Enhanced vitamin A production by engineering transporters, ATP and precursor supply

and introducing hemoglobin Vgb, both enhancing retinol secretion and production. Further precursor supply enhancement resulted in 727.30 ​mg/L retinol from 20 ​g/L glucose in shake flasks, with a carbon conversion rate of 7.62 ​%. These results confirm the combination of transport engineering, energy regulation and precursor supply enhancement as a pivotal strategy for augmenting vitamin A production.