exhibited broad substrate specificity for various 2-oxoacids. NADH was the preferred coenzyme over NADPH for all 2-oxoacids tested. The maximum specific activity of Ae-LdhO on 2-oxoadipate was 454.5 +/- 20.1 U/mg protein at pH 7.0 and 30a"integral. The K (m) values for 2-oxoadipic acid and NADH were 0.32 +/- 0.02 and 0.09 +/- 0.002 mM, respectively. The activity of Ae-LdhO was enhanced in the presence of some metal ions, such as Mg2+, Co2+ or Ni2+, whereas it was completely inhibited by Hg2+, Ag+, Cu2+ and DTT.

العلاقة: BIOTECHNOLOGY AND BIOPROCESS ENGINEERING, v.19, no.6, pp.1048 - 1057; https://link.springer.com/article/10.1007%2Fs12257-014-0381-1Test; https://scholarworks.unist.ac.kr/handle/201301/25313Test; 3392; 27915; 2-s2.0-84921033736; 000348046500015

الإتاحة: https://doi.org/10.1007/s12257-014-0381-1Test
https://scholarworks.unist.ac.kr/handle/201301/25313Test

المؤلفون: Jun, Chanha, Sa, Young Seung, Gu, Sol-A, Joo, Jeong Chan, Kim, Seil, Kim, Kyung-Jin, Kim, Yong Hwan

مصطلحات موضوعية: d-Lactate dehydrogenase, d-Lactic acid, Lactobacillus jensenii, Thermostability

الوصف: The demand on thermostable D-lactate dehydrogenases (D-LDH) has been increased for D-lactic acid production but thermostable D-DLHs with industrially applicable activity were not much explored. To identify a thermostable D-LDH, three D-LDHs from different Lactobacillus jensenii strains were screened by genome mining and then expressed in Escherichia coli. One of the three D-LDHs (D-LDH3) exhibited higher optimal reaction temperature (50 degrees C) than the others. The T-50(10) value of this thermostable D-LDH3 was 48.3 degrees C, much higher than the T-50(10) values of the others (42.7 and 42.9 degrees C) and that of a commercial D-lactate dehydrogenase (41.2 degrees C). The T-m values were 48.6, 45.7 and 55.7 degrees C for the three D-LDHs, respectively. In addition, kinetic parameter (k(cat)/K-m) of D-LDH3 for pyruvate reduction was estimated to be almost 150 times higher than that for lactate oxidation at pH 8.0 and 25 degrees C, implying that D-lactate production from pyruvate is highly favored. These superior thermal and kinetic features would make the D-LDH3 characterized in this study a good candidate for the microbial production of D-lactate at high temperature from glucose if it is genetically introduced to lactate producing microbial. ; close

العلاقة: PROCESS BIOCHEMISTRY, v.48, no.1, pp.109 - 117; http://www.sciencedirect.com/science/article/pii/S1359511312004163Test; https://scholarworks.unist.ac.kr/handle/201301/20357Test; 3192; 26753; 2-s2.0-84874112739; 000316426000014

الإتاحة: https://doi.org/10.1016/j.procbio.2012.11.013Test
https://scholarworks.unist.ac.kr/handle/201301/20357Test
http://www.sciencedirect.com/science/article/pii/S1359511312004163Test

المؤلفون: Gu, Sol-A., Jun, Chanha, Joo, Jeong Chan, Kim, Seil, Lee, Seung Hwan, Kim, Yong Hwan

مصطلحات موضوعية: Enantiopurity, Lactate dehydrogenase, Lactic acid, Lactic acid bacteria

الوصف: Lactobacillus coryniformis is known to produce D-lactic acid as a dominant fermentation product at a cultivation temperature of approximately 30 degrees C. However, the considerable production of L-lactic acid is observed when the fermentation temperature is greater than 40 degrees C. Because optically pure lactates are synthesized from pyruvate by the catalysis of chiral-specific D- or L-lactate dehydrogenase, the higher thermostability of L-LDHs is assumed to be one of the key factors decreasing the optical purity of D-lactic acid produced from L. coryniformis at high temperature. To verify this hypothesis, two types of d-ldh genes and six types of l-ldh genes based on the genomic information of L. coryniformis were synthesized and expressed in Escherichia coll. Among the LDHs tested, five LDHs showed activity and were used to construct polyclonal antibodies. D-LDH1, L-LDH2, and L-LDH3 were found to be expressed in L. coryniformis by Western blotting analysis. The half-life values (t(1/2)) of the LDHs at 40 degrees C were estimated to be 10.50, 41.76, and 2311 min, and the T-50(10) values were 39.50,39.90, and 58.60 degrees C, respectively. In addition, the T-m values were 36.0, 41.0, and 62.4 degrees C, respectively, which indicates that L-LDH has greater thermostability than D-LDH. The higher thermostability of L-LDHs compared with that of D-LDH1 may be a major reason why the enantiopurity of n-lactic acid is decreased at high fermentation temperatures. The key enzymes characterized will suggest a direction for the design of genetically modified lactic acid bacteria to produce optically pure D-lactic acid. (c) 2014 Elsevier Inc. All rights reserved ; close

العلاقة: ENZYME AND MICROBIAL TECHNOLOGY, v.58-59, no., pp.29 - 35; http://www.sciencedirect.com/science/article/pii/S0141022914000404Test; https://scholarworks.unist.ac.kr/handle/201301/20346Test; 3192; 26742; 2-s2.0-84896099648; 000336464600005

الإتاحة: https://doi.org/10.1016/j.enzmictec.2014.02.008Test
https://scholarworks.unist.ac.kr/handle/201301/20346Test
http://www.sciencedirect.com/science/article/pii/S0141022914000404Test

المؤلفون: Min, Kyoungseon, Yeon, Young Joo, Um, Youngsoon, Kim, Yong Hwan

مصطلحات موضوعية: Bioconversion lactic acid, Biotransformations, Enzyme biocatalysis, NAD-independent d-lactate dehydrogenase, Pyruvate production

الوصف: Pyruvate is a significant platform chemical widely used in the agrochemical and pharmaceutical industries. We discovered FAD-containing lactate dehydrogenases (LDHs) from Acetobacter aceti (Aa-LDH) and Acidocella species MX-AZ02 (As-LDH), expressed them in Escherichia coil, optimized their FAD reconstitution, and characterized the recombinants as NAD-independent D-LDHs that are capable of the in vitro biocatalytic production of pyruvate from lactate. Instead of NAD, both Aa-LDH and As-LDH utilized various organic dyes as the electron acceptor. In addition, Aa-LDH and As-LDH exhibited substrate specificity for D-lactate only. Activity was optimized at pH 7.0 and 65 degrees C. The kinetic parameters of Aa-LDH and As-LDH were examined and both enzymes exhibited higher catalytic efficiency (k(cat)/K-m) for 2,6-dichlorophenolindophenol (DCIP), one of the electron acceptors, than D-lactate due to higher binding affinities. When using 10 mM D-lactate as the substrate with stepwise DCIP and D-LDH feeding, Aa-LDH and As-LDH produced 5.48 and 4.09 mM pyruvate, respectively, and the conversion was proportional to the DCIP concentration. ; close

العلاقة: BIOCHEMICAL ENGINEERING JOURNAL, v.105, no., pp.358 - 363; http://www.sciencedirect.com/science/article/pii/S1369703X15300784Test; https://scholarworks.unist.ac.kr/handle/201301/20322Test; 3192; 26718; 2-s2.0-84945151424; 000367776500005

الإتاحة: https://doi.org/10.1016/j.bej.2015.10.008Test
https://scholarworks.unist.ac.kr/handle/201301/20322Test
http://www.sciencedirect.com/science/article/pii/S1369703X15300784Test