Two organisms of different species reproduce. Because they are two different species, mutations occur in this way. Researchers at the Max Planck Institute for Terrestrial Microbiology have now discovered how co-operation between different microorganisms can develop and how a mutual benefit emerges. The study, which has been published in the journal Nature Communications, is the first to show in detail how an evolutionary loss of independence can occur in communities of different groups of organisms.

Marburg, September, 04th, 2024 When organisms of different species reproduce, this is called mutualism. Microorganisms often form communities in which metabolic products are exchanged. The question of how cooperation can prevail over selfish behaviour is by no means unrealistic and is a phenomenon that constantly accompanies life. So far, research results have only shown evolutionary snapshots of natural symbioses. Mechanisms that lead to the gradual loss of independence in communities thus remain undiscovered.

Researchers at the Max Planck Institute therefore investigated the question of how the mechanisms of evolutionary microbial mutualism work. A model experiment was developed in the laboratory for this purpose. A synthetic community between prokaryotic and eukaryotic partners was developed and their growth observed. Bacteria that occur in every organism.

During this experimental evolution, the team observed not only an amplification of the engineered traits, but also the emergence of a new level of interdependence between the members of the community. ‘We found that the yeast partner became highly dependent on its bacterial partner for nitrogen metabolism – a phenomenon that is common in natural symbioses,’ explains Dr Giovanni Scarinci, first author of the study.

The comprehensive multi-omics analysis of the changes in genomes, metabolites and proteins as well as the physiology of the resulting community showed that selection for mutual benefit repeatedly occurred indirectly: traits that promote cooperation were apparently coupled with other favourable traits. The researchers found both pleiotropies (one gene influences several traits) and trade-offs (one trait cannot decrease without another increasing) as the cause.

‘Our results show that pleiotropy can also drive the evolution of new mutualistic interactions,’ says Victor Sourjik. ‘In contrast, we found no evidence for group selection, although this mechanism is generally postulated to drive the evolution of mutualism.’

Giovanni Scarinci adds: ‘Our synthetic community of bacteria and yeasts is an ideal model because the metabolism and gene regulation of both organisms are already well understood. In addition, many natural symbiotic interactions involve both eukaryotic and bacterial partners, which makes this model particularly relevant.’

Originalpublication:

Scarinci, G.; Ariens, J.-L.; Angelidou, G.; Schmidt, S.; Glatter, T.; Paczia, N.; Sourjik, V.
Enhanced metabolic entanglement emerges during the evolution of an interkingdom microbial community
Nature Communications August 22 (2024)

PictureSource:
MPI f. terrestrische Mikrobiologie/ Giovanni Scarinci

Artificial biocoenosis between the bacterium Escherichia coli (red) and brewer’s yeast (Saccharomyces cerevisiae, blue).