Serial adaptive laboratory evolution enhances mixed carbon metabolic capacity of Escherichia coli.. Serial adaptive laboratory evolution enhances mixed carbon metabolic capacity of Escherichia coli.

Microbes have inherent capacities for utilizing various carbon sources, however they often exhibit sub-par fitness due to low metabolic efficiency. To test whether a bacterial strain can optimally utilize multiple carbon sources, Escherichia coli was serially evolved in lactate and glycerol. This yielded two end-point strains that evolved first in lactate then in glycerol, and vice versa. The end-point strains displayed a universal growth advantage on single and a mixture of adaptive carbon sources, enabled by a concerted action of carbon source-specialists and generalist mutants. In addition, deconvolution of transcriptome profiles revealed coordinated activity of transcriptional regulators impart condition-specific regulation of gene expressions. The effectiveness of the serial ALE scheme in bioproduction applications was assessed under single and mixed-carbon culture conditions, in which serial ALE strain exhibited superior productivity of a commodity chemical compared to ancestral strains, highlighting the potential utility of serial ALE in bioproduction applications.