Search Results (149)

Plant growth-promoting bacteria (PGPBs) have emerged as essential biological inputs to improve the establishment, physiological performance and survival of forest species used in ecological restoration programs. The decline of Quercus forests throughout the Mediterranean basin requires innovative and sustainable strategies to improve early seedling establishment. Among possible PGBs, Bacillus pretiosus has attracted significant interest due to its ability to promote plant growth, modulate the nutrient status of the host, and safely interact with native rhizosphere microbiota. At the same time, evaluating urban wastewater waste using PGPB offers a promising circular economy approach. To provide an integrated functional and ecological assessment of B. pretiosus C1, this in silico study harmonizes and reinterprets experimental datasets through contrasting fertigation regimes—water (W), wastewater treatment plant effluent (EDAR) and electrochemically treated effluent (EDARST)—evaluating inoculation (C1) versus uninoculated controls (C0). Inoculation resulted in a consistent positive biometric response, significantly promoting outbreak length (up to +16.2% in EDARST). In addition, B. pretiosus C1 improved nitrogen leaf metabolism, raising crude protein levels (+11.8%), soluble protein and total amino acids (+15.4%). Sequencing and functional profiling of the high-yield 16S rRNA gene revealed that the introduction of strains did not significantly alter the alpha-diversity or overall beta structure of the native rhizosphere microbiome, demonstrating high ecological compatibility. Phenotypic profiling of the resistome by cenoantibiogram did not confirm an increase in resistance to antibiotics at the community level, instead showing a significant reduction in the minimum inhibitory concentration (MIC) for imipenem and amoxicillin/clavulanic acid under the fertigation of effluents. Together, these findings demonstrate that combining effluents valued with p > 0.05 B. pretiosus C1 shows a consistent functional profile with a high-value biotechnological agent, improving the biometric and nutritional status of seedlings without altering the stability of the soil microbial community. This supports its potential application as a safe biofertilizer candidate within forest restoration strategies and One Health, although more prospective field trials will be needed to validate each site. Full article

Consolidated bioprocessing (CBP) using Acetivibrio thermocellus offers a promising route for the direct conversion of recalcitrant lignocellulose into ethanol. In this study, a synergistic co-culture system comprising A. thermocellus C1 and Thermoanaerobacterium thermosaccharolyticum DSM571 was established for the bioconversion of untreated Salix psammophila, a woody biomass native to the desert regions of Inner Mongolia. To enhance fermentation performance, exogenous additives—including Fe₃O₄ nanoparticles, biochar, and CaCO₃—were introduced in combination with process parameter optimization. These additives significantly stimulated microbial ethanol synthesis. Under optimized co-culture conditions, the system demonstrated exceptional cell-wall deconstruction capability, achieving a cellulose degradation rate of 75.04% and a hemicellulose degradation rate of 65.30%. Bioethanol was produced at a yield of 28.95% of the theoretical maximum. These results confirm that simultaneous co-inoculation allows both strains to establish a balanced cooperative interaction from the onset of fermentation, effectively facilitating synergistic sugar utilization and metabolic carbon flux. This high efficiency in raw biomass deconstruction provides a solid laboratory-scale proof-of-concept, highlighting the strong potential of this direct CBP strategy for converting raw desert biomass into high-value bio-based chemicals and fuels. Full article

Soil contamination by mercury (Hg) represents a significant ecotoxicological risk due to its high toxicity and environmental persistence. This study evaluated the effects of the native strain Pseudomonas agronomica on the growth, physiological status and antioxidant response of Lupinus albus cultivated in soils with different Hg concentrations, as well as the influence of inoculation on Hg accumulation and translocation within plant tissues. A pot experiment was conducted using three Hg levels, with and without bacterial inoculation. Plant growth and antioxidant parameters were assessed, Hg concentrations were quantified by ICP-MS, and soil metabolic activity and microbial community structure were analyzed using Biolog EcoPlates^®, cenoantibiogram assays and 16S rRNA gene sequencing. Inoculation with P. agronomica significantly reduced Hg accumulation in roots and leaves (p < 0.001) and malondialdehyde levels (p < 0.05), decreased community-level antibiotic resistance, and increased plant biomass, particularly at intermediate Hg concentrations, while enhancing soil functional diversity without altering alpha diversity. Overall, these findings highlight the potential of Pseudomonas agronomica C69 as a native plant growth-promoting bioinoculant to improve the sustainable cultivation and phytoremediation capacity of low-alkaloid Lupinus albus grown in Hg-contaminated soils. Full article

Cadmium (Cd) contamination of Amazonian cocoa soils threatens Theobroma cacao production, and shade-tree rhizospheres may harbour Cd-tolerant fungi useful for bioremediation. Trichoderma associated with Quararibea sp. remain unexplored. We isolated native Trichoderma from rhizospheres of Inga sp. and Quararibea sp. in Bagua (Peru), and evaluated Cd tolerance (25–200 ppm) through growth inhibition percentage (GIP) and IC₅₀ from dose–response models selected via the Akaike Information Criterion (AIC). Of 16 Trichoderma-like isolates, five met stringent multilocus quality criteria: JSRA09 (Quararibea sp.) and JSRA16, JSRA22, JSRA28, JSRA30 (Inga sp.). Independent Maximum Likelihood trees (ITS, tef1, rpb2) assigned JSRA09 to the T. spirale/T. subuliforme clade, JSRA16 to the T. harzianum complex (affinity to T. lentiforme), JSRA22 and JSRA28 to a clade within the T. koningii/T. koningiopsis complex, and JSRA30 to T. afroharzianum. To the best of our knowledge, JSRA09 represents the first Trichoderma report in Quararibea sp. No strain exceeded 35% inhibition at 200 ppm: JSRA09 and JSRA16 were highly tolerant (GIP < 10%), JSRA28 and JSRA30 moderately tolerant, and JSRA22 tolerant. AIC selection yielded linear responses for JSRA09 and JSRA16, log-logistic (LL.4) for JSRA22, JSRA28 and JSRA30. These native strains are candidates for further screening towards microbial consortia for Cd bioremediation. Full article

More than six decades of human activity in Antarctica resulted in chronic diesel contamination of soils surrounding research stations. Phytoremediation assisted by the native vascular plant Deschampsia antarctica is one of the few remediation strategies compatible with the Antarctic Treaty System guidelines. Securing suitable root-associated microbial resources is central to this approach. This work characterized the bacterial communities of the rhizosphere and root endosphere of D. antarctica growing in a chronically diesel-contaminated soil at Carlini Station and in three pristine sites on 25 de Mayo (King George) Island, South Shetland Islands, combining culture-independent 16S rRNA gene amplicon sequencing, PICRUSt2 functional prediction and culture-dependent bacterial strain isolation. The rhizospheric microbial community was consistently more diverse than those inhabiting the endosphere and was more strongly structured by site and associated soil physicochemical variables, with the contaminated site showing the most distinct composition, whereas the endosphere remained comparatively stable and host-selected. The community associated with the chronically contaminated site showed pronounced compositional differences and higher predicted abundances of hydrocarbon-degradation pathways in the rhizosphere. Polaromonas, Rhodococcus, Mycobacterium and Devosia were repeatedly associated with the community from the contaminated site across taxonomic, biomarker and predicted functional analyses. Members of the genera Polaromonas, Rhodococcus and Devosia were also recovered in culture. These taxa represent suitable candidates for the future development of microbe-assisted phytoremediation strategies in Antarctica. Full article

The functional expression of plant growth-promoting (PGP) traits in soil actinobacteria is conditioned by abiotic factors, yet the combined effects of pH and temperature on their metabolic profiles and the stability of these profiles after encapsulated formulation and post-processing stress remain insufficiently characterized. This study aimed to evaluate the physiological plasticity of native actinobacteria and the expression of plant growth-promoting (PGP) traits under different pH and temperature conditions, as well as their stability after encapsulation, dehydration, and exposure to UV irradiation. Strains isolated from a semi-arid agricultural soil were analyzed to determine their ability to produce indole-3-acetic acid (IAA), siderophores, and phosphatases, as well as their ability to fix nitrogen, degrade cellulose, and tolerate salt stress. Temperature and pH significantly affected all evaluated PGP traits (p < 0.001), and their expression was not directly associated with biomass production. Two strains, S1 and S4, exhibited the highest overall PGP indices. Strain S1 maximized IAA and siderophore production under neutral conditions (pH 7.0, 30 °C), whereas strain S4 maintained more stable phosphatase activity across the tested pH and temperature ranges. Cell viability remained above 85% after encapsulation and dehydration. Dehydration enhanced IAA and siderophore production in strain S1, while strain S4 exhibited transient metabolic activation under UV irradiation in non-dehydrated capsules. The encapsulation matrix preserved cell viability more effectively than it preserved the complete PGP functional profile, indicating that viability alone is an insufficient criterion for evaluating the technological success of alginate-based bioinoculant formulations. These findings highlight the importance of integrating environmental preconditioning and functional stability assessments into the development of robust microbial bioinoculants adapted to agricultural systems subjected to fluctuating environmental conditions. Full article

This study employed sequential inoculation of native non-brewing yeasts Kluyveromyces marxianus YC-T7 and Pichia kudriavzevii QC-P3 to co-ferment dry white wine from Munage, a unique fresh-eating grape variety native to Xinjiang, providing technical support for the development of regionally distinctive wines in Xinjiang. To investigate how mixed fermentation with indigenous Xinjiang non-Saccharomyces (NS) yeasts and Saccharomyces cerevisiae (SC) influences the aromatic profile of Munage wine, two NS strains—K. marxianus YC-T7 and P. kudriavzevii QC-P3—previously isolated and selected by our group were sequentially co-inoculated with S. cerevisiae CEC01. Strain growth dynamics were first characterized in a synthetic grape juice (SGJ) system under varying inoculation protocols; subsequently, Munage grapes were fermented under optimized sequential inoculation to assess physicochemical parameters, volatile aroma composition, and sensory attributes of the resulting dry white wine. Results demonstrated that, under sequential inoculation, the QC-P3 + SC consortium entered the late logarithmic phase on day 4 and achieved a final ethanol concentration of 10.29%vol, whereas the YC-T7 + SC consortium reached the same growth stage on day 5 with 10.27%vol ethanol—confirming robust and timely alcoholic fermentation for both consortia. Consequently, sequential inoculation was adopted as the standard protocol for Munage wine production. All key physicochemical parameters complied with China’s national standards for dry white wine. Relative to pure SC fermentation, the YC-T7 + SC treatment increased tartaric acid, α-ketoglutaric acid, and citric acid contents by 3.15%, 12.16%, and 2.18%, respectively; the QC-P3 + SC treatment induced more pronounced enhancements—22.58%, 51.64%, and 14.70%, respectively. A total of 54 volatile compounds were identified, including 29 esters, 12 alcohols, 7 organic acids, 4 phenolic compounds, and 2 others. Integrated analysis using odor activity values (OAVs), principal component analysis (PCA), and descriptive sensory evaluation consistently revealed that the YC-T7 + SC wine exhibited the highest concentrations of fruit- and flower-associated esters, while the QC-P3 + SC wine was distinguished by a distinctive pineapple-like aroma driven predominantly by ethyl butyrate. Collectively, sequential co-inoculation of indigenous Xinjiang NS strains YC-T7 and QC-P3 with S. cerevisiae significantly improved Munage wine quality—particularly in acidity balance, polyphenol retention, and aromatic complexity—thereby offering both novel microbial resources and a validated technical framework for stylistically authentic vinification of terroir-expressive wines from the Xinjiang region. Full article

The degradation of Calcisols in the arid regions of Central Asia constrains sustainable agricultural production because of low organic matter content, poor aggregate stability, nutrient limitations, and increasing climatic stress. This study evaluated a rhizosphere engineering approach based on the native plant growth-promoting bacterium Pseudomonas veronii Ps-S/Sh-1503/2022 for the rehabilitation of degraded Calcisols. Four-year field experiments (2022–2025) using Sorghum bicolor assessed plant growth, rhizosphere microbial indicators, physiological responses, pathogen suppression, crop productivity, and implementation feasibility through economic and environmental assessments. Inoculation with P. veronii increased root depth by 45%, improved aboveground biomass, increased the ratio of culturable bacteria to Fusarium spp. from 6.1 to 10.3, and reduced Fusarium abundance by 29.4%. Structural equation modeling suggested that trophic support (42.1%), aggregate stabilization (27.4%), biocontrol (23.3%), and defense-related responses (7.2%) were the principal pathways associated with soil rehabilitation. Economic assessment indicated that the combined inoculation and mineral fertilization treatment provided the highest profitability, while environmental assessment estimated potential reductions in mineral fertilizer use and greenhouse gas emissions. These findings suggest that rhizosphere engineering using a native P. veronii strain represents a promising, economically viable, and climate-smart approach for improving the biological functioning of degraded Calcisols and supporting sustainable agricultural production. Full article

The root parasitic weed Phelipanche aegyptiaca poses a serious threat to tomato production in arid regions of Northwest China, yet effective and environmentally friendly control measures remain limited. In this study, an endophytic bacterial strain G24 with strong inhibitory activity against P. aegyptiaca seed germination was isolated from healthy tomato tissues. In vitro germination assays showed that both the fermentation broth and cell-free supernatant of G24 completely inhibited seed germination even at 1000-fold dilution, indicating that the active metabolites are extracellularly produced or released. Pot experiments further demonstrated that G24 inoculation significantly reduced the number, fresh weight, and dry weight of parasitic broomrape nodules on tomato roots, with reductions of 69.4%, 89.0%, and 88.6%, respectively, compared with the control. Moreover, G24 significantly increased tomato stem diameter, indicating its intrinsic plant growth-promoting capacity. Although both sterile NB medium and G24 suspension increased whole-plant fresh weight, no statistically significant difference was observed between the two treatments (p > 0.05). The reduced leaf chlorophyll concentration per unit fresh weight in G24-treated tomatoes was a typical growth dilution effect and did not suppress overall plant performance, and no phytotoxicity was detected. Based on morphological, physiological–biochemical, and multilocus phylogenetic analyses (16S rDNA, gyrB, and rpoB), strain G24 was identified as Lelliottia nimipressuralis. As a native endophyte of tomato, L. nimipressuralis G24 exhibits excellent host compatibility, biocontrol efficacy, and growth-promoting activity, with no adverse effects on tomato development. This study expands the application potential of the genus Lelliottia in parasitic weed management and provides a novel microbial resource for the integrated and sustainable control of P. aegyptiaca. Full article

Monitoring individual strains in complex microbial communities remains a fundamental challenge in microbial ecology and biotechnology. Here, we present an integrated pipeline for identifying and validating strain-specific loci (SSL) in four biotechnologically relevant plant growth promoting strains from three genera (Stenotrophomonas, Bacillus, and Pseudomonas). The pipeline applies a two-round specificity-filtering strategy combining whole-genome comparison and high-sensitivity BLASTn validation of revealed strain-specific loci (SSL) against the NCBI nucleotide database. SSL count decreased with increasing Average nucleotide identity (ANIb) of the strains used for the analysis, ranging from one locus in B. halotolerans (ANIb = 98.91%) to 15 loci in S. rhizophila (ANIb = 86.49%). All 25 SSL were universally AT-rich, mainly accessory-genome-associated, with flanking regions enriched in genes of unknown function (34.6%) and mobile genetic elements (19.2%). TaqMan qPCR assays targeting SSL demonstrated high specificity—no target sequences were detected across ten geographically distinct soil samples, nor in a native rhizosphere metagenome—and sensitivity, with limits of detection of 0.01–0.1 pg of genomic DNA. Spike-in experiments in soil yielded method detection limits (MDL) of 850–15,000 CFU/g. All four strains were detected in the wheat rhizosphere seven days after consortium application in a field experiment, validating the pipeline for multi-strain field monitoring. Full article

The intensive use of synthetic fertilizers in horticulture generates environmental and economic constraints, highlighting the need for sustainable alternatives such as plant growth-promoting bacteria. However, their effectiveness depends on strain adaptation to local conditions. This study evaluated the effect of Gluconacetobacter diazotrophicus (native isolate GIBI029 vs. reference strain ATCC 49037) under four nitrogen (0 and 100% of the recommended dose) and phosphorus (0 and 100% of the recommended dose) fertilization combinations on soil chemical properties, foliar nutrient uptake, and economic performance in greenhouse tomato production in Colombia. The native isolate was associated with higher soil nutrient levels, reaching 185.1 g/kg organic matter, 6.4 g/kg total nitrogen, 284.75 mg/kg available phosphorus, 9.32 cmol/kg calcium, and 3.93 cmol/kg magnesium. In addition, foliar nitrogen content reached 22.4 g/kg in treatments inoculated with GIBI029. These responses were associated with yields up to 106.4 t/ha, exceeding those obtained with the reference strain. Yield data were obtained from a previous study conducted under the same experimental design and environmental conditions and were incorporated here exclusively for the economic assessment. Economically, the native isolate achieved the highest benefit–cost ratio (2.65) and net income (USD 20,106/ha). A strong correlation between soil organic matter and nitrogen (r = 0.99) was observed, indicating a close association between these variables within the evaluated production system. These results suggest that strain origin may influence biofertilization efficiency and indicate that native microbial inoculants can contribute to improved agronomic and economic performance under the conditions evaluated, supporting their use in sustainable tomato production systems. Full article

The increasing global demand for energy has intensified the need for lithium, a critical component in rechargeable batteries and electric vehicles. However, conventional lithium extraction methods are associated with significant environmental impacts. In this study, a one-step bioleaching approach for lithium recovery from mineral concentrates was evaluated using native microbial consortia and isolated bacterial strains. A suitable culture medium was selected, individual strains were isolated, and bioleaching experiments were conducted using a Box–Behnken experimental design. Lithium solubilization and cell density were assessed under different agitation conditions, pulp concentrations, and initial pH values. The highest lithium solubilization (99%) was achieved under non-agitated conditions, with a pulp concentration of 30% and an initial pH of 6. Three bacterial strains (ITDB101, ITDR102, and ITDN103) were identified. The native microbial consortium and the biotic control exhibited the highest lithium solubilization efficiencies (94.5% and 96.3%, respectively), outperforming the individual strains, which achieved solubilization values ranging from 91.73% to 93.27%. X-ray diffraction analysis identified five mineral phases in the concentrate, and comparisons among treatments revealed changes in these phases following bioleaching, supporting the potential of this process as an environmentally friendly alternative for lithium extraction. Full article

Polycyclic aromatic hydrocarbons (PAHs) are persistent and toxic pollutants that accumulate in urban soils, reducing microbial diversity and compromising ecosystem functioning. Developing effective bioremediation strategies requires identifying native degraders and understanding their ecological dynamics under pollutant pressure. Here, we investigated fungal and bacterial communities from PAH-contaminated soil subjected to three consecutive enrichment steps using phenanthrene, fluoranthene, benzo(a)pyrene, benzo(g,h,i)perylene, and their mixture as the sole carbon sources. High-throughput sequencing of ITS2 and V3-V4 amplicons revealed a decline in alpha diversity and a strong restructuring of both communities during the enrichment. Distance-based redundancy analysis showed that contaminant type and enrichment progression jointly shaped community composition, selecting for stress-tolerant taxa. Culturomics yielded 102 fungal isolates, representing 19 taxa, predominantly within Ascomycota. The most represented taxa were Galactomyces pseudocandidus (19 strains), Fusarium oxysporum (five), Stilbella aciculosa and Exophiala attenuata (four each) and Fusarium solani (three). Approximately one-third of isolates harbored associated bacteria, mainly Stenotrophomonas, Bosea and Chitinophaga species. Functional assays identified biosurfactant-producing strains, while microplate screening highlighted Fusarium solani, Galactomyces pseudocandidus and Trametes versicolor as capable of growing under PAH-selective conditions. Overall, our results demonstrate that PAH-contaminated soils host fungal taxa able to persist under pollutant pressure together with recurrent fungi-associated bacteria of potential ecological relevance for bioremediation. Full article

Biosurfactants are surface-active microbial molecules with increasing industrial relevance as sustainable alternatives to synthetic surfactants. Among them, lipopeptides produced by Bacillus species, particularly surfactin, exhibit strong interfacial activity and biological functionality. In this study, rhizospheric soils from the La Araucanía region, Chile, were explored as a source of biosurfactant-producing bacteria. Eighteen strains were isolated, and two high-performing strains, Solo 1 and Solo 4, were identified as Bacillus amyloliquefaciens and Bacillus subtilis, respectively. Both strains harbored the srfAA gene and produced surfactin isoforms confirmed by MALDI-TOF MS. Kinetic analysis revealed distinct production profiles, with Solo 1 reaching a maximum of 90 mg L⁻¹ at 24 h, whereas Solo 4 showed continuous production up to 224.4 mg L⁻¹ at 72 h. Both biosurfactants exhibited high emulsification capacity (>80%) and stability across wide ranges of temperature, pH, and salinity. Importantly, cell-free supernatants from both strains showed antibacterial and antibiofilm activity against Staphylococcus aureus, with Solo 4 reaching 81% biofilm inhibition. In addition, surfactin-enriched extracts inhibited the pathogenic bacterium Pseudomonas syringae and the filamentous fungus Fusarium oxysporum, with Solo 4 consistently showing stronger antimicrobial performance. Overall, these findings identify Solo 4 as a promising native Bacillus strain for future development of biosurfactant-based systems aimed at antimicrobial control, biofilm management, agricultural pathogen suppression, surface sanitation, and environmentally compatible biotechnological processes. Full article

Ornamental fountains in the Alhambra and Generalife (Granada, Spain) constitute complex socio-ecological systems where water, stone, and biological communities interact, making them highly vulnerable to biodeterioration caused by phototrophic microorganisms such as cyanobacteria, green algae, and diatoms. Conventional chemical biocides, although widely applied, present significant drawbacks including toxicity, material degradation, ecological imbalance, and limited long-term effectiveness. In this context, this study evaluated the potential of algicidal bacteria as a sustainable alternative for controlling phototrophic growth in heritage environments. Water samples from eight ornamental fountains were analyzed using 16S ribosomal RNA (16S rRNA) gene sequencing to characterize bacterial communities and identify taxa previously reported with algicidal activity. Statistical analyses were conducted to assess relationships between microbial community structure and biofilm development. In parallel, functional screening assays using filtered fountain waters against Chlorella vulgaris were performed to evaluate intrinsic inhibitory capacity. The most active sample was selected for bacterial isolation and further validation through co-culture assays, cell density measurements, and pulse-amplitude-modulated (PAM) fluorometry. A total of 18 genera with reported algicidal capacity were detected, representing a substantial fraction of the microbiome across all samples. However, no significant association was found between these taxonomic metrics and biofilm development, highlighting a decoupling between taxonomic composition and functional activity. The most active isolate, identified as Stenotrophomonas maltophilia strain LIG25, caused a rapid decline in photosynthetic efficiency and achieved more than 98% inhibition of algal growth. These findings demonstrate that ornamental fountain microbiomes represent a reservoir of native biocontrol agents and support the development of eco-friendly strategies for cultural heritage conservation. Full article