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Li Z.-H.,Tianjin University of Science and Technology | Li Z.-H.,National and Local United Engineering Laboratory of Metabolic Control Fermentation Technology | Li Z.-H.,Tianjin Engineering Laboratory of Efficient and Green Amino Acid Manufacture | Zhang C.-L.,Tianjin University of Science and Technology | And 5 more authors.
Lecture Notes in Electrical Engineering | Year: 2015

To investigate the production of L-glutamic acid with high yield as well as improved purity, the optimization of crystallization process was conducted. During this study, various physicochemical parameters (e.g., initial temperature, cooling rate, acid adding rate, ultrasonic time, and stirring speed) of concentrated isoelectric crystallization method were evaluated to optimize the yield and purity of L-glutamic acid. The optimum crystallization parameters are as follows: acid adding rate 0.5 mL/min, ultrasonic time 10 min, and stirring speed 200 rpm. The yield of L-glutamic acid at optimal condition was 95.4%, attaining a 6.5% growth. The purity of crystallized product exceeded 99%, giving a rise of 4%. The optimal crystallization process with higher yield and improved purity reduces the energy consumption and thus promotes sustainable development. © Springer-Verlag Berlin Heidelberg 2015. Source


Zhang D.-L.,Tianjin University of Science and Technology | Zhang D.-L.,Tianjin Engineering Laboratory of Efficient and Green Amino Acid Manufacture | Zhang D.-L.,National and Local United Engineering Laboratory of Metabolic Control Fermentation Technology | Xu Q.-Y.,Tianjin University of Science and Technology | And 11 more authors.
Modern Food Science and Technology | Year: 2013

The ppnk and gdh encoding NAD kinase (NADK) and glutamate dehydrogenase (GDH) were two important enzymes in the glutamate biosynthesis pathway. The two genes were amplified by polymerase chain reaction (PCR) from the glutamate-producing strain CN1021. The specific activity of NAD kinase in extracts was increased by 2.4-fold, and GDH, by 2.1-fold. When both genes were co-expressed in CN1021, the activity of NADK and GDH were increased by 2.0-fold and 1.5-fold, respectively. The flask fermentation results showed that the separate over-expression of ppnk and gdh in CN1021 approximately 7.9% higher and 1.4% more L-glutamate than the original strain, moreover, co-expressing the two genes strain exhibited 13.2% higher L-glutamate. Taken together, the results demonstrated that co-expression of gdh and ppnk genes can significantly improve the production of L-glutamate. Source


Zhang C.,Tianjin University of Science and Technology | Zhang C.,National and Local United Engineering Laboratory of Metabolic Control Fermentation Technology | Zhang C.,Tianjin Engineering Laboratory of Efficient and Green Amino Acid Manufacture | Du S.,Tianjin University of Science and Technology | And 10 more authors.
Biotechnology Letters | Year: 2015

Objectives: To rationally identify targets for enhancing adenosine production, transcription level of genes involved in adenosine synthesis of Bacillus subtilis XGL was detected during the fermentation process, complemented with metabolite pool analysis. Results: PurR-regulated genes (pur operon and purA) and prs were down-regulated and 5-phosphoribosyl 1-pyrophosphate (PRPP) decreased considerably after 24 h when adenosine significantly accumulated. Since PRPP could strongly antagonize the binding of PurR to its targets, it was inferred that down-regulation of pur operon and purA might be due to a low PRPP pool, which was confirmed by metabolite analysis. So desensitized prs responsible for PRPP synthesis was overexpressed, resulting in increased PRPP concentration and pur operon transcription. To further enhance the adenosine production, desensitized purF and prs were co-overexpressed with integrating additional copy of purA to B. subtilis XGL genome, resulting in 24.3 % (1.29 g/g DCW) higher adenosine production than that by B. subtilis XG. Conclusions: Overexpression of prs, purF and purA under the guidance of transcriptional and metabolite pool analysis significantly increased adenosine production. Strategies used in this study have potential applications for rational modification of industrial microorganisms. © 2015, Springer Science+Business Media Dordrecht. Source


Gui Y.,Tianjin University of Science and Technology | Gui Y.,National and Local United Engineering Laboratory of Metabolic Control Fermentation Technology | Gui Y.,Tianjin Engineering Laboratory of Efficient and Green Amino Acid Manufacture | Ma Y.,Tianjin University of Science and Technology | And 14 more authors.
Journal of Biotechnology | Year: 2016

Here, we report the complete genome sequence of Corynebacterium glutamicum CP, an industrial l-leucine producing strain in China. The whole genome consists of a circular chromosome and a plasmid. The comparative genomics analysis shows that there are many mutations in the key enzyme coding genes relevant to l-leucine biosynthesis compared to C. glutamicum ATCC 13032. © 2016 Elsevier B.V. Source

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