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Carbon dioxide (CO 2 ) is an abundant and cheap carbon source that is partly responsible for global warming in the atmosphere. The objective of this study was to construct a recombinant E. coli strain that can show enhanced production of succinate derived from CO 2 . In this study, we confirmed the enhancement of utilization by analyzing succinate containing one carbon-13 ( 13 C) derived from 13 CO 2 . Firstly, the carbonic anhydrase gene (SP(-)HCCA) derived from Hahella chejuensis KCTC 2396 was over-expressed to enhance carbon flux toward bicarbonate ion (HCO 3 - ) synthesis in E. coli. The phosphoenolpyruvate carboxylase gene (ppc) was over-expressed to enhance the production of oxaloacetate by enhancing the carbon flux. Compared with the control strain, the percentage of the succinate containing one 13 C (succinate 119 ) to total succinate was enhanced by approximately 2.80-fold and the amount of succinate 119 also increased by approximately 4.09-fold in SGJS120. Secondly, the lactate dehydrogenase gene (ldhA) was deleted to re-direct the utilization of the carbon source from glucose to enhance succinate production in SGJS120. However, ldhA deletion did not increase CO 2 utilization in SJGS120. Finally, the phosphotransferase system gene (ptsG) and pyruvate kinase F gene (pykF) were deleted to increase the amount of phosphoenolpyruvate (PEP). SGJS126 (pykF deletion strain) showed the highest increase, which was 6.05-fold higher than the control strain. From the results, SP(-)HCCA overexpression and pykF deletion may be useful for enhancing CO 2 utilization in E. coli. Additionally, engineered strains showed the potential to reduce the cost of succinate production by using an industrially cheaper carbon source such as CO 2 and converting CO 2 to a valuable chemical., (Copyright © 2016. Published by Elsevier B.V.)

Carbon dioxide (CO2) emissions are related to global warming. However, CO2 can be used as an abundant and cheap carbon source for production of valuable chemicals using carbon capture and storage technology. Here, the genes related to carbon flux toward pyruvate biosynthesis in E. coli were deleted to enhance the incorporation of CO2 for succinate production. The codonoptimized carbonic anhydrase gene (SP(-)HCCA) derived from Hahella chejuensis KCTC 2396 and the phosphoenolpyruvate carboxylase gene (ppc) of E. coli W3110 were co-overexpressed to enhance carbon flux toward oxaloacetate synthesis in E. coli. Finally, we constructed SGJS134, which shows the highest production of succinate derived from CO2 compared with other strains. SGJS134 produced approximately 6.5 mM succinate from CO2 and yielded approximately 13.0 mM succinate per dry cell weight. These results may be useful for enhancing the incorporation of CO2 for succinate production in E. coli. Additionally, the metabolic engineering method used in this study will propose the potential of E. coli to convert CO2 to valuable chemicals. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biological ectoine production process for various industrial CH 4 sources. • Model-based operation guide was verified by fermenter-scale experiments. • Correlation between metabolites production and CH 4 removal was investigated. • A determining factor to determine the functionality of methanotrophs. Methanotroph-based CH 4 conversion technology is being widely studied due to its advantages of mild operating conditions and environmental friendliness. In this study, operating strategies were investigated for industrial CH 4 sources in order to widely disseminate methanotroph-based CH 4 conversion technology using the promising strain, Methylotuvimicrobium alcaliphilum 20Z. The optimal O 2 /CH 4 ratio for extremely different CH 4 concentrations was explored based on kinetic-based simulation for biological reaction, and experimentally proven using fermenter-scale experiments. As a result, when high CH 4 concentration is used, ectoine production rate can be maximized (33.8 mg/L·h) at an O 2 /CH 4 ratio of 1 while favoring the " production of metabolites ". On the other hand, in the low CH 4 concentration case, when changing from the general O 2 /CH 4 ratio of 4 to the optimal O 2 /CH 4 ratio (i. e., 1), although the improvement in ectoine concentration was not noticeable (3.9 to 7.5 mg/L·h), the CH 4 conversion rate rapidly decreased (50 to 20 %), suggesting that the focus in the low concentration case should be on " removal of CH 4 ". In the case of biogas, the rapid pH drop caused by the large amount of CO 2 in the feed is offset by a buffer solution, and the concentration of Na+ ions increases during the overall reaction time. Therefore, the production of metaboiltes can be maximized while simultaneously controlling pH and Na+ ion through continuous operation with a high dilution rate (19.8 mg/L·h). Furthermore, major performance indicators for each industrial gas were derived through comprehensive comparative analysis, through which the " dual-functions " of methanotrophs could be emphasized. This study provides a practical and strategic approach for methanotrophs that can flexibly respond to diverse industrial CH 4 sources. [ABSTRACT FROM AUTHOR]