Systems metabolic engineering of escherichia coli for the efficient production of Diamines

Abstract

A diamine is a chemical that contains two amino groups. Diamines are important raw materials with a wide range of applications in the chemical industry. Diamines have been widely used in the production of pharmaceuticals, cosmetic materials, agrochemicals, surfactants and other additives. In this research, we focus on the efficient production of C3-C5 diamines, C3 1,3-diaminopropane, C4 putrescine (or 1,4-diaminobutane), and C5 cadaverine (or 1,5-diaminopentane).

Putrescine, 1,4-diaminobutane, is a native metabolite found in several bacteria at physiological level such as E.coli spp., Bacillus spp. etc. In this study, production of putrescine has been achieved through rational pathway design and systems metabolic engineering using in silico simulation. First, to improve production of putrescine, we use amplification targets by using in silico simulation. Among the targets, we selected 5 genes that are more effective in improving putrescine production than the control strain in a flask culture test. The engineered E.coli strains with individually amplified acnA, acnB, ackA, glk, or ppc were able to produce 1.90g/L, 1.89g/L. 2.04g/L, 2.23g/L and 2.06g/L, respectively, of putrescine in a batch Fermentation. Fed-batch fermentation of these strains led to the enhanced production of putrescine up to 30g/L on average. Second, to increase production of putrescine, we use knock-out targets by using in silico simulation. Third, to reduce acetate formation during fed-batch cultivation, ackA and poxB gene were deleted, respectively. The combinatorial strains produced putrescine with a titer of ca. 2.15g/L in the culture medium of the batch cultivation on average. Cadaverine and 1,3-diaminopropane are same approach as a production of putrescine.

In summary, these improvements make up a new starting point for the construction of more efficient industrial strains for diamine production in E.coli.