Microbial cells for spermidine production

A microbial cell capable of producing spermidine, wherein said microbial cell is genetically modified for overexpression of S-adenosylmethionine decarboxylase (EC 4.1.1.50) and spermidine synthase (EC 2.5.1.16);

• and for enhanced S-adenosylmethionine (SAM) biosynthesis by overexpression of at least one enzyme in the methionine salvage pathway selected from a group consisting of 5-methylthioribose-1-phosphate isomerase (MRI) (EC 5.3.1.23), methylthioribulose-1-phosphate dehydratase (MDE) (EC 4.2.1.109), 2,3-dioxomethiopentane-1-phosphate enolase/phosphatase (EC 3.1.3.77), acireductone dioxygenase (EC 1.13.11.54), and branched-chain amino acid transaminase (BAT) (EC 2.6.1.5, EC 2.6.1.57, EC 2.6.1.42), wherein said microbial cell is genetically modified for attenuated activity of ornithine decarboxylase antizyme (OAZ) and ornithine carbamoyltransferase (OTC) (EC 2.1.3.3), or deletion or disruption of a gene encoding OAZ and a gene encoding OTC, wherein the at least one enzyme for enhanced SAM biosynthesis is overexpressed in an amount to produce an increased amount of spermidine compared to a corresponding microbial cell not overexpressing the at least one enzyme.