Metabolic Engineering for L-lactic acid production in Pichia pastoris

The worldwide growth of the bioplastics market is 5-8% per year. These represent 10-15% of the total plastic market. The increase in this share is expected up to 30% in 2020 representing a market of 20 billion dollars. The sustainable and economically feasible lactic acid production, a precursor for the poly (lactic acid), allows reducing the use of plastics derived from petrochemicals thereby reducing the amount of waste deposited in the environment. The production of L-lactic acid with a low cost can be obtained from the fermentation of industrial residues. Among these, an excellent candidate is the crude glycerol, the main residue of the biodiesel industry. The yeast Pichia pastoris is able to utilize glycerol as a carbon source reaching high cell densities, but is not able to produce lactic acid. Metabolic engineering has been used in our research group to develop recombinants strains of P. pastoris producing lactic acid. Several strategies in order to increase pyruvate conversion into lactic acid were utilized. Recombinant strains were characterized in batch cultivations utilizing crude glycerol as substrate. Genetic modifications were correlated with L-lactic acid yield and productivity.