(+)-Borneol, the main component of "Natural Borneol" in the Chinese Pharmacopoeia, is a high-end spice and precious medicine. Plant extraction cannot meet the increasing demand for (+)-borneol, while microbial biosynthesis offers a sustainable supply route. However, its production was extremely low compared with other monoterpenes, even with extensively optimizing the mevalonate pathway. We found that the key challenge is the complex and unusual dephosphorylation reaction of bornyl diphosphate (BPP), which suffers the side-reaction and the competition from the cellular dephosphorylation process, especially lipid metabolism, thus limiting (+)-borneol synthesis. Here, we systematically optimized the dephosphorylation process by identifying, characterizing phosphatases, and balancing cellular dephosphorylation metabolism. For the first time, we identified two endogenous phosphatases and seven heterologous phosphatases, which significantly increased (+)-borneol production by up to 152%. By engineering BPP dephosphorylation and optimizing the MVA pathway, the production of (+)-borneol was increased by 33.8-fold, which enabled the production of 753 mg/L under fed-batch fermentation in shake flasks, so far the highest reported in the literature. This study showed that rewiring dephosphorylation metabolism was essential for high-level production of (+)-borneol in Saccharomyces cerevisiae, and balancing cellular dephosphorylation is also helpful for efficient biosynthesis of other terpenoids since all whose biosynthesis involves the dephosphorylation procedure.

OBJECTIVETo analyze the relationship between the net photosynthetic rate and the quality of Siraitia grosvenorii.

METHODTaken two species of S. grosvenorii: Yongqing No. 1 and Yehong No. 1 as the experimental material, CI-310 portable photosynthesis system was used to test the net photosynthetic rate in the late growth period; HPLC was used to determine momordica-glycosides V.

RESULTLight compensation point of Yongqing No. 1 was lower than that of Yehong No. 1 and the light saturation point was identical, the weight of dried fruit and the content of momordica-glycosides V of Yongqing No. 1 were higher than those of Yehong No. 1 at the late growth period.

CONCLUSIONThe net photosynthetic rate can be used as an important subservient index to assess the quality of S. grosvenorii.

Cucurbitaceae ; growth & development ; metabolism ; Photosynthesis