Phenotypic plasticity and a new small molecule are involved in a fungal-bacterial interaction

Andrés Andrade-Domínguez,Sergio Encarnación-Guevara,Abigail Trejo-Hernández,Carmen Vargas-Lagunas

doi:10.1038/s41598-021-98474-y

Andrés Andrade-Domínguez, Sergio Encarnación-Guevara + Show 2 more

Open Access

https://doi.org/10.1038/s41598-021-98474-y

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Journal: Scientific Reports	Publication Date: Sep 28, 2021
Citations: 4	License type: open-access

Affiliation: Universidad Nacional Autónoma de México

Abstract

Nitrogen-fixing bacteria have been extensively studied in the context of interactions with their host plants; however, little is known about the phenotypic plasticity of these microorganisms in nonmutualistic interactions with other eukaryotes. A dual-species coculture model was developed by using the plant symbiotic bacterium Rhizobium etli and the well-studied eukaryote Saccharomyces cerevisiae as a tractable system to explore the molecular mechanisms used by R. etli in nonmutual interactions. Here, we show that the fungus promotes the growth of the bacterium and that together, these organisms form a mixed biofilm whose biomass is ~ 3 times greater and is more structured than that of either single-species biofilm. We found that these biofilm traits are dependent on a symbiotic plasmid encoding elements involved in the phenotypic plasticity of the bacterium, mitochondrial function and in the production of a yeast-secreted sophoroside. Interestingly, the promoters of 3 genes that are key in plant bacteria-interaction (nifH, fixA and nodA) were induced when R. etli coexists with yeast. These results show that investigating interactions between species that do not naturally coexist is a new approach to discover gene functions and specialized metabolites in model organisms.

Highlights

Nitrogen-fixing bacteria have been extensively studied in the context of interactions with their host plants; little is known about the phenotypic plasticity of these microorganisms in nonmutualistic interactions with other eukaryotes
When S. cerevisiae Mat α Σ1278h and R.etli CE3 were grown in minimal medium with low glucose concentrations (0.1%), these species adhered to abiotic surfaces to form biofilms (Fig. 1)
Interaction with legumes has shaped and directed the evolution of nitrogen-fixing bacteria[10]. These bacteria have been subject to the pressures imposed by the environment and biotic interactions when they live as saprophytes in the soil

Summary

Introduction

Nitrogen-fixing bacteria have been extensively studied in the context of interactions with their host plants; little is known about the phenotypic plasticity of these microorganisms in nonmutualistic interactions with other eukaryotes. We show that the fungus promotes the growth of the bacterium and that together, these organisms form a mixed biofilm whose biomass is ~ 3 times greater and is more structured than that of either single-species biofilm We found that these biofilm traits are dependent on a symbiotic plasmid encoding elements involved in the phenotypic plasticity of the bacterium, mitochondrial function and in the production of a yeast-secreted sophoroside. The promoters of 3 genes that are key in plant bacteria-interaction (nifH, fixA and nodA) were induced when R. etli coexists with yeast These results show that investigating interactions between species that do not naturally coexist is a new approach to discover gene functions and specialized metabolites in model organisms. Rhizobia supply ammonia or amino acids to the plant and, in return, receive organic acids (principally as the dicarboxylic acids succinate and malate) as a carbon and energy source[10]

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