Search Results (1,393)

For future Mars colonization, crop production will be a challenge due to the chemical composition of the Martian Regolith, which contains perchlorates and heavy metals. This research was conducted to determine if the use of Arbuscular Mycorrhizal Fungi (AMF), Plant Growth-Promoting Bacteria (PGPB), and fertilization have a positive effect on tomato growth in a Martian Regolith Analog. The analog contains 52.54% SiO₂, 1.81% TiO₂, 17.66% Al₂O₃, 9.46% Fe₂O₃, 0.145% MnO, 3.43% MgO, 7.09% CaO, 3.95% Na₂O, 1.96% K₂O, and 0.55% P₂O₅. Two hundred and forty tomato plants were grown for 45 days. One hundred and twenty tomato plants grown over perchlorate-polluted analog (1% m/m) died in less than 2 weeks, while 120 tomato plants grown in a non-polluted analog survived. Forty-eight plants supplemented with Long–Ashton solution increased their shoot length 100% more than the control plants and the plants inoculated with the commercial AMF formulation TM-73^MR and PBB; the latter showed 25% mycorrhizal colonization. There was no significant difference between the growth parameters of inoculated plants and non-inoculated plants. However, there was a significant difference compared to the plants supplemented with Long–Ashton solution. The perchlorate is toxic to tomato plants, and the metal content of the analog was not a limiting factor for tomato growth or AMF colonization. Full article

Conventional and organic agriculture can both cause soil microbial community structure (SMCS) destruction, infertility, and abandonment. The application of soil productivity-improving biofertilizers is a sustainable practice that requires holistic knowledge, including complex biointeractions, diverse microbial metabolism, and culture requirements, the last of which rely on methodology and technology. In this study, a holistic culture-based and meta-analysis approach was employed to explore pristine and domesticated soils for presumptive plant growth-promoting (PGP) bacteria. Various soil samples were logistically acquired and processed using enrichment and heat alternatives. Morphologically diverse isolates were streak-purified and analyzed for 16S rRNA bacterial identification. Meta-analysis of PGP bacteria in domesticated environments was conducted using Google Search and NCBI PubMed. Soil fertility was analyzed for the pH and nitrogen/phosphorus/potassium (NPK) contents using biochemical tests. Notably, 7 genera and 15 species were differentially recovered, with Bacillus being the most prevalent and diverse in species. Conversely, Aeromonas, Lactobacillus, Lelliottia, Pseudomonas, and Staphylococcus were found only in pristine soil. While soil pH was consistent in all pristine soil samples, NPK contents ranged widely across the pristine (i.e., P/K) and domesticated samples (i.e., N/P/K). These findings could enhance biofertilizer SMCS, function, and effectiveness in the agricultural productivity needed to feed the expanding population. Full article

Endophytic bacteria, which reside within plant tissues without causing harm, play crucial roles in promoting plant health and enhancing tolerance to biotic and abiotic stresses, making them highly valuable for sustainable agriculture. This review explores the diversity, mechanisms, applications, and challenges associated with endophytic bacteria in enhancing stress tolerance in plants. Endophytic bacteria display extensive diversity, spanning multiple phyla such as Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria, each contributing uniquely to plant growth and stress tolerance. The functional mechanisms by which endophytic bacteria promote stress tolerance against biotic and abiotic stresses include the induction of plant systemic resistance, synthesis of bioactive compounds, competition for space and resources, nutrient production and transfer, etc. Despite their great potentials, challenges such as the complexity of plant–microbe interactions, variability in bacterial efficacy across different environmental conditions, and the need for advanced identification and application techniques hinder the widespread application of endophytic bacteria in agriculture. This review underscores the importance of harnessing the great potential of endophytic bacteria for developing sustainable agricultural practices and highlights the urgent need for further research to overcome existing challenges. Full article

Oats (Avena sativa L.) are a staple grain and forage crop with substantial market demand. In China, they are the second most-imported forage grass, only after alfalfa (Medicago sativa L.). Enhancing the salt tolerance of oats to facilitate their cultivation in saline areas can thereby increase forage yield and promote the utilization of saline land, which constitutes an important reserve land resource in China. This study aimed to identify the bacterial strain Bacillus sp. LrM2 (hereafter referred to as strain LrM2) to determine its precise species-level classification and evaluate its effects on oat photosynthesis and growth under salt stress through indoor pot experiments. The results indicated that strain LrM2, capable of urease production and citrate utilization, was identified as Bacillus mojavensis. The strain LrM2 had a positive effect on shoot and root growth of oats under 100 mM NaCl stress conditions. Strain LrM2 inoculation modulated osmotic stress in oats under 100 mM NaCl stress by significantly increasing soluble sugar and decreasing proline content in leaves. It inhibited Na⁺ uptake and promoted K⁺ absorption in the roots, thereby reducing Na⁺ translocation to the leaves and mitigating ionic toxicity. Inoculation with strain LrM2 significantly increased photosynthetic pigment content (chlorophyll a, carotenoids), improved gas exchange parameters (stomatal conductance, transpiration rate, net rate of photosynthesis), enhanced PSII photochemical efficiency (maximum quantum yield, coefficient of photochemical quenching, actual photosynthetic efficiency of PSII, electron transfer rate), and reduced the quantum yield of non-regulated energy dissipation. These improvements, coupled with increased relative water content and instantaneous water use efficiency, thereby collectively enhanced the overall photosynthetic performance. In conclusion, strain LrM2 represents a promising bio-resource for mitigating salt stress and promoting growth in oats, with direct applications for developing novel biofertilizers and sustainable agricultural strategies. Full article

Overuse of synthetic pesticides and fertilizers has increased concerns regarding environmental and human health. Indian natural farming practices, which are mainly based on different bioformulations, provide sustainable alternatives to conventional farming. Among other bioformulations, Beejamrit is a cow-based biostimulant that is used for seed treatment to promote seed germination, seed vigor, and tolerance to pathogens. In this study, 16S rRNA amplicon metagenomics and untargeted metabolomics (GC-MS and LC-MS) approaches were employed to evaluate microbial and metabolic profiles of Beejamrit samples, respectively. Metagenomic analysis indicated that Beejamrit consisted of different plant-growth-promoting bacteria, such as Advenella, Comamonas, Lysinibacillus, Acinetobacter, and Arcobacter. GC-MS analysis discovered organoheterocyclics (23%) to be the most prevalent metabolite group in Beejamrit, followed by organic acids (18%) and benzenoids (15%). In LC-MS analysis, lipids (26%) were most abundant, followed by organoheterocyclics (18%) and organic acids (18%). Furthermore, GC-MS and LC-MS analyses identified a wide range of metabolites, including amino acids, organic acids, phenolics, and fatty acids. These findings confirm that Beejamrit contains a wide array of beneficial bacteria and bioactive compounds, thereby elucidating the potential mechanisms behind its efficacy as an effective seed treatment agent. The study offers an initial framework for further standardization and wider application in sustainable agriculture. Full article

Avicennia germinans, a representative of the marine coastal mangrove ecosystem, vital in the Colombian Caribbean, harbors a unique microbial diversity that could contain microorganisms with the potential to promote plant growth of agricultural species such as maize. The objective of this research was to evaluate A. germinans endophytes at different sampling sites and in diverse plant organs in order to identify the growth-promoting role of the most sodium chloride-tolerant endophyte found. These were then inoculated in maize seeds under drought stress conditions simulated by polyethylene glycol (PEG) in vitro. To this end, samples of adult A. germinans plants were collected from four mangrove ecosystems in the Colombian Caribbean. Several isolates were able to tolerate up to 15% NaCl (w/v), produce indole-3-acetic acid (IAA), show proteolytic activity, and inhibit phytopathogenic fungi. The best-performing strain, C1T-KM1901-B, was genomically identified as Bacillus paralicheniformis and evaluated as a bioinoculant in maize seeds under PEG-induced drought stress. Inoculation with B. paralicheniformis significantly increased germination potential and germination index of drought-resistant seeds compared to non-inoculated controls under severe drought stress conditions (40% PEG). In addition, inoculated seedlings exhibited significantly higher roots and shoot fresh and dry biomass at moderate to severe drought stress levels (15% and 20% PEG). These results are position B. paralicheniformis C1T-KM1901-B, isolated from Avicennia germinans, as a promising bioinoculant to enhance maize establishment under drought conditions. Full article

Phosphate-solubilizing rhizobacteria associated with the Solanum tuberosum L. cultivar ‘Superchola’ were isolated and characterized to improve our understanding of plant growth promotion in agricultural systems. Bacteria were isolated by serial dilutions, and the morphology of the colonies was characterized on nutrient agar culture medium. In addition, morphological identification was achieved by Gram staining. The ability to solubilize phosphate was assessed in Pikovskaya agar culture medium, while molecular identification involved the amplification of the partial 16S rRNA gene using the polymerase chain reaction. In the Píllaro canton, the highest number of colony-forming units per gram of soil was recorded at 9.72 × 10⁹. Among the isolated strains, 62% exhibited circular morphology, 92% had a smooth texture, and 85% displayed entire margins. Notably, 83% of the isolates were Gram-negative, with 50% exhibiting a bacillary form. The most effective phosphate solubilizers were from the Mocha canton, particularly the isolate CC-FCAGP-BSF6, which showed superior solubilization capacity. Molecular identification revealed bacterial isolates from four genera, i.e., Bacillus, Pseudomonas, Lysinibacillus, and Paenibacillus. These strains exhibited significant phosphate solubilization in vitro and resulted in increased leaf area (0.21–0.49, p = 0.038), fresh mass (0.46–0.87, p = 0.014), dry mass (0.092–0.096, p = 0.047), and leaf area index (0.14–0.33, p = 0.026) in the S. tuberosum cultivar ‘Superchola’ in vitro plants. This study identifies bacterial species associated with the rhizosphere of S. tuberosum in Ecuador and highlights their potential for promoting plant growth and solubilizing phosphates. Full article

Aims: The plant and soil microbiome serve as a reservoir of beneficial endophytic bacteria, including plant-growth-promoting (PGP) Bacillus subtilis, which enhances nutrient acquisition and protects plants against environmental stresses. We isolated novel bacteria from cultivated peanut plants selected from agricultural fields that survived a season of water scarcity and high temperatures. Experiments were conducted to determine whether plant survival was partially attributable to the presence of beneficial microbes that could be harnessed for future biotechnology applications. Methods and Results: Seven bacterial isolates of Bacillus spp. were identified through 16S rRNA sequencing, revealing close affiliations to B. subtilis, B. safensis, and B. velezensis. Growth curve analysis and colony morphology characterization revealed distinct growth patterns across different media types, while phytohormone production assays demonstrated variable indole-3-acetic acid (IAA) synthesis among isolates. When applied as seed biopriming agents to two hybrid peanut varieties, bacterial inoculation significantly enhanced root surface area and root tip development, with B. subtilis-TAM84A showing the most pronounced effects on ‘Schubert’ roots. In addition, vegetative growth assessments indicated increased branch numbers and plant height, particularly with treatments with B. velezensis strains TAM6B and TAM61A, and a consortium of all isolates. Under drought conditions, inoculated plants exhibited delayed wilting and improved recovery after rehydration, indicating enhanced drought resilience. Conclusions: Several local Bacillus strains recovered from drought-tolerant peanut plants showed improved growth and drought tolerance in greenhouse-grown peanut plants. Ongoing field studies aim to evaluate the potential of regionally adapted microbial populations as soil amendments during planting. Impact Statement: This study demonstrates that local strains of Bacillus isolated from drought-resistant peanut plants possess significant potential as bioinoculants to improve growth and drought tolerance in potted peanut plants. This work provides a foundation for utilizing regionally adapted microbial populations to address agricultural challenges related to water scarcity. Full article

Soil salinization poses a significant threat to global agricultural productivity. Salt-tolerant plant growth-promoting bacteria (ST-PGPB) have shown great potential in enhancing crop resilience under saline stress, yet the molecular basis of their intrinsic tolerance remains incompletely understood. To address this, we employed an integrated genomic, transcriptomic, and biochemical approach to investigate the salt tolerance strategies of Pantoea sp. EEL5, an endophytic ST-PGPB isolated from Elytrigia elongata. The results demonstrated that EEL5 exhibited remarkable salt tolerance and efficiently removed Na⁺ via extracellular adsorption and intracellular accumulation. Genomic analysis identified key genes responsible for Na⁺ efflux, betaine synthesis and transport, and typical plant growth-promoting traits. Under salt stress, transcriptomic profiling revealed a marked upregulation of genes involved in Na⁺ extrusion, antioxidant enzymes, betaine biosynthesis and transport, arginine and proline catabolism, TCA cycle, and electron transport chain, concomitant with a downregulation of genes governing energy-intensive flagellar assembly and chemotaxis. These coordinated responses facilitated Na⁺ exclusion, enhanced antioxidant capacity, accumulated compatible solutes (betaine, glutamate, and GABA), increased energy production, and conserved energy via motility reduction, collectively conferring salt tolerance in EEL5. Our findings elucidate the multi-level salt adaptation mechanisms of EEL5 and provide a genetic foundation for a comprehensive understanding of ST-PGPB. Full article

Continuous monoculture of Panax notoginseng leads to severe replant disease, yet the mechanisms by which root exudates mediate rhizosphere microbiome assembly and pathogen enrichment remain poorly understood. Here, we demonstrate that long-term root exudate accumulation acts as an ecological filter, driving the fungal community toward a phylogenetically impoverished, pathogen-dominated state. Specifically, exudates enriched the soil-borne pathogen Fusarium while reducing the abundance of potentially antagonistic fungi. In contrast, bacterial communities exhibited higher resilience, with exudates selectively enriching oligotrophic taxa such as Terrimonas and MND1, but suppressing nitrifying bacteria (e.g., Nitrospira) and plant-growth-promoting rhizobacteria (PGPR). Microbial functional profiling revealed a shift in nitrogen cycling, characterized by suppressed nitrification and enhanced nitrate reduction. Crucially, co-occurrence network analysis identified bacterial taxa strongly negatively correlated with Fusarium, providing a synthetic community blueprint for biocontrol strategies. Our study establishes a mechanistic link between root exudate accumulation and negative plant–soil feedback in monoculture systems, highlighting microbiome reprogramming as a key driver of replant disease. These insights offer novel avenues for manipulating rhizosphere microbiomes to sustain crop productivity in intensive agricultural systems. Full article

N₂-fixing bacteria have great potential to be used as biofertilizer in agriculture to promote plant growth via nitrogen fixation. In this study, a novel species Fontibacillus forbon sp. nov., with strain BL-9^T as the type strain, was isolated from the rhizosphere of Fraxinus chinensis. Strain BL-9^T was able to fix nitrogen and grow on nitrogen-free medium. Phylogenetic analysis of 16S rRNA gene revealed that strain BL-9^T was most closely related to Fontibacillus phaseoli BAPVE7B (98.03%), followed by Fontibacillus solani A4STR04 (96.72%), Fontibacillus panacisegetis (96.6%), Paenibacillus vini (96.6%), and Paenibacillus segetis DB13260 (96.57%). The phylogenomic tree supported that strain BL-9^T was most closely related to F. phaseoli BAPVE7B. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) between strain BL-9^T and its closely related type strain, F. phaseoli BAPVE7B, were 42.5% and 90.94%, respectively, which were below the values (70% for dDDH and 95% for ANI) for species discrimination. The DNA G+C content of strain BL-9^T was 49.7%. The genome of strain BL-9^T had a nif (nitrogen fixation) gene cluster containing 10 genes (nifB nifH nifD nifK nifE nifN nifX orf1 hesA nifV). The predominant fatty acid was anteiso-C15:0, the major menaquinone was MK-7, and the major polar lipid was diphosphatidylglycerol. Strain BL-9^T and its closely related species of Fontibacillus had some common and distinguished physiological characteristics. Based on genomic, phylogenetic, chemotaxonomic, and phenotypic features, strain BL-9^T represents a novel species of the genus Fontibacillus. The name proposed for this species is Fontibacillus forbon sp. nov., with the type strain BL-9^T. Full article

Plant growth-promoting bacteria (PGPB) could exert positive effects on plant growth and productivity; however, little is known about the effects of variables during the production of PGPB biomass and how they could affect the performances of these microorganisms. This study investigated the effects of pH, temperature, and culture age on the growth of promising PGPBstrains, Bacillus sp. 36M and Stenotrophomonas sp. 20P, isolated from the rhizosphere of durum wheat. A fractional factorial 2^k design was applied to evaluate bacterial growth under varying conditions (pH 5.0–7.5; 15–35 °C; 24–72 h precultures). Multifactorial ANOVA revealed that all independent variables and their interactions significantly affected cell concentration (p < 0.05). Bacillus sp. 36M exhibited optimal growth when inoculated from 24 h cultures and incubated under moderate conditions (15 °C, pH 7.5), whereas Stenotrophomonas sp. 20P showed higher viability with 72 h cultures. These results demonstrate that the inoculum physiological state is a critical determinant of PGPB stress tolerance and should be specifically optimized for each strain. The greater technological robustness of Stenotrophomonas sp. 20P suggests its suitability for biofertilizer formulations requiring extended shelf-life or application under variable environmental conditions. In conclusion, this work provides a quantitative framework for tailoring PGPB production protocols to maximize field performance in sustainable agriculture. Full article

Soil-borne pathogens cause devastating root rot diseases in forest ecosystems, often by inducing dysbiosis in the rhizosphere microbiome. While antagonistic bacteria can suppress disease, their effects frequently extend beyond direct inhibition to include ecological restructuring of resident microbial communities. However, the causal relationships between such microbiome restructuring and disease suppression in tree species remain poorly understood. Here, we show that the antagonistic bacterium B. mojavensis dxk33 effectively suppresses F. solani-induced root rot in C. lanceolata, and that this disease suppression coincides with a partial reversal of pathogen-associated dysbiosis in the rhizosphere. Inoculation with dxk33 significantly promoted plant growth and reduced the disease index by 72.19%, while concurrently enhancing soil nutrient availability and key C-, N- and P-cycling enzyme activities. High-throughput sequencing revealed that dxk33 inoculation substantially reshaped the rhizosphere microbiome, counteracting the pathogen’s negative impact on microbial diversity and coinciding with a shift toward a more stable community structure. Under pathogen stress, dxk33 enriched beneficial bacterial taxa such as Pseudomonas and Sphingomonas and suppressed pathogenic fungi while promoting beneficial fungi such as Mortierella. Linear discriminant analysis and functional prediction further indicated that dxk33 remodeled ecological guilds enriched for mycorrhizal and saprotrophic fungi, and reactivated bacterial metabolic pathways and signaling networks that were suppressed by the pathogen. Taken together, our findings are consistent with a multi-tiered mode of action in which direct antagonism by B. mojavensis dxk33 operates alongside associated changes in the rhizosphere microbiome that resemble a disease-suppressive state, although the present experimental design does not allow a strictly causal role for microbiome reconfiguration in disease suppression to be established. This study provides a mechanistic framework for understanding how microbiome engineering may mitigate soil-borne diseases in perennial trees and highlights the potential of targeted microbial interventions for sustainable forest management. Full article

N is the most crucial nutrient for plant growth and yield. Soybeans require a large amount of N for growth and seed production because of their high protein content. Soybean plants fix N₂ by root nodules in association with soil bacteria, rhizobia, but both the fixed N and the N absorbed from roots are essential to obtain a maximum seed yield. However, excess or inappropriate N fertilizer application represses N₂ fixation and reduces seed yield. A basal deep placement of lime nitrogen promoted soybean seed yield without inhibiting N₂ fixation activity in Japan. This study aimed to evaluate whether this technology can be applied in the Far East of Russia. The effects of deep placement of lime N with a wide row (75 cm) on the growth and seed yield of four Russian varieties were investigated. Without N fertilization, the average seed yield in wide rows was 2.77 t/ha, which was not significantly different from that in narrow rows (2.39 t/ha). Deep placement of lime nitrogen with wide rows increased total mechanical seed yield by 38%, 53%, 17%, and 6% in Primorskaya 4, 13, 81, and 86, respectively. The effect of basal urea application in narrow rows varied among cultivars. Soil analysis and the N composition in xylem sap indicated that the Russian field is richer in soil N than that in Niigata, and the contribution of N derived from N₂ fixation was lower than that in Niigata. The effects of row spacing and N fertilization on seed yield varied by variety; therefore, it is necessary to evaluate each variety to determine the optimal row spacing and N fertilization. The field experiment indicated that the deep placement of lime N promoted seed yield of Russian cultivars. This technique may be applied in soybean cultivation in a large field if the appropriate machine is available. Full article

Burkholderia is a metabolically versatile genus of Gram-negative bacteria that inhabits niches ranging from soil and water to plants and clinical environments. This review provides an integrated examination of Burkholderia species, focusing on their dual roles as both pathogens and beneficial microorganisms. Key pathogenic species, such as members of the Burkholderia cepacia complex and the Burkholderia pseudomallei group, pose significant threats to human, animal, and plant health due to their intrinsic antibiotic resistance and diverse virulence factors. Conversely, several environmental and plant-associated Burkholderia species promote plant growth, enhance nutrient uptake, and serve as biocontrol agents, supporting sustainable agriculture. We synthesize current knowledge across taxonomy, genomics, pathogenicity, beneficial interactions, and secondary metabolite biosynthesis—including the prolific production of antibiotics, toxins, and volatile organic compounds with pharmaceutical and agricultural potential. Advances in high-throughput genomics are revealing substantial genetic diversity, genome plasticity, and mechanisms underlying both pathogenicity and beneficial traits. Clarifying this dual nature and identifying strategies to mitigate risks will guide the safe and effective exploitation of Burkholderia in medicine, agriculture, and biotechnology. Full article