Synthetic cell-cell communication in a three-species consortium for one-step vitamin C fermentation.

Objectives: A three-species consortium for one-step fermentation of 2-keto-L-gulonic acid (2-KGA) was constructed to better strengthen the cell-cell communication. And the programmed cell death module based on the LuxI/LuxR quorum-sensing (QS) system was established in Gluconobacter oxydans to reduce the competition that between G. oxydans and Ketogulonicigenium vulgare.

Results: By constructing and optimizing the core region of the promoter, which directly regulated the expression of lethal ccdB genes in QS system, IR3C achieved the best lethal effect. The consortium of IR3C- K. vulgare-Bacillus megaterium (abbreviated as 3C) achieved the highest 2-KGA titer (68.80 ± 4.18 g/l), and the molar conversion rate was 80.7% within 36 h in 5 l fermenter. Metabolomic analysis on intracellular small molecules of consortia 3C and 1C showed that most amino acids (such as glycine, leucine, methionine and proline) and TCA cycle intermediates (such as succinic acid, fumaric acid and malic acid) were significantly affected. These results further validated that the programmed cell death module based on the LuxI/LuxR QS system in G. oxydans could also faciliate better growth and higher production of consortium 3C for one-step fermentation.

Conclusions: We successfully constructed a novel three-species consortia for one-step vitamin C fermentation by strengthening the cell-cell communication. This will be very useful for probing the rational design principles of more complex multi-microbial consortia.