Natural ecosystems are subjected to unprecedented environmental changes. However, the underlying mechanisms by which environmental perturbations influence ecosystem function and processes are difficult to understand, owing in part to the very complex interactions of components within ecosystems. Recent developments in biological engineering using model microorganisms allow for constructing a synthetic system with components with defined functions, thus providing the opportunity for mechanistic understanding of ecosystem functioning and dynamics in response to environmental purturbations.
In this study, we constructed a synthetic microbial ecosystem consisting of three components: green alga (Chlorella vulgaris), bacterium (engineered E. coli), and ciliate (Tetrahymena thermophila). T. thermophila mainly feeds on E. coli which is nourished by extracellular organic compounds secreted by C. vulgaris. The synthetic microbial ecosystem was then used to examine syntrophic interactions between decomposers and their effects on ecosystem functionality and stability.
Results/Conclusions
By measuring the population density of each species, we found that three components co-existed well for more than three weeks. As expected, the engineered E.coli community displayed obligatory mutualistic interactions with each other. Temporal stability, expressed as the coefficient of temporal variation of comsumers production, was higher in the synthetic system with strong cooperative interactions than in the synthetic system with weak cooperative interactions. These results offer insights into the effects of species interactions in mediating ecosystem dynamics and stability. In future work, we may focus on the construction of artificial ecosystems with stability and tenability and study their responses to environmental perturbations.