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Introduction: The rhizosphere is the zone of soil surrounding plant roots that is directly influenced by root exudates released by the plant, which select soil microorganisms. The resulting rhizosphere microbiota plays a key role in plant health and development by enhancing its nutrition or immune response and protecting it from biotic or abiotic stresses. In particular, plant growth-promoting rhizobacteria (PGPR) are beneficial members of this microbiota that represent a great hope for agroecology, since they could be used as bioinoculants for sustainable crop production. Therefore, it is necessary to decipher the molecular dialog between roots and PGPR in order to promote the establishment of bioinoculants in the rhizosphere, which is required for their beneficial functions. Methods: Here, the ability of root exudates from rapeseed (Brassica napus), pea (Pisum sativum), and ryegrass (Lolium perenne) to attract and feed three PGPR (Bacillus subtilis, Pseudomonas fluorescens, and Azospirillum brasilense) was measured and compared, as these responses are directly involved in the establishment of the rhizosphere microbiota. Results: Our results showed that root exudates differentially attracted and fed the three PGPR. For all beneficial bacteria, rapeseed exudates were the most attractive and induced the fastest growth, while pea exudates allowed the highest biomass production. The performance of ryegrass exudates was generally lower, and variable responses were observed between bacteria. In addition, P. fluorescens and A. brasilense appeared to respond more efficiently to root exudates than B. subtilis. Finally, we proposed to evaluate the compatibility of each plant-PGPR couple by assigning them a "love match" score, which reflects the ability of root exudates to enhance bacterial rhizocompetence. Discussion: Taken together, our results provide new insights into the specific selection of PGPR by the plant through their root exudates and may help to select the most effective exudates to promote bioinoculant establishment in the rhizosphere.

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Introduction: Plant growth-promoting bacteria (PGPB) have been primarily studied for atmospheric nitrogen (N) fixation but they also have the capacity to improve nutrition and yield of crop plants. Methods: Therefore, the objective of this research was to investigate the effects of inoculation with PGPB in association with different N rates on N uptake, grain yield, and oil concentration of dwarf castor beans in succession to legumes and grasses in Ilha Solteira, Brazil. The treatments consisted of N rates (0 to 180 kg ha-1 of N) and inoculation with three plant growth-promoting bacteria (Azospirillum brasiliense, Bacillus subtilis, and Pseudomonas fluorescens, applied by leaf) and a control with no-inoculation. Results: The grain and oil yields of castor beans were increased by 20 and 40% at a rate of 103 kg ha-1 of N in succession to grasses as compared to without N application. In addition, the grain yield of castor bean after legumes was increased by 28, 64, and 40% with estimated rates of 97, 113, and 92 kg ha-1 of N in combination with inoculations of A. brasilense, B. subtilis, and P. fluorescens as compared to without N application, respectively. Shoot, grain, and total N uptake were improved with foliar inoculation of A. brasilense, B. subtilis, and P. fluorescens at the N rates of 45, 90, and 135 kg ha-1, respectively. Discussion and conclusions: Topdressing of N at the rate of 103 kg ha-1 and foliar inoculation in succession to grasses and 180 kg ha-1 of N without the effect of foliar inoculation in succession to legumes are recommended for higher grain and oil yield of castor beans. Foliar inoculations with A. brasilense, B. subtilis, and P. fluorescens increased grain yield under reduced use of N fertilizer by 44, 37, and 49% in dwarf castor cultivation in succession to legumes, potentially contributing to sustainable agriculture.

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The utilization of a novel (systemic) biofertilizer containing Pseudomonas fluorescens, Azospirillum brasilense, and Bacillus subtilis and possessing the technology to facilitate the entry of bacteria through the stomata, was evaluated at three localities in Mexico (Potrero Nuevo, Veracruz; Ameca, Jalisco; and Champotón, Campeche) in two sugarcane varieties (NCO-310 and Mex 57-473) at different time scales. Inoculation of the systemic biofertilizer was imposed over the local agricultural management of the sugarcane; chemical fertilization of the experimental parcels at Potrero Nuevo was done using 70-20-20 and 120-80-80 at Ameca and Champotón. Three doses of the biofertilizer per hectare were applied during the annual productive cycle of sugarcane at each site; one year at Potrero Nuevo and Champotón; and six years at Ameca. The annual sugarcane yield was evaluated at each site. Additionally, sugar quality (°Brix or sucrose content) was evaluated at the three localities, while different variables of stalk performance were also measured at Ameca and Champotón. Our data provide evidence that this systemic biofertilizer consistently and reliably increased the sugarcane yield at all localities during the time of evaluation, ranging from 73.7 tons ha-1 at Potrero Nuevo (2.5 times increase; P < 0.05) and 77.7 tons ha-1 at Ameca (1.9 times increase; P < 0.05) to 23.8 tons ha-1 at Champotón (1.4 times increase; P < 0.05). This increase in sugarcane biomass was related to increased tillering rather than increased stalk height or diameter. This novel biological product improved the sugarcane quality in terms of °Brix (P < 0.05, 2.6° difference) and sucrose content (P < 0.5, 0.7% difference).

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In the healthcare sector, the implementation of standardized procedures, such as those commonly employed in franchises to ensure consistent quality, remains underprioritized. Within this framework, we focus on the importance of standardized central venous catheter (CVC) insertion procedures to prevent healthcare-associated outbreaks. While antimicrobial resistance (AMR) may still not be the most prevalent problem in some institutions, its increasing significance certainly underlines the urgency of infection prevention.We aim to highlight this issue by describing and discussing an outbreak scenario of carbapenem-resistant (CR) Pseudomonas fluorescens bloodstream infections resulting from a deviation from the standardized CVC insertion procedure. This outbreak led to six episodes of catheter related bloodstream infection (CRBSI) in patients with hematologic malignancies, delaying their primary treatment. Nineteen patients were exposed, leading to an attack rate of 31.6%.

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Abstract Pseudomonas fluorescens is one of the main causes of septicemic diseases among freshwater fish, causing severe economic losses and decreasing farm efficiency. Thus, this research was aimed to investigate the occurrence of P. fluorescens in Nile Tilapia (O. niloticus) fish in Egypt, gene sequencing of 16SrDNA gene, and antimicrobial susceptibility. P. fluorescens strains were detected in 32% (128/400) of apparently healthy (9%; 36/400) and diseased (23%; 92/400) Nile tilapia fish. The highest prevalence was observed in gills of fish, 31.3% followed by intestine 26.9%, liver 24.2%, and kidneys 17.6%. The PCR results for the 16SrDNA gene of P. fluorescens showed 16SrDNA gene in 30% of examined isolates. Moreover, Homogeny and a strong relationship between strains of P. fluorescens was confirmed using 16SrDNA sequences. Beside the responsibility of 16SrDNA gene on the virulence of P. fluorescens. The results of antimicrobial susceptibility tests revealed that all strains were resistant to piperacillin (100%), followed by ceftazidime (29.7%), and cefepime (25.8%). The strains of P. fluorescence were highly sensitive to cefotaxime (74.2%), followed by ceftriaxone and levofloxacin (70.3% each). Interestingly, 29.7% of strains of P. fluorescens were multiple antimicrobial-resistant (MAR).

Resumo Pseudomonas fluorescens é uma das principais causas de doenças septicêmicas em peixes de água doce, causando graves perdas econômicas e diminuindo a eficiência da fazenda. Assim, esta pesquisa teve como objetivo investigar a ocorrência de P. fluorescens em peixes de tilápia-do-nilo (O. niloticus) no Egito, sequenciamento do gene 16S rDNA e suscetibilidade antimicrobiana. Cepas de P. fluorescens foram detectadas em 32% (128/400) de peixes tilápia-do-nilo aparentemente saudáveis (9%; 36/400) e doentes (23%; 92/400). A maior prevalência foi observada nas brânquias dos peixes, 31,3%, seguida pelo intestino 26,9%, fígado 24,2% e rins 17,6%. Os resultados da PCR para o gene 16SrDNA de P. fluorescens mostraram o gene 16SrDNA em 30% dos isolados examinados. Além disso, a homogeneidade e uma forte relação entre cepas de P. fluorescens foi confirmada usando sequências de 16SrDNA. Além da responsabilidade do gene 16SrDNA na virulência de P. fluorescens. Os resultados dos testes de suscetibilidade antimicrobiana revelaram que todas as cepas foram resistentes à piperacilina (100%), seguida pela ceftazidima (29,7%) e cefepima (25,8%). As cepas de P. fluorescens foram altamente sensíveis à cefotaxima (74,2%), seguida pela ceftriaxona e levofloxacina (70,3% cada). Curiosamente, 29,7% das cepas de P. fluorescens eram multirresistentes a antimicrobianos (MAR).

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Pseudomonas fluorescens is one of the main causes of septicemic diseases among freshwater fish, causing severe economic losses and decreasing farm efficiency. Thus, this research was aimed to investigate the occurrence of P. fluorescens in Nile Tilapia (O. niloticus) fish in Egypt, gene sequencing of 16SrDNA gene, and antimicrobial susceptibility. P. fluorescens strains were detected in 32% (128/400) of apparently healthy (9%; 36/400) and diseased (23%; 92/400) Nile tilapia fish. The highest prevalence was observed in gills of fish, 31.3% followed by intestine 26.9%, liver 24.2%, and kidneys 17.6%. The PCR results for the 16SrDNA gene of P. fluorescens showed 16SrDNA gene in 30% of examined isolates. Moreover, Homogeny and a strong relationship between strains of P. fluorescens was confirmed using 16SrDNA sequences. Beside the responsibility of 16SrDNA gene on the virulence of P. fluorescens. The results of antimicrobial susceptibility tests revealed that all strains were resistant to piperacillin (100%), followed by ceftazidime (29.7%), and cefepime (25.8%). The strains of P. fluorescence were highly sensitive to cefotaxime (74.2%), followed by ceftriaxone and levofloxacin (70.3% each). Interestingly, 29.7% of strains of P. fluorescens were multiple antimicrobial-resistant (MAR).

Pseudomonas fluorescens é uma das principais causas de doenças septicêmicas em peixes de água doce, causando graves perdas econômicas e diminuindo a eficiência da fazenda. Assim, esta pesquisa teve como objetivo investigar a ocorrência de P. fluorescens em peixes de tilápia-do-nilo (O. niloticus) no Egito, sequenciamento do gene 16S rDNA e suscetibilidade antimicrobiana. Cepas de P. fluorescens foram detectadas em 32% (128/400) de peixes tilápia-do-nilo aparentemente saudáveis ​​(9%; 36/400) e doentes (23%; 92/400). A maior prevalência foi observada nas brânquias dos peixes, 31,3%, seguida pelo intestino 26,9%, fígado 24,2% e rins 17,6%. Os resultados da PCR para o gene 16SrDNA de P. fluorescens mostraram o gene 16SrDNA em 30% dos isolados examinados. Além disso, a homogeneidade e uma forte relação entre cepas de P. fluorescens foi confirmada usando sequências de 16SrDNA. Além da responsabilidade do gene 16SrDNA na virulência de P. fluorescens. Os resultados dos testes de suscetibilidade antimicrobiana revelaram que todas as cepas foram resistentes à piperacilina (100%), seguida pela ceftazidima (29,7%) e cefepima (25,8%). As cepas de P. fluorescens foram altamente sensíveis à cefotaxima (74,2%), seguida pela ceftriaxona e levofloxacina (70,3% cada). Curiosamente, 29,7% das cepas de P. fluorescens eram multirresistentes a antimicrobianos (MAR).

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Pseudomonas fluorescens CFBP2392 has been recognized as a potential biocontrol agent due to its ability to suppress damping-off and root rot disease. This isolate has antibacterial activity in vitro as many other strains from the Pseudomonas fluorescens complex. In this work, the antibacterial and antifungal activity of the strain were explored. Dual culture assays evidenced the antifungal activity of the strain against different phytopathogens: Alternaria sp., Pythium ultimun, Fusarium oxysporum, and Rhizoctonia solani. Purification of an antifungal fraction was performed by preparative HPLC from the chemical extraction of growth media. The fraction showed altered R. solani growth and ultrastructure. Transmission electron microscopy revealed the purified compound induced hypertrophied mitochondria, membranous vesicles, and a higher number of vacuoles in R. salani cytoplasm. In addition, co-cultivation of P. fluorescens CFBP2392 with R. solani resulted in an enlarged and deformed cell wall. To gain genomic insights on this inhibition, the complete genome of P. fluorescens CFBP2392 was obtained with Oxford Nanopore technology. Different biosynthetic gene clusters (BGCs) involved in specialized metabolites production including a lokisin-like and a koreenceine-like cluster were identified. In accordance with the putative BGCs identified, sequence phylogeny analysis of the MacB transporter in the lokisin-like cluster further supports the similarity with other transporters from the amphisin family. Our results give insights into the cellular effects of the purified microbial metabolite in R. solani ultrastructure and provide a genomic background to further explore the specialized metabolite potential.

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Pseudomonas fluorescens group strains can lead to spoilage of milk as well as loss of quality in dairy products through their heat-resistant enzymes. Phages are important alternatives for combating spoilage bacteria in food industry and used successfully in many applications. The aim of this study was the isolation and characterization of phages and to assess the efficiency of a phage cocktail in whole and skimmed milk. For this purpose, phages effective against Pseudomonas fluorescens (L23.2), Pseudomonas tolaasii (P22.1), and Pseudomonas rhodesiae (A11.1) were isolated. Their host range was found to be highly specific, and the transmission electron micrographs indicates that they belonged to Tectiviridae family. Their genome sizes were found to be vary between 38.3 and 53.5 kb. The latent periods and burst sizes were determined as 15, 10, 15 min and 91, 20, 80 PFU/infected cell for L23.2, P22.1, and A11.1, respectively. All three phages were found to be sensitive to low pH and high temperature. The effect of the phage cocktail was monitored in milk with different fat contents during storage at 4 °C for 5 days. As a result, bacterial reductions up to 4.09 and 5.29 log-units were observed for the whole and skimmed milk, respectively. Thus, the efficacy of a phage cocktail against a bacterial mixture of different P. fluorescens strains was tested in milk samples with different fat contents in accordance with real-life scenarios for the first time.

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Introduction and aims: The intensive cropping system and imbalance use of chemical fertilizers to pursue high grain production and feed the fast-growing global population has disturbed agricultural sustainability and nutritional security. Understanding micronutrient fertilizer management especially zinc (Zn) through foliar application is a crucial agronomic approach that could improve agronomic biofortification of staple grain crops. The use of plant growth-promoting bacteria (PGPBs) is considered as one of the sustainable and safe strategies that could improve nutrient acquisition and uptake in edible tissues of wheat to combat Zn malnutrition and hidden hunger in humans. Therefore, the objective of this study was to evaluate the best-performing PGPB inoculants in combination with nano-Zn foliar application on the growth, grain yield, and concentration of Zn in shoots and grains, Zn use efficiencies, and estimated Zn intake under wheat cultivation in the tropical savannah of Brazil. Methods: The treatments consisted of four PGPB inoculations (without inoculation, Azospirillum brasilense, Bacillus subtilis, and Pseudomonas fluorescens, applied by seeds) and five Zn doses (0, 0.75, 1.5, 3, and 6 kg ha-1, applied from nano ZnO in two splits by leaf). Results: Inoculation of B. subtilis and P. fluorescens in combination with 1.5 kg ha-1 foliar nano-Zn fertilization increased the concentration of Zn, nitrogen, and phosphorus in the shoot and grain of wheat in the 2019 and 2020 cropping seasons. Shoot dry matter was increased by 5.3% and 5.4% with the inoculation of P. fluorescens, which was statistically not different from the treatments with inoculation of B. subtilis as compared to control. The grain yield of wheat was increased with increasing nano-Zn foliar application up to 5 kg Zn ha-1 with the inoculation of A. brasilense in 2019, and foliar nano-Zn up to a dose of 1.5 kg ha-1 along with the inoculation of P. fluorescens in the 2020 cropping season. The zinc partitioning index was increased with increasing nano Zn application up to 3 kg ha-1 along with the inoculation of P. fluorescens. Zinc use efficiency and applied Zn recovery were improved at low doses of nano-Zn application in combination with the inoculation of A. brasilense, B. subtilis, and P. fluorescens, respectively, as compared to control. Discussion: Therefore, inoculation with B. subtilis and P. fluorescens along with foliar nano-Zn application is considered a sustainable and environmentally safe strategy to increase nutrition, growth, productivity, and Zn biofortification of wheat in tropical savannah.

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ABSTRACT The production and consumption of blueberry have increased in Mexico owing to its health benefits. Symbiotic relationships have been shown to be crucial in blueberry plants. In particular, phytohormone production by Pseudomonas fluorescens is an important mechanism of plant growth promotion. However, there are only a few reports on the effects of plant growth-promoting bacteria in blueberries. Therefore, we aimed to evaluate the effects of four strains of P. fluorescens (UM16, UM240, UM256, and UM270) and two types of slow-release fertilizer (nitrophosphate and basacote) on the development of blueberry var. Biloxi under greenhouse conditions. Blueberry seedlings obtained from in vitro culture and adapted under greenhouse conditions were inoculated with 1 x 106 CFU with any of the four strains, depending on treatment. Plants inoculated showed increased average plant length, plant fresh weight, root length, and root fresh and dry weight, compared with those with the control treatment (non-inoculated plants). The plants inoculated and fertilized with nitrophosphate had a better development compared with those fertilized with basacote or the control plants (inoculated or fertilized). Inoculated plants fertilized with nitrophosphate also had greater plant length, higher fresh plant weight, longer roots, and greater root fresh and dry weight than the control (non-inoculated or non-fertilized plants). Our study could facilitate the sustainable propagation of blueberry plants.

RESUMEN La producción y consumo de arándano en México se ha incrementado debido a sus beneficios en la salud. Las relaciones simbióticas han mostrado ser cruciales en arándano. En particular, la producción de fitohormonas de P. fluorescens es un mecanismo importante en la promoción del crecimiento en plantas. Sin embargo, hay pocos reportes del efecto de las bacterias promotoras del crecimiento vegetal en arándano. Por lo tanto, nos propusimos evaluar el efecto de cuatro cepas de P. fluorescens (UM16, UM240, UM256 y UM270) y dos fertilizantes de lenta liberación (nitrofosfato y basacote) en el desarrollo de plantas de arándano var Biloxi bajo condiciones de invernadero. Las plántulas de arándano obtenidas de cultivo in vitro, y adaptadas bajo condiciones de invernadero, fueron inoculadas con 1 x 106 UFC con cualquiera de las cuatro cepas, según el tratamiento. Las plantas inoculadas mostraron un mayor incremento en la longitud de la planta, peso fresco de la planta, longitud de la raíz, y peso fresco y seco de la raíz, en comparación con el testigo (plantas no inoculadas). Las plantas inoculadas y fertilizadas con nitrofosfato presentaron una mejor respuesta en su desarrollo, en comparación con las plantas fertilizadas con bascaote y las plantas testigo (inoculadas o fertilizadas). Una de las cepas tuvo un mayor efecto sobre la longitud y peso fresco de la planta, longitud de la raíz, y peso fresco y seco de la raíz, en comparación con el testigo (inoculadas o fertilizadas). Nuestro estudio podría facilitar la propagación sustentable de plantas de arándano.

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Pseudomonas spp. are ubiquitous microorganisms that exhibit intrinsic and acquired resistance to many antimicrobial agents. Pseudomonas aeruginosa is the most studied species of this genus due to its clinical importance. In contrast, the Pseudomonas fluorescens complex consists of environmental and, in some cases, pathogenic opportunistic microorganisms. The records of antimicrobial-resistant P. fluorescens are quite scattered, which hinders the recognition of patterns. This review compiles published data on antimicrobial resistance in species belonging to the P. fluorescens complex, which were identified through phylogenomic analyses. Additionally, we explored the occurrence of clinically relevant antimicrobial resistance genes in the genomes of the respective species available in the NCBI database. Isolates were organized into two categories: strains isolated from pristine sites and strains isolated from human-impacted or metal-polluted sites. Our review revealed that many reported resistant phenotypes in this complex might be related to intrinsic features, whereas some of them might be ascribed to adaptive mechanisms such as colistin resistance. Moreover, a few studies reported antimicrobial resistance genes (ARGs), mainly ß-lactamases. In-silico analysis corroborated the low occurrence of transferable resistance mechanisms in this Pseudomonas complex. Both phenotypic and genotypic assays are necessary to gain insights into the evolutionary aspects of antimicrobial resistance in the P. fluorescens complex and the possible role of these ubiquitous species as reservoirs of clinically important and transmissible ARGs.

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Resumen El modelamiento ¡n silíco ha sido de gran contribución en los procesos proteómicos, desarrollando estructuras de las secuencias proteicas ya existentes, que por motivos de altos costos y las diferentes tecnologías necesarias para el desarrollo de estas metodologías, se encuentran deficientes en el número de modelamientos de proteínas disponibles. Entre aquellas secuencias con carencia de estructura proteica se encuentra la proteína liasa organomercurial (MerB) de Pseudomonas /luorescens, importante en la resistencia al mercurio. En el presente artículo se analizó tanto estructural como funcionalmente la proteína MerB en Pseudomonas jluorescens, utilizando la herramienta de la química estructural "modelamiento por homología" mediante plataformas bioinformáticas, con el fin de obtener un modelo que represente la estructura 3D más precisa y que capturen las mejores variantes estructurales entre todas las posibles conformaciones de las proteínas en la familia. En este trabajo, se desarrolló un método comparativo de la secuencia estudiada con las reportadas en las bases de datos para las proteínas MerB del género Pseudomonas. Se propone un modelo tridimensional para la enzima (MerB) en P. jluorescens, mediante el modelamiento por homología, se muestra la caracterización en la estructura secundaria, terciaria, la caracterización del dominio catalítico y los motivos estructurales presentes.

Abstract In silico modeling has made a great contribution to proteomic processes, developing structures of the already existing protein sequences, which for reasons of high costs and the different technologies necessary for the development of these methodologies, are deficient in the number of models of available proteins. Among those sequences lacking protein structure is the organomercurial lyase (MerB) protein from Pseudomonas fluoresceins, important in mercury resistance. In this article, the MerB protein in Pseudomonas fluorescens was analyzed both structurally and functionally, using the structural chemistry tool "homology modeling" using bioinformatic platforms, in order to obtain a model that represents the most accurate 3D structure and that captures the best structural variants among all the possible conformations of the proteins in the family. In this work, a comparative method of the sequence studied with those reported in the databases for MerB proteins of the genus Pseudomonas was developed. A three-dimensional model for the enzyme (MerB) in P. fluorescens is proposed, through homology modeling, the characterization at the secondary and tertiary structure level, the characterization of the catalytic domain and the structural motifs present is shown.

Resumo A modelagem in silico tem dado um grande contributo para os processos proteómicos, desenvolvendo estruturas de sequências de proteínas já existentes, as quais, pelos elevados custos e pelas diferentes tecnologias necessárias ao desenvolvimento destas metodologias, são deficientes no número de modelos de proteínas disponíveis. Entre as sequências sem estrutura protéica está a proteína organomercurial liase (MerB) de Pseudomonas fluorescens, importante na resistência ao mercúrio. Neste artigo, a proteína MerB em Pseudomonas fluorescens foi analisada estrutural e funcionalmente, usando a ferramenta de química estrutural "modelagem de homologia" usando plataformas de bioinformática, a fim de obter um modelo que represente a estrutura 3D mais precisa e que capture as melhores variantes estruturais. entre todas as conformações possíveis das proteínas da família. Neste trabalho, foi desenvolvido um método comparativo da sequência estudada com aqueles relatados em bancos de dados para proteínas MerB do gênero Pseudomonas. Um modelo tridimensional para a enzima (MerB) em P. fluorescens é proposto, através de modelagem por homologia, a caracterização em nível de estrutura secundária e terciária, a caracterização do domínio catalítico e os motivos estruturais presentes são mostradas.

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The facultative biotrophic basidiomycete Sporisorium scitamineum causes smut disease in sugarcane. This study applied an assay to identify S. scitamineum candidate effectors (CEs) with plant immunity suppression activities by delivering them into Nicotiana benthamiana cells via the type-three secretion system of Pseudomonas fluorescens EtHAn. Six CEs were individually cloned into the pEDV6 vector and expressed by P. fluorescens EtHAn for translocation into the plant cells. Three CEs (g1052, g3890, and g5159) could suppress pattern-triggered immunity (PTI) responses with high reproducibility in different coinfiltration experiments with P. syringae pv. tomato DC3000. In addition, three CEs (g1052, g4549, and g5159) were also found to be AvrB-induced suppressors of effector-triggered immunity (ETI), demonstrating for the first time that S. scitamineum can defeat both PTI and ETI responses. A transcriptomic analysis at different stages of infection by the smut fungus of three sugarcane cultivars with contrasting responses to the pathogen revealed that suppressors g1052, g3890, g4549, and g5159 were induced at the early stage of infection. By contrast, the two CEs (g2666 and g6610) that did not exhibit suppression activities expressed only at the late stage of infection. Moreover, genomic structures of the CEs and searches for orthologs in other smut species suggested duplication events and further divergence in CEs evolution of S. scitamineum. Thus, the transient assay applied here demonstrated the potential of pEDV6 and P. fluorescens EtHAn as biological tools for identifying plant immune suppressors from S. scitamineum.

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RESUMEN El síndrome de Kartagener, el cual hace parte del subgrupo de las discinesias ciliares primarias predispone a infecciones respiratorias recurrentes del tracto respiratorio por Haemophilus influenzae, Staphylococcus aureus y Streptococcus pneumoniae. Se describe a continuación el caso de un paciente con diagnóstico de síndrome de Kartagener en quien se documentó colonización por Pseudomonas fluorescens y neumonía con empiema asociado por Actinomyces spp, una asociación poco frecuente en la literatura.

ABSTRACT Kartagener syndrome, which is part of the subgroup of the primary ciliary dyskinesias, predisposes to recurrent respiratory tract infections due to Haemophilus influenzae, Staphylococcus aureus and Streptococcus pneumoniae. The case of a patient with a diagnosis of Kartagener syndrome in whom colonization by Pseudomonas fluorescens and pneumonia complicated with empyema by Actinomyces spp is a rare association in the literature, which is described below.

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BACKGROUND: Biocontrol strategies are of significant concern for their application in crops. Various green practices have been designed, but almost all of them had delivery constraints. In particular, to design biocontrol strategies against Sclerotium oryzae in flooded rice fields, the active agent should be retained on the plant leaves by spreading application, nevertheless the direct application onto the water produces the biocontrol agent dilution. An effective delivery model was needed. This work aimed to evaluate the effects of chitosan molecular weight on the formation of positively charged Pseudomonas fluorescens-chitosan complex as a floating microcarrier against Sclerotium oryzae. To this end, three different sizes of chitosan [molecular weights (MWs) 20 000, 250 000, and 1 250 000 g mol-1 ] at different pH values (4, 6, and 7) were tested. The electrostatic interaction was analyzed through ζ-potential measurement. An adjustment of the experimental values was carried out for making predictions. The bacteria antifungal activity into the carrier with different chitosan MWs was analyzed. RESULTS: Our results suggest that it is possible to form a bacteria-chitosan complex with a net positive charge under condition that improve bacteria incorporation to the microcarrier technology without harming bacteria viability and antifungal activity. Thus, high chitosan MW (1 250 000 g mol-1 ) at pH 6 is preferable for microcarrier technology. CONCLUSION: Our findings provide relevant information about bacteria-chitosan interaction and may be useful in biocontrol programs that involved these two components as well as situations in which bacteria adsorption to an anionic carrier or anionic surface is desirable.

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RESUMEN Las rizobacterias forman parte de la gran cantidad de microorganismos que actúan como agentes de biocontrol, produciendo metabolitos que inducen resistencia sistémica en las plantas que inhiben el crecimiento de patógenos. El objetivo de esta investigación fue evaluar la capacidad de diez rizobacterias de los géneros Rhizobium, Bradyrhizobium, Sinorhizobium, Ochrobactrum y Pseudomonas para producir ácido cianhídrico (HCN), sideróforos y ácido indol-acético (AIA), disolver fosfato, fijar nitrógeno e inhibir el crecimiento de fitopatógenos. Se realizaron todas las pruebas fisiológicas y bioquímicas correspondientes, así como la prueba de antagonismo in vitro contra los fitopatógenos Fusarium oxysporum, Colletotrichum gloeosporioides y Rhizoctonia solani. Cinco cepas produjeron una mayor cantidad de AIA en relación a las otras en presencia de triptófano, la cepa ES1 (Ochrobactrum sp.) produjo HCN, el 50 % de las cepas evaluadas liberaron sideróforos, el 60 % disolvió fósforo, y todas resultaron positivas para la fijación de nitrógeno. Nueve cepas inhibieron el crecimiento de F. oxysporum entre 40 % y 65 %, la cepa Alf (Pseudomonas fluorescens) inhibió además el crecimiento de C. gloeosporioides en un 22 %, y ninguna inhibió el crecimiento de R. solani. Los rizobios evaluados y la cepa de Pseudomonas fluorescens podrían ejercer efectos beneficiosos sobre las plantas a través de mecanismos directos e indirectos, o una combinación de ambos, lo que las convierte en una opción sostenible para la producción de cultivos.

ABSTRACT Rhizobacteria are part of the large number of microorganisms that act as biocontrol agents, producing metabolites that induce systemic resistance in plants and inhibit the growth of pathogens. The objective of this research was to evaluate the capacity of ten rhizobacteria of the genera Rhizobium, Bradyrhizobium, Sinorhizobium, Ochrobactrum and Pseudomonas to produce hydrogen cyanide (HCN), siderophores and indole acetic acid (IAA), dissolve phosphate, fix nitrogen and inhibit the growth of phytopathogens. All the corresponding physiological and biochemical tests were carried out, in addition to an in vitro antagonism test against the phytopathogens Fusarium oxysporum, Colletotrichum gloeosporioides and Rhizoctonia solani. Five strains produced a greater amount of IAA with respect to the others in the presence of tryptophan, the strain ES1 (Ochrobactrum sp.) produced HCN, 50% of the evaluated strains released siderophores, 60% solubilized phosphorus and all were positive for nitrogen fixation. Nine strains inhibited the growth of F. oxysporum by 40% to 65%. The Alf strain (Pseudomonas fluorescens) inhibited the growth of C. gloeosporioides by 22% while none inhibited the growth of R. solani. The rhizobia tested and the Pseudomonas fluorescens strain may have favorable effects on plants through direct and indirect mechanisms, or a combination of both, making them a sustainable option for crop production.

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BACKGROUND: Cumulative reported evidence has indicated that renewable feedstocks are a promising alternative source to fossil platforms for the production of fuels and chemicals. In that regard, the development of new, highly active, selective, and easy to recover and reuse catalysts for biomass conversions is urgently needed. The combination of enzymatic and inorganic heterogeneous catalysis generates an unprecedented platform that combines the advantages of both, the catalytic efficiency and selectivity of enzymes with the ordered structure, high porosity, mechanical, thermal and chemical resistance of mesoporous materials to obtain enzymatic heterogeneous catalysts. Enzymatic mineralization with an organic silicon precursor (biosilicification) is a promising and emerging approach for the generation of solid hybrid biocatalysts with exceptional stability under severe use conditions. Herein, we assessed the putative advantages of the biosilicification technology for developing an improved efficient and stable biocatalyst for sustainable biofuel production. RESULTS: A series of solid enzymatic catalysts denominated LOBE (low ordered biosilicified enzyme) were synthesized from Pseudomonas fluorescens lipase and tetraethyl orthosilicate. The microscopic structure and physicochemical properties characterization revealed that the enzyme formed aggregates that were contained in the heart of silicon-covered micelles, providing active sites with the ability to process different raw materials (commercial sunflower and soybean oils, Jatropha excisa oil, waste frying oil, acid oil from soybean soapstock, and pork fat) to produce first- and second-generation biodiesel. Ester content ranged from 81 to 93% wt depending on the raw material used for biodiesel synthesis. CONCLUSIONS: A heterogeneous enzymatic biocatalyst, LOBE4, for efficient biodiesel production was successfully developed in a single-step synthesis reaction using biosilicification technology. LOBE4 showed to be highly efficient in converting refined, non-edible and residual oils (with high water and free fatty acid contents) and ethanol into biodiesel. Thus, LOBE4 emerges as a promising tool to produce second-generation biofuels, with significant implications for establishing a circular economy and reducing the carbon footprint.

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Improper nutrient management is one of the major limitations linked with cultivation of Cajanus cajan. This calls for an urgent need for a promising alternative, employing both bioinoculants and chemical fertilizer. Present study attempted to understand the impact of bioinoculants {Azotobacter chroococcum, Bacillus megaterium, and Pseudomonas fluorescens (ABP)} as their mono-inoculations, triple-inoculation, and their combination with different doses of fertilizer on (a) plant parameters, (b) soil nitrogen (N) economy, (c) resident bacterial community, (d) genes and transcripts involved in N cycle, and to evaluate the extent to which fertilizer could be replaced by ABP without compromising on grain yield. Bradyrhizobium sp. was used in all the treatments (as it was recommended for C. cajan). Combined application of bioinoculants and 75% of recommended dose of fertilizer (RDF) led to 1.28-fold enhancement in grain yield as compared to RDF alone. Apart from exerting a positive impact on grain yield, the combined application of ABP and fertilizer led to an improvement in soil fertility, and modified the culturable rhizospheric bacterial community involved in N cycle. Integrated use of bioinoculants and fertilizer led to better N substrate utilization and hence, metabolic diversity when compared with application of fertilizer alone. An increase in the transcripts of nifH gene at the harvest stage in the soil treated with ABP alone and its combination with fertilizer, over individual treatment with fertilizer was observed. The combined use of ABP and fertilizer shaped the resident bacterial community towards a more beneficial community, which helped in increasing soil nitrogen turnover and hence, soil fertility as a whole.

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Amano lipase AK from P. fluorescens was immobilized on different types of chitosan-containing supports. Chitosan lower molecular weight (2.5%), chitosan lower molecular weight/sodium alginate (2.5%/2.5%) and chitosan lower molecular weight/carrageenan (2.5%/2.5%) allowed the highest values of immobilization yields (IY) of 81, 81 and 83%, respectively. Best activity results were achieved using chitosan average molecular weight (5%) and chitosan lower molecular weight/sodium alginate (2.5%/2.5%) as support, with values of 1.40 and 1.30 UpNPB/ggel and with recovery activities of 45.75 and 35.6%, respectively. These derivatives were evaluated in the kinetic resolution of rac-indanol to obtain a key intermediate in the synthesis of a drug used in the treatment of Parkinson's disease. The most efficient derivatives in the kinetic resolution were lipase immobilized on chitosan average molecular weight (5.0%) and chitosan low molecular weight/sodium alginate, the latter leading to obtaining both (S)-indanol and (R)-indanyl acetate with > 99% ee and 50% conversion.

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Bioremediation technology is one of the most profitable and sustainable strategies for remediating soils contaminated with hydrocarbons. This study focuses on assessing the influence of biostimulation and bioaugmentation with Pseudomonas fluorescens to contribute to the removal of total petroleum hydrocarbons (TPHs) of a soil. Laboratory studies were carried out (measurements of emitted CO2, surface tension, and residual TPH) to select the best bioaugmentation and biostimulation treatment. The sources of C, N, and P were glucose-yeast extract, NH4Cl-NaNO3, and K2HPO4-K3PO4, respectively. The effect of culture conditions on the reduction of TPH and respiratory activity was evaluated through a factorial design, 23, in a solid culture system. After 80 days of incubation, it was observed that treatments of yeast extract-NH4Cl-K2HPO4 (Y4) and glucose-NaNO3-K3PO4 (Y5) presented a higher level of TPH removal (20.91% and 20.00% degradation of TPH, respectively). Biostimulation favors the production of biosurfactants, indirectly measured by the change in surface tension in the soil extracts. The treatments Y4 and Y5 showed a lower change value of the surface tension (23.15 and 23.30 mN·m-1 at 25 °C). A positive correlation was determined between the change in surface tension and the removal of TPH; hence there was a contribution of the biosurfactants produced to the removal of hydrocarbons.

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