Producción de esteres de ácidos grasos metilados con propiedades lubricantes en bacteria

HUGO GRAMAJO

Jornada; Ciclo de seminarios en la universidad de Cuernavaca; 2018

Microbial lipid production represents a potential alternative feedstock for oleochemical industries. In a previous work, we engineered into E. coli a polyketide synthase (PKS)-based biosynthetic pathway from Mycobacterium tuberculosis and redefined its biological role towards the production of a variety of multi-methyl-branched esters (MBE). The biosynthetic pathway comprises the enzymes: FadD28; the PKS Mas, which synthetizes multi-methyl-branched fatty acids; and PapA5, that transfers this acyl group to an alcohol. The alcohol that acts as acceptor molecule to form the corresponding MBE was supplemented into the culture media.With the aim to develop a whole de novo bioprocess (i.e. without using exogenous alcohol), an E. coli co-culture system was engineered to modularize the ―alcohol biosynthetic pathway‖ and the ―PKS-based biosynthetic pathway‖.Thus, the MBE producing strain (RQ5 pMB22) was cultivated with an isobutanol producing E. coli strain. The last one, was obtained by transforming E. coli BL21 with pIAA11 and pIAA12 plasmids, encoding the enzymes necessary for the biosynthesis of isobutanol from glucose. The genes encoded in pIAA12 were later integrated into the chromosome, generating a new strain, CB1, that produced 18.75±0.45 mM of isobutanol after 24h of induction, an increase of 1800% with respect to BL21 original strain. When CB1 was cocultivated with RQ5 pMB22 in a minimal M9 medium, the consortium CB1/RQ5 at the best inoculation ratio of 1:2, produced 30.48±2.02 μg MBE ml-1. This yield was comparable to that exhibited by a monoculture based on the single-cell RQ5 pMB22 with the external addition of isobutanol into the growth media.