Engineering the\nMethylerythritol Phosphate Pathway\nand Using a Temporal Promoter for Enhanced Lycopene Production in Rhodobacter sphaeroides HY01

Rhodobacter sphaeroides HY01 is\na high-yield strain for industrial production of coenzyme Q<sub>10</sub> (Q<sub>10</sub>), indicating its potential for producing other terpenoids.\nHowever, the production of Q<sub>10</sub> substantially depletes isoprene\nprecursors, nearly eliminating other terpenoids like spheroidene and\nspheroidenone commonly found in wild-type R. sphaeroides. Lycopene was used as an example to demonstrate its potential for\nterpenoid biosynthesis. By refactoring the methylerythritol phosphate\n(MEP) pathway, such as overexpressing <i>crtE</i> and introducing <i>crtI</i><sub>4</sub>, lycopene production reached 126.1 mg/L\nin HY01. However, further overexpression of the deoxy-d-xylulose-5-phosphate\nsynthase, 1-deoxy-d-xylulose 5-phosphate reductoisomerase,\nand isopentenyl-diphosphate isomerase genes led to strain degradation,\nsignificantly reducing lycopene production. Fine-tuning the engineered\nPrrAB two-component system, which upregulated the MEP pathway, increased\nlycopene production to 154.9 mg/L. Inspired by this result, a series\nof native promoters with varying strengths were identified and characterized\nthrough transcriptomic analysis during the late fermentation stage.\nUsing these temporal promoters to control genes in the MEP pathway\nultimately increased lycopene production to 283.1 mg/L, the highest\nreported in R. sphaeroides. These results\nunderscore the potential of HY01 as a chassis for terpenoid biosynthesis.