Fed-Batch fermentation of Escherichia coli for a PKS-derived methyl-branched ester production

MENENDEZ-BRAVO, SIMON; SABATINI, MARTÍN; ROULET, JULIA; COMBA, SANTIAGO; ARABOLAZA, ANA LORENA; GRAMAJO, HUGO CESAR

Mar del Plata

Congreso; LI Reunión Anual SAIB; 2015

Microbial fatty acid (FA)-derived molecules have emerged as promising alternatives to petroleum-based chemicals for reducing dependence on fossil hydrocarbons. In this sense, we have successfully engineered into Escherichia coli a mycocerosic polyketide synthase-based biosynthetic pathway from Mycobacterium tuberculosis and redefined its biological role towards the production of multi-methyl-branched-esters (MBE) with novel chemical structures. In this work we aimed to develop a fed-batch fermentation process in order to increase MBE production yields. To achieve this goal we cultured the E. coli MBE producer strain in 1 L fermentors, using a glucose-based minimal media. After optimization of medium composition and growth parameters for this particular strain, we focused our study on determining the optimal protein induction timing and inducer concentration, in order to maximize the volumetric production of the lipid product. After all of these steps, we scaled up the process to a 75 L fermentation. Finally, we developed a protocol for MBE purification from total lipid extracts, based on the differential silica adsorption affinity of the MBE esters in comparison to the phospholipid and fatty acid fractions of the extract. After that, a silica column based purification of MBE led us to obtain the pure product, suitable for physicochemical properties measurements.