Journal of Synthetic Biology http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Synthetic Crossfeeding Cocultures in Yeast: Computational Model of Autoregulation and Design of a Tryptophan Export Device Sun, 22 Feb 2015 07:02:05 +0000 http://www.hindawi.com/journals/jsb/2015/178514/ In order to contribute to the design of crossfeeding systems, we modeled population control in a coculture of two crossfeeding strains of an organism, each of which secretes a metabolite the other strain requires to grow. Differential equations show that the steady-state population ratio can be tuned by varying the ratio of the metabolite secretion rates, as long as they fall within a range determined by the nature of the organism. Numerical simulations of Trp/His crossfeeding in budding yeast suggest that the time required to reach steady state populations critically depends on the capacity of the cells to uptake the crossfeeding amino acids. We also engineered and evaluated a novel genetic device that secretes tryptophan-rich peptides with a cell penetrating sequence. Experimental validation showed that the device increases tryptophan secretion and enables growth of a trp− strain in a coculture in synthetic medium lacking tryptophan. Alan Bush, Manuel Giménez, Alicia Grande, Luciano Gastón Morosi, Verónica Parasco, María Alejandra Parreño, Mario Rugiero, Germán Sabio, Alejandro Colman-Lerner, Alejandro Daniel Nadra, and Ignacio Enrique Sánchez Copyright © 2015 Alan Bush et al. All rights reserved.