Multi-host lifestyle in plant-beneficial bacteria: an evolutionary advantage for survival and dispersal?

Plants harbour a wide diversity of microorganisms that efficiently colonize different internal and external plant organs and compartments, including the phyllosphere (above-ground plant surface), spermosphere (seeds and area surrounding seeds), endosphere (internal tissues) and rhizosphere (roots and soil in the vicinity of plant roots), establishing complex and dynamic interactions with the host plants (Trivedi et al., 2020). The plant microbiome plays major roles in the nutrition, growth and resistance against biotic and abiotic threats (Trivedi et al., 2020; Bakker and Berendsen, 2022; Yuan et al., 2022) and there is complex communication between microorganisms and their plant hosts (Berlanga- Clavero et al., 2020; Rico-Jiménez et al., 2022). Indeed, the secretion of a great variety of plant compounds directs the assembly of plant-associated microbial communities and it has been proposed that plants produce a range of chemical signals to selectively recruit specific microorganisms in order to assemble protective microbiomes that enable them to cope with the imposed biotic and abiotic stresses (Rizaludin et al., 2021; Rolli et al., 2021; Trivedi et al., 2022). As a consequence of this selective pressure exerted by the plants, the microbial composition of the rhizosphere and the non-rooted bulk soil differ – with the rhizosphere having a larger microbial abundance but lower diversity (Berlanga- Clavero et al., 2020; Sokol et al., 2022).Spanish Ministry for Science and Innovation/Agencia Estatal de Investigacion PID2019-103972GA-I00 RYC2019-026481-

The emerging role of auxins as bacterial signal molecules: Potential biotechnological applications

This study was supported through grants from the Spanish Ministry for Science and Innovation/Agencia Estatal de Investigación 10.13039/501100011033 (PID2019-103972GA-I00 to M.A.M., PID2020- 112612GB-I00 to T.K. and PID2020-116261GB-I00 to J.A.G.) and the Junta de Andalucía (grant P18- FR-1621 to T.K.). A.R. was supported by the Ramon y Cajal R&D&i Programme (RYC2019- 026481-I) from the Spanish Ministry for Science and Innovation/Agencia Estatal de Investigación 10.13039/501100011033 y FSE ‘El FSE invierte en tu futuro’.Microorganisms are exposed in their natural niches to a wide diversity of sig- nal molecules. Specific detection of these signals results in alterations in mi- crobial metabolism and physiology. Auxins like indole-3-acetic acid are key phytohormones that regulate plant growth and development. Nonetheless, auxin biosynthesis is not restricted to plants but is ubiquitous in all kingdoms of life. This wide phylogenetic distribution of auxins production, together with the diversity of regulated cellular processes, have made auxins key intra- and inter-kingdom signal molecules in life modulating, for example microbial physiology, metabolism and virulence. Despite their increasing importance as global signal molecules, the mechanisms by which auxins perform their regu- latory functions in microorganisms are largely unknown. In this article, we outline recent research that has advanced our knowledge of the mechanisms of bacterial auxin perception. We also highlight the potential applications of this research in aspects such as antibiotic production, biosensor design, plant microbiome engineering and antivirulence therapies.Spanish Ministry for Science and Innovation/Agencia Estatal de Investigacion PID2020-112612GB-I00, PID2020-116261GB-I00, RYC2019- 026481-IJunta de Andalucia P18-FR-1621, PID2019-103972GA-I0

Potential of the quorum-quenching and plant-growth promoting halotolerant Bacillus toyonensis AA1EC1 as biocontrol agent

The use of fertilizers and pesticides to control plant diseases is widespread in intensive farming causing adverse effects together with the development of antimicrobial resistance pathogens. As the virulence of many Gram-negative phytopathogens is controlled by N-acyl- homoserine lactones (AHLs), the enzymatic disruption of this type of quorum-sensing (QS) signal molecules, mechanism known as quorum quenching (QQ), has been proposed as a promising alternative antivirulence therapy. In this study, a novel strain of Bacillus toyonensis isolated from the halophyte plant Arthrocaulon sp. exhibited numerous traits associated with plant growth promotion (PGP) and degraded a broad range of AHLs. Three lactonases and an acylase enzymes were identified in the bacterial genome and verified in vitro. The AHL-degrading activity of strain AA1EC1 significantly attenuated the virulence of relevant phytopathogens causing reduction of soft rot symptoms on potato and carrots. In vivo assays showed that strain AA1EC1 significantly increased plant length, stem width, root and aerial dry weights and total weight of tomato and protected plants against Pseudomonas syringae pv. tomato. To our knowledge, this is the first report to demonstrate PGP and QQ activities in the species B. toyonensis that make this strain as a promising phytostimulant and biocontrol agent.Spanish Ministry for Science and Innovation/Agencia Estatal de Investigación 10.13039/501100011033ESF Investing in your future (Grant: RYC2019- 026481-I)Spanish Ministry for Science and Innovation/Agencia Estatal de Investigación 10.13039/501100011033 (Grant: PID2019-106704RB-100)Consejería de Universidad, Investigación e Innovación de la Junta de AndalucíaERDF A way of making Europe (Grant: B-AGR-222-UGR20

Specific Gene Loci of Clinical Pseudomonas putida Isolates

Pseudomonas putida are ubiquitous inhabitants of soils and clinical isolates of this species have been seldom described. Clinical isolates show significant variability in their ability to cause damage to hosts because some of them are able to modulate the host’s immune response. In the current study, comparisons between the genomes of different clinical and environmental strains of P. putida were done to identify genetic clusters shared by clinical isolates that are not present in environmental isolates. We show that in clinical strains specific genes are mostly present on transposons, and that this set of genes exhibit high identity with genes found in pathogens and opportunistic pathogens. The set of genes prevalent in P. putida clinical isolates, and absent in environmental isolates, are related with survival under oxidative stress conditions, resistance against biocides, amino acid metabolism and toxin/antitoxin (TA) systems. This set of functions have influence in colonization and survival within human tissues, since they avoid host immune response or enhance stress resistance. An in depth bioinformatic analysis was also carried out to identify genetic clusters that are exclusive to each of the clinical isolates and that correlate with phenotypical differences between them, a secretion system type III-like was found in one of these clinical strains, a determinant of pathogenicity in Gram-negative bacteria.Work in the authors’ laboratories was supported by ERANET Pathogenomics programme through the ADHERS project (Ref: BIO2008-04419-E) and Fondos FEDER from the European Union through project BIO2010-17227 of the Ministry of Economy and Competitivity of Spain. Bio-Iliberis R&D provided supportPeer reviewe

Analysis of the pathogenic potential of nosocomial Pseudomonas putida strains

The Supplementary Material for this article can be found online at: http://journal.frontiersin.org/article/10.3389/fmicb.2015.00871Pseudomonas putida strains are ubiquitous in soil and water but have also been reported as opportunistic human pathogens capable of causing nosocomial infections. In this study we describe the multilocus sequence typing of four P. putida strains (HB13667, HB8234, HB4184, and HB3267) isolated from in-patients at the Besançon Hospital (France). The four isolates (in particular HB3267) were resistant to a number of antibiotics. The pathogenicity and virulence potential of the strains was tested ex vivo and in vivo using different biological models: human tissue culture, mammalian tissues, and insect larvae. Our results showed a significant variability in the ability of the four strains to damage the host; HB13667 did not exhibit any pathogenic traits, HB4184 caused damage only ex vivo in human tissue cultures, and HB8234 had a deleterious effect in tissue culture and in vivo on rat skin, but not in insect larvae. Interestingly, strain HB3267 caused damage in all the model systems studied. The putative evolution of these strains in medical environments is discussed.Work in this study was supported by the ERANET Pathogenomics Program through the ADHERS-Signature Project (reference: BIO2008-04419-E)Peer reviewe

Intermittent Hypoxia Is Associated With High Hypoxia Inducible Factor-1α but Not High Vascular Endothelial Growth Factor Cell Expression in Tumors of Cutaneous Melanoma Patients

Epidemiological associations linking between obstructive sleep apnea and poorer solid malignant tumor outcomes have recently emerged. Putative pathways proposed to explain that these associations have included enhanced hypoxia inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) cell expression in the tumor and altered immune functions via intermittent hypoxia (IH). Here, we examined relationships between HIF-1α and VEGF expression and nocturnal IH in cutaneous melanoma (CM) tumor samples. Prospectively recruited patients with CM tumor samples were included and underwent overnight polygraphy. General clinical features, apnea-hypopnea index (AHI), desaturation index (DI4%), and CM characteristics were recorded. Histochemical assessments of VEGF and HIF-1α were performed, and the percentage of positive cells (0, 75%) was blindly tabulated for VEGF expression, and as 0, 0-5.9, 6.0-10.0, >10.0% for HIF-1α expression, respectively. Cases with HIF-1α expression >6% (high expression) were compared with those 75% of cells was compared with those with <75%. 376 patients were included. High expression of VEGF and HIF-1α were seen in 88.8 and 4.2% of samples, respectively. High expression of VEGF was only associated with increasing age. However, high expression of HIF-1α was significantly associated with age, Breslow index, AHI, and DI4%. Logistic regression showed that DI4% [OR 1.03 (95% CI: 1.01-1.06)] and Breslow index [OR 1.28 (95% CI: 1.18-1.46)], but not AHI, remained independently associated with the presence of high HIF-1α expression. Thus, IH emerges as an independent risk factor for higher HIF-1α expression in CM tumors and is inferentially linked to worse clinical CM prognostic indicators.IA is supported by SEPAR (086/2014 and 595/2017). MM-G is supported by the Instituto de Salud Carlos III (PI16/01772) and cofinanced by the European Development Regional Find “A way to achieve Europe” (ERDF) and SEPAR (211/2012). ER-F is the recipient of a postdoctoral fellowship from “Fundación Científica de la Asociación Española Contra el Cáncer” and supported by FMM-2013/0075 of “Fundación Mutua Madrileña.” JR-P is supported by FIS 2014/1737 from the Spanish Ministry of Health. RF is supported in part by the Spanish Ministry of Economy and Competitiveness—Instituto de Salud Carlos III (FIS-PI14/00004); DG is supported by National Institutes of Health grant 1R01HL130984 and by the Herbert T. Abelson Chair in Pediatrics

Intermittent hypoxia is associated with high hypoxia inducible factor-1α but not high vascular endothelial growth factor cell expression in tumors of cutaneous melanoma patients

Epidemiological associations linking between obstructive sleep apnea and poorer solid malignant tumor outcomes have recently emerged. Putative pathways proposed to explain that these associations have included enhanced hypoxia inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) cell expression in the tumor and altered immune functions via intermittent hypoxia (IH). Here, we examined relationships between HIF-1α and VEGF expression and nocturnal IH in cutaneous melanoma (CM) tumor samples. Prospectively recruited patients with CM tumor samples were included and underwent overnight polygraphy. General clinical features, apnea-hypopnea index (AHI), desaturation index (DI4%), and CM characteristics were recorded. Histochemical assessments of VEGF and HIF-1α were performed, and the percentage of positive cells (0, 75%) was blindly tabulated for VEGF expression, and as 0, 0-5.9, 6.0-10.0, >10.0% for HIF-1α expression, respectively. Cases with HIF-1α expression >6% (high expression) were compared with those 75% of cells was compared with those with <75%. 376 patients were included. High expression of VEGF and HIF-1α were seen in 88.8 and 4.2% of samples, respectively. High expression of VEGF was only associated with increasing age. However, high expression of HIF-1α was significantly associated with age, Breslow index, AHI, and DI4%. Logistic regression showed that DI4% [OR 1.03 (95% CI: 1.01-1.06)] and Breslow index [OR 1.28 (95% CI: 1.18-1.46)], but not AHI, remained independently associated with the presence of high HIF-1α expression. Thus, IH emerges as an independent risk factor for higher HIF-1α expression in CM tumors and is inferentially linked to worse clinical CM prognostic indicators

Estudio del metabolismo del formaldehído en Pseudomonas putida KT2440

Tesis Univ. Granada. Departamento de Fisiología Vegetal. Leída el 10 de noviembre de 200

Histamine: A Bacterial Signal Molecule

This work was supported by FEDER funds and the Fondo Social Europeo through grants from the CSIC to M.A.M. (PIE-202040I003), the Spanish Ministry for Science, Innovation and Universities to M.A.M. (PID2019-103972GA-I00), the Junta de Andalucia to T.K. (P18-FR-1621) and Spanish Ministry of Economy and Competitiveness (BIO2016-76779-P to T.K. and BIO2016-74875-P to J.A.G.). A.R. was supported by the Spanish Ministry of Science and Innovation, Promotion of Talent and its Employability-Ramon y Cajal R&D&i Programme (RYC2019-026481-I).Bacteria have evolved sophisticated signaling mechanisms to coordinate interactions with organisms of other domains, such as plants, animals and human hosts. Several important signal molecules have been identified that are synthesized by members of different domains and that play important roles in inter-domain communication. In this article, we review recent data supporting that histamine is a signal molecule that may play an important role in inter-domain and inter-species communication. Histamine is a key signal molecule in humans, with multiple functions, such as being a neurotransmitter or modulator of immune responses. More recent studies have shown that bacteria have evolved different mechanisms to sense histamine or histamine metabolites. Histamine sensing in the human pathogen Pseudomonas aeruginosa was found to trigger chemoattraction to histamine and to regulate the expression of many virulence-related genes. Further studies have shown that many bacteria are able to synthesize and secrete histamine. The release of histamine by bacteria in the human gut was found to modulate the host immune responses and, at higher doses, to result in host pathologies. The elucidation of the role of histamine as an inter-domain signaling molecule is an emerging field of research and future investigation is required to assess its potential general nature.European CommissionFondo Social Europeo through CSIC PIE-202040I003Spanish Ministry for Science, Innovation and Universities PID2019-103972GA-I00Junta de Andalucia P18-FR-1621Spanish Ministry of Economy and Competitiveness BIO2016-76779-P BIO2016-74875-PSpanish Ministry of Science and Innovation, Promotion of Talent and its Employability-Ramon y Cajal RDi Programme RYC2019-026481-

Intermittent hypoxia is associated with high hypoxia inducible factor-1α but not high vascular endothelial growth factor cell expression in tumors of cutaneous melanoma patients

Epidemiological associations linking between obstructive sleep apnea and poorer solid malignant tumor outcomes have recently emerged. Putative pathways proposed to explain that these associations have included enhanced hypoxia inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) cell expression in the tumor and altered immune functions via intermittent hypoxia (IH). Here, we examined relationships between HIF-1α and VEGF expression and nocturnal IH in cutaneous melanoma (CM) tumor samples. Prospectively recruited patients with CM tumor samples were included and underwent overnight polygraphy. General clinical features, apnea-hypopnea index (AHI), desaturation index (DI4%), and CM characteristics were recorded. Histochemical assessments of VEGF and HIF-1α were performed, and the percentage of positive cells (0, 75%) was blindly tabulated for VEGF expression, and as 0, 0-5.9, 6.0-10.0, > 10.0% for HIF-1α expression, respectively. Cases with HIF-1α expression > 6% (high expression) were compared with those 75% of cells was compared with those with < 75%. 376 patients were included. High expression of VEGF and HIF-1α were seen in 88.8 and 4.2% of samples, respectively. High expression of VEGF was only associated with increasing age. However, high expression of HIF-1α was significantly associated with age, Breslow index, AHI, and DI4%. Logistic regression showed that DI4% [OR 1.03 (95% CI: 1.01-1.06)] and Breslow index [OR 1.28 (95% CI: 1.18-1.46)], but not AHI, remained independently associated with the presence of high HIF-1α expression. Thus, IH emerges as an independent risk factor for higher HIF-1α expression in CM tumors and is inferentially linked to worse clinical CM prognostic indicators