Jiangnan University

Qiuling Luo

Xiulai Chen

Jia Liu

Liming Liu

Jing Wu

Wei Song

Cong Gao

Guipeng Hu

Quan Zhang

Wenxiu Tang

Chen Shen

Danlei Ma

Shanshan Pei

The disclosure discloses construction and application of an engineered strain offor producing malic acid by fixing CO, and belongs to the field of fermentation. The engineered strain is obtained by performing genetic engineering transformation onMG1655; the genetic engineering transformation includes knocking out a fumarate reductase gene, a fumarase gene, a lactate dehydrogenase gene and an alcohol dehydrogenase gene and freely overexpressing a formate dehydrogenase, an acetyl coenzyme A synthetase, an acylated acetaldehyde dehydrogenase, a formaldehyde lyase, a dihydroxyacetone kinase, a malic enzyme and a phosphite oxidoreductase to obtain a strain GH0407. The strain is used for producing malic acid by fermentation, anaerobic fermentation is performed for 72 hours with COand glucose as a co-substrate, the production of malic acid reaches 39 g/L, the yield is 1.53 mol/mol, and accumulation of malic acid in the original strain is not achieved.

Construction and application of engineered strain offor producing malic acid by fixing CO

The invention provides a recombinantstrain for producing succinic acid and a construction method thereof. The by-product encoding genes in thestrain FMME-N-2 are knocked out to obtain thestrain FMME-N-5 (ΔfocA-pflB-ΔldhA-Δpta-ackA); and the phosphoenolpyruvate carboxykinase pck derived fromand the phosphite dehydrogenase ptxD derived fromwere overexpressed. The constructed plasmid pTrcHisA-pck-ptxD was introduced into the expression hostFMME-N-5 (ΔfocA-pflB-ΔldhA-Δpta-ackA), and the cells were screened in a plate containing ampicillin, to obtain an engineered strainFMME-N-5 (ΔfocA-pflB-ΔldhA-Δpta-ackA)-pck-ptxD that can efficiently produce succinic acid. After fermentation by a two-stage fermentation strategy, the production of succinic acid reaches 137 g/L, the yield of succinic acid is up to 1 g/g glucose, and the space time yield is 1.43 g/L/h, while no by-products of lactic acid and formic acid are accumulated, and the acetic acid content is 1-2 g/L.

Recombinantstrain for producing succinic acid and construction method thereof

The disclosure discloses preparation of an L-amino acid deaminase mutant and application thereof, belonging to the technical field of gene engineering. Through pmirLAAD protein modification, analysis of a flexible loop structure around a binding site of the pmirLAAD product, and design of the best mutant, the modification method of the disclosure overcomes the defect that the catalytic efficiency of the previous wild-type enzyme is reduced due to product inhibition, and is tested by experiments. Compared with the control, the catalytic efficiency (1.61 mM&#xb7;min) and the product inhibition constant (5.4 mM) of the finally obtained best mutant pmirLAADare respectively increased by 5.2 times and 5.7 times. The yield of &#x3b1;-ketoisovaleric acid can reach 96.5 g/L, and the transformation rate is greater than 97%. By adopting the method of the disclosure, the cost can be greatly reduced, and the industrialization process of production of &#x3b1;-ketoisovaleric acid by an enzymatic transformation method is accelerated.

Preparation of L-amino acid deaminase mutant and application thereof

The present invention relates to the field of biotechnology engineering. It provides a recombinantthat can produce fructosylated chondroitin with high yields and the method for constructing the recombinant strain. The present invention discloses a method for constructing an expression plasmid pETM6R1-RBS-glmM-GGGS-glmS that contains a glmM and a glmS gene under regulation of ribosome binding sites. The recombinant plasmid was transformed intoK4 to obtain a recombinantstrain ZQ33 that can produce fructosylated chondroitin up to 3.99 g&#xb7;Lby fed-batch fermentation in a 5-L fermentor, which was increased by 108.90% compared to that of the wild type strain.

Recombinantfor high efficiency production of fructosylated chondroitin and method for making thereof

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Wuxi, China

Qiuling Luo