Search Results (276)

Excessive acidity restricts the utilization of citrus pulp, a major by-product of the dried tangerine peel industry. To overcome this bottleneck, a functional microbial consortium (BsHpMrF) comprising Bacillus subtilis L4, Hanseniaspora pseudoguilliermondii B4, and Monascus ruber CGMCC 10910 was constructed for efficient biological deacidification. The consortium exhibited a synergistic effect, achieving an 88.23% reduction in total acidity and converting the acidic pulp into a neutral, bio-stabilized substrate. Untargeted metabolomics analysis revealed that this efficiency was driven by the concurrent activation of the TCA cycle and glyoxylate shunt for organic acid mineralization, coupled with membrane lipid remodeling (increased unsaturation) to enhance acid tolerance. Notably, the fermentation process functioned as a “metabolic factory”, significantly enriching the matrix with bioactive lipids (e.g., 10-HDA, nervonic acid) and indole-3-acetic acid (IAA, 414.28 mg/L). Application assays demonstrated that the fermentation products acted as a potent biostimulant for soybean sprouts, significantly promoting lateral roots and eliciting the accumulation of antioxidant phenolics and flavonoids. This study provides a sustainable “waste-to-treasure” strategy, valorizing acidic citrus pulp into a functional biostimulant for high-quality edible sprout production, thereby achieving a sustainable “waste-to-food” circular loop. Full article

Water deficit is a major abiotic constraint limiting peanut (Arachis hypogaea L.) production. This study evaluated the combined effects of filter cake, foliar application of an amino acid-based biostimulant, microbial consortium inoculation, on peanut growth, physiology, and yield under water scarcity conditions. Treatments were arranged in a split-plot design with four replicates, where filter cake (0 and 5 t ha⁻¹) was assigned to main plots, amino acid application to subplots (0.25 and 0.50 L ha⁻¹), and microbial consortium to sub-subplots (100 and 200 mL m⁻²). At 50 days after sowing, plant growth parameters, relative chlorophyll content, and aboveground biomass were assessed, while yield components and seed yield were determined at harvest. Results indicated that the combined treatment with 5 t ha⁻¹ filter cake, 0.50 L ha⁻¹ amino acids, and 200 mL m⁻² microbial consortium, consistently produced the highest main stem length (increase of 40%), aboveground biomass accumulation (increase of 41%), number of matured pods per plant (increase of 38%), seed mass per plant (increase of 87%), and final seed yield (increase of 86%) compared to the lowest-input treatment (F₀A_0.25M₁₀₀) under water-limited conditions. These findings indicate that the integrated fertilization can improve phenological, physiological, and yield responses and represents a sustainable approach to improve peanut resilience and productivity under water scarcity. Full article

Microbial oil production has gained attention as a sustainable and cost-effective alternative to conventional vegetable and fish oils. Among oleaginous microorganisms, Yarrowia lipolytica is notable for its ability to accumulate lipids exceeding 20% of its dry weight. This study aimed to evaluate semi-continuous cultivation as a strategy for sustainable microbial oil production by Y. lipolytica, while also assessing the potential utility of the spent supernatant. Three different feeding frequencies were evaluated. In the 24 h feeding regime, the maximum oil concentration reached 11.22 g/L, decreasing to 8.43 g/L by the 88th hour. In the 6–6–12 h feeding strategy, crude protein content peaked at 43.75% of dry mass at 22 h. Fatty acid profiling revealed consistently low saturated fatty acid (SFA) levels (4.93–10.30%), while unsaturated fatty acids (UFA) dominated (89.69–95.05%). Monounsaturated fatty acids (MUFA) were predominant, reaching up to 81.24%, whereas polyunsaturated fatty acids (PUFA) ranged from 20.78% to 29.98%. Oleic acid was the most abundant fatty acid across all conditions. This composition supports the potential of microbial oil from Y. lipolytica as a sustainable alternative edible lipid ingredient for human food applications, complementing conventional plant-based oils. The favorable unsaturated fatty acid profile indicates its potential suitability for incorporation into food formulations requiring nutritionally desirable lipid sources. As part of the sustainability-oriented approach of the study, the freeze-dried post-culture supernatant was also evaluated for its potential further utilization. With a calorific value of 10.43 kJ/g and significant phosphorus and potassium levels, it shows potential as a biofuel feedstock and as a biofertilizer or biostimulant. Full article

Biostimulants offer a sustainable strategy to improve plant growth and stress resilience, particularly under limited water availability. We evaluated seven biostimulant treatments, including beneficial bacteria, mycorrhizal fungi, seaweed extract with humic acid, and their combinations, on early growth and physiological responses of tomato (Solanum lycopersicum L.) under well–watered and drought-stressed conditions. Plants were assessed before and after a seven-day controlled drought period using a range of morphological and physiological traits, including height, effective quantum yield of PSII (Φ_PSII), stomatal conductance (g_s), and leaf pigment profile. Results showed that microbial treatments that included Bacteria + Mycorrhizae (B + M) maintained Φ_PSII above 0.60 and preserved height gain relative to the control, while seaweed-based formulations with humic acid (S + H) exhibited significant reductions in height of up to 35% compared with full irrigation. In addition, the bacterial treatment (B) significantly increased the root/shoot ratio under drought, indicating enhanced carbon allocation to roots. These findings demonstrate that specific microbial-based biostimulant combinations can better maintain physiological performance and growth under water limitation, supporting their potential use in sustainable tomato production systems. Full article

This review investigates the multifaceted roles of nitrogen-fixing and phosphate-mobilizing bacteria in natural ecosystems, with a particular focus on their contributions to plant growth and sustainable soil management. These microbial communities contribute substantially to nutrient cycling by converting atmospheric nitrogen into plant-available forms and mobilizing insoluble phosphorus in soil, thereby enhancing soil fertility and promoting sustainable plant productivity. This review synthesizes current knowledge on the mechanisms underlying biological nitrogen fixation, phosphate solubilization and mineralization, and the production of plant growth–promoting metabolites. Particular attention is given to plant–microbe interactions and their role in improving nutrient availability, regulating plant physiological processes, and enhancing tolerance to abiotic stresses such as salinity, drought, and heavy metal contamination. The findings underscore the ecological importance of these plant-associated microbial communities and highlight their potential applications in biofertilizer and biostimulant development for sustainable agriculture and reduced dependence on synthetic fertilizers. Full article

2-Amino-3-methylhexanoic acid (AMHA), as a naturally occurring α-amino acid, exhibits excellent bioactivity in inducing plant resistance to biotic and abiotic stresses, promoting plant growth and alleviating pesticide damage. However, its low yield in nature has hindered its industrialization. This study aims to address the current challenges in AMHA production, including synthetic difficulties, low yield, and poor production safety. We investigated the production capacity of Serratia marcescens NAU002-4 using high-performance liquid chromatography (HPLC), orthogonal experiments, and ion exchange chromatography (IEC), supplemented by precursor feeding assays. Optimization of the fermentation medium revealed that 10 g/L corn steep liquor as the nitrogen source and 10 g/L threonine as the precursor resulted in maximal yield. Further optimization of fermentation parameters—initial pH 7.2, inoculation volume 6%, stirring speed 180 rpm, and aeration rate 350 L/h—led to an AMHA titer of 504 mg/L. In parallel, field trials were conducted to evaluate the effects of pure, biosynthetic AMHA on tea plant growth and photosynthetic performance, using plant physiological data and chlorophyll fluorescence rise kinetics. The results demonstrated that biosynthetic AMHA significantly enhances tea plant growth and photosynthetic efficiency, providing a scientific basis for its development and application as a novel biostimulant. Full article

Phytophthora cinnamomi Rands, an oomycete pathogen of global relevance, is a major driver of cork oak (Quercus suber L.) decline and mortality in Mediterranean forests. Its management remains challenging in multifunctional landscapes where forestry and agriculture intersect, such as Mediterranean oak dehesas. Conventional fungicides are used against P. cinnamomi, but their negative environmental impacts underscore the need for alternative management in agroforestry systems. This study evaluated whether a commercially available microbial biostimulant, VESTA, enhances physiological performance and mitigates pathogen pressure in Q. suber. Seedlings were inoculated with P. cinnamomi and treated with the bioinoculant via fertigation or watering to substrate saturation, under controlled greenhouse conditions. Plant physiological parameters and soil oomycete inoculum concentrations were measured to assess treatment efficacy. Both application methods significantly improved physiological performance in inoculated and mock-inoculated plants. Photosynthesis, stomatal regulation, and water balance were most affected. Quantitative PCR analyses revealed a strong pathogen reduction, with DNA concentrations approximately tenfold lower in treated substrates (~0.001 ng mL⁻¹) than untreated controls (~0.011 ng mL⁻¹). Overall, the product enhanced Q. suber resilience by improving plant physiological responses and reducing pathogen abundance, supporting its potential as a bio-based tool for nurseries and restoration in Mediterranean ecosystems. Field studies are needed to validate these findings under natural variability and optimize long-term application strategies. Full article

Abiotic stresses severely constrain crop productivity by disrupting cellular redox homeostasis and hormone signaling. Although individual stresses differ in origin, plant responses converge on a conserved regulatory system centered on reactive oxygen species (ROS) and phytohormone crosstalk. Controlled ROS production in chloroplasts, mitochondria and the apoplast functions as a signaling mechanism that interacts dynamically with abscisic acid, auxin, ethylene, jasmonate and cytokinin pathways through shared regulatory nodes, including nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and redox-sensitive transcriptional cascades. Endogenous metabolites, including phenolics, terpenoids, carotenoids, alkaloids, polyamines, glutathione and signaling peptides, are embedded within this network and modulate its amplitude and sensitivity. In parallel, non-microbial biostimulants derived from seaweeds, higher plants, protein hydrolysates and humic substances have been widely reported to enhance crop performance under abiotic stress. However, mechanistic integration between biostimulant research and plant stress signaling remains limited. In this review, we propose that terrestrial plant- and algal-derived biostimulants act not as external substitutes for hormones or antioxidants but as modulators of endogenous ROS–hormone signaling hubs. We first synthesize the current understanding of redox–hormone integration under abiotic stress, then examine endogenous metabolites as intrinsic regulators of this network, followed by an analysis of biostimulants in relation to shared regulatory nodes. By positioning biostimulant action within the established redox–hormone network, we provide a mechanistic framework that links stress biology with agronomic application and supports rational strategies to enhance crop resilience. Full article

Compost-based biostimulants (CBB) have emerged as a promising tool in sustainable agriculture, offering an eco-friendly approach to improving soil health, crop productivity, and environmental resilience. Derived from the controlled biodegradation of organic waste, CBB contains a diverse array of beneficial microorganisms, humic substances, and bioactive compounds that act synergistically to stimulate plant growth and soil biological activity. Mechanistically, CBB enhances nutrient acquisition by increasing plant-available nitrogen and phosphate solubility, promoting root development through phytohormone synthesis, and improving stress tolerance by modulating plant defense pathways and antioxidant activity. Additionally, their application enhances soil structure, microbial diversity, and carbon sequestration, making them integral to climate-smart agriculture. Despite their growing relevance, several challenges impede the widespread adoption of CBB. Variability in compost quality, lack of standardized production protocols, limited field-scale validation, and inconsistent regulatory frameworks hinder reproducibility and commercialization. Addressing these gaps requires interdisciplinary research that integrates microbiology, biochemistry, agronomy, and data science to better understand how microbial metabolites interact and optimize formulation strategies. Future research should prioritize the standardization of composting methods, long-term multi-crop field evaluations, and integration with precision agriculture tools for real-time soil monitoring. Policy harmonization, quality assurance frameworks, and farmer education are also vital for ensuring safe and effective use of CBB. Full article

The effectiveness of poly(isosorbide carbonate) (PIC)—a bio-based polycarbonate synthesized from isosorbide (ISB)—degradation products in complex soil environments remains unverified. In the present study, the agricultural potential of PIC ammonolysis products—comprising urea and ISB—as a nitrogen (N) fertilizer was evaluated in a soil system. A pot experiment was conducted using komatsuna (Brassica rapa var. perviridis) to compare PIC degradation products with commercial urea, a urea and ISB mixture, and a no-N control. Application of PIC degradation products significantly enhanced plant growth, yielding fresh weight and N uptake comparable to those associated with commercial urea. The calculated N recovery efficiency for the PIC degradation products was 50%, falling within the typical range (30–60%) for inorganic fertilizers. Contrary to previous in vitro study results, ISB exhibited no significant biostimulant effect in the soil environment, likely owing to rapid microbial degradation. These findings serve as a preliminary proof-of-concept that PIC degradation products are a highly effective and bioavailable N source. Overall, the results suggest that if scaled appropriately, PIC ammonolysis products could contribute to circular use pathways for this specific plastic. Nonetheless, further studies across a broader range of crops and soils are required to confirm the generalizability of these results. Full article

This study evaluated the effects of biostimulant treatments on the ionic composition and yield of ‘Formosa’ papaya (Carica papaya L.) subjected to varying water replacement levels. The research utilized a randomized complete block design in a split-plot scheme comprising three irrigation depths (100%, 75%, and 50% ETc) and four biological treatments: control, Trichoderma harzianum, Ascophyllum nodosum, and Bacillus aryabhattai. Contrary to initial expectations, water restriction was associated with increased yield and leaf concentrations of zinc (Zn) and nitrogen (N), challenging the hypothesis that water restriction limits production. Quantitative results showed that T. harzianum under 75% ETc attained 93.29 kg plant⁻¹, whereas the control at 50% ETc recorded 19.14 g kg⁻¹ of N. Under 50% ETc, B. aryabhattai increased the bacterial population to 10.46 log10 CFU g⁻¹ soil compared to the control. The T. harzianum-based biostimulant reduced leaf sodium (Na) under 75% ETc and maintained the nutrient accumulation order K > N > Ca > Fe > Mn > Zn > Cu > Na. Conversely, B. aryabhattai and A. nodosum improved yield under 100% ETc through N accumulation. This study confirms that microbial and seaweed-based biostimulants mitigate water stress through rhizosphere modification and nutritional homeostasis, offering a practical strategy for sustainable fruit production in semi-arid regions. Full article

Modern agriculture is undergoing a paradigm shift toward eco-friendly methodologies that enhance seed material quality while minimizing chemical inputs. This study evaluates the impact of Effective Microorganism (EM) exposure (variants E1 and E2) on the morpho-physiological parameters and phytosanitary health of potato tubers. The primary objective was to determine the efficacy of microbial priming in suppressing the infection rates of Streptomyces scabies (common scab) and Rhizoctonia solani (black scurf) across 14 genetically diverse cultivars. A three-year field experiment (2019–2021) was conducted using a split-plot design with three replications. The study analyzed the interaction between EM exposure times and the genetic resistance potential of the selected cultivars. Statistical analysis confirmed that pre-planting microbial treatments significantly inhibited pathogen development. EM applications (E1 and E2) reduced the infection rates of both S. scabies and R. solani through an “escape mechanism,” whereby treated tubers exhibited accelerated biomass accumulation and reached physiological maturity before peak pathogen pressure. Furthermore, treatments optimized the physiological state and vigor of the tubers, establishing a robust physiological barrier against soil-borne infections. The application of EMs proves to be a highly effective, non-invasive biostimulation method. A significant difference was observed in the responding varieties between EM treatments and the cultivars innate genetic resistance, particularly in cultivars with higher baseline resistance. The use of EM biostimulants significantly modifies the health of tubers, and the direction of these changes is strictly determined by the variety factors. The results suggest that microbial priming not only enhances plant growth kinetics but also induces systemic resistance, offering a viable ecological alternative to traditional chemical seed dressings in sustainable potato production. Full article

Alkali–thermal treatment of waste activated sludge (WAS) can produce a liquid fertilizer (LF) rich in plant nutrients and biostimulants. However, studies on its actual effects on plant growth and soil quality during field application remain limited. This study employed pot experiments to investigate the impacts of LF substitution (0%, 50%, 100%) for urea on pakchoi cabbage yield, soil physicochemical properties, and microbial communities. The results demonstrated that the LF100 treatment (complete substitution) exhibited the most favorable performance in terms of both plant yield and soil quality enhancement. Compared to the CK, LF0, and LF50 treatments, the LF100 treatment increased various growth and soil parameters: fresh and dry weights of pakchoi cabbage by 50.31–110.61% and 52.48–72.00%, respectively; total soil nitrogen by 1.54–9.09%; total soil phosphorus by 13.89–54.56%; soil available phosphorus by 37.51–116.88%; as well as soil urease, invertase, and protease activities by 2.73–9.41%, 17.11–32.52%, and 7.14–36.36%, respectively. Meanwhile, soil microbial diversity in all fertilized groups was higher than in CK, and it increased with the rising LF substitution ratios. Furthermore, the dominant phyla of LF100 soil microbial community included Actinobacteriota, Proteobacteria, Acidobacteriota, and Crenarchaeota, encompassing multiple bacterial genera involved in carbon/nitrogen cycling and nitrogen fixation. Thus, this liquid fertilizer carries resource utilization potential as a urea substitute, offering valuable insights for sustainable agricultural development. Full article

Nutrient surpluses in regions with intensive livestock farming challenge sustainable crop production and have driven interest in alternative fertilization strategies and microbial biostimulants. Although microbial inoculation (MO) has been extensively studied in plant production, its agronomic relevance under field conditions remains controversial due to inconsistent outcomes. To address these inconsistencies, we conducted three-year field trials on two well-fertilized sandy sites in northern Germany. A microbial consortium consisting of Rhizoglomus irregulare, Funneliformis mosseae, Funneliformis caledonium, and Bacillus atrophaeus Abi05 was applied to silage maize (cultivar Amaroc S230) under contrasting fertilization regimes. In two of three years, microbial inoculation increased dry mass yield in the absence of starter fertilization, whereas both a high nutrient input variant (100 kg ha⁻¹ diammonium phosphate, DAP) and a lower nutrient input organo-mineral microgranular fertilizer (25 kg ha⁻¹) suppressed inoculant effects. Notably, yields from plots amended solely with the microbial inoculant reached at least the same level as those obtained with starter fertilization. In the third year, under drought conditions, defined as soil water contents below 10% in the 0–30 cm depth, no positive yield responses to microbial inoculation were observed. Quantitative PCR-based analyses of pre-sowing soils revealed that the abundances of Firmicutes, β-Proteobacteria, and total fungi were associated with yield responses, with Firmicutes and β-Proteobacteria showing negative and fungi showing positive correlations; together, these microbial predictors explained 38% of the variance in inoculant-induced yield response. Our findings demonstrate that soil microbiome characteristics can predict inoculant performance and that microbial inoculation is most effective without starter fertilization and under adequate soil moisture. Full article

In line with sustainability goals, biological alternatives to chemical fumigants are increasingly in demand to support intensive baby leaf lettuce cultivation systems. This study evaluated the combined effects of soil disinfestation strategies and foliar biostimulants on crop performance and nutritional quality. With the aim of evaluating the interactive effects of biofumigation and the application of Trichoderma spp., Ascophyllum nodosum extract, and vegetable protein hydrolysate, an experiment was conducted under controlled growing conditions, integrating microbial and foliar treatments on two lettuce cycles. Soil microbial load, plant biometric traits, ionic profiles, antioxidant activity, and polyphenolic compounds were quantified. Biofumigation induced a marked recovery of bacterial populations, while both soil treatments resulted in sustained fungal suppression and the absence of detectable Fusarium spp. Biofumigation consistently increased fresh and dry biomass, highlighting its dual sanitizing and fertilizing role. Foliar biostimulants, particularly vegetable protein hydrolysate, significantly enhanced dry matter accumulation, reduced nitrate concentration, and improved cation uptake. Antioxidant activity and phenolic metabolism were strongly stimulated by Trichoderma spp. and protein hydrolysate, with significant synergistic effects on key hydroxycinnamic acids and flavonoids. These findings indicate that integrating biological soil disinfestation with foliar biostimulation improves yield stability and nutritional quality, supporting a sustainable framework for high-value baby leaf lettuce production. Full article