Construction of Coculture System Containing Escherichia coli with Different Microbial Species for Biochemical Production

Programming Dynamic Division of Labor Using Horizontal Gene Transfer

The metabolic engineering of microbes has broad applications, including biomanufacturing, bioprocessing, and environmental remediation. The introduction of a complex, multistep pathway often imposes a substantial metabolic burden on the host cell, restraining the accumulation of productive biomass and limiting pathway efficiency. One strategy to alleviate metabolic burden is the division of labor (DOL) in which different subpopulations carry out different parts of the pathway and work together to convert a substrate into a final product. However, the maintenance of different engineered subpopulations is challenging due to competition and convoluted interstrain population dynamics. Through modeling, we show that dynamic division of labor (DDOL), which we define as the DOL between indiscrete populations capable of dynamic and reversible interchange, can overcome these limitations and enable the robust maintenance of burdensome, multistep pathways. We propose that DDOL can be mediated by horizontal gene transfer (HGT) and use plasmid genomics to uncover evidence that DDOL is a strategy utilized by natural microbial communities. Our work suggests that bioengineers can harness HGT to stabilize synthetic metabolic pathways in microbial communities, enabling the development of robust engineered systems for deployment in a variety of contexts.

Establishment of synthetic microbial consortia with Corynebacterium glutamicum and Pseudomonas putida: Design, construction, and application to production of γ-glutamylisopropylamide and l-theanine

Microbial synthetic consortia are a promising alternative to classical monoculture for biotechnological applications and fermentative processes. Their versatile use offers advantages in the degradation of complex substrates, the allocation of the metabolic burden between individual partners, or the division of labour in energy utilisation, substrate supply or product formation. Here, stable synthetic consortia between the two industrially relevant production hosts, Pseudomonas putida KT2440 and Corynebacterium glutamicum ATCC13032, were established for the first time. By applying arginine auxotrophy/overproduction and/or formamidase-based utilisation of the rare nitrogen source formamide, different types of interaction were realised, such as commensal relationships (+/0 and 0/+) and mutualistic cross-feeding (+/+). These consortia did not only show stable growth but could also be used for fermentative production of the γ-glutamylated amines theanine and γ-glutamyl-isopropylamide (GIPA). The consortia produced up to 2.8 g L-1 of GIPA and up to 2.6 g L-1 of theanine, a taste-enhancing constituent of green tea leaves. Thus, the advantageous approach of using synthetic microbial consortia for fermentative production of value-added compounds was successfully demonstrated.

Programming dynamic division of labor using horizontal gene transfer

The metabolic engineering of microbes has broad applications, including in biomanufacturing, bioprocessing, and environmental remediation. The introduction of a complex, multi-step pathway often imposes a substantial metabolic burden on the host cell, restraining the accumulation of productive biomass and limiting pathway efficiency. One strategy to alleviate metabolic burden is division of labor (DOL), in which different subpopulations carry out different parts of the pathway and work together to convert a substrate into a final product. However, the maintenance of different engineered subpopulations is challenging due to competition and convoluted inter-strain population dynamics. Through modeling, we show that dynamic division of labor (DDOL) mediated by horizontal gene transfer (HGT) can overcome these limitations and enable the robust maintenance of burdensome, multi-step pathways. We also use plasmid genomics to uncover evidence that DDOL is a strategy utilized by natural microbial communities. Our work suggests that bioengineers can harness HGT to stabilize synthetic metabolic pathways in microbial communities, enabling the development of robust engineered systems for deployment in a variety of contexts.