Synthetic microbial communities

Abstract

While natural microbial communities are composed of a mix of microbes with often unknown functions, the construction of synthetic microbial communities allows for the generation of defined systems with reduced complexity. Used in a top-down approach, synthetic communities serve as model systems to ask questions about the performance and stability of microbial communities. In a second, bottom-up approach, synthetic microbial communities are used to study which conditions are necessary to generate interaction patterns like symbiosis or competition, and how higher order community structure can emerge from these. Besides their obvious value as model systems to understand the structure, function and evolution of microbial communities as complex dynamical systems, synthetic communities can also open up new avenues for biotechnological applications.

Figure 1

The six basic motifs of microbial interactions. Blue and yellow circles denote different microbial strains respectively, while boxes represent metabolites. Stimulating and inhibitory interactions mediated by species traits or metabolites are indicated with red and green arrows respectively. References are to studies in which synthetic microbial communities corresponding to the given interaction type are developed. In case of a syntrophy, the first microbe in the food chain (blue circle) is inhibited by the accumulation of its own waste product in the environment (mainly via thermodynamic limitations). This inhibition is relieved by the second microbe (yellow organism), which uses the waste product of the first microbe as a food source. Hence, both organisms benefit from the presence of the other.