Selective Nitrogen Delivery to Regulate and Optimize Synthetic Microbial Consortia for Biochemical Production

Scott Scholz, Ian Graves and Xiaoxia (Nina) Lin

Cellular and Molecular Biology PhD Program and Department of Chemical Engineering, University of Michigan, Ann Arbor, MI

Many chemicals, including platform molecules used as building blocks for various final products, can potentially be produced using bio-based systems as sustainable alternatives. Lignocellulosic biomass is a particularly desirable feedstock due to its widespread availability. However, it is highly resistant to degradation. One approach to improve the efficiency of its conversion into desired products has been to combine different biochemical steps, from cellulase enzyme production, enzymatic hydrolysis of lignocellulose, to conversion of sugars into desired products, into a single reaction vessel, termed consolidated bioprocessing (CBP). In this project we employ a microbial consortia-based approach to enable CBP. Although consortia-based microbial production systems offer many advantages, such as modular design and high efficiency of individual specialized organisms, they present new challenges in population regulation.

We have developed a new method to dynamically regulate the growth and production performance of synthetic microbial consortia for the production of commodity chemicals from lignocellulosic biomass. Specifically, we have developed a selective nutrient delivery platform that can enable tuning of consortia member performance without making additional genetic modifications. By selectively delivering nitrogen, we can tune the composition of organisms within consortia over a wide range. We have used this method to control the performance of three different synthetic consortia for the production of two commodity chemicals from cellulosic feedstocks.