Microbial production of natural sweeteners, diterpenoid steviol glycosides

A method for producing steviol or steviol glycoside comprising:

• culturing an E. coli strain having balanced expression of (1) an upstream methylerythritol pathway (MEP) that produces isopentyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP), with respect to (2) a downstream pathway that produces steviol or steviol glycoside from said IPP and DMAPP, the downstream pathway comprising a recombinantly expressed copalyl diphosphate synthase (CPS), kaurene synthase (KS), a geranylgeranyl diphosphate synthase (GGPPS) kaurenoic acid 13-hydroxylase (KAH) and kaurene oxidase (KO), and optionally one or more Stevia UDP glycosyl transferase enzymes;
• wherein said balanced expression is obtained by increasing or decreasing the expression level of a downstream pathway module and increasing or decreasing the expression level of an upstream pathway module together in E. coli, and identifying an E. coli strain with higher production of steviol or steviol glycoside and/or lower accumulation of indole as having balanced expression.