Search Results (838)

To address yttrium (Y) contamination from ion adsorption mining, this study developed a combined microbial phytoremediation strategy for dual objectives: ensuring crop safety in Lactuca sativa and enhancing Y recovery by Solanum nigrum. Two specific microbial consortia were constructed from rare earth tailings isolates: inoculant I (bacterial: Enterobacter sp., Serratia sp., Bacillus sp.) applied to L. sativa, and inoculant II (fungal: Penicillium sp., Aspergillus sp., Talaromyces sp.) applied to S. nigrum. Inoculant I increased L. sativa biomass by 26% while reducing Y content in roots and rhizosphere soil solution by 47% and 56%, respectively, potentially through down-regulation of amino acid metabolites. Inoculant II increased Y content in the S. nigrum rhizosphere soil solution by 89%, linked to up-regulation of organic acids and coumarin derivatives. Both consortia reduced plant stress markers and enhanced soil enzyme activities. These findings demonstrate that specialized microbial consortia can differentially regulate Y behavior in the rhizosphere—immobilizing it in a crop for food safety, while enhancing its bioavailability for a hyperaccumulator—offering a targeted strategy for managing rare earth element-contaminated agricultural soils. Full article

Ledum palustre (L. palustre) is widely used in drug development because of its antibacterial and analgesic effects. However, wild L. palustre is often affected by wildfires, resulting in unstable yields. Forest fires represent a major disturbance in northern forest ecosystems and profoundly affect shrub vegetation and its associated rhizosphere microbial communities. In this study, we investigated a fire chronosequence (1991, 2004, 2012, 2017, and 2020) to systematically examine the morphological traits of L. palustre, rhizosphere soil physicochemical properties, and microbial community characteristics and to identify the key drivers underlying these patterns. The results revealed that postfire recovery time significantly influenced the morphological traits of L. palustre. The biomass, branch number, basal diameter, and plant height of the shrubs at the 1991 burned site increased by 270.49%, 36.11%, 79.32%, and 191.36%, respectively (p < 0.05). From unburned soils, 29 bacterial and 29 fungal isolates were obtained, with Bacillus sp. and Oidiodendron sp. being the dominant culturable bacterial and fungal taxa, respectively. With increasing postfire recovery time, soil moisture, total nitrogen, ammonium, nitrate, soil organic carbon, acid phosphatase (AP) and N-acetyl-β-D-glucosaminidase (NAG) activity significantly decreased. Early fire disturbance markedly altered soil microbial abundance and community composition, leading to an overall decrease in bacterial α diversity. The bacterial community structure at the 2020 burn site and the fungal community structure at the 2012 burn site significantly differed. Mantel tests revealed significant positive correlations between branch number and basal diameter (p < 0.01) and significant negative correlations between plant height and stem density (p < 0.001). Soil carbon and hydrolysable nitrogen were significantly positively correlated with AP and NAG activities (p < 0.001). Moreover, soil physicochemical properties significantly shaped soil microbial community structures, with bacterial communities in early postfire sites driven by total carbon and nitrogen (p < 0.05), whereas fungal communities in the 2012 burned site were influenced primarily by β-N-acetylglucosaminidase (BG) activity (p < 0.05). Fire disturbance drives successional changes in the rhizosphere microbial community structure and function by altering the soil nutrient status and enzyme activity, which in turn influences the morphological traits of L. palustre. This study provides a theoretical basis for improving the yield of L. palustre by exploring the variation in rhizosphere microorganisms. Full article

This study investigates the impact of inoculating seeds with bacterial endophytes isolated from Vitis amurensis Rupr. on endophytic community composition in Arabidopsis thaliana (L.) Heynh. Ten bacterial isolates of the genera Agrobacterium, Bacillus, Curtobacterium, Erwinia, Frondihabitans, Gordonia, Pantoea, Pseudomonas, Sphingomonas, and Xanthomonas were applied to seeds and some visible phenotypic effects were observed on plant growth after two weeks. High-throughput sequencing of 16S rRNA revealed that the native endophytic microbiome of A. thaliana was dominated by Gammaproteobacteria, Actinomycetes, Bacteroidia, and Alphaproteobacteria. The key families were Microscillaceae, Chitinophagaceae, Rhizobiaceae, Rhodanobacteraceae, Nocardioi-daceae, Nocardiaceae, Xanthomonadaceae, Devosiaceae, Microbacteriaceae, Crocinitomi-caceae, Pseudomonadaceae, Solimonadaceae, Comamonadaceae, Caulobacteraceae, and Micrococcaceae. Arabidopsis seed inoculation with Agrobacterium sp. R8SCh-B12, Curtobacterium sp. P7SA-B3, and Gordonia aichiensis P6PL2 significantly reduced alpha diversity (Shannon index) and altered beta diversity relative to controls, indicating strong community restructuring. These three isolates, along with Pseudomonas sp. R8SCh-B2, Sphingomonas sp. RA62c-B5, Xanthomonas sp. R7SCh-B6, and Bacillus velezensis AMR25, successfully colonized the plant tissues, as evidenced by significant increases in genus-specific amplicon sequence variants, ASVs (up to 17,820-fold for Curtobacterium sp. ASV33). In contrast, Pantoea sp. P7SCH-B5, Erwinia sp. R8SCh-B3, and Frondihabitans sp. RA62c-B2 failed to colonize A. thaliana, despite being applied to the seeds, suggesting the existence of mechanisms restraining colonization. These findings demonstrate that only a subset of grapevine-derived endophytes can effectively colonize A. thaliana, and that successful colonization correlates with significant shifts in the native microbiome, even in the absence of overt phenotypic changes. This emphasizes the importance of strain-specific compatibility in plant–endophyte interactions. Thus, we report the first descriptions of several novel endophytes that colonized Arabidopsis plants and establish a convenient model to investigate plant–bacterial interactions. Full article

Biosurfactant-producing microorganisms play an important ecological role in soils impacted by hydrophobic contaminants by enhancing substrate bioavailability and influencing microbial interactions. In this study, we critically evaluated the reliability of commonly used screening methods for biosurfactant detection. A total of 71 microbial isolates (16 bacteria and 55 fungi) were obtained from vegetable oil-contaminated soil and screened using a multi-step approach combining enzymatic assays (lipolytic and hemolytic activity) and physicochemical methods, including drop-collapse, oil spreading, emulsification index (E₂₄), and surface tension reduction. Although 21 isolates exhibited lipolytic activity and 9 showed hemolysis, inconsistent responses among assays revealed significant limitations of individual screening methods. Only two bacterial isolates consistently tested positive across all criteria. When cultivated in mineral salt medium supplemented with hydrophobic substrates, both isolates produced stable emulsions and significantly reduced surface tension (from 54.26 mN/m to 31.46 mN/m). Substrate-dependent variation was observed for isolate C3, which showed reduced surface tension (39.63 mN/m) when grown with biodiesel. These findings highlight the risk of relying on single assays and emphasize the need for integrated screening strategies to ensure reliable detection of biosurfactant-producing microorganisms. Full article

Polyhydroxyalkanoates (PHAs) are biodegradable microbial polyesters that represent a promising sustainable alternative to petroleum-based plastics. Salterns, hypersaline environments, are recognized as significant sources of halotolerant microorganisms that can produce PHAs in high-salinity conditions; however, Vietnamese saltern ecosystems have not been extensively investigated. This research aimed to isolate and initially characterize salt-tolerant bacteria capable of synthesizing PHAs from the Hon Khoi saltern in Khanh Hoa Province, Vietnam. A total of 37 halotolerant bacterial isolates were obtained, and potential PHA-producing strains were initially screened using Sudan Black B and Nile Blue A. TEM microscopy was then employed to confirm the existence of PHA granules. Furthermore, FTIR spectroscopy and GC–MS/MS spectrometry were utilized to analyze the chemical structure and monomer composition of the extracted polymers. Six isolates were identified as PHA-producing bacteria, including Salinivibrio sp. HK101 and HK116, Halomonas sp. HK105, Priestia sp. HK125 and HK142, and Bacillus sp. HK130. These strains exhibited growth across 3–10% NaCl and temperatures from 25 to 45 °C. Priestia sp. HK142 and Salinivibrio sp. HK101 exhibited the most substantial PHA accumulation, achieving 50.72 ± 1.83% and 42.07 ± 1.8% of DCW, respectively. These results indicate that the Hon Khoi saltern represents a promising source of halotolerant PHA-producing bacteria with potential relevance for future biopolymer production studies. Full article

Fusarium wilt, caused by Fusarium oxysporum f. sp. niveum (Fon), severely restricts the sustainable development of the global watermelon industry. While conventional chemical fungicides of this disease have triggered prominent ecological issues, Bacillus-based microbial biocontrol, which combines inherent environmental compatibility with stable control efficacy, has emerged as a key green alternative to chemical management. However, the biocontrol potential of Bacillus sonorensis against this disease has not yet been fully investigated. In this study, we isolated 56 bacterial strains from healthy watermelon rhizosphere soil, and obtained a Fon-antagonistic strain A-5 with the strongest activity (70.15% mycelial inhibition rate), which was identified as B. sonorensis via polyphasic taxonomic analysis. In vitro assays showed that the sterile fermentation filtrate of strain A-5 had a maximum 81.05% inhibition rate against Fon, and its volatile organic compounds also significantly suppressed Fon growth, with broad-spectrum antifungal activity against four common phytopathogenic fungi. Functional tests confirmed that strain A-5 could secrete cell wall-degrading enzymes, produce siderophores and synthesize indole-3-acetic acid, and 17 antimicrobial secondary metabolite biosynthetic gene clusters were identified in its genome. Pot experiments verified that strain A-5 had a 78.04% relative control efficacy against watermelon Fusarium wilt, which significantly reduced seedling disease incidence and upregulated defense-related antioxidant enzyme activities in watermelon leaves. In general, B. sonorensis A-5 is a promising novel biocontrol agent for green management of watermelon Fusarium wilt. Full article

We have evaluated the growth characteristics of the model plant Arabidopsis thaliana after inoculation of A. thaliana seeds with the most common endophytes of wild grapevine Vitis amurensis Rupr., namely bacteria Rhizobium (syn. Agrobacterium) sp., Bacillus velezensis, Curtobacterium sp, Erwinia sp., Gordonia aichiensis, Pantoea sp., Pseudomonas sp., Sphingomonas sp., Xanthomonas sp., and the fungi Biscogniauxia sp., Cladosporium sp., Didymella sp., Exobasidium sp., Penicillium sp., Pestalotiopsis sp, and Xylaria sp. A positive effect on plant growth was observed in A. thaliana following seed inoculation with endophytic fungi (Xylaria sp., Didymella sp., and Exobasidium sp.) and bacteria (Gordonia aichiensis and Sphingomonas sp.). The inoculation with the fungi Xylaria sp., Didymella sp., Exobasidium sp., and Penicillium sp. significantly increased seed production in A. thaliana by 2.5–5-fold. The analysis of the phytohormone-regulating gene transcription in A. thaliana plants following inoculation with the grapevine endophytic microorganisms suggests that plant growth was enhanced through transcriptional changes in individual genes of hormone biosynthetic pathways. Consequently, endophytic bacteria and fungi from V. amurensis may serve as potential natural growth stimulators for agricultural plants. Full article

The large-scale production of microbial bioplastics remains limited by high production costs, reliance on refined substrates, and inefficient utilization of agro-industrial residues. Although sugarcane bagasse has been explored as a carbon source for polyhydroxyalkanoate production, studies have predominantly focused on poly (3-hydroxybutyrate) (PHB), with limited reports on copolymer synthesis from pentose-rich lignocellulosic streams. In this study, a newly isolated Bacillus sp. HLI02 was employed for the biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), using pentosan-rich sugarcane bagasse hydrolysate as an inexpensive and sustainable carbon source. Fermentation parameters were systematically optimized at different pH and temperature, and the strain demonstrated efficient conversion of xylose-rich hydrolysate into PHBV without the requirement for external nutrient supplementation. Under optimized conditions (pH 7.0, 37 °C, and C/N ratio of 40), a maximum PHBV yield of 2 g/L, corresponding to 59.5% of cell dry weight, was achieved. Structural and compositional analyses using Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy confirmed successful PHBV copolymer formation with well-defined structural characteristics. Thermal analysis revealed a decomposition temperature of 166 °C, indicating good thermal stability. The produced PHBV further exhibited favourable biocompatibility and biodegradability, supporting its potential applicability in sustainable packaging and related sectors. This work demonstrates the effective conversion of hemicellulosic sugarcane bagasse hydrolysate into PHBV using a newly isolated Bacillus strain, highlighting an underexplored route for copolymer production from agro-waste–derived C5 sugars. By integrating low-cost feedstock utilization with process optimization and comprehensive polymer characterization, this study contributes to the development of economically viable and sustainable bio-based polymer production strategies. Full article

A decrease in pH can affect the biochemical properties of a sulfate reduction system, but the stress responses to such pH fluctuations and acid-adaptive mechanisms of the microorganisms remain incompletely understood. Here, we compared the sulfate (SO₄²⁻) reduction performance of a sulfate-reducing consortium (SRB system) and a pure Desulfovibrio sp. system (Des. system, control) under pH 7.0, 5.5, and 5.0 via batch experiments. A key novelty is the integration of microbial physiology and metagenomics to reveal adaptive mechanisms: the Des. system showed significant inhibition of growth and sulfate reduction with decreasing pH, while the SRB system maintained superior SO₄²⁻ removal efficiency through three synergistic adjustments: (1) physiological regulation (enhanced H⁺-ATPase activity, stress protein production, and cell membrane cyclopropane fatty acid content); (2) microbial community restructuring (enrichment of acid-resistant Bacillus and Clostridium); and (3) functional gene upregulation (sulfate import, dissimilar sulfate reduction, sulfide oxidation, and SO_x system-related genes, p < 0.05). This study links physiological responses to metagenomic functional shifts under acid stress, providing critical theoretical support for applying sulfate-reducing consortia in acidic sulfate-containing wastewater remediation. Full article

We evaluated the algicidal properties of Bacillus Ba3 fermentation broth combined with clay for harmful algae bloom (HAB) control through in situ enclosure experiments in Suao Bay, China. It was indicated by the results that the combination significantly reduced HAB abundance, turbidity and phosphorous in water without affecting zooplankton and small fish. The treatment achieved 99.8% (Phase 1) and 100% (Phase 2, with sediment) removal rates for harmful dinoflagellates, primarily Prorocentrum donghaiense and Karenia mikimotoi, while demonstrating high taxonomic selectivity, allowing beneficial diatom populations such as Chaetoceros spp. to remain resilient. This synergy is attributed to clay acting as a physical carrier that brings adsorbed algicidal metabolites into direct, prolonged contact with algal membranes. This method shows promise for prolonged dinoflagellate control and may offer an economical and environmentally sound approach to HABs. More research is needed to establish its action on a wider scale in marine environments. Full article

Bacterial endophytes isolated from medicinal and wild plant species have recently gained significant attention for their medicinal properties, often closely linked to those of their plant hosts. This study identified two endophytic Bacillus isolates using 16S rRNA sequencing-based phylogeny. The impact of sublethal concentrations (0.5 mg/mL) of cadmium and hydrogen peroxide on metabolite production and bioactivity was also investigated. Phytochemical testing and antimicrobial and antioxidant assays revealed shifts in metabolite production under stress conditions. According to the phylogenetic analysis, Bacillus sp. NV35 and NV1 are respectively related to Bacillus cereus and B. mycoides. Phytochemical screening of methanolic crude extracts from both isolates tested positive for alkaloids, flavonoids, and saponins. Notably, tannins were detected only after cadmium treatment, while steroids were present following exposure to both cadmium and H₂O₂. LC-MS fingerprinting confirmed the presence of several tannins and steroids in treated samples. The untreated crude extracts exhibited an IC₅₀ of ~3 mg/mL with the DPPH assay, which decreased to ~1.5 mg/mL after treatment with cadmium or H₂O₂, demonstrating enhanced antioxidant potential under stress conditions. Additionally, extracts from both treated and untreated bacteria displayed antimicrobial activity against selected bacterial pathogens, with MIC values ranging from 62.5 μg/mL to 125 μg/mL. LC-MS analysis identified various antimicrobial and antioxidant metabolites, including phenoxymethylpenicilloyl, maculosin, (S,R,S)-alpha-tocopherol, 3-indoleacrylate, procyanidin A2, cis-11-eicosenamide, 3-hydroxy-3-phenacyloxindole, and 9-octadecenamide. Full article

Integrated fertilization using reduced chemical fertilizers and bio-organic fertilizers can maintain soil fertility with lower chemical inputs, yet its systemic effects on disease control, soil microbes, yield, and quality are not fully clear. This study aimed to: (1) evaluate the effects of Bacillus amyloliquefaciens Z2 and Trichoderma harzianum T22, alone or combined, on suppressing Fusarium wilt (Fusarium oxysporum f. sp. cucumerinum) and promoting cucumber growth in pot experiments; and (2) assess the field efficacy of reduced chemical fertilizer (75% N) plus microbial bio-organic fertilizer (25% N) for disease control, growth enhancement, and yield and quality improvement. To achieve these objectives, pot experiments were first conducted, followed by field experiments. Pot results indicated that individual and combined inoculants notably decreased the disease index (DI) by 40.48–68.75%, and significantly increased cucumber fresh shoot biomass by 16.86–26.75%, with the combined inoculants exhibiting the greatest effect. Field experiments indicated that the synthetic microbial bio-fertilizer has a greater advantage in promoting cucumber growth and disease suppression compared to a single bacterial bio-organic fertilizer. Specifically, the application of combined bio-fertilizers exhibited the best performance in decreasing cucumber DI by 51.54%, improving cucumber fresh shoot biomass by 12.19%, and enhancing cucumber yield by 21.02%, along with significantly improving fruit vitamin C content by 21.17% and increasing fruit total amino acids by 26.23% compared with the control. Rhizosphere soil analysis revealed that the application of combined bio-fertilizers enriched beneficial bacterial families (JG30-KF-AS9 and Sphingomonadaceae) and fungal genera (Chaetomiaceae and Condenascus) with known biocontrol functions and suppressed the proliferation of Fusarium. Overall, the integrated use of reduced chemical fertilizer combined with synthetic bio-organic fertilizer effectively suppresses cucumber wilt, optimizes microbial community structure, and improves cucumber yield and quality, furnishing a valuable foundation for microbial-assisted sustainable crop production. Full article

Fermentation with various microorganisms modifies the quality of coffee. In animal-digested coffee, enzymatic activity also affects coffee characteristics. However, limited information is available on in vitro coffee modification employing both mechanisms simultaneously in controlled conditions. In this study, robusta green beans were modified with selected bacterial species (Bacillus subtilis, Gluconobacter sp., Lactiplantibacillus plantarum) and pepsin, which was introduced at the soaking or fermentation stage. The characteristics of green and roasted coffee were analyzed, including the amount of basic aroma precursors, antioxidant activity, acrylamide concentration and volatile organic compound (VOC) content. The number of bacterial cells increased by 1.95–2.64 logCFU/mL during the modification process; pepsin addition did not affect their growth significantly. The use of acid-producing bacteria (APB) resulted in higher consumption of sucrose but also in greater retention of bioactive compounds and higher antioxidant activity. The acrylamide content in fermented and roasted beans was below 10 μg/100 g dry matter; the lowest values were reported after modification with L. plantarum. The combination of tested bacterial and enzymatic processes changed the content and composition of VOCs. Further research should focus on sensory attributes as the result of the combined modification process. Full article

Tomato is the most widely consumed vegetable worldwide and serves as an important source of vitamins and minerals. Using the Bacillus species as biocontrol agents and plant growth promoters is a sustainable approach to optimize production and mitigate the effects of root-infecting phytopathogenic fungi, thereby reducing reliance on chemical inputs. This study evaluated the effectiveness of a Bacillus sp.-based bioinoculant, produced in a 7 L bioreactor, for controlling root phytopathogens and enhancing tomato yields under field conditions. The trial was conducted at an experimental field of the Universidad Nacional Agraria La Molina (Lima, Peru) using a randomized complete block design with four blocks. Treatment means were compared using Tukey’s multiple range test (α = 0.05) to evaluate treatment effects. The treatments included three concentrations of the bioinoculant (10%, 20%, and 30%) derived from an initial concentration of 1 × 10⁸ CFU/mL of a Bacillus halotolerans IcBac2.1 strain sourced from the LEMyB laboratory strain collection, a commercial biological product (1 × 10⁹ CFU/g), and uninoculated control. Applications were made for the following four key stages of crop development: 10 days after germination, when transplanting through root dipping, 7 days after transplanting, and at the onset of flowering. In all treated groups, applications were directed to the plant crown, whereas the control group received no treatment. The evaluated variables included plant height (cm), stem diameter (mm), root disease incidence (%), chlorophyll index (SPAD), °Brix, pH, vitamin C (mg/100 g), total protein (mg/100 g) and crop yield (t/ha). The greatest plant growth-promoting effects were observed in plants inoculated with the 20% bioinoculant and in the commercial product treatment, as evidenced by increased plant height, greater fruit diameter, caliber, and length, as well as lower root disease incidence (2.86% and 1.43%, respectively). In addition, yields were highest in these treatments (29.9 and 25.2 t ha⁻¹, respectively) compared with 14.5 t ha⁻¹ in the control. These results indicate that a 20% B. halotolerans-based bioformulation, similar to the commercial formulation, promotes plant growth, improves agronomic performance, and reduces root disease incidence in tomato crops. Full article

Strain 11B20 was isolated from a commercial field of maize (Zea mays L.) located in the Yaqui Valley, Mexico. The draft genome sequence revealed a genomic size of 3,759,824 bp, 41.6% G + C content, 973,288 bp N50, 2 L50, and 29 contigs. According to the 16S rRNA gene, strain 11B20 belongs to the genus Bacillus. Genome annotation revealed 3952 coding DNA sequences (CDSs) grouped into 319 subsystems. Among these, several CDSs were associated with traits related to plant growth promotion, including (i) virulence, disease, and defense (33 CDSs); (ii) iron acquisition and metabolism (28 CDSs); and (iii) secondary metabolism (6 CDSs), among others. In vitro, metabolic analysis (IAA, siderophore biosynthesis; phosphorus solubilization; and tolerance to thermal, hydric, and saline stress) confirmed the genomic background of this strain. Finally, in planta assays showed that the inoculation of Bacillus sp. 11B20 significantly (p ≤ 0.05) increased the root length (48.2%) and root dry weight (35.4%) versus non-inoculated maize plants. Thus, this is the first report of Bacillus sp. 11B20 as a promising beneficial strain for sustainable corn production, and further research is needed to ensure the success of the application of this strain in agriculture. Full article