Thomas Ledger

Adolfo Ibáñez University · Facultad de Ingeniería y Ciencias

Background and Aims Nitrogen (N) is essential for plant growth, yet the role of diazotrophic bacteria in non-nodulating plants, particularly from the β-class Pseudomonadota, remains unclear. We explored the mechanisms underlying the interaction of Cupriavi- dus taiwanensis LMG19424, belonging to this group and known for nodulation induction in Mimo...

Background and Aims Nitrogen (N) is essential for plant growth, yet the role of diazotrophic bacteria in non-nodulating plants, particularly from the β-class Pseudomonadota, remains unclear. We explored the mechanisms underlying the interaction of Cupriavidus taiwanensis LMG19424, belonging to this group and known for nodulation induction in Mimosa...

Introduction This work investigates whether rhizosphere microorganisms that colonize halophyte plants thriving in saline habitats can tolerate salinity and provide beneficial effects to their hosts, protecting them from environmental stresses, such as aromatic compound (AC) pollution. Methods To address this question, we conducted a series of expe...

As holobiont, a plant is intrinsically connected to its microbiomes. However, some characteristics of these microbiomes, such as their taxonomic composition, biological and evolutionary role, and especially the drivers that shape them, are not entirely elucidated. Reports on the microbiota of Arabidopsis thaliana first appeared more than ten years...

Background Rhizosphere microorganisms play a crucial role in plant health and development. Plant root exudates (PRE) are a complex mixture of organic molecules and provide nutritional and signaling information to rhizosphere microorganisms. Burkholderiaceae species are non-abundant in the rhizosphere but exhibit a wide range of plant-growth-promoti...

Plants must deal with harsh environmental conditions when colonizing abandoned copper mine tailings. We hypothesized that the presence of a native microbial community can improve the colonization of the pioneer plant, Baccharis linearis , in soils from copper mining tailings. Plant growth and microbial community compositions and dynamics were deter...

In Veliz-Cuba and Stigler 2011, Boolean models were proposed for the lac operon in Escherichia coli capable of reproducing the operon being OFF, ON and bistable for three (low, medium and high) and two (low and high) parameters, representing the concentration ranges of lactose and glucose, respectively. Of these 6 possible combinations of parameter...

Numerous microbial taxa establish natural relations with plants, and especially endophytes can be relevant in the development and growth promotion of their host. In this work, we explore the diversity of non-halophilic microorganisms inhabiting the endosphere of the halophyte Arthrocnemum macrostachyum. A total of 1045 isolates were recovered using...

There have been over 25 independent unicellular to multicellular evolutionary transitions, which have been transformational in the complexity of life. All of these transitions likely occurred in communities numerically dominated by unicellular organisms, mostly bacteria. Hence, it is reasonable to expect that bacteria were involved in generating th...

Abiotic stress has a growing impact on plant growth and agricultural activity worldwide. Specific plant growth promoting rhizobacteria have been reported to stimulate growth and tolerance to abiotic stress in plants, and molecular mechanisms like phytohormone synthesis and 1-aminocyclopropane-1-carboxylate deamination are usual candidates proposed...

Salinity is one of the major limitations for food production worldwide. Improvement of plant salt-stress tolerance using plant-growth promoting rhizobacteria (PGPR) has arisen as a promising strategy to help overcome this limitation. However, the molecular and biochemical mechanisms controlling PGPR/plant interactions under salt-stress remain uncle...

It becomes increasingly clear that the basis of antibiotic resistance problem among bacterial pathogens is not confined to the borders of clinical microbiology but has broader ecological and evolutionary associations. This Research Topic “Role and prevalence of antibiosis and the related resistance genes in the environment” in Frontiers in Microbio...

Although not fully understood, molecular communication in the rhizosphere plays an important role regulating traits involved in plant-bacteria association. Burkholderia phytofirmans PsJN is a well-known plant growth promoting bacterium, which establishes rhizospheric and endophytic colonization in different plants. A competent colonization is essen...

Aims This work addresses the relevant effects that one single compound, used as model herbicide, provokes on the activity/survival of a suitable herbicide degrading model bacterium and on a plant that hosts this bacterium and its bacterial rhizospheric community. Methods The effects of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), on Acaci...

The role of broad-host range IncP-1ε plasmids in the dissemination of antibiotic resistance in agricultural systems has not yet been investigated. These plasmids were detected in total DNA from all of 16 manure samples and in arable soil based on a novel 5′-nuclease assay for real-time PCR. A correlation between IncP-1ε plasmid abundance and antibi...

Plant rhizosphere and internal tissues may constitute a relevant habitat for soil bacteria displaying high catabolic versatility towards xenobiotic aromatic compounds. Root exudates contain various molecules that are structurally related to aromatic xenobiotics and have been shown to stimulate bacterial degradation of aromatic pollutants in the rhi...

Functional distribution of unique genes. COG categories are as follows: Information storage and processing: A, RNA processing, modification; B, chromatin structure; J, translation, ribosomal structure/biogenesis; K, transcription; L, DNA replication, recombination, repair. Cellular processes: D, cell division, chromosome partitioning; M, cell envel...

Functional annotation of key metabolic genes of C. necator JMP134. (0.27 MB DOC)

Cupriavidus necator JMP134 is a Gram-negative beta-proteobacterium able to grow on a variety of aromatic and chloroaromatic compounds as its sole carbon and energy source. Its genome consists of four replicons (two chromosomes and two plasmids) containing a total of 6631 protein coding genes. Comparative analysis identified 1910 core genes common t...

Cupriavidus necator JMP134(pJP4) is able to grow on 3-chlorobenzoate (3-CB), a model chloroaromatic pollutant. Catabolism of 3-CB is achieved via the expression of the chromosomally encoded benABCD genes and the tfd genes from plasmid pJP4. Since passive diffusion of benzoic acid derivatives at physiological pH is negligible, the uptake of this com...

Phenoxyalkanoic compounds are used worldwide as herbicides. Cupriavidus necator JMP134(pJP4) catabolizes 2,4-dichlorophenoxyacetate (2,4-D) and 4-chloro-2-methylphenoxyacetate (MCPA), using tfd functions carried on plasmid pJP4. TfdA cleaves the ether bonds of these herbicides to produce 2,4-dichlorophenol (2,4-DCP) and 4-chloro-2-methylphenol (MCP...

Ralstonia eutropha JMP134 (pJP4) is a useful model for the study of bacterial degradation of substituted aromatic pollutants. Several key degrading capabilities, encoded by tfd genes, are located in the 88 kb, self-transmissible, IncP-1 beta plasmid pJP4. The complete sequence of the 87,688 nucleotides of pJP4, encoding 83 open reading frames (ORFs...

Ralstonia eutropha JMP134(pJP4) degrades 3-chlorobenzoate (3-CB) by using two not completely isofunctional, pJP4-encoded chlorocatechol degradation gene clusters, tfdCIDIEIFI and tfdDIICIIEIIFII. Introduction of several copies of each gene cluster into R. eutropha JMP222, which lacks pJP4 and thus accumulates chlorocatechols from 3-CB, allows the d...

Many bacteria can grow on chloroaromatic pollutants because they can transform them into chlorocatechols, which are further degraded by enzymes of a specialized ortho-cleavage pathway. Ralstonia eutropha JMP134 is able to grow on 3-chlorobenzoate by using two pJP4-encoded, ortho-cleavage chlorocatechol degradation gene clusters (tfdC(I)D(I)E(I)F(I)...