Search Results (190)

Soil salinization and selenium (Se) deficiency threaten global food security. This study developed a composite bioinoculant combining ACC deaminase-producing Serratia liquefaciens and biogenically synthesized nano-selenium (SeNPs) to alleviate saline–alkali stress and enhance Se nutrition in rice (Oryza sativa L.). A strain of S. liquefaciens with high ACC deaminase activity was isolated and used to biosynthesize SeNPs with stable physicochemical properties. Pot experiments showed that application of the composite inoculant (S3: S. liquefaciens + 40 mmol/L SeNPs) significantly improved seedling biomass (fresh weight +53.8%, dry weight +60.6%), plant height (+31.6%), and root activity under saline–alkali conditions. S3 treatment also enhanced panicle weight, seed-setting rate, and grain Se content (234.13 μg/kg), meeting national Se-enriched rice standards. Moreover, it increased rhizosphere soil N, P, and K availability and improved microbial α-diversity. This is the first comprehensive demonstration that a synergistic bioformulation of ACC deaminase PGPR and biogenic SeNPs effectively mitigates saline–alkali stress, enhances soil fertility, and enables safe Se biofortification in rice. Full article

Soybean (Glycine max) is a protein-rich legume crop that plays an important role in achieving food security. The aim of this study was to isolate soybean-nodulating rhizobia from Côte d’Ivoire soils and evaluate their potential as efficient strains in order to develop local bioinoculants. For this objective, 38 composite soil samples were collected from Côte d’Ivoire’s five major climatic zones. These soils were used as substrate to trap the nodulating rhizobia using the promiscuous soybean variety R2-231. A total of 110 bacterial strains were isolated and subsequently identified. The analysis of ITS (rDNA16S-23S), glnII and recA sequences revealed a relatively low genetic diversity of these native rhizobia. Moreover, the ITS phylogeny showed that these were scattered into two Bradyrhizobium clades dominated by the B. elkanii supergroup, with ca. 75% of all isolates. Concatenated glnII-recA sequence phylogeny confirmed that the isolates belong in the majority to ‘B. brasilense’, together with B. vignae and some putative genospecies of Bradyrhizobium that needs further elucidation. The core gene phylogeny was found to be incongruent with nodC and nifH phylogenies, probably due to lateral gene transfer influence on the symbiotic genes. The diversity and composition of the Bradyrhizobium species varied significantly among different sampling sites, and the key explanatory variables identified were carbon (C), magnesium (Mg), nitrogen (N), pH, and annual precipitation. Based on both shoot biomass and leaf relative chlorophyll content, three isolates consistently showed a higher symbiotic effectiveness than the exotic inoculant strain Bradyrhizobium IRAT-FA3, demonstrating their potential to serve as indigenous elite strains as bioinoculants. Full article

Heavy metal contamination in paddy fields poses serious risks to food safety and crop productivity. This study evaluated the potential of native soil fungi as bioinoculants to reduce metal uptake in rice cultivated under contaminated conditions. Eight fungal strains—four indigenous and four allochthonous—were selected based on their plant growth-promoting traits, including siderophore production and phosphate solubilization. Additional metabolic analysis confirmed the production of bioactive secondary metabolites. In a greenhouse experiment, three rice cultivars were grown under permanent flooding (PF) and alternate wetting and drying (AWD) in soil enriched with arsenic, cadmium, chromium, and copper. Inoculation with indigenous fungi under AWD significantly reduced the arsenic accumulation in rice shoots by up to 75%. While AWD increased cadmium uptake across all cultivars, fungal inoculation led to a moderate reduction in cadmium accumulation—ranging from 15% to 25%—in some varieties. These effects were not observed under PF conditions. The results demonstrate the potential of native fungi as a nature-based solution to mitigate heavy metal stress in rice cultivation, supporting both environmental remediation and sustainable agriculture. Full article

The nursery phase is vital for forest regeneration, yet studies on plant growth-promoting (PGP) bacteria to enhance sustainable nursery production in forest species are scarce. This study explores whether endophytic bacteria from disease-resistant Pinus pinea L. can improve germination and seedling quality in susceptible Pinus radiata D. Don. Root endophytes were isolated, screened for PGP traits, and identified via 16S rRNA gene sequencing. Bacterial formulations were applied to P. radiata seeds to determine their impact on germination and plant quality indicators (photosynthetic pigments and other metabolites). Paenibacillaceae (19%) and Bacillaceae (13%) were predominant among 68 isolates, with 94% producing indole-3-acetic acid, and Burkholderiaceae showing the broadest PGP trait diversity. Seedlings inoculated with formulation C3 (Caballeronia R.M3R3, Rhodococcus T.M4R4, and Mesorhizobium R.M1R2) displayed an improved germination rate (89% compared to 71% from the uninoculated control), while those inoculated with formulation P4 (Paenibacillus T.M5R4, Bacillus R.M2R7, Acinetobacter T.M2R22, and Paraburkholderia R.M1R3) showed an improved germination rate (81%), increased amount of starch (0.4-fold), and free amino acids (1.5-fold). This study presents a comprehensive approach, from endophyte isolation to in vivo tests, highlighting two bacterial formulations as candidates for further proof-of-concept nursery trials. Ultimately, these bioinoculants represent eco-friendly strategies to enhance forest seedling establishment and support sustainable forest management. Full article

The development of efficient bioinoculant formulations requires compounds with stabilizing, thickening, and carrier functions to preserve microbial viability and promote biological activity in soil. However, the majority of studies evaluate inoculant formulations predominantly in terms of bacterial viability, overlooking other important performance parameters. This study employed an integrative approach combining in vitro and plant-based assays to assess the effects of starch, carboxymethyl cellulose (CMC), and trehalose in formulations containing Azospirillum brasilense, Bradyrhizobium diazoefficiens, Methylobacterium symbioticum, and Paenibacillus alvei, applied to Glycine max seeds. Our hypothesis was that the presence of these additives, each with distinct functional roles (starch as a slow-release carbon source, CMC as a structural agent and protector against physical stress, and trehalose as an osmoprotectant and membrane stabilizer), would influence not only bacterial viability but also the seed germination, growth, and physiological responses of inoculated G. max plants. Starch improved viability in A. brasilense formulations, while both starch and trehalose had positive effects on M. symbioticum. These additives also enhanced plant traits, including dry biomass, chlorophyll content, carboxylation efficiency (A/Ci), and photochemical efficiency (Fv/Fm and Pi_Abs). Trehalose was particularly effective in formulations with B. diazoefficiens and M. symbioticum, supporting its use as a versatile stabilizer. In contrast, CMC (0.25%) negatively impacted bacterial viability, especially for B. diazoefficiens and P. alvei, and impaired physiological parameters in G. max when combined with M. symbioticum. These results highlight the need to evaluate formulation components not only for their physical roles but also for their specific interactions with microbial strains and effects on host plants. Such an integrative approach is essential for designing stable, efficient bioinoculants that align with sustainable agricultural practices. Full article

Strain 53B2 was isolated from a commercial maize (Zea mays L.) field located in the Yaqui Valley, Mexico. Its draft genome comprises 5,844,085 bp, with a G + C content of 37.5%, an N50 of 602,122 bp, an L50 of 4, and a total of 129 contigs. Genome-based taxonomic affiliation showed this strain belonged to Priestia megaterium. Genome annotation revealed 6394 coding DNA sequences (CDSs), organized into 332 subsystems. Among these, several CDSs were associated with traits relevant to plant growth promotion, including categories such as iron acquisition and metabolism (40 CDSs) and secondary metabolism (6 CDSs), among others. In vitro metabolic assays supported genomic predictions, confirming the strain’s ability to produce IAA, solubilize phosphate, and tolerate abiotic stress. Additionally, greenhouse trials demonstrated that inoculation with Priestia megaterium 53B2 significantly enhanced plant growth parameters (p ≤ 0.05) versus uninoculated control: stem height increased by 22.8%, root length by 35.7%, stem and root fresh weights by 39.6% and 66.1%, and stem and root dry weights by 33.7% and 44.7%, respectively. This first report on the beneficial potential of Priestia megaterium 53B2 highlights its potential as a sustainable bioinoculant for maize cultivation. Full article

Cyanobacteria-based bioinoculants represent a sustainable solution for enhancing soil fertility and crop productivity. This research assessed the biofertilizing potential of two indigenous nitrogen-fixing cyanobacteria strains (Nostoc punctiforme Har. and Anabaena cylindrica Lemmerm.) on tomato growth and yield. A greenhouse experiment was conducted to study their effects on soil properties, plant growth and physiology, and fruit yield/quality. The strains were applied individually, as a consortium, or combined with organic or mineral fertilizers at half the standard dose (50%). All bioinoculants improved soil fertility, plant growth, and fruit yield/quality compared to the control. The most significant improvement was observed in the consortium amended with 50% of conventional fertilizer (compost or NPK), compared with individual strains. Correlation analysis revealed strong positive associations between photosynthetic pigments, plant productivity, and fruit biochemical traits, indicating coordinated physiological responses under the applied treatments. The results demonstrated that the consortium of diazotrophic terrestrial cyanobacteria possesses tomato biofertilizer properties that can be efficiently used in crop production. These findings suggest that such formulations offer a cost-effective approach to tomato cultivation and present a sustainable alternative for integrated and optimized fertilizer management. Full article

Plant-growth-promoting fungi (PGPF) play a central role in promoting sustainable agriculture by improving plant growth and resilience. The aim of this literature review is to survey the impacts of Trichoderma spp. and Penicillium spp. on various agricultural and horticultural plants. The information provided in this manuscript was obtained from randomized control experiments, review articles, and analytical studies and observations gathered from numerous literature sources such as Scopus, Google Scholar, PubMed, and Science Direct. The keywords used were the common and Latin names of various agricultural and horticultural species, fungal endophytes, plant-growth-promoting fungi, Trichoderma, Penicillium, microbial biostimulants, and biotic and abiotic stresses. Endophytic fungi refer to fungi that live in plant tissues throughout part of or the entire life cycle by starting a mutually beneficial symbiotic relationship with its host without any negative effects. They are also capable of producing compounds and a variety of bioactive components such as terpenoids, steroids, flavonoids, alkaloids, and phenolic components. Penicillium is extensively known for its production of secondary metabolites, its impact as a bioinoculant to help with crop productivity, and its effectiveness in sustainable crop production. The plant-growth-promotion effects of Trichoderma spp. are related to better absorption of mineral nutrients, enhanced morphological growth, better reproductive potential and yield, and better induction of disease resistance. Both Penicillium spp. and Trichoderma spp. are effective, affordable, safe, and eco-friendly biocontrol agents for various plant species, and they can be considered economically important microorganisms for both agricultural and horticultural sciences. The present review article aims to present the most up-to-date results and findings regarding the practical applications of two important types of PGPF, namely Penicillium spp., and Trichoderma spp., in agricultural and horticultural species, considering the mechanisms of actions of these species of fungi. Full article

This study aims to identify the optimal conditions—host, plant material, seasonality, and agricultural practices—for isolating and developing a collection of culturable endophytic microorganisms to support sustainable Olea europaea L. cultivation. Samples were collected from three Sicilian olive cultivars (‘Nocellara del Belice’, ‘Nocellara Etnea’, and ‘Nocellara Messinese’) and six wild olive accessions across different phenological phases and under organic and conventional agronomic management. Endophytes were isolated from leaves and twigs using a culture-dependent approach, and their taxonomic diversity and plant-growth-promoting (PGP) traits were analyzed. A total of 133 endophytic isolates were identified, spanning bacterial (Proteobacteria, Firmicutes, and Actinobacteria) and fungal (Ascomycota and Basidiomycota) phyla. Wild olive trees contributed more than cultivated varieties to enriching the diversity and composition of culturable endophyte collection as well as twigs instead of leaves. Winter sampling allowed to implement the taxonomic genera of olive endophyte collection. Both farming systems favored an increase in the composition of microbial collection, though organic farming systems supported greater microbial richness. Functional analysis highlighted key PGP traits in a selection of bacterial isolates, including indole-3-acetic acid and siderophore production, nitrogen fixation, and antifungal activity. Bacillus spp. dominated enzymatic activities, such as amylase, protease, and lipase production, as well as antifungal activity against the olive fungal pathogen Neofusicoccum vitifusiforme. This research highlights the significant diversity and functional potential of Mediterranean olive endophytes. Our findings emphasize the role of native microbial communities as bio-inoculants, promoting plant growth, nutrient uptake, and disease resistance. These insights lay the groundwork for developing targeted olive-microbial consortia for biocontrol and stress tolerance applications. Full article

Soil microbes are important for maintaining agricultural ecosystems by promoting nutrient cycling, plant growth, and soil resilience. Microbial-based inoculants, such as bio-inoculants and bioremediation agents, have been identified as suitable means to promote soil health, reduce environmental deterioration, and achieve sustainable agriculture. Bio-inoculants, such as biofertilizers and biopesticides, promote nutrient availability, plant growth, and chemical input dependency reduction. Diverse microbial populations, especially plant growth-promoting bacteria (PGPB), enhance resistance by promoting a symbiotic association with plants and inducing natural resistance against insects. Bioremediation, the second significant microbial intervention, is the use of microorganisms for detoxifying and rehabilitating polluted soils. Methods effectively degrade organic pollutants, immobilize heavy metals, and mitigate the toxic effects of industrial and agricultural pollutants. Recent advances in microbial ecology and biotechnology, such as metagenomics, have transformed the knowledge of microbial soil communities, and tailor-made microbial formulations and monitoring equipment may be developed to maximize their activity. Though promising, environmental heterogeneity, scalability, and lack of field-based evidence constrain their widespread application. Multidimensional applications of microbial solutions in agroecology are explored in this review, with a focus on their potential in maintaining soil health, crop production, and environmental sustainability. It also addresses the application of bioremediation and microbial inoculants in agroecosystems and technological innovations with future research objectives. Microbial innovation to shape the soil microbiome offers a valid tool for addressing global challenges in agriculture, food security, and ecological resilience in the context of climate change. Full article

Egypt’s rapid population increase has resulted in higher water demand. It may significantly reduce the amount of water available for agriculture, increasing the chance of using saline water in agriculture. Using saline water certainly poses a major threat to maize growth and may severely affect the growth and productivity of this important crop. Therefore, the aim of this study was to isolate newly native salt-tolerant bacteria from Egyptian saline soils and assess their ability to produce growth-promoting substances under salinity stress, as well as test the mitigating impact of these isolated salt-tolerant bacteria along with arbuscular mycorrhizal fungi (AMF) in maize plants under salinity stress. We isolated ninety-seven salt-tolerant bacterial isolates, and these isolates show a high ability to grow under different concentrations of NaCl. The nine most efficient isolates show a high ability to produce indole acetic acid (IAA), gibberellic acid (GA), P-solubilized exopolysaccharides (EPS), proline, and antioxidants under different NaCl concentrations. Using the 16S rRNA gene, the most effective isolate STB 89 was identified, and its impact, along with AMF, on the growth of salinity-stressed maize was tested in a pot experiment. Our results showed that the growth parameters (shoot length, root length, dry weight, and leaf area), photosynthetic-related pigments (Chlorophyll a, b, and carotenoids), NPK content, and antioxidant enzymes (PPO, POX, and CAT) were improved significantly at p ≤ 0.05 due to the bioinoculant applications, while reduced proline accumulation, Na uptake, and the Na⁺/K⁺ ratio in maize plant tissues were observed compared to the control plants. Moreover, the indices of AMF colonization in maize roots and the count of bacteria in the rhizosphere were enhanced due to the bioinoculant applications under salinity stress. In addition, we found that the combined application was more pronounced than the individual application impact. Hence, our results recommended that salt-tolerant bacteria (STB 89) could support salinity, mitigating the impact of AMF in maize plants, as well as allowing better practical techniques for maize cultivation and soil sustainability under salinity stress. Full article

Peanut (Arachis hypogaea L.) is one of the most important oilseeds crops worldwide. Through symbiosis with the bacterium Bradyrhizobium sp., peanuts can assimilate atmospheric nitrogen, reducing the need for chemical fertilizers. However, this nitrogen fixation process is highly sensitive to environmental factors that can inhibit the early stages of symbiotic interaction. In this study, we propose the encapsulation of Bradyrhizobium sp. SEMIA6144 and the flavonoid naringin (Nar) in alginate beads to improve flavonoid stability and promote nodulation kinetics in peanuts. Three types of beads were synthesized: A (control, SEMIA6144 only); B (SEMIA6144 induced with 10 µM Nar); and C (SEMIA6144 co-entrapped with 1 mM Nar). Although Nar increased cell mortality (2-fold compared to control) and reduced metabolic activity—particularly at 1 mM—cells in beads B and C responded by altering their membrane fatty acid profile (30% and 55.5% of 18:1, respectively) leading to a reduction in saturated fatty acids (5.8% and 13.1% for 16:0 and 18:0 in B; 11.8% and 21.2% in C). Bacterial release kinetics followed a primarily Fickian diffusion model, with minor matrix–bacteria interactions in Nar-treated beads. Notably, bacterial release in peanut root exudates was 6%, 10%, and 11% higher for beads A, B, and C, respectively, compared to release in physiological solutions. Nar-beads enhanced the formation of curved root hairs, promoted bacterial colonization in root hair zones, and stimulated the appearance of rosette-like structures associated with nodule initiation. In conclusion, encapsulating Bradyrhizobium sp. SEMIA6144 with Nar in beads represents a promising strategy to improve symbiotic nitrogen fixation in peanuts. Full article

Sugarcane (Saccharum spp.) stands out in the context of sustainable agricultural production due to its versatility and energy potential. However, management challenges, such as nitrogen (N) fertilization associated with microbiological action, require improvement. In this context, the use of the bacterium Azospirillum brasilense has been studied as an alternative to reducing the use of mineral fertilizers. The objective of this study was to evaluate the application of Azospirillum brasilense in the planting furrow of sugarcane in terms of leaf diagnosis, nutrient uptake, yield and technological quality of the stalks, and total fresh and dry biomass of the aerial parts of the plants. The experiment was conducted under field conditions at two locations during the 2022/2023 growing season. The soils in Areas 1 and 2 were classified as medium-textured oxisol and sandy-textured oxisol, respectively. The experimental design was a randomized block design with four replications. The treatments were as follows: (T1) 28 kg ha⁻¹ of N; (T2) 14 kg ha⁻¹ of N; (T3) T2 + 0.2 L ha⁻¹ of inoculant; (T4) T2 + 0.4 L ha⁻¹ of inoculant; (T5) T2 + 0.6 L ha⁻¹ of inoculant; (T6) T2 + 0.8 L ha⁻¹ of inoculant. In Area 1, treatment T5 showed a total fresh biomass yield of the aerial parts that was 34% higher than T2. Total dry biomass, tillering, stalk yield, and technological parameters did not differ significantly between treatments in either area. In terms of nutrient uptake, treatment T5 consistently ranked among those with the highest averages for P, K, Ca, Mg, S, Fe, Mn, and Zn in both experimental areas. The dendrogram showed similar results between treatments T1 and T5. The application of 0.6 L ha⁻¹ of the solution containing Azospirillum brasilense, combined with 50% of the recommended N dose, increased total fresh biomass production. Total dry biomass, stalk yield, tillering, and technological variables of the crop were not affected by the presence of the bacterium. Full article

This study investigated the role of Lacticaseibacillus paracasei K-68 (LABK) and cocktail LAB (LABC) as silage inoculants to enhance corn silage fermentation quality and microbial stability. Silage spoilage is primarily caused by undesirable microbes such as Clostridium, Klebsiella, yeasts, and molds. The isolated LAB strain K-68 exhibited strong antibacterial and antifungal activity, particularly against spoilage organisms, and was identified as L. paracasei. Experimental silages inoculated with LABK or a LABC significantly improved fermentation profiles, with reduced pH and increased lactic acid levels. Microbial counts revealed that LAB-inoculated silages had higher LAB counts and significantly reduced yeast and mold populations. Furthermore, there were no significant differences in acetic acid, isobutyric acid, and propionic acid levels. High-throughput sequencing confirmed that LABK-treated silage was dominated by Lacticaseibacillus paracasei, whereas LABC-treated silage supported more diverse microbiota, including Pediococcus pentosaceus, Lacrimispora xylanolytica, and Levilactobacillus brevis. Both treatments suppressed spoilage-associated genera such as Clostridium and Klebsiella. Furthermore, correlation analysis showed that Lacticaseibacillus abundance was positively associated with lactic acid production and negatively correlated with pH and yeast levels. L. paracasei K-68 is a promising bio-inoculant for corn silage production since it promotes beneficial microbial dominance and suppresses spoilage organisms better than cocktail LAB. Full article

Global agricultural productivity and ecosystem sustainability face escalating threats from multiple abiotic stresses, particularly heavy metal contamination, drought, and soil salinization. In this context, developing effective strategies to enhance plant stress tolerance has emerged as a critical research frontier. Phosphate-solubilizing microorganisms (PSMs) have garnered significant scientific attention due to their capacity to convert insoluble soil phosphorus into plant-available forms through metabolite production, and concurrently exhibiting multifaceted plant growth-promoting traits. Notably, PSMs demonstrate remarkable potential in enhancing plant resilience and productivity under multiple stress conditions. This review article systematically examines current applications of PSMs in typical abiotic stress environments, including heavy metal-polluted soils, arid ecosystems, and saline–alkaline lands. We comprehensively analyze the stress-alleviation effects of PSMs and elucidate their underlying mechanisms. Furthermore, we identify key knowledge gaps and propose future research directions in microbial-assisted phytoremediation and stress-mitigation strategies, offering novel insights for developing next-generation bioinoculants and advancing sustainable agricultural practices in challenging environments. Full article