Biology subjects

Jafra, S. J.

Publications and source records attributed to Jafra, S. J..

3 recordsLinked to original sources

bioRxiv2023

Carbon source and surface type influence the early-stage biofilm formation by rhizosphere bacterium Pseudomonas donghuensis P482.

The competence of bacteria to colonize different environmental niches is often determined by their ability to form biofilms. This depends on both cellular and extracellular factors, such as individual characteristics of a strain, type of colonized surface (abiotic or biotic) or availability and source of nutrients. Pseudomonas donghuensis P482 efficiently colonizes rhizosphere of various plant hosts, but a connection between plant tissue colonization and biofilm formation has not been verified for P482 up to date. Here we demonstrate that the ability of P482 to form biofilm on abiotic surfaces and the structural characteristics of the biofilm are connected to the type of carbon source available to the bacteria, with glycerol promoting formation of developed biofilm at early stages. Also, the type of substratum, polystyrene or glass, significantly influences the ability of P482 to attach to the surface, possibly due to hydrophobic effects. Moreover, mutants in genes associated with motility or chemotaxis, synthesis of polysaccharides, and encoding proteases or regulatory factors, affected in biofilm formation on glass were fully capable of colonizing root tissue of both tomato and maize hosts. This indicates that the ability to form biofilm on distinct abiotic surfaces does not simply correlate with the efficient colonization of rhizosphere and formation of biofilm on plant tissue by P482.

microbiology↗

bioRxiv2023

Being spontaneous has its costs! Characterization of the spontaneous phage ΦD5-resistant mutants of Dickeya solani strain IPO 2222

Lytic bacteriophages able to infect and kill Dickeya spp. can be readily isolated from virtually all Dickeya spp.-containing environments, yet little is known about the selective pressure those viruses exert on their hosts. Here, we identified two spontaneous D. solani IPO 2222 mutants (0.8% of all obtained mutants), DsR34 and DsR207, resistant to infection caused by lytic phage vB_Dsol_D5 ({Phi}D5) that expressed a reduced ability to macerate potato tuber tissues compared to the wild-type, phage-susceptible D. solani IPO 2222 strain. Genome sequencing revealed that genes encoding: secretion protein HlyD (mutant DsR34) and elongation factor Tu (EF-Tu) (mutant DsR207) were altered in these strains. Both mutations impacted the proteomes of cells grown in both rich and minimal media, including the abundance of the cell envelope and transmembrane transport-associated proteins. Furthermore, features essential for the ecological success of these mutants in a plant environment, including their ability to use various carbon and nitrogen sources, produce plant cell wall degrading enzymes, ability to form biofilms, siderophore production, swimming and swarming motility and virulence in planta were assessed. Compared to the wild-type strain, D. solani strain IPO 2222, mutants DsR34 and DsR207 had a reduced ability to macerate chicory leaves and to colonize and cause symptoms in growing potato plants. The implications of the {Phi}D5 resistance on driving traits affecting the ecological performance of D. solani are discussed.

microbiology↗

bioRxiv2022

Shared and host-specific transcriptomic response of Pseudomonas donghuensis P482 to the exudates of tomato (Dicot) and maize (Monocot) shed light on the host-adaptive traits in the promiscuous root colonizing bacteria

Plants of different genotypes and physiological states recruit different populations of root microbiota. The selection is driven by the immune response of the plant and the composition of root exudates. Some bacteria, including Pseudomonas spp., are promiscuous root colonizers. It is yet unclear what particular changes in lifestyle enable them to thrive in the company of different plant hosts. In this study, we used RNAseq to identify genes of the differential (host-specific) and shared (host-independent) transcriptomic responses of a biocontrol strain Pseudomonas donghuensis P482 to the root exudates of two phylogenetically distinct plant species, tomato (Dicot) and maize (Monocot), both of which can be colonized by the bacterium. The host-independent response of P482 to exudates involved upregulated expression of arsenic resistance genes and bacterioferritin synthesis. Contrary, we observed downregulation of pathways related to sulfur assimilation, sensing of ferric citrate and/or other iron carriers, the acquisition of heme, the assembly of the type VI secretion system, and amino acid transport. Pathways upregulated in P482 specifically by tomato exudates included nitric oxide detoxification, repair of iron-sulfur clusters, respiration through the cyanide-insensitive cytochrome bd, and catabolism of amino acids and/or fatty acids. The maize-specific response included upregulation of genes associated with motility, the activity of MexE and two other RND efflux pumps, and copper tolerance. To provide more context to the study, we determined the chemical composition of exudates by GC-MS, NMR, and LC-SRM. Our results bring new insight into the host-driven metabolic adaptations of promiscuous root colonizing bacteria. Significance statementUnderstanding factors determining the composition and the activity of plant-associated microbiota is crucial to harnessing their potential to benefit plant health. Traits that enable microorganisms to colonize plants have long been the subject of study, with many important factors identified for particular host-microbe systems. However, studies involving more than a single plant host are rare. This results in many unanswered questions on the host-specific and universal aspects of metabolism that enable more promiscuous root colonizers to interact with different plant hosts. The presented study begins to fill this knowledge gap by providing data on the metabolic pathways involved in the differential and shared response of Pseudomonas donghuensis strain P482 to the exudates of phylogenetically distant plant species: tomato and maize.

microbiology↗