Search Results (1,524)

Acidic soils are widespread in global agroforestry systems and severely constrain crop production through proton stress, aluminum/manganese phytotoxicity, phosphorus fixation, and rhizosphere microbiome reassembly. Rhizosphere diazotrophs can theoretically contribute to plant nitrogen (N) nutrition and stress adaptation. However, their N-fixation efficiency and growth-promoting effects in acidic soils are often highly unstable, limiting the predictability of field applications. This narrative mechanistic review synthesizes and critically interprets evidence on the physicochemical filters governing diazotroph survival in acidic soils, nitrogenase regulation, root-exudate-mediated recruitment, multi-guild microbial interactions, and the conditional design of synthetic microbial communities (SynComs) and inoculant formulations. We further discuss the potential complementary roles of phosphate-solubilizing bacteria (PSB) and arbuscular mycorrhizal fungi (AMF) and propose minimum reporting standards to improve field translatability. The synthesis indicates that effective diazotroph-mediated crop promotion depends on pH buffering, metal detoxification, carbon supply, phosphorus availability, host compatibility, and native microbiome receptivity. The proposed evidence-chain and microbiome-compatibility framework is a conceptual guide for evaluating these linked conditions rather than an empirically validated predictive model. Full article

Plant growth-promoting bacteria (PGPB) enhance plant development through mechanisms such as the production of indole-3-acetic acid (IAA). However, endophytic bacteria associated with aquatic plants, particularly watermeal (Wolffia spp.), remain poorly explored. This study investigated the potential of bacterially derived crude IAA extract for enhancing watermeal growth and accumulation of secondary metabolites in watermeal. This study isolated and screened endophytic bacteria from watermeal for IAA production, identifying Klebsiella variicola W1/6 as the most efficient producer. Optimization using response surface methodology (RSM) revealed optimal conditions at pH 5.84, 5 days of incubation, and 10.63% (v/v) inoculum size. Crude IAA extract significantly enhanced watermeal growth under both laboratory and greenhouse conditions. Notably, the combination of 0.5 ppm crude IAA extract with 50% chemical fertilizer produced growth comparable to that of the full fertilizer treatment, indicating reduced fertilizer requirement. These findings highlight the potential of bacterially derived IAA from K. variicola W1/6 as a microbial biostimulant for sustainable aquatic plant cultivation. Full article

Aquaponics combines aquaculture and hydroponics, offering an integrated and sustainable food production system. This study investigated the probiotic properties, plant growth-promoting (PGP) activity, and nitrifying capacity of twelve lactic acid bacteria (LAB) strains isolated from an aquaculture farm environment on the Ivory Coast for their potential application in aquaponic systems. All isolates demonstrated antagonistic activity against key pathogenic indicator strains, except Vibrio cholerae, and displayed varying levels of surface hydrophobicity (5.50 ± 0.70% to 22.83 ± 1.17%) and auto-aggregation (32.50 ± 0.08% to 52.89 ± 0.39%) after 24 h. Antioxidant activity was significantly higher in cell-free supernatants (~71–79%) than in intact cells (~30–33%). Bile salt tolerance (0.3%, 4 h) ranged from 2.13 ± 0.76% to 40.87 ± 2.12%, and survival under pH 1.5 with pepsin for 3 h varied from 4.84 ± 0.26% to 53.98 ± 13.28%. All isolates produced lactic, acetic, citric, malic, and propionic acid and exhibited amylase and cellulase activity; none showed hemolytic activity. Only LAB 11 produced indole-3-acetic acid (17.72 ± 0.06 μg/mL), siderophores, and phosphate-solubilization activity for PGP traits, and this group significantly enhanced maize seed germination (86.66 ± 5.77%) and radicle length (7.00 ± 0.52 mm) compared to the control (63.33 ± 32.14% and 4.94 ± 1.52 mm), respectively. LAB 1 and LAB 10 demonstrated the highest ammonia-oxidizing capacity in vitro and in trout pond water. LAB 1, LAB 10, and LAB 11 were confirmed by whole genome sequencing analysis to be Enterococcus faecalis strains with a favorable-safety genomic profile and probiotic characteristics. These three strains therefore represent promising candidates for consortium-based applications in aquaponics systems. Full article

Crop production is continually exposed to a wide range of abiotic stresses that negatively affect growth and yield, posing a severe threat to global food security. Plant growth-promoting bacteria (PGPB) promote nutrient assimilation, activate antioxidant enzymes, and stimulate phytohormone production to mitigate abiotic stress. However, the effective application of PGPB in the field depends on host colonization, soil specificity, and susceptibility to competitive microbial communities. Recently, non-thermal plasma (NTP) has emerged as a revolutionary tool for sustainable agriculture, making it a priority to develop efficient, low-cost, and eco-friendly strategies to enhance seed vitality and manage abiotic stress. Plasma-generated reactive oxygen and nitrogen species (RONS) have been shown to mediate intracellular redox homeostasis and the antioxidant defense signaling network. Furthermore, plasma stimulates MAPK cascades and stress-responsive genes such as LEA1, SnRK2, P5C, and the SOS pathway, ionic balance, and membrane stability, ultimately supporting plant stress adaptation to drought, salinity, and heavy metals. Plasma-induced RONS signaling activates PGPB functional traits such as root colonization, biofilm formation, nutrient mobilization, and plant growth-promoting activities. However, the molecular mechanisms underlying NTP-PGPB microbial multiple stress adaptation and the long-term ecological stability and biosafety of microbial communities remain inadequately resolved. Consequently, future integration of multi-omics approaches, synthetic microbial communities, and field-scale validation is required to explore the mechanistic advances of plasma-modulated microbiome interactions to enable agricultural applications. Full article

Polygonatum cyrtonema Hua polysaccharides (PCPs) are bioactive components with antioxidant and immunomodulatory properties. However, whether the polysaccharides derived from elder Polygonatum cyrtonema exhibit superior health benefits remains unclear. This study systematically compared the in vitro fermentation characteristics, gut microbiota-modulating effects, and short-chain fatty acid (SCFA) production of PCPs extracted from three-year-old (TPP), five-year-old (FPP), and eight-year-old (EPP) plants using a human fecal fermentation model. The fermentation dynamics were evaluated by monitoring pH, OD₆₀₀, and the consumption of total and reducing sugars, while the structural degradation and compositional differences in PCPs were tracked via molecular weight distribution and monosaccharide composition analysis. The results showed that all three PCPs were degraded and utilized by gut microbiota, accompanied by decreased pH, increased OD₆₀₀, and enhanced antioxidant activities. High-throughput 16S rDNA sequencing revealed that, at the phylum level, all PCPs increased the Firmicutes/Bacteroidetes ratio. At the genus level, they reduced the abundance of harmful bacteria such as Sutterella and increased beneficial bacteria including Bifidobacterium and Megasphaera. Furthermore, gas chromatography (GC) analysis demonstrated that, compared with FPP, TPP and EPP significantly promoted the production of SCFAs. In summary, this study indicates that the in vitro fermentation characteristics and prebiotic properties of PCPs vary with growth years, and a comprehensive evaluation suggests that three-year-old Polygonatum cyrtonema Hua represents a promising raw material for the development of functional foods. Full article

Salinity stress is one of the major stressors that limits yield potential in field crops. Salinity-led imbalances in ionic and water potential, as well as oxidative damage, impair photosynthesis. Plant-growth-promoting rhizobacteria (PGPRs) have been demonstrated to mitigate salinity-stress-induced damage through various mechanisms such as biofilm and exopolysaccharide production, modulation of plant root architecture or molecular signaling involving modulation of sodium/potassium efflux transporters. PGPRs are known to induce biosynthesis and signaling of various phytohormones in plants. PGPR-derived phytohormones can in turn regulate molecular signaling involved in maintaining ion fluxes, preventing salinity-induced senescence, and reinforcing plant root architecture, thereby maintaining plant growth and development under saline conditions. In this review, we provide comprehensive advances on how PGPRs modulate and integrate biosynthesis and/or signaling of various phytohormones, such as auxins, cytokinins, gibberellin, ethylene, abscisic acid, salicylic acid, jasmonates, brassinosteroids and strigolactones, to reshape plant architecture, physiological and biochemical responses in plants under salinity. We integrate molecular evidence with morpho-physiological studies and propose a phytohormone-centric framework to select strains that optimize growth, ion homeostasis and plant stress resilience under salinity. Full article

Duckweed-associated plant growth-promoting bacteria have attracted attention for their potential to enhance duckweed biomass production. However, the mechanisms underlying isolate-specific growth promotion are unclear. This study compared the effects of two duckweed-associated bacterial isolates, Terrimicrobium sp. PS02 and Aeromicrobium sp. PS05, on the growth, biomass composition, colonization behavior, and transcriptomic responses of Spirodela polyrhiza. Biomass composition and transcriptome analyses were performed to characterize the host responses. Both isolates enhanced duckweed biomass; PS02 increased it 1.2-fold, whereas PS05 induced a significant 1.4-fold increase compared to the uninoculated control. PS05 established bacterial populations approximately one order of magnitude higher than those of PS02 and formed dense extracellular polymeric substance-mediated microcolonies on the surface. Transcriptome analysis revealed that PS05 induced 1108 differentially expressed genes, compared with 454 in PS02, indicating greater host transcriptomic reprogramming. Functional enrichment of transcriptome responses showed that PS05 preferentially regulates carbohydrate biosynthesis, central carbon metabolism, and starch biosynthesis, significantly enhancing starch accumulation and turion formation without reducing protein or photosynthetic pigment content. This study provides evidence linking bacterial colonization, host transcriptomic regulation, carbon allocation, and biomass production in duckweed, offering a basis for engineering high-performance duckweed–microbiome systems for sustainable biomass production. 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

Agriculture faces the challenge of transitioning toward sustainable practices, driving the use of plant growth-promoting bacteria (PGPB). However, these bacteria suffer critical losses in viability due to environmental stress and drying processes. Although synthetic hydrogels offer protection, their low biodegradability and toxicity pose ecological risks, positioning dextran hydrogels produced by Leuconostoc sp. as a biocompatible biotechnological alternative, despite challenges related to their mechanical stability. The methodology employed consisted of systematic literature mapping in the Scopus database for the period 2010–2026. The search was conducted on 2 May 2026, using a defined search equation, and 447 documents were processed using RStudio (Bibliometrix), VOSviewer, and Plotly Studio to analyze trends and collaboration networks. The results of the systematic mapping reveal an exponentially growing field (R² = 0.998), led by Agricultural Sciences (23.5%) and Biochemistry (16%). China and India dominate scientific output in terms of volume, while Italy and the United States lead in qualitative impact, with researchers such as Cimini, Schiraldi, and Pandey as key references. An evolution is confirmed from the basic characterization of Leuconostoc sp. toward the development of matrices for immobilizing PGPB, reducing viability losses from 6 log to manageable levels of 4 log CFU. Cluster analysis shows a clear trend toward nanotechnology and “smart hydrogels” responsive to multiple stimuli. Finally, strategic gaps were identified in the creation of predictive release models, as well as an urgent need to democratize the technology through low-cost processes, essential aspects for consolidating sustainable precision agriculture. Full article

Microbial biostimulants and microbial plant protection products overlap in biological function, creating both R&D opportunities and regulatory challenges. In particular, multi-strain bacterial consortia may simultaneously affect nutrient mobilisation and abiotic stress tolerance, induce resistance, and demonstrate direct antagonism against phytopathogens. This multifunctionality complicates early product development because strain identity alone is sometimes insufficient in predicting product function, efficacy, or the most appropriate regulatory and claims strategy. Here, we used non-targeted LC-MS metabolomics as a hypothesis-generating tool to support formulation decisions for microbial consortia. Three bacterial consortia were compared: a full soil-oriented consortium C1 containing Bacillus spp., Rhodopseudomonas palustris, Nitrosomonas europaea, and Nitrobacter winogradskyi; a Bacillus-only consortium C2 intended for foliar stress-resilience applications; and a Bacillus-only consortium C3 grown with a chitin-related inducer to promote biocontrol-associated metabolism. Metabolomic profiling revealed clear differences between formulations. The full consortium C1 showed higher relative abundances of features putatively associated with biofertilising and growth support, whereas the Bacillus-only consortium C2 contained features putatively associated with biocontrol and induced resistance that were not detected in C1 under the applied criteria. The addition of the chitin-related inducer (C3) did not yield a completely distinct metabolite profile but increased the relative abundance of selected features putatively associated with biocontrol, while decreasing features putatively annotated as auxin-related or associated with abiotic stress responses. These results suggest that non-targeted metabolomics can help differentiate metabolic profiles putatively associated with biostimulant- and plant-protection-oriented formulations and thereby support prioritisation before extensive greenhouse or field testing. By linking formulation, medium composition, and microbial interactions to measurable metabolic signatures, metabolomics provides an evidence-based, hypothesis-generating framework for formulation development and the prioritisation of subsequent efficacy trials. Full article

Halotolerant plant growth-promoting bacteria offer a sustainable strategy to improve crop performance under saline conditions. This study evaluated Agave tequilana Weber var. Azul leaf juice was used as an alternative growth medium for Kocuria sediminis AS04, and the bacterium’s ability to alleviate salt stress in chiltepin (Capsicum annuum) was evaluated. The chiltepin seedlings were grown in a specialized chamber and exposed to higher salt levels (200, 400, and 600 mM NaCl) for 10 days. During this time, the protective effect of K. sediminis AS04, which was held in a polymer film, was examined. K. sediminis AS04 grew well in a medium containing 25% agave juice and urea, reaching a density of 1.3 × 10¹⁰ CFU mL⁻¹. Compared with conventional Tryptic Soy Broth, the medium formulated from agave leaf juice and urea could reduce the cost per kilogram of biomass by approximately 4-fold. Under severe salinity stress, plants inoculated with immobilized K. sediminis at 600 mM NaCl exhibited the highest shoot biomass (0.31 g⁻¹ plant), root length (50.7 mm), and proline accumulation (11.25 µmol g⁻¹ fresh weight), whereas uninoculated plants displayed reduced biomass (0.16 g plant⁻¹) and shorter roots (34.5 mm). At 600 mM NaCl, inoculation increased shoot biomass, root length, and plant survival by approximately 94%, 47%, and 200%, respectively, compared with uninoculated seedlings. This method values agro-industrial waste and enhances chiltepin performance under high-salinity conditions. It promotes sustainable production and helps create affordable inoculants for agricultural biotechnology. Full article

Bioprospecting of plant growth-promoting bacteria enables the identification of beneficial microbial resources with significant potential for sustainable agricultural applications. In this context, strain TRQ48 was isolated from a commercial field of wheat (Triticum turgidum L. subsp. durum) located in the Yaqui Valley, Mexico, with the aim of exploring its plant growth-promoting potential. The draft genome sequence presented a genomic size of 2,777,016 bp, 32.5% G + C content, 665,763 bp N50, 2 L50, and 19 contigs. Taxonomic affiliation demonstrated that strain TRQ48 belonged to Mammaliicoccus sciuri. Genome annotation identified 2756 coding DNA sequences (CDS) distributed into 259 subsystems, highlighting CDS associated with iron acquisition and metabolism, stress response, and virulence, disease, and defense, among others. Metabolic assays reflect the strain’s capacity to produce siderophores and auxins, relating these positive traits to significantly (p ≤ 0.05) promote growth of wheat shoot length (7.09%) and root and shoot dry weight (75% and 18.43%) compared to uninoculated wheat plants. Biosafety testing indicated that the strain is susceptible to commonly used antibiotics and lacks clinically relevant resistance profiles, matching genomic analysis, which did not reveal any critical virulence factors. Thus, although the presented results show that M. sciuri TRQ48 is a promising beneficial biosafe strain, further studies are still needed to evaluate its performance under agro-ecosystems at commercial levels. Full article

Brazilian cattle production relies predominantly on pasture systems, many of which are degraded by nutrient depletion, particularly nitrogen deficiency. Plant growth-promoting bacteria (PGPB) offer a sustainable strategy to improve pasture productivity, but their effects are often host-specific and remain poorly explored in Paspalum. This study evaluated the effect of inoculation with Azospirillum brasilense strains CNPSo 2083 (=Ab-V5) and CNPSo 2084 (=Ab-V6) and Pseudomonas fluorescens strain CNPSo 2719 (=CCTB 03), applied by seed inoculation or leaf spray, on the root morphology and shoot growth of four Paspalum accessions under controlled axenic greenhouse conditions, evaluated in an early growth stage at 35 days after emergence. Genotype-specific responses were the central finding of this study: Paspalum malacophyllum BGP-293 showed negligible responses to inoculation, whereas BGP-486—of the same species—increased root dry weight by up to 43% and root tissue density by up to 30% in all inoculated treatments. In Paspalum regnellii BGP-112, seed inoculation produced stronger root responses than foliar spray, increasing root dry weight by up to 38% and root area by up to 40%. In Paspalum rojasii BGP-149, inoculation induced root architectural remodeling without increasing root biomass—root area increased by up to 92% and total root length by up to 97%, relative to the control—indicating an efficient root-foraging strategy. P. fluorescens favored root-foraging traits and tissue density, whereas A. brasilense preferentially stimulated root-hair elongation. These accession-level contrasts, rather than a single generalizable trend, are the main contribution of this work: they support tailored, genotype-specific PGPB strategies for sustainable tropical pastures. Full article

Biological control strategies are increasingly being explored as sustainable alternatives for managing rice blast disease caused by Magnaporthe oryzae. In this study, we characterized three Bacillus pumilus isolates (DC01, DC09, and DC13) and evaluated their antifungal and plant-beneficial properties against M. oryzae. Whole-genome sequencing revealed multiple biosynthetic gene clusters associated with the production of antimicrobial metabolites. All three isolates inhibited fungal growth in dual-culture assays, whereas heat-stable diffusible antifungal activity was primarily associated with the cell-free supernatants of DC09 and DC13. Exposure to bacterial supernatants disrupted fungal development, inducing abnormal hyphal morphology in M. oryzae characterized by bulbous swelling, altered polarity, and increased branching. Volatile organic compound assays further revealed that the DC isolates suppress fungal growth in the absence of physical contact. The isolates additionally inhibited the growth of other phytopathogenic fungi and selected human bacterial pathogens. All strains exhibited plant growth-promoting traits, including indole-3-acetic acid production and osmotic stress tolerance, whereas DC09 also displayed phosphate-solubilizing activity. Importantly, soil inoculation with the DC isolates significantly reduced rice blast disease severity and induced expression of defense-associated genes involved in jasmonic acid/ethylene signaling and immune priming. Collectively, these findings identify the DC isolates, particularly DC09 and DC13, as promising multi-mechanistic biological control agents for sustainable rice blast management. Full article

This research focused on the plant growth-promoting properties of endophytic bacteria isolated from Morisonia scabrida, a tree adapted to heat stress. Sixteen bacterial strains were isolated; among them, S1R21 tolerated 50 °C; S1H21 inhibited the growth of Fusarium sp. FH at 25 and 30 °C; and S1R16 inhibited Alternaria sp. ATCC20084 and F. oxysporum CTLM12 at 25 and 30 °C. Regarding enzymatic activities, S1R21 exhibited amylase activity at 30 °C; S1T20 showed proteinase activity at 37 °C; S1T11 showed pectinase activity at 37 °C; S1R16 and S1R9 demonstrated lipase activity; and S1R20 showed CMCase activity at 30 °C. S1T1 solubilized tricalcium phosphate at 25 and 30 °C; S1H5 produced siderophores at 30 °C; and S1T11 produced IAA and fixed nitrogen at 30 and 37 °C. With respect to germination percentage of corn and alfalfa, the highest values were achieved with strain S1R21 at 30 and 37 °C. Seven strains were selected and identified by 16S rDNA analysis as Bacillus albus S1H21, Bacillus cereus S1R21, Lysinibacillus fusiformis S1R9, Enterobacter sp. (S1H5 and S1R8), Klebsiella sp. S1R16 and Stutzerimonas stutzeri S1T11. Most of these strains increased growth parameters of Zea mays and Medicago sativa, with Stutzerimonas stutzeri S1T11 standing out regarding high aerial and root length, as well as fresh and dry weight. This research study is one of the few studies on endophytic bacteria associated with the Morisonia scabrida tree. It demonstrates that its bacterial diversity could contribute to various biological roles, such as that of plant growth promoter under heat stress. Full article