Use of pantothenate as a metabolic switch increases the genetic stability of farnesene producing Saccharomyces cerevisiae

We observed that removing pantothenate (vitamin B-5), a precursor to co-enzyme A. from the growth medium of Saccharomyces cerevisiae engineered to produce beta-farnesene reduced the strain's farnesene flux by 70%, but increased its viability, growth rate and biomass yield. Conversely, the growth rate and biomass yield of wild-type yeast were reduced. Cultivation in media lacking pantothenate eliminates the growth advantage of low-producing mutants, leading to improved production upon scale-up to lab-scale bioreactor testing. An omics investigation revealed that when exogenous pantothenate levels are limited, acyl-CoA metabolites decrease, beta-oxidation decreases from unexpectedly high levels in the farnesene producer, and sterol and fatty acid synthesis likely limits the growth rate of the wild-type strain. Thus pantothenate supplementation can be utilized as a metabolic switch for tuning the synthesis rates of molecules relying on CoA intermediates and aid the economic scale-up of strains producing acyl-CoA derived molecules to manufacturing facilities. (C) 2014 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.