Search Results (1,743)

This study investigated the effects of lactic acid bacteria (LAB) inoculants on silage quality, mycotoxin, bacterial community, and aerobic stability of barley yellow dwarf virus (BYDV)-infected oat silage. A 2 × 4 factorial design was employed using healthy (H) and naturally BYDV-infected (S) oats, consisting of four additive treatments, Lactiplantibacillus plantarum (TX), Lentilactobacillus buchneri (YX), their combination (FH), and sterile water as the control (CK), with three replicates per treatment (24 silos in total). Fermentation quality and mycotoxin content were analyzed after 75 days of ensiling and 4 days of aerobic exposure, with the day-75 bacterial community characterized. BYDV infection severely impaired raw material quality, significantly reducing water-soluble carbohydrate (WSC) content by approximately 27.0% while elevating aflatoxin (AFT), zearalenone (ZEN), and deoxynivalenol (DON) concentrations by approximately 58.8%, 44.6%, and 54.3%, respectively (p < 0.01). Microbial analysis revealed that LAB inoculation effectively restructured the fermentation microbiota, with TX increasing Lactiplantibacillus abundance, FH suppressing Enterococcus while promoting Lentilactobacillus, and YX enriching Leuconostoc. Furthermore, TX increased crude protein (CP) content and lowered pH and ammonia nitrogen levels; YX boosted acetic acid accumulation and enhanced aerobic stability post-exposure, thereby enhancing aerobic stability; and FH preserved higher dry matter, WSC, and ether extract contents (p < 0.05). In S group, TX was most effective against AFT, reducing it by 24.0–31.1%, whereas FH showed superior efficacy against ZEN and DON, with reductions of 15.1–17.4% and 13.3–16.5%, respectively (p < 0.05). Consequently, LAB inoculation improves silage quality and reduces mycotoxins in diseased forage, with L. plantarum alone or combined with L. buchneri recommended for its utilization. Full article

To investigate the regulatory effects of salt-tolerant plant growth-promoting rhizobacteria (PGPR) on crop growth under salt stress and to identify superior bacterial resources for saline–alkaline soil improvement, the maize variety Ningdan 33 was used as the experimental material. Strain XJ-33, a salt-tolerant PGPR isolated from saline–alkaline soil in Ningxia, was selected for inoculation. Based on morphological observation, physiological and biochemical tests, and 16S rRNA gene sequencing, the strain was identified as Pseudomonas glycinae. This strain can tolerate extreme conditions of up to 10% NaCl and a pH of 11.0, and exhibits multiple plant growth-promoting traits, including the production of siderophores and indole-3-acetic acid (IAA), as well as ACC deaminase activity. The results showed that inoculation with XJ-33 significantly promoted the growth of maize seedlings under salt stress. Compared with the control, inoculated plants exhibited significant increases in plant height, root length, and biomass (both fresh and dry weights), with the most pronounced increments observed in shoot and root dry weights, which increased by 82.61% and 81.63%, respectively. Physiological and biochemical analyses revealed that leaf SPAD values, chlorophyll content, and nitrogen content increased by 15.00%, 13.18%, and 18.47%, respectively, following inoculation. Additionally, root activity (indicated by dehydrogenase activity) was significantly enhanced. In terms of stress physiology, inoculation improved the osmotic adjustment capacity of the plants; the levels of soluble sugars, soluble proteins, and proline in both leaves and roots increased significantly, whereas the malondialdehyde (MDA) content, an indicator of membrane lipid peroxidation, decreased significantly. Furthermore, the antioxidant enzyme system was positively modulated: superoxide dismutase (SOD) and catalase (CAT) activities were significantly elevated in both leaves and roots, while peroxidase (POD) activity decreased. In conclusion, strain XJ-33 exhibits robust salt tolerance and strong plant growth-promoting capabilities. It can alleviate salt-induced damage in maize by regulating osmotic balance, enhancing antioxidant defenses, and promoting nutrient uptake, thereby demonstrating significant application potential for saline–alkaline soil improvement and the development of microbial agents. Full article

Entomopathogenic fungi are increasingly recognized as multifunctional bioinputs, but robust methodological approaches are needed to evaluate their compatibility with established microbial inoculants and their effects on plant performance. Our study proposes an integrative framework to assess Metarhizium–Bradyrhizobium interactions in soybean (Glycine max), combining laboratory compatibility screening with greenhouse assessment. First, Metarhizium anisopliae LCM S04 and Metarhizium brunneum LCM S11 were tested against Bradyrhizobium diazoefficiens BR 85 (=SEMIA 5080) and Bradyrhizobium japonicum BR 86 (=SEMIA 5079) using dual-culture assays in a medium that supported the growth of both fungal and bacterial partners, allowing direct evaluation of intermicrobial compatibility. Subsequently, the microorganisms were evaluated in soybean under greenhouse conditions through direct seed inoculation. Each seed received bacterial culture, fungal suspension, or both (including absolute and nitrogen-fertilized controls). Plants were maintained under controlled conditions for 47 days. Plant height, leaf production, branching, nodulation, biomass, and root morphology were assessed. No inhibition zones were observed in vitro, and co-inoculation did not impair nodulation. The combination BR 86 + LCM S04 improved fine root number in soybean. This framework provides a reproducible approach for evaluating microbial compatibility and functional bioinput benefits and can be adapted to crops other than soybean. Full article

Soybean (Glycine max (L.) Merr.) is a key legume with high agronomic and nutritional value, widely cultivated for its high-protein seeds and its capability to improve soil fertility through biological nitrogen fixation. Recently, co-inoculation strategies combining Rhizobia bacteria with growth-enhancing fungi from the genus Trichoderma have gained increasing attention as a way to enhance soybean productivity and resilience under variable environmental conditions. The present study, conducted in 2023–2024, examined how seed inoculation treatments (Bradyrhizobium japonicum and Trichoderma viride) affect soybean productivity, seed quality, and soil biochemical changes expressed as the activity levels of selected soil enzymes—dehydrogenases (DHA), catalase (CAT), acid phosphatase (ACP), and alkaline phosphatase (ALP)—as well as the biological fertility index (BIF). The findings indicated that co-inoculation positively influenced plant productivity and produced the highest seed yields among all treatments tested, exceeding the control by 25.6%. Furthermore, inoculated seeds were characterized by improved seed quality, expressed by higher germination capacity (80%) and greater average seedling length (4.74 cm). The bacterial strains used to inoculate soybean seeds increased soil biochemical activity and improved fertility, particularly under unfavorable rainfall distribution during the growing season. Co-inoculation can be recommended as an effective and environmentally friendly element of soybean cultivation technology, supporting yield stability in variable weather conditions. Further research is recommended in longer multi-year series and under various habitat conditions. Full article

Wheat straw (WS) is an abundant crop residue with considerable potential as a ruminant feed; however, its utilization is severely constrained by a recalcitrant lignocellulosic structure. This study evaluated the effects of five alkali-resistant cellulolytic bacterial inoculants on the structural carbohydrate composition and in vitro ruminal fermentation characteristics of ammoniated wheat straw. A 6 × 3 factorial arrangement was employed, with six treatments (ammoniated WS as a control and five cellulolytic bacterial strains: X67, C72, S87, D100, and X107) and three storage durations (7, 14, and 21 days). The results showed that the bacterial treatments caused moderate losses of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, and cellulose at 7 and 14 days. The X107 treatment exhibited the lowest hemicellulose content, 2.1% lower than the ammoniated control. After 48 h of in vitro incubation, all bacterial treatments significantly increased potential gas production, 48 h methane production, in vitro DM digestibility (IVDMD), and in vitro NDF digestibility (IVNDFD). The S87 treatment achieved the highest IVDMD and IVNDFD, exceeding the ammoniated control by 14.9% and 32.5%, respectively, at 7 days (p < 0.05). All bacterial treatments maintained relatively high total volatile fatty acid (VFA) concentrations. Furthermore, the bacterial treatments increased the relative proportions of ruminal cellulolytic microbes at 7 and 14 days. By 21 days, no significant differences were observed in DM loss or microbial proportions among treatments. These findings indicate that the application of cellulolytic bacterial additives, with appropriate selection of bacterial strain and storage duration, exerts synergistic positive effects on the feeding value of alkali-pretreated wheat straw. The S87 treatment with a 7-day storage duration proved most effective. Full article

Origanum L. (Lamiaceae) is a commercially important medicinal and aromatic plant genus worldwide. Endophytic bacterial communities are recognized for promoting plant growth and physiology, although their interactions with host metabolism remain insufficiently understood. In this work, an in vitro model of axenic Origanum heracleoticum plants was established to investigate the relationship between endophytic bacteria and their tissue of origin. Specifically, we evaluated the adaptation of two strains, Bacillus sp. OHL2 and Pseudomonas sp. OHS18, and the potential role of Bacillus sp. OHL2 in modulating plant physiology and secondary metabolism. Bacterial inoculation and re-isolation highlighted niche-specific adaptation and possible co-evolution within the host, suggesting an active role of the plant in regulating bacterial colonization within the endosphere. Inoculation with Bacillus sp. OHL2 significantly enhanced photosynthetic rate, leaf area, dry weight, and chlorophyll content. No substantial overall changes in secondary metabolism were detected. Rosmarinic acid was the predominant phenolic, while monoterpenes dominated, with carvacrol dominant. A significant tissue-by-inoculation interaction was observed for α-humulene, which decreased in leaves of inoculated plants. Overall, the in vitro system provides a valuable platform to study plant–endophyte interactions and bacterial mechanisms underlying the stimulation of plant growth and metabolic responses. Full article

Reducing reliance on chemical nitrogen fertilizers while maintaining rice productivity is a key challenge in sustainable agriculture. In this study, a composite inoculant of three diazotrophic strains (Paenibacillus azotifigens, Paenibacillus azotofixans, and Phytobacter diazotrophicus) was applied by root drenching at the heading stage of field-grown rice. Soil physicochemical properties, rice yield, and soil bacterial and fungal communities were assessed at harvest using spike-in-based absolute quantification amplicon sequencing. Inoculation increased rice yield by 5.5% and significantly elevated soil nitrate nitrogen (NO₃⁻-N) (+343%), with a trend toward higher available phosphorus, while total nitrogen, phosphorus, and carbon remained unchanged. Bacterial absolute abundance was approximately 2.6-fold higher in inoculated plots, while fungal abundance declined, resulting in a substantially elevated bacteria-to-fungi ratio; community composition and diversity indices showed no significant changes. The inoculant strains were not detectably enriched at harvest, yet functional groups associated with nitrification, nitrogen fixation, and organic matter decomposition were consistently elevated and positively associated with reactive nutrient fractions. These results suggest that diazotrophic inoculants may promote yield through transient microbial community activation and nutrient form transformation rather than persistent colonization, and highlight the value of absolute quantification for detecting inoculation-induced shifts in microbial community size. Full article

The growth of vegetable plants is dependent on numerous environmental factors, including the presence of rhizosphere bacteria that produce phytohormones and support mineral uptake. The aim of this study was to determine the effect of symbiotic bacteria belonging to the Rhizobium leguminosarum species and other PGPR bacteria: Bacillus cereus, Chryseobacterium lathyri, and Lysinibacillus fusiformis, on seed germination and plant growth of a few crop species (i.e., white cabbage, broccoli, red pepper, and sugar beet). Three inoculation variants were tested: a mixture of R. leguminosarum strains (R), a mixture of other PGPR bacteria (B), and a combination of both of them (R + B). Biometric parameters such as seed germination, seedling growth, and the length and weight of upper parts and roots were determined. Our results showed diverse responses of the studied crop species to the bacterial mixtures used. In the case of variants R and R + B, the strongest effect of inoculation on seed germination and plant growth was observed. The obtained results indicated the agricultural potential of the analyzed bacterial consortia as biological support for the production of vegetable crops. They also emphasize the need for further research on their effectiveness in various environmental conditions. Full article

Sugarcane smut is a fungal disease caused by Sporisorium scitamineum. To explore its biological control strategies, this study collected rhizosphere soil of sugarcane, isolated and identified biocontrol bacteria from it, and conducted multi-level control efficacy evaluations. The results showed that five bacterial strains with effective antagonistic activity against the sexual mating and teliospore germination of S. scitamineum were isolated and identified: 2143-2 (Pseudomonas baetica), 2143-4 (Bacillus subtilis), 2143-6 (Burkholderia diffusa), Y8-2 (Pseudomonas reinekei), and Y8-3 (Bacillus amyloliquefaciens). The results of the pot inoculation experiments showed that all five strains could prolong the incubation period of sugarcane smut and significantly reduce the disease incidence, demonstrating marked control effects, with strains 2143-4 and Y8-2 being the most effective. The results of the field inoculation experiments and natural field infection experiments indicated that strain Y8-2 exhibited the best biocontrol efficacy against sugarcane smut, with control efficacies of 68.40% and 73.99% in the field inoculation experiments, and 65.73% under natural field infection conditions. In addition, the biocontrol strains could improve the physiological stress-tolerance characteristics of sugarcane plants, which was conducive to enhancing the resistance of sugarcane plants to sugarcane smut. Full article

Microalgae-based regulation is increasingly recognized as an eco-friendly strategy for improving water quality and nutrient management in intensive aquaculture systems. Although its effects on bacterial communities have been extensively investigated, its ecological impacts on higher trophic levels—particularly eukaryotic plankton communities across different size fractions—remain poorly understood. In this study, two indigenous microalgae species, Nannochloropsis oculata and Thalassiosira weissflogii, were inoculated into shrimp rearing water to elucidate the dynamics and interactions among microalgae, nutrient factors, and eukaryotic plankton communities across the small-sized (0.22–3 μm) and large-sized (>3 μm) fractions. The results revealed significant differences in the composition and diversity of both plankton size fractions under different microalgae treatments. Partial least squares path modeling indicated that microalgae influenced plankton communities both directly and indirectly through nutrient-mediated pathways. According to the neutral community model, microalgae inoculation was associated with an increased contribution of deterministic processes to community assembly. Variance partitioning further revealed that the large-sized community was primarily governed by microalgae, whereas the small-sized community was mainly shaped by rearing time, indicating size-dependent assembly mechanisms. The average variation degree and coefficient of variation, combined with effect-size analyses, indicated that N. oculata inoculation was associated with higher short-term community stability, an effect most pronounced in the large-sized fraction. Overall, these findings demonstrate that microalgal inoculation modulates the structure, assembly processes, and short-term stability of eukaryotic plankton communities, providing new insights into size-dependent, microalgae-driven assembly mechanisms and their potential to stabilize plankton communities for sustainable aquaculture management. Full article

Continuous cropping obstacles (CCOs) severely disrupt the soil physical structure, nutrient cycling, and microbial community balance, leading to decreased crop productivity. However, the effects of soil amendment interventions on bacterial, fungal, and archaeal communities in foxtail millet (Setaria italica (L.) P. Beauvois.) systems are not well comprehended. Selected physical, chemical, biological soil amendment and crop rotations were evaluated for their effects on rhizosphere soil microbial diversity, composition, network characteristics, community assembly processes, niche breadth, and multi-functionality. High-throughput sequencing of 16S rRNA and ITS regions demonstrated that earthworm castings significantly enhanced archaeal Chao1, Shannon diversity, and multi-functionality. Meanwhile, Bacillus mucilaginosus enhanced fungal diversity, and B. subtilis promoted bacterial network complexity. In continuous cropping soil alone, microbial communities exhibited low diversity and were predominantly governed by ecological drift. In contrast, soil amendment treatments shifted assembly toward deterministic processes, including homogeneous and heterogeneous selection. However, the analysis demonstrated greater complexity and niche width in bacterial communities than in fungal or archaeal communities, with keystone modules driven by Actinomycetota, Ascomycota, and Halobacteriota. Structural equation modeling indicated that soil physicochemical properties directly mediated rhizosphere soil microbial alpha diversity, which in turn positively influenced multi-functionality. Overall, organic amendments and microbial inoculants were associated with increases in microbial diversity, network stability, and functionality in this pot experiment, suggesting that such practices may help mitigate CCOs and sustainably improve foxtail millet productivity in dryland agricultural systems. Full article

The aim of this study was to isolate and molecularly identify lactic acid bacteria (LAB) associated with the epiphytic microflora and silage of wheatgrass (Agropyron spp.), as well as to evaluate their biotechnological potential as starter cultures for the ensiling of difficult-to-ensile forage crops under the climatic conditions of northern Kazakhstan. A total of 63 bacterial isolates were obtained and grown on MRS medium under different temperature conditions. Based on growth characteristics, pH values, and titratable acidity, 15 highly active strains were selected, demonstrating stable acidification (pH 3.99–4.75) and high metabolic activity. All isolates were catalase negative and capable of fermenting a wide range of carbohydrates and polyols, although pronounced strain-specific differences were observed. The selected strains exhibited proteolytic and antagonistic activity against test microorganisms and showed high tolerance to osmotic stress, maintaining growth at NaCl concentrations of up to 8–10%. Molecular identification based on 16S rRNA gene sequencing revealed that nine technologically significant strains belonged to the species Lactococcus garvieae, Pediococcus acidilactici, Lactiplantibacillus plantarum, Enterococcus faecalis and Enterococcus faecium. The results obtained in this study demonstrate the high environmental adaptability of the isolated strains and confirm their potential for the development of effective microbial inoculants aimed at improving fermentation processes and enhancing the preservation of difficult-to-ensile forage crops under cold-climate conditions. Full article

Beneficial fungal–bacterial interactions are important drivers of rhizosphere microecology and plant–soil functional coupling in conifer seedling systems, but their strain-combination-specific effects remain insufficiently understood. In this study, Pinus sylvestris var. mongolica seedlings were inoculated with three plant growth-promoting rhizobacteria (PGPR) strains, Serratia plymuthica A13, Acinetobacter lwoffii A07, and Pseudomonas koreensis A20, the ectomycorrhizal fungal strain Suillus luteus N94, and their corresponding co-inoculation combinations. Seedling growth, root architecture, plant nutrients, soil nutrients, soil enzyme activities, bacterial and fungal communities, differential taxa, network key taxa, and plant–soil functional indices were analyzed. Different inoculation treatments produced treatment- and trait-specific responses, with several N94–PGPR combinations showing advantages in particular growth, root, and soil functional traits, while some single-inoculation treatments also showed distinct positive effects. N94_A20 showed the greatest increases in seedling height, total dry weight, soil available phosphorus, and soil multifunctionality, whereas N94_A07 showed the strongest root architecture response and relative interaction index. Co-inoculation also reshaped rhizosphere bacterial and fungal communities and generated treatment-specific microbial enrichment patterns. Massilia, Ramlibacter, Holtermanniella, and Naganishia were positively associated with plant–soil functional indices. These results indicate that PGPR–N94 co-inoculation promotes conifer seedling growth through coordinated changes in root architecture, nutrient acquisition, soil biochemical function, and rhizosphere microbial community assembly. Full article

Beneficial and pathogenic fungal inoculation can substantially influence plant growth by reshaping rhizosphere microbial communities. However, how different fungal inoculants differentially affect microbial community assembly processes, co-occurrence network stability, keystone taxa distribution, and their potential associations with plant growth remains poorly understood. Cucumber was used as the model plant, and Fusarium oxysporum (pathogenic, Foc) and Trichoderma guizhouense (beneficial, Tri) were selected as inoculants. 16S rRNA and ITS2 amplicon sequencing were used to investigate the diversity, composition, assembly processes, and co-occurrence network structure of rhizosphere bacterial and fungal communities, respectively. In addition, we used Zi–Pi topological role analysis, functional prediction, Mantel tests and random forest to characterize keystone taxa and link microbial assembly, network stability to plant nutrient and biomass traits. Foc decreased bacterial diversity while Tri increased it. Tri was associated with greater microbial network connectivity and complexity, as well as network characteristics consistent with higher inferred stability, with more connector keystone taxa enriched in glycan and terpenoid metabolic functions; by contrast, Foc simplified network structure and enriched saprotrophic fungal keystones. Bacterial assembly shifted toward deterministic processes under Foc, whereas stochastic processes remained predominant in Tri and control treatments. Random forest further confirmed divergent drivers: bacterial assembly depended mostly on community composition, while fungal assembly was regulated by plant nutrients and fungal diversity. All microbial properties were tightly linked to plant biomass and nutrient accumulation. Collectively, beneficial and pathogenic fungi exert opposing influences on rhizosphere microbial organization: Tri was associated with more connected microbial communities and a greater diversity of predicted functional traits, whereas Foc strengthened environmental filtering and simplified community structure, with plant–microbe–nutrient feedbacks likely contributing to rhizosphere assembly and ecosystem functionality. Full article

The Qinghai–Tibet Plateau, a globally significant ecological barrier and a core pastoral region, is persistently constrained by cold and arid climatic conditions, nutrient poor soils, and progressive grassland degradation. These challenges necessitate maintaining forage productivity while enhancing ecological stability. Medicago sativa L., valued for its high nutritional quality and capacity for biological nitrogen fixation, has been widely incorporated into regional grassland systems. Rhizobial inoculation, as an environmentally sustainable agronomic practice, is regarded as an effective approach to improving nutrient use efficiency and promoting ecological restoration; however, its underlying mechanisms in cold and arid environments remain insufficiently understood. This study established a field experiment in Delingha, Qaidam Basin, using the cultivar ‘Beilin 201’. Treatments included an uninoculated control (CK) and four rhizobial seed coating rates: E1 (0.75 g·m⁻²), E2 (1.50 g·m⁻²), E3 (2.24 g·m⁻²), and E4 (3.00 g·m⁻²). The effects on yield, rhizosphere soil physicochemical properties, bacterial community structure, and molecular ecological networks were systematically evaluated. The composite microbial inoculant maintained Medicago sativa L. yield, with only modest and non-significant increases in some treatments. In contrast, soil organic matter increased significantly with application rate (p < 0.001), suggesting a stronger short-term effect on soil properties than on yield. Although network vulnerability was lowest in E4, the differences among treatments were not statistically significant. Mixed effects modeling showed that soil factors (74.79%) and microbial factors (25.12%) jointly influenced yield variation. Structural equation modeling further revealed that microbial factors exerted a positive direct effect on yield (0.3), whereas soil factors exhibited a stronger direct effect (0.57), with inoculation rate primarily influencing yield indirectly through soil mediated pathways. This study elucidates the ecological functions and regulatory mechanisms of rhizobial formulations in high elevation dryland ecosystems and provides both theoretical support and practical guidance for the rational application of microbial fertilizers and the sustainable management of forage systems on the Qinghai–Tibet Plateau. Full article