Search Results (37)

2,2′,4,4′-Tetrabromodiphenyl ether (BDE-47) is a refractory organic pollutant that is characterized by its persistence, toxicity and potential for bioaccumulation. As a typical biocontrol bacteria, Pseudomonas protegens has not been reported to degrade organic pollutants in the environment. A single strain of Pseudomonas protegens was isolated and acclimated from municipal sludge, and its ability to degrade BDE-47 was investigated. The enhancing effects of different carbon sources and inducers on Pseudomonas protegens were also examined. Through the reinforcement of bacterial enhancers, Pseudomonas protegens was applied to remediate soil and water contaminated with BDE-47. Based on colony characteristics, physiological and biochemical properties, and 16S rDNA gene sequence homology analysis, the strain was identified as Pseudomonas protegens and named YP1. This marks the first discovery of Pseudomonas protegens being capable of degrading BDE-47. Strain YP1 utilized BDE-47 as a carbon source and achieved a degradation rate of 69.57% after 75 h of incubation under conditions of 37 °C, pH 7, and constant temperature in a dark shaking incubator. After comparing the actual enhancement effects, glucose was selected as the carbon source and 2,4-dichlorophenol as the inducer to improve the environmental remediation capability of Pseudomonas protegens. After 14 days of remediation, the degradation rates of BDE-47 in contaminated soil and water reached 48.26% and 52.60%, respectively. The Pseudomonas protegens strain obtained from municipal sludge through screening, acclimation, and enhancement processes exhibits excellent environmental remediation capabilities and promising practical application prospects. Full article

Foliar application of biostimulants can be a valid option to reach the goal of sustainable intensification in agriculture, especially in extensive crops such as durum wheat. However, due to the wide range of active ingredients and their mixtures available in the market, the need to select the most efficient product in a specific growing environment is of dramatic importance to achieve remarkable results in yield and grain quality. To analyze the potential of different active ingredients, a field trial was performed in two consecutive growing seasons (2023 and 2024) under Mediterranean climatic conditions. A randomized block design with three replicates was used. Durum wheat cultivar “Iride” was treated with the following five foliar biostimulants in comparison with the untreated control (T0): seaweed and plant extracts (T1); micronized vaterite (T2); culture broth of Pseudomonas protegens (T3); humic and fulvic acids (T4); organic nitrogen fertilizer (N 5%) containing glycine betaine (T5). Biostimulant treatment was applied at the end of tillering and at heading. Root length, chlorophyll content, grain yield, yield components and grain quality were measured and subjected to a one-way analysis of variance. As compared to the control, seaweed and plant extracts as well as micronized vaterite showed the best results in terms of grain yield (29% and 24% increase, respectively), root length (120% and 77% increase, respectively) and grain protein content (one percentage point increase, from approx. 12% to 13%). The results from this study can help Mediterranean farmers and researchers to develop new fertilization protocols to reach the goals of the “Farm to Fork” European strategy. Full article

Novel three-dimensional porous composites of alginate–pectin (A/P) with zinc- or manganese-substituted hydroxyapatites (A/P-ZnHA and A/P-MnHA) were synthesized via lyophilization and calcium cross-linking. Powder X-ray diffraction and infrared spectroscopy analyses confirmed single-phase apatite formation (crystallite sizes < 1 µm), with ZnHA exhibiting lattice contraction (*c*-axis: 6.881 Å vs. 6.893 Å for HA). Mechanical testing revealed tunable properties: pristine A/P sponges exhibited an elastic modulus of 4.7 MPa and a tensile strength of 0.10 MPa, reduced by 30–70% by HA incorporation due to increased porosity (pore sizes: 112 ± 18 µm in the case of MnHA vs. 148 ± 23 µm-ZnHA). Swelling capacity increased 2.3–2.8-fold (125–155% vs. 55% for A/P), governed by polysaccharide interactions. Scanning electron microscopy investigation showed microstructural evolution from layered A/P (<100 µm) to tridimensional architectures with embedded mineral particles. The A/P-MnHA composites demonstrated minimal cytotoxicity for the NCTC cells and good viability of dental pulp stem cells, while A/P-ZnHA caused ≈20% metabolic suppression, attributed to hydrolysis-induced acidification. Antibacterial assays highlighted A/P-MnHA′s broad-spectrum efficacy against Gram-positive (Bacillus atrophaeus) and Gram-negative (Pseudomonas protegens) strains, whereas A/P-ZnHA targeted only the Gram-positive strain. The developed composite sponges combine cytocompatibility and antimicrobial activity, potentially advancing osteoplastic materials for bone regeneration and infection control in orthopedic/dental applications. Full article

Background/Objectives: Endophytes can produce bioactive metabolites similar to their host plants. CM-YJ44 (Pseudomonas protegens CHA0, 99.24% similarity), an endophyte from Dendrobium officinale, has not yet validated hypoglycemic potential. This study aimed to evaluate its anti-insulin resistance (IR) activity and metabolite profile. Methods: The fermentation broth of CM-YJ44 was separated into three fractions (CM-YJ44-1, -2, and -3) using semi-preparative high-performance liquid chromatography (pre-HPLC). An IR HepG2 cell model was constructed to evaluate their glucose uptake capacity. CM-YJ44-3 was further tested for oxidative stress, inflammatory, and insulin signaling pathway activation. Metabolites in CM-YJ44-3 were preliminarily identified using the Q Exactive Focus LC-MS system (QE), and the dendrobine content was quantified by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS). Molecular docking was performed to predict the binding affinities between dendrobine and target proteins. Results: Among the three fractions, CM-YJ44-3 significantly reduced nitric oxide (NO) and reactive oxygen species (ROS) levels in IR cells, enhanced glycogen synthesis, upregulated the activities of pyruvate kinase (PK) and hexokinase (HK), and suppressed the expression of inflammatory factors. Its mechanism of action was mainly through activation of the IRS1/PI3K/Akt/GSK3β/GLUT4 signaling pathway. QE analysis preliminarily identified 24 metabolites in CM-YJ44-3. Quantitative analysis by UPLC-MS/MS showed that the dendrobine content was 78.73 ± 4.29 ng/mL. Molecular docking results indicated that dendrobine exhibited binding energies below −5 kcal/mol with multiple target proteins involved in this signaling pathway, suggesting it may be a key bioactive component responsible for the anti-IR effect. Conclusions: This study provides the first evidence of hypoglycemic bioactive metabolite production by strain CM-YJ44, indicating its potential as a novel microbial candidate for alleviating IR. Full article

In the present study, the strain Rhizopus oryzae EMM was isolated from germinated autochthonous red maize seeds, which were harvested in a region of San Diego-Buenavista, Papalotla, Tlaxcala, Mexico, where cobs with fungal infections have been observed. This fungal strain caused wilting in the maize seedlings. Pseudomonas protegens EMM-1 was tested for its ability to inhibit R. oryzae EMM, both in culture media and in association with maize plantlets. P. protegens EMM-1 inhibited the growth of R. oryzae EMM under all culture media conditions explored. The ability of P. protegens EMM-1 to inhibit the growth of R. oryzae EMM associated with plants was evaluated in both a hydroponic system and in vermiculite. In both systems, P. protegens EMM-1 strongly inhibited the growth of R. oryzae EMM. The dry weight of root plants infected with R. oryzae EMM and inoculated with P. protegens EMM-1 increased to 0.43 g, while that of plants infected only with R. oryzae EMM reached just 0.19 g under hydroponic conditions. However, no differences were observed under vermiculite conditions. The dry weight of the aerial region of plants infected with R. oryzae EMM and inoculated with P. protegens EMM-1 was greater than that of plants infected only with R. oryzae EMM, both under hydroponic and vermiculite conditions. These results indicate that P. protegens EMM-1 inhibits the infection caused by R. oryzae EMM, thereby improving plant growth. Moreover, the genome analysis of P. protegens EMM-1 revealed the presence of several genes that potentially encode for antimicrobial compounds, which could strengthen the potential use of P. protegens EMM-1 as a biocontrol agent in maize plants. Full article

Hydrocarbon fuel biofouling and biocorrosion require expensive cleanup of aviation infrastructures unless appropriate sustainment measures are applied. The identification of novel biological control agents offers promising alternatives to the current chemical biocides used in fuel sustainment. In this study, 496 microbial fuel isolates from our in-house repository were screened to identify new endogenously produced antimicrobial compounds. Using agar plug screening, liquid culture growth testing, and Jet A fuel culture assays, the two fuel-isolate strains Pseudomonas protegens #133, and Bacillus subtilis #232 demonstrated promising biocontrol activity against bacteria, yeast, and filamentous fungi. Liquid chromatography-quadrupole time of flight tandem mass spectrometry (LC-QTOF-MS/MS) of #232 culture filtrate identified several common lipopeptide antimicrobials including gageostatin C, gageopeptin B, and miscellaneous macrolactins. In contrast, LC-QTOF-MS/MS identified the siderophore pyochelin as one of the predominant compounds in #133 culture filtrate with previously demonstrated antimicrobial effect. Jet fuel microbial consortium culture testing of #133 culture filtrate including flow-cytometry live/dead cell mechanism determination demonstrated antimicrobial action against Gram-positive bacteria. The study concludes that antimicrobial compounds secreted by #133 have bactericidal effects against Gordonia sp. and cause cell death through bacterial lysis and membrane damage with potential applications in the biocidal treatment of hydrocarbon-based aviation fuels. Full article

Aluminum toxicity in acidic soils threatens rice (Oryza sativa L.) cultivation, hindering agricultural productivity. This study explores the potential of plant growth-promoting rhizobacteria (PGPR) as a novel and sustainable approach to mitigate aluminum stress in rice. Two rice varieties, INIAP-4M and SUPREMA I-1480, were selected for controlled laboratory experiments. Seedlings were exposed to varying aluminum concentrations (0, 2, 4, 8, and 16 mM) in the presence of four PGPR strains: Serratia marcescens (MO4), Enterobacter asburiae (MO5), Pseudomonas veronii (R4), and Pseudomonas protegens (CHAO). The INIAP-4M variety exhibited greater tolerance to aluminum than SUPREMA I-1480, maintaining 100% germination up to 4 mM and higher vigor index values. The study revealed that rhizobacteria exhibited different responses to aluminum concentrations. P. protegens and S. marcescens showed the highest viability at 0 mM (2.65 × 10¹⁰ and 1.71 × 10¹⁰ CFU mL⁻¹, respectively). However, P. veronii and S. marcescens exhibited the highest viability at aluminum concentrations of 2 and 4 mM, indicating their superior tolerance and adaptability under moderate aluminum stress. At 16 mM, all strains experienced a decrease, with P. protegens and E. asburiae being the most sensitive. The application of a microbial consortium significantly enhanced plant growth, increasing plant height to 73.75 cm, root fresh weight to 2.50 g, and leaf fresh weight to 6 g compared to the control (42.75 cm, 0.88 g, and 3.63 g, respectively). These findings suggest that PGPR offer a promising and sustainable strategy to bolster rice resilience against aluminum stress and potentially improve crop productivity in heavy metal-contaminated soils. Full article

The ability of some rhizosphere bacteria to mitigate herbicidal stress in cultivated plants may be useful in agriculture and bioremediation. There is poor understanding of how bacteria directly or through herbicide degradation affect the biochemical processes in plants exposed to sulfonylurea herbicides. In this study, treatment with a combination of herbicide metsulfuron-methyl (MSM) and bacteria (Pseudomonas protegens DA1.2 or P. chlororaphis 4CH) of wheat (Triticum aestivum L.) and canola (Brassica napus L.) plants was carried out. Activity of glutathione-S-transferase (GST), an important enzyme for the herbicide detoxification, and acetolactate synthase (ALS), a target for MSM in plants, was measured by spectrophotometric assays. MSM residues were analyzed using the HPLC-MS. Then, 24 h after bacterial treatment, GST activity increased by 75–91% in wheat and by 38–94% in canola. On the 30th day, a decrease in MSM in the soil associated with bacterial treatment was 54.6–79.7%. An increase in GST activity and acceleration of MSM degradation were accompanied by a decrease in inhibition of the ALS enzyme in plants, which indicated a mitigation of the toxic effect. The results obtained are evidence that rhizospheric bacteria can have beneficial effects on plants exposed to MSM due to the combination of abilities to directly affect detoxification enzymes in plants and degrade MSM in the soil. Full article

Fungal trunk disease (FTD) poses a significant threat to hazelnut (Corylus avellana L.) production worldwide. In Chile, the fungus Diplodia mutila, from the Botryosphaeriaceae family, has been frequently identified causing this disease in the Maule and Ñuble Regions. However, control measures for D. mutila remain limited. This research aimed to evaluate the effectiveness of chemical and biological fungicides against D. mutila under in vitro, controlled pot experiment, and field conditions. An in vitro screening of 30 fungicides was conducted. The effectiveness was assessed by measuring the length of vascular lesions in hazelnut branches inoculated with D. mutila mycelium disks under controlled and field conditions. Field trials were conducted in a hazelnut orchard in Ñiquén, Ñuble Region, Chile. The results showed that three biological and five chemical fungicides were selected in vitro with >31% inhibition after 14 days. In pot experiments, all fungicides reduced necrotic lesions on branches by 32% to 61%. In field experiments, the most effective systemic fungicides were fluopyram/tebuconazole, fluxapyroxad/pyraclostrobin, and tebuconazole, while the effectiveness of antagonists Pseudomonas protegens ChC7 and Bacillus subtilis QST713 varied with seasonal temperatures. Effective conventional and biological fungicides against D. mutila could be integrated into disease management programs to protect hazelnut wounds from infections. Full article

Pollution from crude oil and its derivatives poses a serious threat to human health and ecosystems, with accidental spills causing substantial damage. Biodegradation, using microorganisms to break down these contaminants, presents a promising and cost-effective solution. Exploring and utilizing new bacterial strains from underexplored habitats could improve remediation efforts at contaminated sites. This study aimed to evaluate the hydrocarbon biodegradation capacity of bacteria isolated from agricultural soils in Huamachuco, Peru. Soil samples from Oca crops were collected and bacteria were isolated. Biodegradation assays were conducted using diesel as the sole carbon source in the Bushnell Haas Mineral medium. Molecular characterization of the 16S rRNA gene identified four strains. Diesel biodegradation assays at 1% concentration were performed under agitation conditions at 150 rpm and 30 °C, and monitored on day 10 by measuring cellular biomass (OD₆₀₀), with hydrocarbons analyzed by gas chromatography. The results showed Pseudomonas protegens (PROM2) achieved the highest efficiency in removing total hydrocarbons (91.5 ± 0.7%). Additionally, Pseudomonas citri PROM3 and Acinetobacter guillouiae ClyRoM5 also demonstrated high capacity in removing several individual hydrocarbons. Indigenous bacteria from uncontaminated agricultural soils present a high potential for hydrocarbon bioremediation, offering an ecological and effective solution for soil decontamination. Full article

The relationships between plants and bacteria are essential in agroecosystems and bioinoculant development. The leaf endophytic Pseudomonas protegens E1BL2 was previously isolated from giant Jala maize, which is a native Zea mays landrace of Nayarit, Mexico. Using different Mexican maize landraces, this work evaluated the strain’s plant growth promotion and biocontrol against eight phytopathogenic fungi in vitro and greenhouse conditions. Also, a plant field trial was conducted on irrigated fields using the hybrid maize Supremo. The grain productivity in this assay increased compared with the control treatment. The genome analysis of P. protegens E1BL2 showed putative genes involved in metabolite synthesis that facilitated its beneficial roles in plant health and environmental adaptation (bdhA, acoR, trpE, speE, potA); siderophores (ptaA, pchC); and extracellular enzymes relevant for PGPB mechanisms (cel3, chi14), protection against oxidative stress (hscA, htpG), nitrogen metabolism (nirD, nit1, hmpA), inductors of plant-induced systemic resistance (ISR) (flaA, flaG, rffA, rfaP), fungal biocontrol (phlD, prtD, prnD, hcnA-1), pest control (vgrG-1, higB-2, aprE, pslA, ppkA), and the establishment of plant-bacteria symbiosis (pgaA, pgaB, pgaC, exbD). Our findings suggest that P. protegens E1BL2 significantly promotes maize growth and offers biocontrol benefits, which highlights its potential as a bioinoculant. Full article

Seed treatment with plant growth-promoting bacteria represents the primary strategy to incorporate them into agricultural ecosystems, particularly for crops under extensive management, such as maize. In this study, we evaluated the seed bacterization levels, root colonization patterns, and root competitiveness of a collection of autochthonous Pseudomonas isolates that have demonstrated several plant-probiotic abilities in vitro. Our findings indicate that the seed bacterization level, both with and without the addition of various protectants, is specific to each Pseudomonas strain, including their response to seed pre-hydration. Bacterization kinetics revealed that while certain isolates persisted on seed surfaces for up to 4 days post-inoculation (dpi), others experienced a rapid decline in viability after 1 or 2 dpi. The observed differences in seed bacterization levels were consistent with the root colonization densities observed through confocal microscopy analysis, and with root competitiveness quantified via selective plate counts. Notably, isolates P. protegens RBAN4 and P. chlororaphis subsp. aurantiaca SMMP3 demonstrated effective competition with the natural microflora for colonizing the maize rhizosphere and both promoted shoot and root biomass production in maize assessed at the V3 grown stage. Conversely, P. donghuensis SVBP6 was detected at very low levels in the maize rhizosphere, but still exhibited a positive effect on plant parameters, suggesting a growth-stimulatory effect during the early stages of plant development. In conclusion, there is a considerable strain-specific variability in the maize seed bacterization and survival capacities of Pseudomonas isolates with plant-probiotic traits, with a correlation in their root competitiveness under natural conditions. This variability must be understood to optimize their adoption as inputs for the agricultural system. Our experimental approach emphasizes the critical importance of tailoring seed bacterization treatments for each inoculant candidate, including the selection and incorporation of protective substances. It should not be assumed that all bacterial cells exhibit a similar performance. Full article

Improving the quality of tree planting material for carbon sequestration through reforestation can help solve environmental problems, including the need to reduce the concentration of carbon dioxide in the atmosphere. The purpose of this study was to investigate the possibility of using humic substances in combination with rhizosphere microorganisms Pseudomonas protegens DA1.2 and Pseudomonas sp. 4CH as a means to stimulate the growth of seedlings of pine, poplar, large-leaved linden, red oak, horse chestnut, and rowan. Humic substances stimulated the growth of shoots and roots of pine, large-leaved linden, and horse chestnut seedlings. The effects of bacteria depended on both plant and bacteria species: Pseudomonas protegens DA1.2 showed a higher stimulatory effect than Pseudomonas sp. 4CH on pine and linden, and Pseudomonas sp. 4CH was more effective in the case of chestnut. An additive effect of humates and Pseudomonas protegens DA1.2 on the growth rate of pine and linden saplings was discovered. Poplar, red oak, and rowan seedlings were unresponsive to the treatments. The growth-stimulating effects of the treatments are discussed in connection with the changes in carbon, chlorophyll, and nitrogen contents in plants. The results show the need for further research in bacterial species capable of stimulating the growth of plant species that were unresponsive in the present experiments. Full article

Algae and bacteria have co-occurred and coevolved in common habitats for hundreds of millions of years, fostering specific associations and interactions such as mutualism or antagonism. These interactions are shaped through exchanges of primary and secondary metabolites provided by one of the partners. Metabolites, such as N-sources or vitamins, can be beneficial to the partner and they may be assimilated through chemotaxis towards the partner producing these metabolites. Other metabolites, especially many natural products synthesized by bacteria, can act as toxins and damage or kill the partner. For instance, the green microalga Chlamydomonas reinhardtii establishes a mutualistic partnership with a Methylobacterium, in stark contrast to its antagonistic relationship with the toxin producing Pseudomonas protegens. In other cases, as with a coccolithophore haptophyte alga and a Phaeobacter bacterium, the same alga and bacterium can even be subject to both processes, depending on the secreted bacterial and algal metabolites. Some bacteria also influence algal morphology by producing specific metabolites and micronutrients, as is observed in some macroalgae. This review focuses on algal-bacterial interactions with micro- and macroalgal models from marine, freshwater, and terrestrial environments and summarizes the advances in the field. It also highlights the effects of temperature on these interactions as it is presently known. Full article