Artículos (Microbiología y Parasitología)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11055

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Emergence and persistence of ESBL- and carbapenemase-producing Klebsiella pneumoniae-related species in Barcelona wastewater treatment plants
(American Society for Microbiology, 2026-06-30) Ballen, Victoria; Delgado, Karol; Pinar-Mendez, Anna; Vilaro, Carles; Galofre, Belen; Marti, Sara; Alcalde Rico, Manuel; Soto, Sara M.; Microbiología y Parasitología; Instituto de Salud Carlos III; Generalitat de Catalunya; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España
The World Health Organization classifies extended-spectrum beta-lactamase (ESBL) and carbapenemase-producing Klebsiella pneumoniae as critical-priority pathogens due to their high incidence, mortality, transmissibility, rapid resistance acquisition, and limited treatment options. Beyond clinical settings, their detection in wastewater treatment plants (WWTPs) provides an opportunity to assess their prevalence, persistence, and circulation within wastewater systems. This study characterized 37 antibiotic-resistant K. pneumoniae-related species strains isolated from two WWTPs in the metropolitan area of Barcelona, analyzing their antimicrobial resistance (AMR) profiles, antimicrobial resistance genes (ARGs), biocide and heavy metal tolerance genes (HMTGs), virulence factor genes (VFGs), biofilm-forming capacity, and conjugation ability. Among them, 70.3% were multidrug-resistant (MDR), and 16.2% were extensively drug-resistant. Whole-genome sequencing revealed diverse ARGs; all strains carried β-lactam resistance genes (14 ESBL and 12 carbapenemase producers), nearly all (96.9%) carried biocide or HMTGs, 64.9% harbored integrases, and all carried VFGs. Core-genome SNP analysis identified closely related strains across sampling periods and treatment stages, suggesting long-term persistence within the wastewater treatment system, despite biological and chemical processes in secondary treatment. Most strains (67.6%) displayed biofilm-forming capacity, and conjugation assays confirmed horizontal gene transfer in five of the seven ESBL-producing strains tested. High-risk clones were predominantly detected in the IFAS secondary treatment stage of the Gavà-Viladecans WWTP. The three strains recovered from the reclaimed water of the Baix Llobregat WWTP were ESBL or carbapenemase producers. Altogether, these results provide genomic and phenotypic evidence of the persistence and circulation of antibiotic-resistant K. pneumoniae-related species within wastewater treatment systems.IMPORTANCEWWTPs are essential for urban sanitation and environmental protection. Understanding how clinically relevant pathogens, such as ESBL and carbapenemase-producing K. pneumoniae-related species strains, behave in these settings may inform public health considerations. Investigating the presence and persistence of high-risk MDR pathogens in WWTPs helps identify circulation of AMR, assess the risk of gene transfer, and evaluate the potential for co-selection with other contaminants. This knowledge supports efforts to improve wastewater treatments, strengthen environmental surveillance, and develop integrated One Health strategies to limit the spread of AMR across human, animal, and environmental sectors.
Uncovering the endophytic bacterial diversity and crop improvement potential under salinity stress in the halophyte Halocnemum strobilaceum
(Elsevier, 2026-05-21) Romano Rodríguez, Elena; Flores Duarte, Noris J.; Pajuelo Domínguez, Eloísa; Rodríguez Llorente, Ignacio David; Mateos Naranjo, Enrique; Redondo Gómez, Susana; Navarro de la Torre, Salvadora; Biología Vegetal y Ecología; Microbiología y Parasitología; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Union (UE); Universidad de Sevilla
Halophytes are considered promising sources of halophilic and halotolerant bacteria for biotechnological applications in agriculture, particularly as soil salinization threatens crop yield. Although interest in halophyte- associated endophytic bacteria has increased in recent years, their diversity remains insufficiently explored. In this study, we investigated the diversity of the bacterial endobiome of H. strobilaceum from three populations in Murcia, Spain. A total of 76 endophytic bacterial strains were isolated and identified using 16S rRNA gene sequencing. Most isolates (96.05%) exhibited in vitro plant growth-promoting traits, including phosphate and potassium solubilization, auxin and siderophores production, biofilm formation, and plant health-related enzymatic activities. To assess their biostimulant potential, selected strains (EE4, EE22 T , TE3 T , and EE7 T ) were tested individually and as a consortium using Medicago sativa grown under salinity stress. Bacterial inoculation significantly improved plant growth and physiological performance, with the consortium showing the strongest positive effects compared with the individual strains. Eight isolates were selected for whole-genome sequencing based on 16S rRNA gene analysis. Comparative genomic analyses, including average nucleotide identity and digital DNA–DNA hybridization, revealed four novel species belonging to the genera Kushneria and Vreelandella (ANI<95–96%, dDDH<70%), and their physiological, genetic, and biochemical characteristics are described. Based on phylogenomic studies, we have proposed the name Kushneria halocnemicola sp. nov. TE3 T xerophytica sp. nov. EE22 T , Vreelandella halophytica sp. nov. EE7 T , Vreelandella and Vreelandella mediterranea sp. nov. TE19 . Overall, this study provides new insights into the diversity of halophyte endophytic bacteria and reports novel species for biotechnological applications in agriculture under salinity stress.
Plant-Based Flavones of Therapeutic Interest Loaded into Polymeric Nanoparticles
(MDPI, 2026-05-29) Espíndola, Cecilia; Martín, Victoria I.; Bernal Pérez, Eva; Lebrón Romero, José Antonio; Moyá Morán, María Luisa; Ruiz de la Haba, Rafael; Sánchez-Porro Álvarez, Cristina; Ventosa Ucero, Antonio; Granados Carrera, Carmen M.; López-Cornejo, María del Pilar; Ostos Marcos, Francisco José; Química Física; Microbiología y Parasitología; Ingeniería Química; Gobierno de España; Junta de Andalucía; Universidad de Sevilla
Background/Objectives: Flavonoids are low-molecular-weight polyphenolic compounds that are universally distributed in plants. They are a chemically varied group of secondary metabolites with a broad range of biological activity. The use of flavonoids is known to decrease the risk of many chronic diseases due to their radical scavenging, antioxidant, anti-inflammatory, anticarcinogenic, and antimutagenic properties. Limitations in the use of flavonoids include their low water solubility and poor stability, and therefore their low bioavailability. The encapsulation of flavonoids in different nanocarriers has helped to overcome this limitation. Taking this into account, in this work, the encapsulation of four flavones with several therapeutic applications—7-hydroxyflavone, 7,8-dihydroxyflavone, baicalein, and luteolin—in poly(lactic-co-glycolic) acid (PLGA)-derived polymeric nanoparticles (NPs) has been investigated. Methods: A physicochemical characterization of the NPs has been carried out using different techniques, including the evaluation of antioxidant and antimicrobial activities. Results: In all cases, the incapsulation efficiency of the four flavones in the prepared NPs was high (>90%), the zeta potential was about −31 mV, and the size was nanometric (~450 nm). The drug release from the nanoparticles was also studied, showing first-order kinetics. Statistical tools were applied to the release rate constants. The antioxidant activity and the in vitro antimicrobial activity of the free and flavone-loaded NPs were investigated, in the case of the latter using Gram-positive and Gram-negative bacteria. Results show that when the flavones are encapsulated, they retain their therapeutic properties. Conclusions: In summary, PLGA-based NPs not only prevent flavone degradation but also significantly boost solubility, ultimately optimizing bioavailability. Our results underscore these NPs as a promising platform for efficient flavone delivery.
Genome sequence of Stenotrophomonas indicatrix CPHE1, a powerful phenanthrene-degrading bacterium
(Springer Nature, 2023-01-18) Lara Moreno, Alba; Morillo, Esmeralda; Merchán Ignacio, Francisco; González Pimentel, José Luis; Villaverde, Jaime; Microbiología y Parasitología; Bioquímica Vegetal y Biología Molecular; Ministerio de Economía y Competitividad (MINECO). España
Environmental pollution caused by polycyclic aromatic hydrocarbons (PAHs) involves a high-risk and have received considerable attention due to their carcinogenic, teratogenic, and mutagenic properties. Phenanthrene (PHE) is a low molecular weight PAH, which has three benzene rings. It is one of the most common PAH found in contaminated environments mainly due to its low volatilization ability and hydrophobic character. A PHE degrading bacterium was isolated from an industrial contaminated soil using enrichment culture techniques. Based on macroscopic, microscopic examination and phylogenetic analysis, this bacterium was classified as Stenotrophomonas indicatrix and named strain CPHE1. Several authors have reported about bacteria stains, which can degrade PHE, but this is the first time where the ability of S. indicatrix to biodegrade and mineralize PHE has been demonstrated.
Judicial Opinion 130
(Society General Microbiology, 2024) Arahal, David R.; Bull, Carolee T.; Christensen, Henrik; Chuvochina, Maria; Dunlap, Christopher; Montero-Calasanz, María del Carmen; Parker, Charles T.; Vandamme, Peter; Ventosa Ucero, Antonio; Goker, Markus; Microbiología y Parasitología; National Institute of Food and Agriculture. United States.; Australian Research Council; Ministerio de Universidad e Investigación. Italia.; Plan Nacional de Recuperación y Resiliencia (PNRR). Italia.
Opinion 130 deals with a Request for an Opinion asking the Judicial Commission to clarify whether the genus name Rhodococcus Zopf 1891 (Approved Lists 1980) is illegitimate. The Request is approved and an answer is given. The name Rhodococcus Zopf 1891 (Approved Lists 1980) is illegitimate because it is a later homonym of the validly published cyanobacterial name Rhodococcus Hansgirg 1884. The Judicial Commission also clarifies that it has the means to resolve such cases by conserving a name over an earlier homonym. It is concluded that the name Rhodococcus Zopf 1891 (Approved Lists 1980) is significantly more important than the name Rhodococcus Hansgirg 1884 and therefore the former is conserved over the latter. This makes the name Rhodococcus Zopf 1891 (Approved Lists 1980) legitimate.
Judicial Opinion 132
(Microbiology Society, 2025) Arahal, David R.; Bull, Carolee T.; Christensen, Henrik; Chuvochina, Maria; Dunlap, Christopher; Montero-Calasanz, Maria Del Carmen; Parker, Charles T.; Vandamme, Peter; Ventosa Ucero, Antonio; Göker, Markus; Microbiología y Parasitología; USDA National Institute of Food and Agriculture (NIFA) United States; Italian National Biodiversity Future Center; Ministero dell'Università e della Ricerca. Italia; Piano Nazionale di Ripresa e Resilienza (PNRR). Italia
Opinion 132 deals with a Request for an Opinion asking the Judicial Commission to assess the nomenclatural status of Skermania piniformis (Blackall et al. 1989) Chun et al. 1997, a new combination affected by an unusual change in the epithet of its basonym, Nocardia pinensis Blackall et al. 1989. This is done by re-evaluating Opinion 85, which sets a precedent. The reasons and consequences of this earlier Opinion are explained in detail, and corresponding guidelines for orthographic corrections are given, along with further guidance derived from more recently published Judicial Opinions. The request to change the epithet to Skermania pinensis corrig. (Blackall et al. 1989) Chun et al. 1997 is granted, and it is also emphasized that this does not affect the legitimacy or the date of valid publication of the names involved. The Judicial Commission also grants the third request made in the same article and rules that, according to Rule 54 of the International Code of Nomenclature of Prokaryotes (ICNP), it is not necessary, and even unwise, to propose two names for the same taxon in the same study to replace an illegitimate name.
Accelerated ibuprofen removal in soils via bioaugmentation: Insights into the involved microbiomes
(Elsevier, 2026) Madrid, Fernando; Morillo, Esmeralda; Martin-Sánchez, Pedro M.; Villaverde, Jaime; Lara Moreno, Alba; Microbiología y Parasitología; Junta de Andalucía; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Ibuprofen (IBP), a widely used pharmaceutical compound, is increasingly detected in soils, raising concerns regarding its persistence and potential impacts on microbial communities and crop health. This study evaluated the adsorption, desorption, and biodegradation of IBP in three soils (ALC, CON, ETS) with contrasting agricultural uses, physicochemical and microbiological characteristics, and monitored shifts in microbial communities during bioremediation. Sorption was weak and strongly influenced by soil organic matter. Desorption was substantial in ALC and CON soils (38–50%) but nearly negligible in ETS (<6.5%). Biodegradation assays confirmed microbial activity as the primary dissipation pathway. Abiotic controls exhibited limited removal (14–23.5%), whereas endogenous microbiota facilitated faster dissipation in ALC and CON (DT₅₀ = 3.3 days) and slower in ETS (12.2 days), associated with its low desorption rate. Bioaugmentation with the IBP-degrading C7 consortium markedly accelerated dissipation across all soils (DT₅₀ = 0.3–0.6 days), demonstrating its strong potential for IBP remediation.
Modelling and optimization of cadmium adsorption using dead Pseudomonas biomass isolates from brassware effluents using Box-Behnken Design and Artificial Neural Networks
(Elsevier, 2026) Mrizak, Fatima ez Zahrae; Hamidallah, Konouz; Elsenety, Mohamed M.; Benali, Mona; Amine Chajid, Mohamed; Rodríguez Llorente, Ignacio David; Merzouki, Mohammed; Microbiología y Parasitología
This study investigates the potential of indigenous dead Pseudomonas biomass isolated from brassware workshop effluents as a potential adsorbent for cadmium elimination from effluents, addressing the dual challenge of metallic pollution and industrial waste management. The optimization of cadmium adsorption capacity by dead Pseudomonas biomass has been accomplished through a Box-Behnken Design integrated with Response Surface Methodology and Artificial Neural Networks. Optimal parameters identified (temperature 45°C, pH 9, biosorbent dose 2 g. L−1, contact duration 75 min) enabled achievement of a maximum removal efficiency of 99.69 %. The dead Pseudomonas biomass was characterized using X-ray diffraction, iodine index determination, scanning electron microscopy, zeta potential analysis, X-ray fluorescence spectroscopy, Brunauer-Emmett-Teller surface analysis, and Fourier-transform infrared spectroscopy. The favorable mesoporous structure (specific surface 16.69 m2. g−1, pore volume 0.02294 cm3.g−1, average pore diameter 5.50 nm) for metallic ion diffusion has been confirmed. Adsorption equilibrium analysis indicates that the Langmuir model best represents the process, with a maximum adsorption capacity of 52.34 mg. g−1 consistent with monolayer adsorption on homogeneous sites. Kinetic study validates the pseudo-second-order model as the best fit, suggesting chemisorption as the rate-limiting step. Thermodynamic parameters confirm the spontaneous and endothermic nature of biosorption. Overall, this work demonstrates a circular economy approach by valorizing industrial effluents into efficient biosorbents, simultaneously addressing pollution control and waste management challenges in the metal finishing industry.
Acute gluten-induced inflammatory response highlights CCL20 as a potential biomarker for celiac disease
(Frontiers Media SA, 2026) Gómez-Aguililla, Sara; Farrais, Sergio; López-Palacios, Natalia; Arau, Beatriz; Senosiain, Carla; Infante-Menéndez, Jorge; Ruiz Carnicer, Ángela; Fernández-Bañares, Fernando; Sousa Martín, Carolina; Núñez, Concepción; Microbiología y Parasitología; Agencia Estatal de Investigación. España; Instituto de Salud Carlos III; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Background: Diagnosis of celiac disease (CD) remains challenging in individuals already on a gluten-free diet (GFD). Although several alternative methods have been proposed, they have limitations. Identifying inflammation-related proteins that rapidly respond to gluten exposure in blood may offer diagnostic alternatives. We aimed to characterize the inflammatory protein response to gluten in patients with CD on a GFD, and to assess the diagnostic potential of candidate biomarkers and their association with clinical symptoms.Methods: Seventeen patients with CD and 15 non-CD individuals on a GFD (≥ 1 month) consumed 10 g of gluten. Serum, plasma and clinical symptoms were collected at baseline and 4 h post-gluten ingestion to assess changes in 92 inflammation-related proteins. CCL20 levels were also measured by ELISA in plasma from 13 patients with CD and 11 non-CD individuals from the initial cohort, and in an additional group of 28 individuals evaluated for suspected CD, three of whom received a final diagnosis of CD. In 15 patients with CD, the results were compared to those of other diagnostic approaches.Results: Twelve proteins showed significantly different fold changes following gluten challenge between CD and non-CD groups. Six showed an AUC ≥80%, and CCL20 achieved 81.3-85.7% sensitivity and 88.9-92.7% specificity for CD diagnosis. CCL20 level increases post-gluten challenge were higher in patients with vomiting but were also observed in those with absent or mild symptoms.Conclusion: Gluten reintroduction triggers alterations in the inflammation-related protein profile of patients with CD. CCL20 emerges as a promising diagnostic candidate, its increase in plasma or serum, with low dependence on symptom presentation, may complement existing diagnostic approaches.
Effect of Bacille Calmette–Guérin vaccination on immune responses to SARS-CoV-2 and COVID-19 vaccination
(Wiley, 2025-01-20) Messina, Nicole L.; Germano, Susie; Chung, Amy W.; van de Sandt, Carolien E.; Stevens, Natalie E.; Allen, Lilith F.; BRACE Trial Consortium Group; Pascual Hernández, Álvaro; Rodríguez-Baño, Jesús; Medicina; Microbiología; National Health and Medical Research Council; Royal Children's Hospital Foundation; Bill and Melinda Gates Foundation; Minderoo Foundation; Swiss National Science Foundation (SNFS); Australian Research Council; CTS210: Resistencia a Antimicrobianos
Objectives: Bacille Calmette–Guérin (BCG) vaccination has off-target effects on disease risk for unrelated infections and immune responses to vaccines. This study aimed to determine the immunomodulatory effects of BCG vaccination on immune responses to vaccines against SARS-CoV-2. Methods: Blood samples, from a subset of 275 SARS-CoV-2-naïve healthcare workers randomised to BCG vaccination (BCG group) or no BCG vaccination (Control group) in the BRACE trial, were collected before and 28 days after the primary course (two doses) of ChAdOx1-S (Oxford-AstraZeneca) or BNT162b2 (Pfizer-BioNTech) vaccination. SARS-CoV-2-specific antibodies were measured using ELISA and multiplex bead array, whole blood cytokine responses to γ-irradiated SARS-CoV-2 (iSARS) stimulation were measured by multiplex bead array, and SARS-CoV-2-specific T-cell responses were measured by activation-induced marker and intracellular cytokine staining assays. Results: After randomisation (mean 11 months) but prior to COVID-19 vaccination, the BCG group had lower cytokine responses to iSARS stimulation than the Control group. After two doses of ChAdOx1-S, differences in iSARS-induced cytokine responses between the BCG group and Control group were found for three cytokines (CTACK, TRAIL and VEGF). No differences were found between the groups after BNT162b2 vaccination. There were also no differences between the BCG and Control groups in COVID-19 vaccine-induced antigen-specific antibody responses, T-cell activation or T-cell cytokine production. Conclusion: BCG vaccination induced a broad and persistent reduction in ex vivo cytokine responses to SARS-CoV-2. Following COVID-19 vaccination, this effect was abrogated, and BCG vaccination did not influence adaptive immune responses to COVID-19 vaccine antigens.
Uncovering the Prokaryotic Diversity of Hypersaline Soils of Odiel Saltmarshes Natural Area Through Metagenome-Assembled Genomes
(Multidisciplinary Digital Publishing Institute (MDPI), 2026-02-18) Galisteo Gómez, Cristina; Puente-Sánchez, Fernando; Ruiz de la Haba, Rafael; Bertilsson, Stefan; Ventosa Ucero, Antonio; Sánchez-Porro Álvarez, Cristina; Microbiología y Parasitología; Ministerio de Ciencia e Innovación (MICIN). España; Swedish Research Council (Vetenskapsrådet)
The hypersaline soils of the Odiel Saltmarshes Natural Area in Southwest Spain harbor highly diverse microbial communities adapted to extreme conditions. However, their genomic diversity remains largely unexplored. In addition to high salinity, these soils are contaminated with heavy metals, creating a hostile environment of great interest for studying extremophilic microorganisms and their metabolic adaptations. This study aims to characterize the uncovered prokaryotic taxa as Candidatus species inhabiting the hypersaline soils of the Odiel Saltmarshes, based on their metagenomic assembled genomic sequences. The reconstructed genomes were assessed for quality based on completeness and contamination thresholds and subsequently taxonomically classified. Comparative genomic analysis of six high-quality MAGs revealed key metabolic traits related to survival under extreme salinity and heavy metal conditions. The findings provide new insights about microbial diversity of hypersaline environments and expand the catalog of known prokaryotic genomes. Detailed characterization of six novel Candidatus taxa highlights the unique adaptations of these microorganisms, enhancing our understanding of life in extreme habitats.
Standardizing Intestinal Permeability Assessment: Optimization of Gluten Dose and Urine Collection Times for u-GIP and Lactulose:Mannitol Ratio in Healthy Volunteers
(Multidisciplinary Digital Publishing Institute (MDPI), 2026-02-28) Rodríguez-Ramírez, Raquel; Fernández Peralbo, María Auxilidiadora; Cebolla, Ángel; Sousa Martín, Carolina; Microbiología y Parasitología; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
Urinary gluten immunogenic peptides (u-GIPs) have been proposed as a complementary marker to classical intestinal permeability tests based on lactulose, mannitol, and the lactulose:mannitol ratio (LMR). However, the effects of gluten dose, urine collection interval, and sampling strategy on their performance remain insufficiently defined. This study evaluated these variables to support protocol standardization. Data from four standardized protocols including 46 healthy adults exposed to 0, 2, 4, or 10 g of gluten were analyzed. All participants ingested fixed doses of lactulose and mannitol. Urine was collected cumulatively (0–6 h and 0–15 h) or by individual voids. u-GIP levels were measured by lateral-flow immunoassay, and lactulose and mannitol by ion chromatography. u-GIP excretion showed a clear dose dependence. Lactulose excretion increased transiently only at the 10 g dose during the 0–6 h interval, while mannitol excretion and LMR were unaffected. The u-GIP excretion index showed linear proportionality at the 2 g and 4 g doses but exhibited saturation kinetics at the 10 g dose. The 4 g dose showed the lowest interindividual variability. Sampling strategies yielded equivalent results. A 4 g gluten challenge combined with a 6 h urine collection demonstrated effectiveness in healthy volunteers and may be suitable for clinical application. Further research involving larger cohorts of both healthy individuals and patients with intestinal hyperpermeability is required to validate this method.
Antimicrobial Resistance in Bacterial Strains of Agricultural Interest: Predictions Based on Genomic Data
(Multidisciplinary Digital Publishing Institute (MDPI), 2025-12-20) Pajuelo Domínguez, Eloísa; Medina Rodríguez, Manuel; Flores Duarte, Noris J.; Doukkali, Bouchra; Mesa Marín, Jennifer; Rodríguez Llorente, Ignacio David; Navarro Torre, Salvadora; Microbiología y Parasitología; Fertiberia S.L
Background: Plant growth promoting bacteria (PGPB) are non-pathogenic bacteria that enhance plant growth through several mechanisms such as nutrient mobilization, phytohormones production, defense against phytopathogens, and alleviation of plant stress. Hence, these bacteria are used as ecologic biofertilizers to diminish the use of agrochemicals. Nevertheless, some PGPR strains can harbor antibiotic resistance determinants and the possibility of spreading them upon releasing these bacteria is an environmental concern. Objectives: The objectives of this work are as follows: (1) evaluating the antibiotic resistance in a collection of PGPB, and (2) prospecting antibiotic resistance genes in the genomes of PGPB in order to predict the risk for antibiotic resistance dissemination. Methods: The resistance towards 12 antibiotics in a collection of 20 PGPB (10 Gram-positive and 10 Gram-negative strains) has been evaluated using disk diffusion in agar, broth microdilution, and agar dilution tests. In addition, the whole genomes of six strains have been sequenced in order to find the correlation between the resistance levels and AMR genes by using bioinformatic tools. Results: The results indicated a wide range of halo diameters, but in general Gram-negatives showed higher resistance compared to Gram-positives. The four most resistant strains and the two more susceptible strains were selected for further analysis and sequencing the whole genomes. The resistant strains were identified as Achromobacter spanius N6, Leclercia adecarboxylata H17, Priestia aryabhattai strain MHA1, and Bacillus cereus N25. The susceptible strains were identified as Pantoea sp. S3 and Priestia megaterium MS4. Mining antibiotic resistance genes in the genomes confirmed the existence of resistance determinants responsible for the phenotypic behavior, indicating the potential of genomics for predicting antibiotic resistance in PGPB. However, there was not an exact correspondence between the presence of the genes and the level of resistance, suggesting the existence of additional regulatory mechanisms. Conclusions: The information obtained by genomics must be complemented experimentally by tests for antibiotic resistance determination. In this regard, it is necessary to develop a global antibiotic resistance database for PGPB, due to the difficulty of interpretation of the antibiotic susceptibility tests after comparing the experimental results with those tabulated for clinical species.
Effect of combined copper, salt and plant growth promoting rhizobacteria inoculation on the growth, photosynthesis and ion accumulation in the halophyte Salicornia ramosissima: a phytoremediation perspective
(Elsevier, 2026-02-27) Mesa Marín, Jennifer; Redondo Gómez, Susana; Rodríguez Llorente, Ignacio David; Pajuelo Domínguez, Eloísa; Mateos Naranjo, Enrique; Microbiología y Parasitología; Biología Vegetal y Ecología; Junta de Andalucía; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla
Salicornia ramosissima is a C3 halophyte native to salt marshes of southwestern Spain, where it naturally thrives under salinity and heavy metal pollution. Despite its ecological and agricultural significance, its potential for phytoremediation has been understudied. This work explores the effect of salinity (0, 10 and 60 g L−1 NaCl), copper (0 and 1000 ppm Cu) and bacterial bioaugmentation (four different consortia) on the growth, photosynthesis and ion accumulation capacity of S. ramosissima under greenhouse conditions. High salinity resulted in negative effects for S. ramosissima growth (40% decrease in dry weight) and photosynthesis (decline of 40% net photosynthetic rate and 50% stomatal conductante), thriving best under low to moderate salinity. The addition of 1000 ppm Cu to the substrate exacerbated growth inhibition (up to 77%) under non and high salinity, but not under moderate salinity. Also, S. ramosissima was an effective accumulator of both Na and Cu, accumulating twice the Na in shoots than in roots while retaining the majority of Cu in roots. Another key finding was that Plant Growth Promoting Rhizobacteria (PGPR) bioaugmentation in Cu-contaminated substrate led to a x4.5 increase in plant growth, a notable recovery in photosynthetic parameters (especially iWUE, up to 1000%) and promoted up to a 3x greater accumulation of Cu in the roots. Each inoculum showed different effects in plants and survival rate. Combining S. ramosissima with PGPR could be a sustainable tool for the phytostabilization of Cu and the phytoextraction of Na, allowing to use S. ramosissima in bioremediation and agriculture.
Biodegradable polyacrylamide-based hydrogels with unique bactericidal and osteoinductive properties to improve the clinical success of porous titanium implants
(Elsevier, 2026-01) Martínez Muñoz, Guillermo; Castellano Pozo, Maikel; Merinero de los Santos, Manuel; Casado Jurado, David; Huertas Sánchez, Pablo; Pajuelo Domínguez, Eloísa; Miguel Rodríguez, Manuel de; Begines Ruiz, Belén; Torres Hernández, Yadir; Alcudia Cruz, Ana; Química Orgánica; Genética; Microbiología y Parasitología; Citología e Histología Normal y Patológica; Ingeniería y Ciencia de los Materiales y del Transporte; Química Orgánica y Farmacéutica; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
Stress-shielding phenomenon, infections, and limited bone integration are traditional drawbacks associated with titanium implants. Biodegradable polyacrylamide-based hydrogels synthesized with an 8-fold scaled up, disulfide bond-containing crosslinker, were prepared to overcome these limitations. Hydrogels' biodegradability in the presence of glutathione has been demonstrated. Additionally, hydrogels exhibited strong antibacterial activity against pathogens such as P. aeruginosa and S. aureus, along with promising osseointegrative properties, in vitro fibroblast (CCL-1) viability, and in vivo biocompatibility in C. elegans. Porous titanium (Ti) fabricated via space-holder technique were infiltrated with previously described hydrogels. The optimal system, featuring a 4 wt% crosslinked acrylamide-based hydrogel infiltrated into 60 vol%, 355–500 μm Ti substrate, showed excellent biomechanical integrity and biofunctionality, supporting its potential as a safe and effective bone implant. Additionally, the study introduces streamlined, cost-effective methodologies for implant testing and characterization.
Structured Promoter Variability in Epigenetically Regulated Operons Contributes to Surface Adaptation in Salmonella
(Wiley, 2026-02-12) Fernández Fernández, Rocío; Gutiérrez Pozo, Gabriel; Piubeli, Francine; Garmendia, Junkal; Beuzón, Carmen R.; Sánchez Romero, María Antonia; Microbiología y Parasitología; Genética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
Bacterial adaptation to dynamic and hostile environments often relies on the ability to modify surface structures, which are subjected to strong selective pressures. While mutations in coding sequences that alter surface structures have long been recognised as key drivers of bacterial adaptation, this study reveals structured promoter variation as a novel additional layer of functional adaptation. Focusing on the opvAB operon in Salmonella, epigenetically regulated by the coordinated action of Dam methylation and OxyR binding, we investigated the evolutionary dynamics and regulatory architecture of its regulatory region. Comparative genomics of Salmonella subspecies revealed striking variability in this regulatory region. Notably, the opvAB promoter exhibited mutations clustering at specific, recurrent positions, suggesting lineage-specific fine-tuning through structured and potentially functional variability, further demonstrated experimentally by phase variation analysis within clonal populations at the single bacterial cell level. Our findings highlight a potentially overlooked evolutionary mechanism by which bacteria can modulate gene expression through a balance between conservation and variability in regulatory elements. This structured promoter variation likely complements genetic and epigenetic strategies, offering a new perspective on how bacterial populations adapt to environmental challenges.
Investigating the mechanisms underlying phytoprotection by plant growth-promoting rhizobacteria in Spartina densiflora under metal stress
(Wiley, 2018-05) Paredes Páliz, Karina Inés; Rodríguez Vázquez, Raquel; Duarte, Bernardo; Caviedes Formento, Miguel Ángel; Mateos Naranjo, Enrique; Redondo Gómez, Susana; Caçador, M.I.; Rodríguez Llorente, Ignacio David; Pajuelo Domínguez, Eloísa; Microbiología y Parasitología; Biología Vegetal y Ecología; Junta de Andalucía; Universidad de Sevilla; Ministerio de Economía y Competitividad (MINECO). España; Fundação para a Ciência e Tecnologia; SENESCYT
Pollution of coasts by toxic metals and metalloids is a worldwide problem for which phytoremediation using halophytes and associated microbiomes is becoming relevant. Metal(loid) excess is a constraint for plant establishment and development, and plant growth promoting rhizobacteria (PGPR) mitigate plant stress under these conditions. However, mechanisms underlying this effect remain elusive. The effect of toxic metal(loid)s on activity and gene expression of ROS-scavenging enzymes in roots of the halophyte Spartina densiflora grown on real polluted sediments in a greenhouse experiment was investigated. Sediments of the metal-polluted joint estuary of Tinto and Odiel rivers and control, unpollutred samples from the Piedras estuary were collected and submitted to ICP-OES. Seeds of S. densiflora were collected from the polluted Odiel marshes and grown in polluted and unpolluted sediments. Rhizophere biofilm-forming bacteria were selected based on metal tolerance and inoculated to S. densiflora and grown for 4 months. Fresh or frozen harvested plants were used for enzyme assays and gene expression studies, respectively. Metal excess induced SOD (five-fold increase), whereas CAT and ascorbate peroxidase displayed minor induction (twofold). A twofold increase of TBARs indicated membrane damage. Our results showed that metal-resistant PGPR (P. agglomerans RSO6 and RSO7 and B. aryabhattai RSO25) contributed to alleviate metal stress, as deduced from lower levels of all antioxidant enzymes to levels below those of non-exposed plants. The oxidative stress index (OSI) decreased between 50 and 75% upon inoculation. The results also evidenced the important role of PAL, involved in secondary metabolism and/or lignin synthesis, as a pathway for metal stress management in this halophyte upon inoculation with appropriate PGPR, since the different inoculation treatments enhanced PAL expression between 3.75- and five-fold. Our data confirm, at the molecular level, the role of PGPR in alleviating metal stress in S. densiflora and evidence the difficulty of working with halophytes for which little genetic information is available.
Unveiling balanced prenatal microbial colonization in amniotic fluid through an integrated culture and sequencing approach
(Springer Nature, 2026-01-09) González Rovira, María; Sáinz Bueno, José Antonio; García Díaz, Lutgardo; Martínez-Pancorbo, C.; Sánchez, J.; Gutiérrez Pozo, Gabriel; Magoutas, K.; Mesías-Pérez, A.; Mellado Durán, María Encarnación; Payne, M.; Sousa Martín, Carolina; Moreno Amador, María de Lourdes; Microbiología y Parasitología; Cirugía; Genética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Federación de Asociaciones de Celíacos de España (FACE); Universidad de Sevilla
Background The evidence of a low-biomass microbial community in the amniotic fluid (AF) is challenging the traditional concept of a sterile womb. To clarify microbial presence and host responses, a comprehensive, multi-methodological approach is required. Methods We designed an optimized culturing strategy that maximized microorganism recovery by implementing differential centrifugation and concentration of AF samples, followed by plating onto four distinct selective media types and incubation under both stringent aerobic (up to two weeks) and prolonged anaerobic (up to four weeks) conditions, including an initial pre-enrichment step in Brain Heart Infusion (BHI) broth for low-abundance organisms. These results were combined with PacBio 16S rRNA gene sequencing, Illumina shotgun metagenomics, and antimicrobial peptides (AMP) detection. Using this approach, we characterized microbial presence in 154 AF samples across gestational stages. Data normality was assessed with the Shapiro-Wilk test, guiding the selection of both parametric and non-parametric tests, and a p-value of < 0.05 was considered statistically significant. Results We detected culturable microorganisms in 33.1% of samples, with a higher proportion in elective caesarean Sect. (55.0%) compared to amniocentesis (29.5%), suggesting increased microbial load toward term. We applied stringent contamination controls, and repeatedly recovered viable microorganisms Bacillus, Cutibacterium, Micrococcus, and Staphylococcus, with Cutibacterium acnes and Staphylococcus epidermidis common. Both sequencing methods revealed a low-biomass, low-diversity microbial community with high inter-individual variability. Notably, striking microbial discordance in diamniotic twin pregnancies, challenged intrauterine homogeneity. Higher Human Beta Defensin (HBD) -1 levels correlated with absence of culturable bacteria or microbial DNA, while levels of HBD-1, HBD-3, and LL-37 were reduced in Staphylococcus-positive samples, suggesting a dynamic interplay between specific bacteria and host defences. Conclusions Our findings indicate that viable bacteria and/or DNA can transiently access the prenatal environment microbial balance. We propose a novel perspective of a potential regulatory axis between microorganisms and AMP.
Enhanced Diclofenac Biodegradation by Bacterial Strains and a Microbial Consortium from Activated Sludge: Toxicity Assessment and Insights into Microbial Community Dynamics
(MDPI, 2026-02-02) Lara Moreno, Alba; Rodríguez Morillo, Belén; Madrid, Fernando; Villaverde, Jaime; Villaverde, Jaime; Mejías Padilla, Carmen; Alonso Álvarez, Esteban; Morillo, Esmeralda; Química Analítica; Microbiología y Parasitología; Junta de Andalucía; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Diclofenac (DCF) is a widely used non-steroidal anti-inflammatory drug whose presence in environmental matrices has led to its classification as an emerging contaminant. Developing effective and sustainable removal strategies is therefore essential. In this study, Pseudomonas aeruginosa CSWD.1, Pseudomonas sp. CSWD.2, and a microbial consortium (MC) were isolated from activated sludge through enrichment cultures with DCF and employed as laboratory models to investigate DCF biodegradation capacity under a biosafety-aware framework. Biodegradation assays supplemented with glucose showed limited removal (45.5%) by CSWD.1, whereas CSWD.2 and the MC achieved complete elimination (100%) of 10 mg L−1 DCF in 21 and 5 days, respectively. Three extracellular metabolites, 4’-hydroxy-diclofenac (4’-OH-DCF), 5-hydroxy-diclofenac (5-OH-DCF), and putative NO2-DCF, were detected, with concentrations varying during degradation. Persistence of 4’-OH-DCF and tentatively identified NO2-DCF after 28 days was potentially associated with increased toxicity relative to the abiotic control. Overall, the results suggest that evaluating metabolites and their toxicity is essential, requiring isolation of additional microorganisms able to degrade 4’-OH-DCF and NO2-DCF to combine with the microorganisms isolated in this study. Metabarcoding analysis of the microbial consortium after bioremediation revealed the dominant bacterial population of Burkholderia (88.9% relative abundance) and a predominant fungal genus Talaromyces (80.1%), indicating that both bacteria and fungi may be associated with DCF transformation. These results provide insights into microbial community dynamics and their potential application in designing effective consortia for DCF bioremediation.
Estuaries of the Tinto, Odiel and Piedras rivers as source of new species of Pseudomonas with biofertilizer potential under stress conditions
(Nature, 2025-12-09) Flores Duarte, Noris J.; Rodríguez Llorente, Ignacio David; Pajuelo Domínguez, Eloísa; Redondo Gómez, Susana; Mateos Naranjo, Enrique; Navarro de la Torre, Salvadora; Biología Vegetal y Ecología; Microbiología y Parasitología; Junta de Andalucía; European Union (UE)
The estuaries of the Tinto, Odiel, and Piedras rivers have been extensively studied by several groups due to ecological aspects such as heavy metal contamination, nutrient deficiency and degradation influenced by climate change. Aimed to recover these ecosystems, a large collection of plant growth-promoting bacteria (PGPB), several of them previously identified as new species, was isolated from the rhizosphere and tissues of native plants. In this study, we analyse the strains N4, N8T, L1T, and SDT3T as potential new species. A phylogenomic analysis revealed that four strains belong to the genus Pseudomonas, forming distinct clades with full support. Digital DNA-DNA hybridization and average nucleotide identity values were below the species delineation thresholds (70% and 95–96%), confirming the novelty of strains N8T, L1T, and SDT3T, while N4 and N8T were identified as the same species. As a result, we propose the names Pseudomonas medicae sp. nov., Pseudomonas onubensis sp. nov., and Pseudomonas spartinae sp. nov., with P. medicae comprising two strains. These strains, previously identified as PGPB, harboured genes related to PGP traits and were further characterized phenotypically and biochemically. To evaluate the agroecological potential of N8T strain, it was tested in co-inoculation with the corresponding rhizobia on lentil, pea, alfalfa, and bean under greenhouse conditions. In all legumes, N8T enhanced shoot and root biomass, increased nodule numbers, and improved nitrogen content compared with single rhizobia inoculation. In summary, these estuarine ecosystems are not only ecologically significant for their microbial diversity but also serve as reservoirs of beneficial bacteria with promising agroecological applications.

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