Engineering cyanobacteria as the basis for a synthetic microbial community

In nature, different microorganisms form highly complex communities in which every species has a distinct role. To increase our understanding of the complex structures and interactions within microbial communities and the role of each microbial partner, the design and analysis of simplified microbial model communities is necessary.

In this collaborative project, our goal is the de novo design of a synthetic microbial cross-kingdom community based on the well characterized and genetically amenable model organisms representing cyanobacteria (Synechocystis sp. PCC 6803, or Synechococcus elongatus PCC 7942), ascomycete (Saccharomyces cerevisiae) and basidiomycete fungi (Ustilago maydis).

Co-cultivation is based on the carbon source sucrose, which is produced by the phototrophic cyanobacterium using light and carbon dioxide. Sucrose secretion into the culture medium is achieved by inducible, heterologous expression of a sucrose permease gene in the cyanobacteria. This approach is often combined with salt stress or metabolic pathway engineering to increase sucrose production and secretion.

An important aspect for creating a synthetic community is to design and establish tools for the formation of stable co-cultures and the analysis/quantification of the microbial partners of the community. Thus, in this part of the project, we test different cultivation devices and photobioreactor setups for online monitoring of co-cultures as well as single-cell flow cytometry analysis for quantification of individual populations within the co-culture. Another important aspect for the formation of a synthetic microbial community is the characterization of the optimal cultivation conditions for cyanobacterial sucrose production and simultaneous growth of all co-culture partners. In order to track the carbon source sucrose and other important metabolites within the co-culture, we also intend to establish biosensors in cyanobacteria.

Exploiting these established tools, we will create a stable synthetic microbial community which will then be further used to characterize the nutrient exchange in microbial consortia with a special focus on carbon economics and logistics.

Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB1535 - Project ID 458090666.

Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Major Research Instrumentation INST 208/808-1.