Biology subjects

Arguelles Arias, A.

Publications and source records attributed to Arguelles Arias, A..

5 recordsLinked to original sources

bioRxiv2023

Deciphering the biology and chemistry of the mutualistic partnership between Bacillus velezensis and the arbuscular mycorrhizal fungus Rhizophagus irregularis

Arbuscular mycorrhizal (AM) fungi (e.g. Rhizophagus irregularis) recruit specific bacterial species in their hyphosphere. However, the chemical interplay and the mutual benefit of this intricate partnership have not yet been investigated especially as it involves bacteria known as strong producers of antifungal compounds such as Bacillus velezensis. Here, we show that the soil dwelling B. velezensis migrates along the hyphal network of the AM fungus R. irregularis, forming biofilms and inducing metabolic fluxes that contributes to host plant root colonization by the bacterium. During hyphosphere colonization, R. irregularis modulates the biosynthesis of specific lipopeptides and antimicrobial compounds in B. velezensis as a mechanism toward-off mycoparasitic fungi and bacteria to ensure stable coexistence. These mutual benefits are extended into a tripartite context via the provision of enhanced protection to the host plant through the induction of systemic resistance.

microbiology↗

bioRxiv2023

The fate of bacterial secondary metabolites in the rhizosphere: Streptomyces degrades and feeds on cyclic lipopeptides produced by competitors

Cyclic lipopeptides are key bioactive secondary metabolites produced by some plant beneficial rhizobacteria such as Pseudomonas and Bacillus. They exhibit antimicrobial properties, promote induced systemic resistance in plants and support key developmental traits including motility, biofilm formation and root colonization. However, our knowledge about the fate of lipopeptides once released in the environment and especially upon contact with neighboring rhizobacteria remains limited. Here, we investigated the enzymatic degradation of Bacillus and Pseudomonas cyclic lipopeptides by Streptomyces venezuelae. We observed that Streptomyces is able to degrade the three lipopeptides surfactin, iturin and fengycin upon confrontation with of B. velezensis in vitro and in planta according to specific mechanisms. S. venezuelae was also able to degrade the structurally diverse sessilin, tolaasin, orfamide, xantholisin and putisolvin-type lipopeptides produced by Pseudomonas, indicating that this trait is likely engage in the interaction with various competitors.Furthermore, the degradation of CLPs is associated with the release of free amino and fatty acids and was found to enhance Streptomyces growth, indicating a possible nutritional utilization. Thereby, this work stresses on how the enzymatic arsenal of S. venezuelae may contribute to its adaptation to BSMs-driven interactions with microbial competitors. The ability of Streptomyces to degrade exogenous lipopeptides and feed on them adds a new facet to the implications of the degradation of those compounds by Streptomyces, where linearization of surfactin was previously reported as a detoxification mechanism. Additionally, we hypothesize that lipopeptide-producing rhizobacteria and their biocontrol potential are impacted by the degradation of their lipopeptides as observed with the polarized motility of B. velezensis, avoiding the confrontation zone with Streptomyces and the loss of antifungal properties of degraded iturin. This work illustrates how CLPs, once released in the environment, may rapidly be remodeled or degraded by members of the bacterial community, with potential impacts on CLP-producing rhizobacteria and the biocontrol products derived from them.

microbiology↗

bioRxiv2023

Mechanosensing and Sphingolipid-Docking Mediate Lipopetide-Induced Immunity in Arabidopsis

Bacteria-derived lipopeptides are immunogenic triggers of host defenses in metazoans and plants. Root-associated rhizobacteria produce cyclic lipopeptides that activate systemically induced resistance (IR) against microbial infection in various plants. How these molecules are perceived by plant cells remains elusive. Here, we reveal that immunity activation in Arabidopsis thaliana by the lipopeptide elicitor surfactin is mediated by docking into specific sphingolipid-enriched domains and relies on host membrane deformation and subsequent activation of mechanosensitive ion channels. This mechanism leads to host defense potentiation and resistance to the necrotroph B. cinerea but is distinct from host pattern recognition receptor-mediated immune activation and reminiscent of damage-induced plant immunity.

plant biology↗

bioRxiv2021

Chelator sensing and lipopeptide interplay mediates molecular interspecies interactions between soil bacilli and pseudomonads

AbstractSome bacterial species are important members of the rhizosphere microbiome and confer protection to the host plant against pathogens. However, our knowledge of the multitrophic interactions determining the ecological fitness of these biocontrol bacteria in their highly competitive natural niche is still limited. In this work, we investigated the molecular mechanisms underlying interactions between B. velezensis, considered as model plant-associated and beneficial species in the Bacillus genus, and Pseudomonas as a rhizosphere-dwelling competitor. Our data show that B. velezensis boosts its arsenal of specialized antibacterials upon the perception of the secondary siderophore enantio-pyochelin produced by phylogenetically distinct pseudomonads and some other genera. We postulate that B. velezensis has developed some chelator sensing systems to learn about the identity of its surrounding competitors. Illustrating the multifaceted molecular response of Bacillus, surfactin is another crucial component of the secondary metabolome mobilized in interbacteria competition. Its accumulation not only enhances motility but, unexpectedly, the lipopeptide also acts as a chemical trap that reduces the toxicity of other lipopeptides released by Pseudomonas challengers. This in turn favors the persistence of Bacillus populations upon competitive root colonization. Our work thus highlights new ecological roles for bacterial secondary metabolites acting as key drivers of social interactions.

microbiology↗

bioRxiv2021

Surfactin stimulated by pectin molecular patterns and root exudates acts as a key driver of Bacillus-plant mutualistic interaction

Bacillus velezensis is considered as model species belonging to the so-called B. subtilis complex that typically evolved to dwell in the soil rhizosphere niche and establish intimate association with plant roots. This bacterium provides protection to its natural host against diseases and represents one of the most promising biocontrol agents. However, the molecular basis of the cross-talk that this bacterium establishes with its natural host has been poorly investigated. We show here that these plant-associated bacteria have evolved some polymer-sensing system to perceive their host and that in response, they increase the production of the surfactin-type lipopeptide. Furthermore, we demonstrate that surfactin synthesis is favoured upon growth on root exudates and that this lipopeptide is a key component used by the bacterium to optimize biofilm formation, motility and early root colonization. In this specific nutritional context, the bacterium also modulates qualitatively the pattern of surfactin homologues co-produced in planta and mainly forms variants that are the most active at triggering plant immunity. Surfactin represents a shared good as it reinforces the defensive capacity of the host. ImportanceWithin the plant-associated microbiome, some bacterial species are of particular interest due to the disease protective effect they provide via direct pathogen suppression and/or stimulation of host immunity. While these biocontrol mechanisms are quite well characterized, we still poorly understand the molecular basis of the cross talk these beneficial bacteria initiate with their host. Here we show that the model species Bacillus velezensis stimulates production of the surfactin lipopeptide upon sensing pectin as cell surface molecular pattern and upon feeding on root exudates. Surfactin favors bacterial rhizosphere fitness on one hand and primes the plant immune system on the other hand. Our data therefore illustrate how both partners use this multifunctional compound as unique shared good to sustain mutualistic interaction.

microbiology↗