GNPS - Pseudomonas putida as saviour for troubled Synechococcus elongatus in a synthetic co-culture: Interaction studies based on a multi-OMICs approach

In their natural environments, microbes rarely exist in isolation. Instead, they thrive in consortia where diverse interactions take place. In this study, a defined synthetic coculture of phototrophic S. elongatus cscB, which feeds the heterotrophic P. putida cscRABY with sucrose, was investigated to identify potential interactions. In initial experiments, a remarkable growth-promoting effect brought about by the presence of the heterotrophic partner, on the cyanobacterium was observed, leading to a growth increase of up to 60 percent. Vice versa, the cyanobacterium had a neutral effect on P. putida cscRABY, highlighting the resilience against stress of Pseudomonads and their potential as co-culture partners. A suitable reference process reinforcing the growth-promoting effect was established in a parallel operating photobioreactor system. This set the basis for the analysis of the co-culture at transcriptional, proteomic, and metabolomic level. This multi-OMICs approach revealed several moderate changes, including alterations in the core metabolism, transportation, and stress signalling in both microbes, indicating multi-level interactions. These findings provide valuable insights into the complex dynamics within the co-culture system, suggesting the exchange of further molecules beyond the unidirectional feeding with sucrose.