Metabolic cooperation between conspecific genotypic groups contributes to bacterial fitness

Abstract

Microbial interactions are important for the survival of species and the stability of the microbial ecosystem. Although bacteria have diverse conspecific genotypes in the natural microbial ecosystem, little is known about whether wild-type strains within species would interact with each other and how the intraspecific interaction influences the growth of the species. In this work, using Lactobacillus acetotolerans, a dominant species with diverse conspecific genotypes in natural food fermentation ecosystems as a case, we studied the interactions between different genotypic groups of this species. In interspecific and intraspecific pairwise cocultures, the growth of L. acetotolerans decreased, but the increase of the phylogenetic similarity would reduce this negative effect, indicating a potential intraspecific interaction of this species. Meanwhile, the strain classification method affected the analysis of intraspecific interactions, which can be efficiently demonstrated using 99.5% average nucleotide identity (ANI) as the strain-level classification method. Using this ANI classification method, we revealed the population fitness significantly increased in cocultures of different genotypic groups. Facilitation involving 11 amino acids was identified between different ANI genotypic groups, which was beneficial for increasing population fitness. This work revealed that wild-type conspecific strains could interact with each other via cooperative metabolic changes and benefit each other to increase fitness. It shed new light on the survival and stability of species in natural microbial ecosystems.

Modeling Microbial Community Networks: Methods and Tools for Studying Microbial Interactions

“…These communities exhibit a variety of emergent behaviors such as biofilm formation and quorum sensing as a consequence of several inter/intraspecies interactions that range from competition for nutrient sources to cooperative networks coordinated by metabolite exchange [2,3]. An understanding of the nature of microbial interactions can help us better understand mechanisms of their stability and function [4]. However, dynamic and complex interactions within microbial communities can rarely be classified under one category.…”