Spatio-Temporal dynamics of microbial co-cultures at the single-cell level in Picoliter-Scale microfluidic growth-chambers

Microfluidic single-cell cultivation is a promising technology to study individual microbial cells and micro populations under precisely controlled and dynamic environments at the micrometre scale. Traditional bulk cell culture methods typically obscure interactions and the diversity within cell populations, making it difficult to examine individual cell performances in complex biological systems, such as mixed cultures. We have developed a microfluidic setup that enables microfluidic batch-mode cultivations of cultures growing in isolated and fixed-volume (pL – nL range) monolayer growth chambers. Our system has been successfully applied to analyse the behaviour of several co-cultures and we expect to present latest data from several collaborative research projects.

The first example is the CoNoS co-culture model, in which two amino acid auxotrophic C. glutamicum strains rely on each other for growth. This work is part of the Simbal 2.0 DFG Priority Program 2170 "InterZell". Another exemplary co-culture involves an Escherichia coli "producer" organism and a Corynebacterium glutamicum "cheater" organism that requires the producer"s iron chelators for the iron uptake. The third example inhibits microorganisms competing for a scarce iron resource. More specific, one of the interacting organisms is an iron storage protein deficient mutant, which will be outcompeted in low iron environments. These two co-cultures are being investigated within the SFB 1535 MibiNet "Microbial networking – from organelles to cross-kingdom communities".

All three investigated co-cultures exhibit distinct biological behaviours (cooperation, cheating, competition), demonstrating the versatility of our new microfluidic batch chip. Key analyses of these co-cultures include single-cell growth rates, colony composition, and insights into "spatial biology".