Search Results (414)

The most common reason for a decrease in the quantity and quality of produced crops is microbial diseases. The aims of this study were to evaluate the antagonistic activity of Streptomyces sp. CACIS-1.16CA against plant pathogenic fungi and to assess its bioactive metabolites to inhibit fungal conidial germination. Antagonistic evaluations of fungal phytopathogens were performed using dual and multiple confrontation assays. Additionally, the inhibitory effect of the bioactive extract (BE) containing secondary metabolites produced by the CACIS-1.16CA strain on the germination of conidia from some fungi was tested. The results indicate that Streptomyces sp. CACIS-16CA inhibited the growth of all tested pathogens (16 strains) with percentages of inhibition (PIs) ranging from 43.3% to 72%, while S. lydicus inhibited 13 of the 16 fungi, with PI values from 35.6% to 68.5%. Moreover, CACIS-1.16CA exerted superior PI values (significant differences at p < 0.05) than S. lydicus against the damping-off fungi consortia with Phytophthora capsici, Fusarium oxysporum, and Rhizoctonia solani. Otherwise, an inhibitory effect was observed on the germination of conidial cells due to the interaction with the BE in Alternaria sp., Botrytis cinerea, and Colletotrichum spp. In conclusion, Streptomyces sp. CACIS-1.16CA may serve as an effective and natural alternative for managing several fungal plant diseases. Full article

The prolonged and intensive use of chemical inputs in agriculture, particularly synthetic fertilizers, has generated a variety of environmental and agronomic challenges. This has intensified the need for alternative, viable, and sustainable solutions. Plant-associated microbes have emerged as promising candidates in this regard. While research has largely focused on bacteria and fungi, comparatively less attention has been paid to other microbial groups such as microalgae and cyanobacteria. These photosynthetic microorganisms offer multiple agronomic benefits, including the ability to capture CO₂, assimilate essential micro- and macroelements, and synthesize a wide range of high-value metabolites. Their metabolic versatility enables the production of bioactive molecules with biostimulant and biocontrol properties, as well as biofertilizer potential through their intrinsic nutrient content. Additionally, several cyanobacterial species can fix atmospheric nitrogen, further enhancing their agricultural relevance. This review aims to summarize the potential of these microorganisms and their application in the agriculture sector, focusing primarily on their biofertilization, biostimulation, and biocontrol capabilities and presents a compilation of the products currently available on the market that are derived from these microorganisms. The present work also identifies the gaps in the use of these microorganisms and provides prospects for developing a suitable solution for today′s agriculture. Full article

Bacillus amyloliquefaciens is a well-recognized biocontrol agent and plant growth promoter. This study characterized the endophytic B. amyloliquefaciens LJ1, isolated from Nanguo pear fruit, through whole-genome sequencing and functional analyses. The B. amyloliquefaciens LJ1 genome (3,947,365 bp, 46.48% GC content) encodes 3757 protein-coding sequences. Genomic analysis revealed diverse carbohydrate-active enzymes (CAZymes) and 12 secondary metabolite biosynthetic gene clusters, including those potentially producing surfactin, fengycin, bacillibactin, and bacilysin. Safety assessments, including hemolysis, indole production, biogenic amine production, and a 21 day mice-feeding trial, indicated no adverse effects, suggesting B. amyloliquefaciens LJ1 is non-pathogenic. In vitro assays demonstrated significant inhibitory activity against Penicillium expansum, a major post-harvest pathogen, by suppressing spore germination and germ-tube elongation. These results suggest that B. amyloliquefaciens LJ1 possesses significant biocontrol potential and could be a promising agent for sustainable disease management in Nanguo pear and potentially other crops. Full article

The biocontrol strain Streptomyces pratensis S10 was isolated from tomato leaf mold. The fermentation broth of strain S10 can effectively control Fusarium head blight (FHB), caused by Fusarium graminearum. Enhancing antifungal activity is essential in advancing its commercialization. In this study, we aimed to improve the antifungal activity of S10 by integrating fermentation optimization and genetic engineering. Single-factor experiments revealed that seven parameters, namely corn flour, yeast extract, NaNO₃, CaCO₃, K₂HPO₄, KCl, ZnSO₄·7H₂O, and MnCl₂·4H₂O, were identified as significant components. A Plackett–Burman design (PDB) indicated that corn flour, yeast extract, and ZnSO₄·7H₂O were the most critical variables affecting its inhibitory activity and mycelial biomass. The fermentation medium was further determined based on the steepest climbing experiment and a Box–Behnken design (BBD), and the mycelial dry weight of S. pratensis S10 was improved from 2.13 g/L in Gauze’s synthetic No. 1 medium to 8.12 g/L in the optimized medium, closely aligning with the predicted value of 7.98 g/L. Under the optimized medium, the antifungal rate of F. graminearum increased from 67.36 to 82.2%. The spore suspension of strain S10 cultured in the optimized medium substantially improved its biocontrol efficacy against FHB. Moreover, disruption of the key gene tetR led to increased antifungal activity of strain S10 against F. graminearum. Importantly, the antifungal activity of ΔtetR was greatly increased under the optimized fermentation medium. This study suggests that the gene tetR negatively regulates bioactive compound biosynthesis, and the optimized medium provides favorable conditions for the growth of S10. These observations establish an extended basis for the large-scale bioactive metabolite secretion of S. pratensis S10, providing a strong foundation for sustainable FHB management in agriculture. Full article

Myxobacteria, a group of swarming, predatory soil bacteria, are of interest because of their biocontrol potential. In this study, the inhibitory effects of 13 strains of myxobacteria were examined against four different phytopathogenic fungi, as follows: two isolates of Rhizoctonia solani from different AG groups and one isolate each from Sclerotinia sclerotiorum and the oomycete Pythium ultimum. Inhibition levels varied among phytopathogens, with slow-growers being more susceptible than fast-growers. Myxococcus xanthus BS 248, M. flavus ATCC 29617, and M. coralloides BS249 were the most inhibitory strains tested. non-contact and contact inhibition on agar media between phytopathogens and myxobacteria were visually discernible. This distinction potentially reflects the activity of low-molecular-weight metabolites and high-molecular-weight lytic enzymes, respectively. In a pot soil study, the inhibitory effect of a mixture of two strains of myxobacteria against two strains of R. solani was apparent from the reduced disease in cucumber seedlings compared to controls without myxobacteria. This is the first report of an in vivo inhibitory effect of myxobacteria against Rhizoctonia. The survival of M. xanthus BS248 in sterile soil amended with rabbit manure (1:1) increased up to five weeks compared to one week in soil without the manure, suggesting that organic amendment could enrich myxobacteria in soil. Full article

Improving the efficacy of microbial biocontrol agents is a pivotal strategy for sustainable management of rice blast and sheath blight caused by Pyricularia oryzae and Rhizoctonia solani, respectively, in Vietnam. In this study, Trichoderma sp. TVN-A0 and Trichoderma sp. TVN-H0 were irradiated by gamma to generate mutants for screening the enhanced antagonistic activity against P. oryzae and R. solani. The potential mutants were screened by antifungal metabolite production via the cellophane membrane assay (I_CM), antagonistic performance through dual culture confrontation assays (I_DC), volatile organic compound bioassays (I_VOCs), and chitinase activity. As a result, among five potential mutants derived from each wild-type strain (AM1-AM5 and HM1-HM5), mutant AM2 originated from TVN-A0, and mutant HM2 derived from TVN-H0 demonstrated the highest inhibition rates and chitinase activities. The AM2 exhibited I_CM of 96.71% against R. solani, 92.57% against P. oryzae, I_DC of 87.76%, and I_VOCs of 83.57%, while HM2 possessed I_CM of 95.33% against R. solani, 85.28% against P. oryzae, I_DC of 91.24%, and I_VOCs of 79.33%. The genetic differences among mutants and their parents were investigated by RAPD. The non-GMO AM2 and HM2 mutants are promising candidates for biocontrol of the diseases caused by P. oryzae and R. solani in Vietnam. Full article

Aflatoxins are carcinogenic secondary metabolites produced by Aspergillus species and are common contaminants of many crops including maize. Atoxigenic Aspergillus flavus strains, formulated as biocontrol products such as Aflasafe^® TZ01, that comprises a mixture of four native atoxigenic strains, are used as pre-harvest agents to suppress toxigenic strains and reduce aflatoxin levels. This study assessed the intended and potential unintended impacts of Aflasafe^® TZ01 on mycotoxin contamination in maize. A total of 158 samples 79 from treated and 79 from untreated fields were collected from Chemba and Kiteto districts in Tanzania. Multi-mycotoxin analysis was conducted using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Detected toxins included aflatoxins (AFB1, AFB2, AFG1, AFG2), trichothecenes, and fumonisins (FB1, FB2, FB3). Non-parametric paired t-test analysis showed significant reductions in AFB1 (62%, p = 0.024) in treated samples. The mean concentrations of Fusarium mycotoxins such as NIV, T2, and ZEN were higher in treated maize. However, statistical analysis showed that these differences were only numerical trends, and were not significant (p > 0.05). These findings confirm the efficacy of Aflasafe^® TZ01 in reducing aflatoxins, while underscoring the importance of continued monitoring for other mycotoxins as part of integrated mycotoxin management strategies to mitigate both aflatoxins and co-occurring toxins. Full article

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), threatens banana and plantain production throughout South America. Because Colombian biosafety regulations restrict in vitro work with Foc TR4, we tested the antifungal activity of Nostoc commune against F. oxysporum race 2 isolated from cv. ‘Manzano’ (Musa AAB). An ethanolic extract of the cyanobacterium (EEC) was profiled by gas chromatography and evaluated with a Kirby–Bauer assay (1000–4000 ppm; n = 4). Synthetic Sico^® and botanical Timorex^® served as positive controls, and solvent-free plates were the negative control. Growth reduction (GR) and percentage inhibition of radial growth (PIRG) were analysed with Student’s t-test (α = 0.05). Forty-two compounds—mainly fatty and carboxylic acids associated with antifungal activity—were detected. Sico achieved complete inhibition (100 ± 0%), Timorex suppressed 76 ± 2%, and 4 000 ppm EEC curtailed mycelial expansion by 45 ± 3% (p < 0.01). Although less potent than commercial fungicides, EEC impeded F. oxysporum growth, demonstrating that N. commune synthesises bioactive metabolites. Optimising cyanobacterial cultivation and formulation could yield a sustainable biocontrol alternative for managing Fusarium wilt in the region. Full article

Fungi of the genus Trichoderma show strong potential as biological control agents (BCAs) against grapevine trunk diseases (GTDs) through mechanisms like antibiotic metabolite production and lytic enzymes. This study evaluated the biocontrol activity of four native Trichoderma strains—T. gamsii T065 and T071, T. carraovejensis T154, and T. harzianum T214—against Phaeoacremonium minimum, Phaeomoniella chlamydospora, and Diplodia seriata. Culture filtrates obtained at 8, 16, and 24 days post-incubation were tested using antibiogram and mycelial inhibition assays. Strains T071, T154, and T214 effectively inhibited D. seriata, while T154 and T214 also suppressed P. chlamydospora. Nevertheless, the limited effectiveness of all filtrates against P. minimum suggests that antibiosis is not the predominant mechanism involved in its control. These findings highlight the potential of specific Trichoderma strains and incubation times to directly control GTD pathogens and support the development of scalable biocontrol solutions. Full article

The genus Trichoderma plays a pivotal role in sustainable agriculture through its multifaceted contributions to plant health and productivity. This review explores Trichoderma’s biological functions, including its roles as a biocontrol agent, plant growth promoter, and stress resilience enhancer. By producing various enzymes, secondary metabolites, and volatile organic compounds, Trichoderma effectively suppresses plant pathogens, promotes root development, and primes plant immune responses. This review details the evolutionary adaptations of Trichoderma, which has transitioned from saprotrophism to mycoparasitism and established beneficial symbiotic relationships with plants. It also highlights the ecological versatility of Trichoderma in colonizing plant roots and improving soil health, while emphasizing its role in mitigating both biotic and abiotic stressors. With increasing recognition as a biostimulant and biocontrol agent, Trichoderma has become a key player in reducing chemical inputs and advancing eco-friendly farming practices. This review addresses challenges such as strain selection, formulation stability, and regulatory hurdles and concludes by advocating for continued research to optimize Trichoderma’s applications in addressing climate change, enhancing food security, and promoting a sustainable agricultural future. Full article

Common bean (Phaseolus vulgaris L.) is a critical protein-rich legume supporting food and nutritional security globally. However, Fusarium wilt, caused by Fusarium solani, remains a major constraint to production, with yield losses reaching up to 84%. While biocontrol strategies have been explored, most microbial agents are sourced from mesophilic environments and show limited effectiveness under abiotic stress. Here, we report the isolation and characterization of extremophilic Bacillus spp. from the hypersaline Lake Bogoria, Kenya, and their biocontrol potential against F. solani. From 30 isolates obtained via serial dilution, 9 exhibited antagonistic activity in vitro, with mycelial inhibition ranging from 1.07–1.93 cm 16S rRNA sequencing revealed taxonomic diversity within the Bacillus genus, including unique extremotolerant strains. Molecular screening identified genes associated with the biosynthesis of antifungal metabolites such as 2,4-diacetylphloroglucinol, pyrrolnitrin, and hydrogen cyanide. Enzyme assays confirmed substantial production of chitinase (1.33–3160 U/mL) and chitosanase (10.62–28.33 mm), supporting a cell wall-targeted antagonism mechanism. In planta assays with the lead isolate (B7) significantly reduced disease incidence (8–35%) and wilt severity (1–5 affected plants), while enhancing root colonization under pathogen pressure. These findings demonstrate that extremophile-derived Bacillus spp. possess robust antifungal traits and highlight their potential as climate-resilient biocontrol agents for sustainable bean production in arid and semi-arid agroecosystems. Full article

Burkholderia gladioli is a multifaceted bacterium with both pathogenic and beneficial strains, and nonpathogenic Burkholderia species have shown potential as plant growth-promoting rhizobacteria (PGPRs) and biocontrol agents. However, the molecular mechanisms underlying their beneficial functions remain poorly characterized. This study systematically investigated the antimicrobial mechanisms and plant growth-promoting properties of B. gladioli strain ZBSF BH07, isolated from the grape rhizosphere, by combining genomic and functional analyses, including whole-genome sequencing, gene annotation, phylogenetic and comparative genomics, in vitro antifungal assays, and plant growth promotion evaluations. The results showed that ZBSF BH07 exhibited broad-spectrum antifungal activity, inhibiting 14 grape pathogens with an average inhibition rate of 56.58% and showing dual preventive/curative effects against grape white rot, while also significantly promoting grape seedling growth with increases of 54.9% in plant height, 172.9% in root fresh weight, and 231.34% in root dry weight. Genomic analysis revealed an 8.56-Mb genome (two chromosomes and one plasmid) encoding 7431 genes and 26 secondary metabolite biosynthesis clusters (predominantly nonribosomal peptide synthetases), supporting its capacity for antifungal metabolite secretion, and functional analysis confirmed genes for indole-3-acetic acid (IAA) synthesis, phosphate solubilization, and siderophore production. These results demonstrate that ZBSF BH07 suppresses pathogens via antifungal metabolites and enhances grape growth through phytohormone regulation and nutrient acquisition, providing novel insights into the dual mechanisms of B. gladioli as a biocontrol and growth-promoting agent and laying a scientific foundation for developing sustainable grapevine disease management strategies. Full article

Root rot is one of the most serious diseases affecting Astragalus membranaceus, significantly reducing its yield and quality. This study focused on root rot in Astragalus membranaceus var. mongholicus. Pathogenic fungi were isolated and identified. The pathogenicity of seven strains of pathogenic fungi was verified according to Koch’s postulates. The inhibitory effects of eight classic fungicides and nine strains of biocontrol agents on the pathogenic fungi were determined using the mycelial growth rate method. Through morphological and ITS phylogenetic analyses, strains CDF5, CDF6, and CDF7 were identified as Fusarium oxysporum, while strains CDF1, CDF2, CDF3, and CDF4 were identified as Fusarium solani. Indoor virulence tests showed that, among the eight tested fungicides, carbendazim exhibited the strongest inhibitory effect on the mycelial growth of both F. oxysporum and F. solani, with a half-maximal effective concentration (EC₅₀) value of (0.44 ± 0.24) mg/mL, making it a highly promising chemical agent for the control of A. membranaceus var. mongholicus root rot. Among the nine biocontrol agents, KRS006 showed the best inhibitory effect against the seven pathogenic strains, with an inhibition rate ranging from 42.57% to 55.51%, and it can be considered a candidate strain for biological control. This study identified the biocontrol strain KRS006 and the chemical fungicide carbendazim as promising core agents for the biological and chemical control of A. membranaceus var. mongholicus root rot, respectively, providing a theoretical foundation for establishing a dual biocontrol–chemical control strategy. Based on the excellent performance of the biocontrol bacteria and fungicides in the pathogen control tests, future research should focus on field trials to verify the synergistic effect of this integrated control strategy and clarify the interaction mechanism between the antibacterial metabolites produced by the biocontrol bacteria KRS006 and carbendazim. Additionally, continuous monitoring of the evolution of Fusarium spp. resistance to carbendazim is critical to ensure the long-term sustainability of the integrated control system. Full article

Mycotoxins are secondary metabolites produced by various fungal species that can contaminate food and feed, posing significant risks to human and animal health. In aquaculture, the replacement of fishmeal with alternative protein sources has increased the risk of mycotoxin contamination, becoming a major challenge in fish feed production. Current data highlights that fish are exposed not only to common mycotoxins but also to emerging ones, raising concerns about human exposure through fish consumption. In this review, we draw attention to the toxicity data of key emerging mycotoxins from Fusarium (enniatins, ENNs; beauvericin, BEA) and Alternaria (alternariol monomethyl ether, AME; alternariol, AOH), their occurrence in aquafeeds and in commercially relevant fish species in Europe, and potential biocontrol approaches to prevent/mitigate contaminations. From the present review, it emerged that these mycotoxins exhibit in vitro cytotoxic properties. Their prevalence and concentrations vary widely both among aquafeeds, depending on the sample’s origin, and among fish species. Biocontrol approaches using microorganisms or natural compounds show promise as sustainable solutions to limit contamination. However, further research is essential to address data gaps and to allow for a proper risk assessment and, if necessary, the implementation of effective management measures. Full article

The interactions of Fusarium graminearum PG-Fg1 and its main trichothecenes with the 28 Trichoderma isolates were studied in vitro. The antagonistic effect assessed by dual-culture tests showed that Trichoderma isolates arrested the growth of PG-Fg1 after contact, overgrew the PG-Fg1 colony and inhibited the production of deoxynivalenol (DON), 3-acetyl-deoxynivalenol (3-ADON), and 15-acetyldeoxynivalenol (15-ADON) by up to 95.3%, 99.4%, and 99.6%, respectively. PG-Fg1 was hard to overgrow Trichoderma for further extension. Additionally, the inhibitory effects on PG-Fg1 by the Trichoderma metabolites, including volatiles and non-volatiles, were also investigated. Most of the Trichoderma isolates produced metabolites which inhibited PG-Fg1 growth and mycotoxins production. Specifically, Trichoderma non-volatiles and volatiles showed Fusarium growth inhibition rates ranging from 7% to 72% and 3% to 32%, respectively. Notably, non-volatile compounds from two isolates and volatiles from one isolate up-regulated the expression of DON biosynthesis genes (tri4 and tri5), leading to increased production of DON, 3-ADON, and 15-ADON. This study highlights the potential risk posed by certain Trichoderma strains as microbial agents, which can stimulate toxigenic fungi to produce higher levels of mycotoxins. Based on our results and previous reports, when selecting Trichoderma species as biocontrol agents against Fusarium graminearum, its effects on mycotoxins production should be carefully assessed, particularly given observed stimulatory impacts. Full article