Although lignocellulosic sugars have been proposed as the primary feedstock for the biological production of renewable fuels and chemicals, the availability of fatty acid (FA)-rich feedstocks and recent progress in the development of oil-accumulating organisms make FAs an attractive alternative. In addition to their abundance, the metabolism of FAs is very efficient and could support product yields significantly higher than those obtained from lignocellulosic sugars. However, FAs are metabolized only under respiratory conditions, a metabolic mode that does not support the synthesis of fermentation products. In the work reported here we engineered several native and heterologous fermentative pathways to function in Escherichia coli under aerobic conditions, thus creating a respiro-fermentative metabolic mode that enables the efficient synthesis of fuels and chemicals from FAs. Representative biofuels (ethanol and butanol) and biochemicals (acetate, acetone, isopropanol, succinate, and propionate) were chosen as target products to illustrate the feasibility of the proposed platform. The yields of ethanol, acetate, and acetone in the engineered strains exceeded those reported in the literature for their production from sugars, and in the cases of ethanol and acetate they also surpassed the maximum theoretical values that can be achieved from lignocellulosic sugars. Butanol was produced at yields and titers that were between 2-and 3-fold higher than those reported for its production from sugars in previously engineered microorganisms. Moreover, our work demonstrates production of propionate, a compound previously thought to be synthesized only by propionibacteria, in E. coli. Finally, the synthesis of isopropanol and succinate was also demonstrated. The work reported here represents the first effort toward engineering microorganisms for the conversion of FAs to the aforementioned products.

Itaconic acid is a metabolite produced from biotechnological pathway using the microorganism Aspergillus terreus. It is used in a wide number of sectors such as industry, agriculture and health. Based on its chemical properties, itaconic acid is a great interest for replacing polymers and resins derived from petroleum. However, its production is still expensive and this latter hinders large scale studies regarding itaconic acid production. Nowadays, simulation is a great alternative to overcome this problem. It allows researchers to make a more effective evaluation and self-assessment, reducing costs and avoiding losses at large scale operation. For that reason, the purpose of this research is performing an Itaconic acid production simulation on industrial scale using SuperPro Designer software. Costs reduction improvement is also analyzed. 90g/L of glycerol, 1g/L of NH4NO3 and 1.25 of KH2PO4 are set up on simulation as media composition reported from references. Results regarding itaconic acid crystals showed a productivity of 171 kg/h and an operating cost closed to 42.0 USD/kg. Interestingly, a 17 % productivity increase is reached by proposing a stream recycling based on itaconic acid recovering from downstream centrifugation processing. The latter based on a higher productivity estimated (200 kg/h). Also average costs are reduced at 12 % since 38.1 USD/kg is found using improvements mentioned. Results found here demonstrate the potential usage of simulators for estimating costs and production which allows predicting the bioprocess feasibility.