Forbidden FRUITS identifies genetic engineering strategies to stably produce any compound of interest in any microorganism for which a metabolic model exists. As a proof of concept, we implemented Forbidden FRUITS strategies in Synechocystis PCC6803 for the production of salicylic acid, mannitol and lactate to indicate the generalizability of different compounds within one species. The cyanobacterium Synechocystis PCC 6803 is able to produce different kinds of compounds from the substrates CO2, H2O and sunlight. Therefore this microorganism can be used to produce compounds in a more sustainable way. The Molecular Microbial Physiology (MMP) group of the University of Amsterdam has already been working with cyanobacteria, especially Synechocystis PCC 6803. Their knowledge about these bacteria helped us with implementing strategies. Furthermore, the compounds which we tried to make have commercial value. The compound salicylic acid is used as aspirin precursor and also in skin - and hair products. Mannitol is used in medication and as a natural sweetener. Lactate is the commodity compound for the production of bioplastic. The majority of the plastics are made from fossil fuels, causing an influx of CO2 in the atmosphere. With the help of this engineered cyanobacterium we will be able to produce plastics in a more sustainable way.
Besides showing that Forbidden FRUITS could be used to make different compounds within the same species, we also wanted to provide evidence that it could be used to make the same compound across different species. Therefore, we are implementing the Forbidden FRUITS strategies for the production of compounds from our synechocystis branch in other microbial species.
Below you can see that we have designed models to produce salicylic acid in both Synechocystis PCC 6803 and Escherichia coli. Escherichia coli (E. coli) is one of the most researched bacteria. The available knowledge about this organism helped us with the implementation of the strategy. Furthermore, we implemented Forbidden FRUITS strategies for the production of lactate in Synechocystis PCC 6803 and Synechococcus UTEX 2973. Synechococcus UTEX 2973, also a cyanobacterium, is chosen for its high growth rate and its sustainable production possibilities. We chose to explore both salicylic acid and lactate production as they explore the potential of non-native production via two common metabolic nodes: pyruvate and oxaloacetate respectively.
Taken together, these projects demonstrate that the growth-coupled production of the compound salicylic acid and lactate can be achieved in different species, and that the node through which they were may be promising to use for other strategies in the future. This supports our aim to provide evidence that any compound can be produced in any microorganism (for which a metabolic model exists) using Forbidden FRUITS.