From Microbial Dynamics to Functionality in the Rhizosphere: A Systematic Review of the Opportunities With Synthetic Microbial Communities

Abstract

Synthetic microbial communities (SynComs) are a useful tool for a more realistic understanding of the outcomes of multiple biotic interactions where microbes, plants, and the environment are players in time and space of a multidimensional and complex system. Toward a more in-depth overview of the knowledge that has been achieved using SynComs in the rhizosphere, a systematic review of the literature on SynComs was performed to identify the overall rationale, design criteria, experimental procedures, and outcomes of in vitro or in planta tests using this strategy. After an extensive bibliography search and a specific selection process, a total of 30 articles were chosen for further analysis, grouping them by their reported SynCom size. The reported SynComs were constituted with a highly variable number of members, ranging from 3 to 190 strains, with a total of 1,393 bacterial isolates, where the three most represented phyla were Proteobacteria, Actinobacteria, and Firmicutes. Only four articles did not reference experiments with SynCom on plants, as they considered only microbial in vitro studies, whereas the others chose different plant models and plant-growth systems; some of them are described and reviewed in this article. Besides, a discussion on different approaches (bottom-up and top-down) to study the microbiome role in the rhizosphere is provided, highlighting how SynComs are an effective system to connect and fill some knowledge gaps and to have a better understanding of the mechanisms governing these multiple interactions. Although the SynCom approach is already helpful and has a promising future, more systematic and standardized studies are needed to harness its full potential.

Uncovering New Insights and Misconceptions on the Effectiveness of Phosphate Solubilizing Rhizobacteria in Plants: A Meta-Analysis

“…Recent studies concerning synthetic microbial communities (SynComs) aim to expand the current application strategies of single and multispecies inocula ( de Souza et al, 2020 ; Marín et al, 2021 ). SynComs are composed of PGPR species and strengthened with both accessory and keystone species to obtain a robust diversity and maintain the functional stability, respectively ( Sánchez-Cañizares et al, 2017 ).…”

Comparative Analysis of the Microbial Community Structures Between Healthy and Anthracnose-Infected Strawberry Rhizosphere Soils Using Illumina Sequencing Technology in Yunnan Province, Southwest of China

“…Wu et al ( 2021 ) investigated the differences between Chinese wheat yellow mosaic resistant and susceptible wheat root endosphere and rhizosphere microbial, and the results revealed that beneficial rhizosphere microbes, such as Xanthomonadales, Actinomycetales, Sphingomonas, Rhizobium, Bacillaceae, Bacillus, Streptomycetaceae, Streptomyces, Nocardioides, Pseudonocardia, Bradyrhizobium, Pseudonocardiaceae , and Solibacteraceae , were enriched in the resistant wheat root. Some studies revealed that potential beneficial microbes, such as Bacillus, Paenibacillus, Streptomyces, Pseudomonas, Flavobacterium, Arthrobacter, Rhizobium, Microbacterium, Micrococcous , and Burkholderia , can establish disease suppression by a single strain or SynComs (synthetic microbial communities) via an antagonistic effect to protect the host from pathogens' invasion and attack (Weller et al, 2002 ; Lee et al, 2021 ; Li et al, 2021c ; Marín et al, 2021 ). In this study, Streptomyces, Azospirillum , and Bacillus were identified as the potentially beneficial bacterial genera; some studies show that species within these genera can be used to biocontrol strawberry anthracnose; other beneficial microbes, such as Chromobacterium, Caulobacter, Paenibacillus, Enterobacter, Arthrobacter, Azoarcus, Microbacterium, Pantoea, Flavobacterium , and Pseudomonas , were also detected in rhizosphere soils, and their relative abundances were changed after plants were infected by pathogens.…”

Auxin-Producing Bacteria from Duckweeds Have Different Colonization Patterns and Effects on Plant Morphology

“…Confirmation of this type of results by applying the more definitive LC–MS method to determine the identity and quantity of auxin(s) that are being produced would be important. Future work to quantify the concentration of DAB-derived IAA produced in vivo will be invaluable for creating synthetic DAB communities and understanding how they can be deployed to improve duckweed growth [ 45 ].…”