Metabolic engineering of Escherichia coli for adipic acid production / 生物工程学报

Adipic acid is a high-value-added dicarboxylic acid which is primarily used in the production of nylon-66 for manufacturing polyurethane foam and polyester resins. At present, the biosynthesis of adipic acid is hampered by its low production efficiency. By introducing the key enzymes of adipic acid reverse degradation pathway into a succinic acid overproducing strain Escherichia coli FMME N-2, an engineered E. coli JL00 capable of producing 0.34 g/L adipic acid was constructed. Subsequently, the expression level of the rate-limiting enzyme was optimized and the adipic acid titer in shake-flask fermentation increased to 0.87 g/L. Moreover, the supply of precursors was balanced by a combinatorial strategy consisting of deletion of sucD, over-expression of acs, and mutation of lpd, and the adipic acid titer of the resulting E. coli JL12 increased to 1.51 g/L. Finally, the fermentation process was optimized in a 5 L fermenter. After 72 h fed-batch fermentation, adipic acid titer reached 22.3 g/L with a yield of 0.25 g/g and a productivity of 0.31 g/(L·h). This work may serve as a technical reference for the biosynthesis of various dicarboxylic acids.

The effect of thyroidectomy on male rats fed two antagonist lipid diets. IV. The fatty acid content of mitochondrial lipids of heart and gastrocnemic muscles

The fatty acid (FA) contents of heart and gatrocnemic muscle mitochondrial lipids of thyroidecromized and control (sham-operated) were analyzed. Animals were fed either an n-6 polyunsaturated (PUFA)-rich diet A or an n- PUFA-rich diet B during 30 days. It was observed alteraions in the composition of FA of those cell organelles caused by the absence of the thyroid gland. Some of these alterations were dependent of the type of used diet. Thyroidecromy caused an increase of P?S ratio in heart and gastrocnemic muscle but only for animals fed diet B. Thyroidectomy caused an increase of n-6/n-3 ratio in heart of rats fed diet A and in gastrocnemic muscle of rats fed diet B and it caused a decrease of n-6/n-3 ratio of heart of rats fed diet A and in gastrocnemic muscle of rats fed diet B. The absence of thyroid gland in some way may interfer in the FA metabolism and in the rate of FA incorporation into endogeneous lipids but in a different process dependent of type of tissue and of used lipid diet