Trehalose is a non-reducing disaccharide with a wide range of applications in food, cosmetic, and pharmaceutical industries. Cyanobacteria are promising cell factories to produce biochemicals by using solar energy and CO₂. Trehalose is biosynthesized at low intracellular concentrations as a salt-inducible compatible solute in some cyanobacteria. In the current study, we demonstrated the efficient trehalose production without salt induction in cyanobacteria by metabolic engineering. The trehalose transporter 1 (TRET1) from an anhydrobiotic insect (Polypedilum vanderplanki) was successfully expressed in the engineered strains and the intracellular trehalose was efficiently secreted to the medium. As the results, the engineered strain co-expressing maltooligosyl trehalose synthase (MTS), maltooligosyl trehalose trehalohydrolase (MTH) and TRET1 secreted 97% of trehalose to the medium, and the titer was up to 2.7 g/L in 15 days. In addition, 5.7 g/L trehalose was produced by semi-continuous cultivation in 34 days. Taken together, this work demonstrates cyanobacteria can be applied as cell factories for direct sunlight-driven conversion of CO₂ into excreted trehalose.

海藻糖是一种非还原性二糖，在食品、化妆品和制药行业有广泛的应用。蓝藻是很有前途的细胞工厂，可以利用太阳能和 CO ₂生产生化产品。海藻糖是在低细胞内浓度下生物合成的，作为某些蓝藻中的盐诱导相容溶质。在目前的研究中，我们通过代谢工程证明了在蓝藻中没有盐诱导的有效海藻糖生产。来自无水生物昆虫 ( Polypedilum vanderplanki ) 的海藻糖转运蛋白 1 (TRET1)) 在工程菌株中成功表达，细胞内海藻糖被有效分泌到培养基中。结果表明，共表达麦芽寡糖基海藻糖合酶（MTS）、麦芽寡糖基海藻糖海藻糖水解酶（MTH）和TRET1的工程菌株向培养基分泌了97%的海藻糖，15天内滴度高达2.7 g/L。此外，半连续培养34天可生产5.7g/L海藻糖。总而言之，这项工作表明蓝藻可以用作细胞工厂，用于将 CO ₂直接转化为排泄的海藻糖。