Plant growth-promoting rhizobacteria behaviour dynamics under environmental perturbations: Selection of social and resilient consortia

The application of microbial consortia as biofertilizers has proven to be more efficient than the use of individual microorganisms. Their functional effectiveness is mainly determined by the interactions between consortium members, which decrease when antagonistic interactions predominate. However, when applied in the field, these biofertilizers are subjected to constantly changing environmental parameters that affect the growth and interactions of their members. The BSocial tool ( http://m4m.ugr.es/BSocial.html ) was used to evaluate the impact of environmental parameters (temperature, salinity and drought) across 26 different pulse perturbations on social behaviour and resilience of 8 plant growth-promoting rhizobacteria (PGPRs), belonging to different genera ( Azospirillum, Bacillus, Bradyrhizobium, Ensifer and Pseudomonas ). We observed that B. subtilis exhibited positive social behaviour (synergistic or beneficial interactions) under all perturbations, whereas the four Pseudomonas strains displayed consistent negative behaviour (antagonistic or disadvantageous interactions). In contrast, A. brasilense, B. valentinum and E. medicae exhibited positive or neutral behaviour only under half of the tested perturbations. Of the 255 consortia that make up the complete combination of the studied strains, 131 were resilient to multiple stresses. Under the different perturbations, 21 social consortia (i.e. strains with positive and neutral behaviour) were predicted, with a species diversity between 1 and 7. All social consortia, except for one, were resilient to multiparametric stresses. However, only X022 and X093 were selected as candidate social biofertilizers due to their resilience and high social potential. Furthermore, a positive correlation was observed between increased species richness and enhanced resilience across all environmental parameters studied. • Overall, social behaviour remained stable under the perturbations. • Social consortia are highly resilient to multiparametric stresses. • Resilience of consortia is positively correlated with species richness. • Bacillus subtilis TMO presented the best social and resilient potential. • The addition of a new species increases relative resilience by approximately 5%.