Researchers Develop Alcohol Tolerant Synechocystis sp.

Synechocystis sp. PCC 6803 is an attractive organism for the production of alcohols. However, the produced alcohol is toxic to Synechocystis sp., hindering industrial applications. Hence, researchers want to engineer organisms with strong alcohol tolerance. Takuya Matsusako of Osaka University in Japan aimed to increase alcohol tolerance genes in Synechocystis sp. via adaptive laboratory evolution.

Isobutanol-tolerant strains of Synechocystis sp. PCC 6803 were obtained by long-term passage culture experiments using medium containing 2 g/L isobutanol. These evolved strains were capable of growing on medium with 5 g/L isobutanol, on which the parental strain could not grow. Analysis of the evolved strains revealed that they acquired resistance ability due to combinatorial malfunctions of several genes including slr1044 (mcpA) and slr0369 (envD), or slr0322 (hik43) and envD.

The tolerant strains demonstrated stress resistance against isobutanol as well as a wide variety of alcohols. And with the introduction of an ethanol-producing pathway into the evolved strain, its productivity successfully increased to 142% of the control strain.