2024 AIChE Annual Meeting
Enhancement of Photosynthetic Sorbitol Production in the Cyanobacterium Synechococcus sp. PCC 7002
Sorbitol is a sugar alcohol with broad uses in the food, cosmetic, and pharmaceutical industries. It is also considered a "top 12" biobased chemical by the U.S. Department of Energy due to its utility as a high value building block chemical. As a potential and more sustainable production route, sorbitol biosynthesis has been engineered in Synechococcus sp. PCC 7002, a photoautotrophic microorganism that utilizes CO₂ and light for growth. While initial strains successfully produced sorbitol, final titers were low, and growth was impaired due to the promiscuous activity of the final pathway enzyme, sugar alcohol phosphatase. To address this, a homologous enzyme with high specificity towards sorbitol-6-phosphate was identified. Next, to further improve sorbitol production, additional Calvin cycle enzymes were over-expressed to overcome inherent kinetic bottlenecks. Lastly, the growth media was optimized to overcome nutrient depletion, thereby further enhancing sorbitol production.