Soil-borne fungal and oomycete pathogens endanger global crop production, highlighting the need for sustainable alternatives to chemical fungicides. In this study, an antagonistic actinomycete isolated from agricultural soil was identified as Streptomyces hachijoensis JCK-6068 through 16S rRNA sequencing and phylogenetic analysis. S. hachijoensis JCK-6068 exhibited broad-spectrum antifungal and antioomycete activity in dual-culture and minimum inhibitory concentration assays. Biochemical characterization revealed the production of multiple hydrolytic enzymes, including cellulase, chitinase, protease, and gelatinase, along with the phytohormone indole-3-acetic acid. Volatile organic compounds produced by JCK-6068 strongly inhibited pathogen growth in vitro, and gas chromatography-mass spectrometry identified 2-methyl-2-bornene as the predominant component. In vivo assays demonstrated that curative application of the 10-fold diluted fermentation broth provided effective control of creeping bentgrass dollar spot (74.31%), pepper Phytophthora blight (68.88%), cucumber Fusarium wilt (61.11%),and cucumber damping-off (88.89%). Preventive treatment with 1000-fold dilution of fermentation broth is as effective as chemical fungicides in controlling cucumber damping-off and Fusarium wilt. Furthermore, treatment of PR1::GUS transgenic Arabidopsis thaliana seedlings with JCK-6068-derived materials induced strong PR1 expression, indicating elicitor activity consistent with salicylic acid-responsive defenses signaling. To facilitate practical application, a wettable powder formulation derived from the n-butanol extract of JCK-6068 was evaluated under greenhouse conditions, achieving 91.67% control of cucumber Fusarium wilt at a 500-fold dilution and 77.78% control of cucumber damping-off at a 250-fold dilution, comparable to commercial chemical fungicides. Collectively, these findings highlight the multifaceted biocontrol potential of S. hachijoensis JCK-6068 as a sustainable biocontrol agent for soil-borne fungal disease.

Pine wilt disease (PWD) is a devastating disease caused by the pinewood nematode (Bursaphelenchus xylophilus). Its substantial ecological disruption harms global forestry and poses serious economic challenges. Although previous research has demonstrated that Bacillus subtilis JCK-1398 has the potential to induce systemic resistance in pine trees, the ecological mechanisms underlying its biocontrol efficacy remain underexplored. This study investigated how JCK-1398 treatment influences rhizosphere- and nematode-associated microbial communities to mitigate PWD. Metabarcoding analyses revealed that JCK-1398 treatment increased the abundance of beneficial microbial taxa (e.g., Nocardioides and Mesorhizobium) in the rhizosphere microbiome. Concurrently, nematode-associated microbial communities became dominated by Pantoea, a genus with known nematicidal properties. Isolation and characterization of Pantoea dispersa BC11 confirmed that it significantly limits nematode viability. These findings highlight the multifaceted defense that JCK-1398 offers, not only inducing systemic resistance, but also orchestrating beneficial microbiome dynamics. This study emphasizes the potential of manipulating a microbial holobiont for eco-friendly and sustainable disease management. The ability of JCK-1398 to recruit and enhance microbial allies offers a novel framework for developing biocontrol agents, with implications for managing PWD and other plant-pathogen systems.

Fire blight is one of the devastating bacterial diseases that occur in the rose family plants such as pears and apples. The causative bacterium is Erwinia amylovora, and it is known to be difficult to control. In this study, we prepared a suspension concentrate for microbials (SM) formulation using the eco-friendly microorganism Bacillus velezensis 8-2 and evaluated the control efficacy of B. velezensis 8-2 SM against fire blight of apples. This strain has been previously reported to produce difficidin, oxydifficidin, iturin A, fengycin, and surfactin, which have antimicrobial activity against plant pathogenic bacteria and fungi. B. velezensis 8-2 SM exhibits a strong antibacterial effect against fire blight, suggesting that these metabolites showed antimicrobial activity against E. amylovora. The B. velezensis 8-2 SM treatment group showed a similar level of control efficacy to the streptomycin wettable powder control group in both seedling and mature tree tests, and exhibits significantly higher activity than commercial biopesticide control group. In conclusion, B. velezensis 8-2 SM is an eco-friendly fire blight control agent based of antibacterial activity, which has industrial value in that it dramatically improves effectiveness compared to existing biopesticides and can overcome the limitations of antibiotics.

Tomato bacterial wilt and apple fire blight, caused by Ralstonia solanacearum and Erwinia amylovora, respectively, are highly destructive diseases that threaten global agriculture productivity. Increasing resistance of these pathogens to conventional antibiotics and copper-based pesticides highlights the urgent need for sustainable, eco-friendly biocontrol alternatives. This study aimed to evaluate the biocontrol potential of the azomycin-producing Streptomyces sp. JCK-8368 (hereafter JCK-8368) against tomato bacterial wilt and apple fire blight, and to investigate its possible resistance-inducing mechanism. The culture filtrate (CF) of JCK-8368, containing azomycin, was applied to the plant at 1,000-fold (100 ng/mL), 500-fold (200 ng/mL), and 250-fold (400 ng/mL) dilutions via foliar spraying or soil drenching. Purified azomycin was tested at concentrations from 1 ng/mL to 1000 ng/mL. Disease severity and control efficacy were assessed, and expression of defense-related genes (PR1, PR2, PR3, and PR5) was also analyzed. Foliar spraying and soil drenching with JCK-8368 CF significantly reduced tomato bacterial wilt severity, with control efficacies of 52.22% (1000-fold), 11.11% (500-fold), and 35.55% (250-fold) in foliar application, 90.00%, 77.78%, and 52.22% in soil drenching, respectively. The reversed dose-response pattern in soil drenching indicated higher efficacy at lower concentrations. In apple fire blight control, soil drenching with CF at a 1,000-fold dilution achieved foliar spraying (78.38%) efficacy, exceeding soil drenching (50.88%). In particular, purified azomycin most effectively reduced tomato bacterial wilt at 100 ng/mL (57.14% efficacy) and showed a clear dose-dependent effect from 1 to 100 ng/mL. The plants treated with JCK-8368 CF and azomycin upregulated defense-related genes such as PR1, PR2, PR3, and PR5, suggesting systemically acquired resistance and pathogenesis-related defense pathways. This is the first report demonstrating the application of azomycin against plant bacterial diseases, showing that low concentrations of JCK-8368 and purified azomycin can effectively control tomato bacterial wilt and apple fire blight through induced resistance. Azomycin-producing Streptomyces sp. JCK-8368 offers a promising, sustainable alternative to chemical pesticides, warranting further field validation and formulation development for agricultural use.

Fusarium head blight (FHB) primarily caused by Fusarium species including F. graminearum and F. asiaticum, is a major fungal disease affecting wheat, rice, and other cereal crops worldwide. Chemical fungicides remain the primary means of FHB management owing to their convenience and efficacy. Nonetheless, the overuse of chemical pesticides has led to fungicide resistance, human health effects, and environmental contamination, driving a shift toward biocontrol agents as sustainable alternatives for managing plant pathogens. This study aims to evaluate Streptomyces sp. JCK-7385, a rice-associated isolate, is an environmentally friendly biocontrol agent against FHB. The strain produced indole-3-acetic acid, siderophore, and 1-aminocyclopropane-1-carboxylic acid deaminase, as well as extracellular enzymes including cellulase, gelatinase, and chitinase. JCK-7385 treatments induced defense-related marker gene PR1 expression in transgenic Arabidopsis, as confirmed via β-glucuronidase assays, suggesting an induced resistance mechanism. In greenhouse trials, the JCK-7385 cell suspension and its suspension concentrate formulation (JCK-7385 SC) at a 2,000-fold concentration effectively reduced FHB incidence in rice by 42.3% and 52.5%, respectively. JCK-7385 SC also maintained high efficacy (54.4% control value) after storage at 45°C for 6 weeks. Furthermore, the integrated treatment of JCK-7385 SC and the chemical fungicide (Peulrei) significantly enhanced FHB control compared to single treatments, achieving 63.3% and 71.7% efficacy in rice and wheat, respectively. Field trials demonstrated that this collaborative treatment effectively suppressed FHB development in rice by 52.0%, outperforming individual applications. These findings suggest that Streptomyces sp. JCK-7385 has strong potential as a biological fungicide for FHB management through an induced resistance mechanism.

BACKGROUND:Natamycin is a polyene macrolide produced by Streptomyces spp. with broad-spectrum antifungal activity. Agro-industrial by-products are abundant and nutrient-rich resources that can be converted into sustainable bioproducts. This study aimed to investigate their application in natamycin production via solid-state fermentation (SSF) using Streptomyces lydicus JCK-6019, with the goal of developing a dual-function product with plant growth-promoting and biocontrol properties. RESULTS:Optimization results revealed that a substrate mixture of brown rice and sesame seed cake (2:1, w/w) supplemented with 3% (w/w) rice hull, 80% (v/w) initial moisture content, and 30% (v/w) inoculum size produced the highest natamycin yield (18.55 mg/gds) in 250 mL flasks at 28 °C on day 7. Scaling up to a 2.5 L system with 70% moisture and 15% inoculum size further increased the yield to 20.22 mg/gds on day 6. This SSF product significantly promoted cucumber seedling growth, increasing plant height, leaf width, and biomass. It also increased chlorophyll content by 147.40%, reduced malondialdehyde content by 36.72%, and enhanced antioxidant enzyme activities (polyphenol oxidase by 42.16% and peroxidase by 26.99%). The 300-fold diluted SSF product exhibited a control value of 90.91% against cucumber damping-off caused by Rhizoctonia solani, comparable to a commercial fungicide. Moreover, the SSF product exhibited high storage stability, retaining over 95% natamycin activity after 1 year of storage at 25 °C. CONCLUSION:This study showed a cost-effective and eco-friendly approach for natamycin production from agro-industrial by-products, highlighting its SSF product potential as a stable biofungicide and plant growth promoter in sustainable agriculture. © 2025 Society of Chemical Industry.

Soft rot caused by Pectobacterium carotovorum subsp. carotovorum is a highly destructive disease that significantly affects kimchi cabbage production. Biological control agents that utilize polyketides derived from Bacillus spp. have emerged as an effective strategy for managing this disease. However, the biosynthetic efficiency of these secondary metabolites is often limited by restricted intracellular pools of acetyl-CoA and malonyl-CoA, the key building blocks for polyketide synthesis. In this study, we investigated a method for enhancing oxydifficidin production in Bacillus velezensis 8-2 by increasing the availability of acetyl-CoA and malonyl-CoA. Exogenous supplementation with acetate (41.1 mM) and citrate (17.1 mM) significantly upregulated the expression of key genes involved in pyruvate metabolism, the tricarboxylic acid cycle, and polyketide biosynthesis. This metabolic rewiring increased the titer and yield coefficient of oxydifficidin by 132.5 % and 159.6 %, respectively, thereby enhancing its biocontrol efficacy against soft rot in kimchi cabbage. These findings suggest that targeted precursor supplementation can be an effective strategy to enhance oxydifficidin production and the biocontrol efficacy of B. velezensis 8-2 against soft rot.

Oleamide (cis-9-octadecenamide), a primary fatty acid amide derived from oleic acid, is well known in mammalian systems for its roles in neural and immune regulation. However, its function in plant immunity has remained unexplored. In this study, oleamide was identified as the major bioactive metabolite of Streptomyces lydicus JCK-6019 and was characterized as a novel plant resistance inducer (PRI) in cucumber. Although oleamide exhibited no direct antifungal activity against Fusarium oxysporum f. sp. cucumerinum and Rhizoctonia solani AG-4 in vitro, in vivo assays demonstrated strong disease suppression. Preventive application of oleamide achieved 66.28 % control of Fusarium wilt at 0.1 ng/mL, comparable to the commercial PRI Bion (69.77 %), and 80 % control of damping-off at 0.01 ng/mL, whereas Bion was ineffective. Physiological assays revealed that oleamide reduced malondialdehyde accumulation while enhancing peroxidase and polyphenol oxidase activities, indicating activation of antioxidant defense. Gene expression analysis further revealed upregulation of key defense-related genes (PR1, PR2, PR4, WRKY30, WRKY67, ERF003, peroxidase, and cellulose synthase), which are involved in salicylic acid and jasmonic acid/ethylene signaling, transcriptional regulation, reactive oxygen species metabolism, and cell wall strengthening. Collectively, these results indicate that oleamide primes cucumber defense responses rather than acting as a fungitoxic compound. To our knowledge, this is the first report identifying oleamide as a PRI effective against two major soil-borne cucumber diseases. Its nanogram-level efficacy, non-toxic nature, and capacity to activate plant immunity highlight its potential as an eco-friendly alternative to synthetic fungicides for sustainable crop protection.

Pine wilt disease (PWD), caused by pinewood nematodes (Bursaphelenchus xylophilus), poses a significant threat to forestry worldwide. This study introduces a novel biocontrol strategy using Bacillus subtilis JCK-1398, which was selected and identified for its resistance-induction potential after extensive screening of microbial strains from pine tissues. The bacterium was found to biostimulate resistance in Pinus densiflora. Comprehensive analyses, including transcriptomics, qPCR assays, and high-performance liquid chromatography (HPLC), revealed that B. subtilis JCK-1398 significantly upregulates defense-related genes and stimulates pinoresinol production, a compound linked to resistance against nematodes. Treatment with B. subtilis JCK-1398 suppressed nematode migration and reduced nematode populations within pine tissues, effects attributed to the enhanced tree defense response. Field trials corroborated these findings, demonstrating a 72 % decrease in PWD incidence with aerial application of JCK-1398, confirming its potential for large-scale forest application. This biocontrol strategy, leveraging the stimulation of plant defense by B. subtilis JCK-1398, presents a promising and scalable, eco-friendly solution for managing PWD. Overall, this study provides new insights into the interactions between the bioagent, the host tree, and the pest nematode, offering an effective and sustainable approach to mitigate pine wilt disease.

Leaf blight caused by Stemphylium vesicarium is one of the most important fungal diseases of garlic (Allium sativum L.) worldwide, which results in a reduction of quality and yield. The breeding of resistant cultivars is an efficient approach to decrease the use of chemical fungicides and minimize crop losses. In this study, to find the resistant garlic resources against S. vesicarium, we evaluated the resistance degree of 20 garlic germplasms. To do this, garlic seedlings at four-leaf stage were rubbed with nonabsorbent cotton and then inoculated with spore suspension (3.0×105 spores/ml of potato dextrose broth) of S. vesicarium by spray method. Three to seven days after inoculation, the infected leaf area (%) of garlic seedling was measured. ‘Daeseo’ and ‘Namdo’ were included as susceptible and resistant control cultivars, respectively. After 3 to 7 days of incubation, the infected leaf area (%) of garlic seedling was measured. Our results showed that IT245512, IT245528, and IT244068 lines exhibited the highest resistance against S. vesicarium, whereas IT257134 and IT253043 lines were more susceptible than the susceptible cultivar ‘Daeseo’. Based on the results, the resistant genetic resources selected in this study can be used a basic material for resistant garlic breeding system against leaf blight.

A novel Gram-negative, white-pigmented, and auxin-producing strain, 20NA77.5T, was isolated from fresh water during cyanobacterial bloom period. Pairwise comparison of the 16S rRNA gene sequences showed that strain 20NA77.5T belonged to the genus Undibacterium and exhibited the highest sequence similarity to the type strains of Undibacterium danionis (98.00

Effective control of shot-hole disease in flowering cherries is challenging because of multiple causative pathogens (bacteria and fungi). Bacillus species are well-known for their ability to control plant pathogens; therefore, biological control potential of a Bacillus isolate, B. velezensis 8–2, against SH disease on flowering cherry trees was investigated. This study revealed strong antimicrobial activity of Bacillus velezensis 8–2 against various plant pathogenic bacteria and fungi, particularly focusing on Xanthomonas arboricola pv. pruni (Xap) and Mycosphaerella cerasella (Mc), which cause shot-hole (SH) disease in flowering cherry trees. In vitro assays showed that the fermentation filtrate of B. velezensis 8–2 inhibited bacterial and fungal growth with minimum inhibitory concentrations of 1.25–10

The conservation of the endangered Korean fir, Abies koreana, is of critical ecological importance. In our previous study, a yeast-like fungus identified as Aureobasidium pullulans AK10, was isolated and shown to enhance drought tolerance in A. koreana seedlings. In this study, the effectiveness of Au. pullulans AK10 treatment in enhancing drought tolerance in A. koreana was confirmed. Furthermore, using transcriptome analysis, we compared A. koreana seedlings treated with Au. pullulans AK10 to untreated controls under drought conditions to elucidate the molecular responses involved in increased drought tolerance. Our findings revealed a predominance of downregulated genes in the treated seedlings, suggesting a strategic reallocation of resources to enhance stress defense. Further exploration of enriched Kyoto Encyclopedia of Genes and Genomes pathways and protein-protein interaction networks revealed significant alterations in functional systems known to fortify drought tolerance, including the terpenoid backbone biosynthesis, calcium signaling pathway, pyruvate metabolism, brassinosteroid biosynthesis, and, crucially, flavonoid biosynthesis, renowned for enhancing plant drought resistance. These findings deepen our comprehension of how AK10 biostimulation enhances the resilience of A. koreana to drought stress, marking a substantial advancement in the effort to conserve this endangered tree species through environmentally sustainable treatment.

Leaf blight of onion caused by Stemphylium vesicarium is the most destructive fungal disease worldwide, which leads to decrease quality and seed production of onion. This study was conducted to evaluate the resistance degree of 110 onion germplasm against S. vesicarium. To investigate resistance to leaf blight, the genetic resources of onion were tested by following method. Onion seedlings at four-leaf stage were rubbed with nonabsorbent cotton and inoculated with spore suspension (1.0×105 spores/ml of potato dextrose broth) of S. vesicarium by spray method. Five to 7 days after inoculation, infected leaf area (%) of onion seedling was measured. Our results showed that IT274921, IT304144, IT274929, and IT274930 lines exhibited the highest resistance against S. vesicarium. And IT330615 and IT288913 lines was identified as moderately resistant to leaf blight, whereas IT299972, IT327434, IT337262, and IT337275 lines were the most susceptible cultivars to the fungus. On the basis of the results, we suggest that the resistant genetic resources can be used a basic material for resistant onion breeding system against leaf blight.

Fusarium head blight (FHB) is a destructive disease caused by several species of Fusarium, such as Fusarium graminearum and F. asiaticum. FHB affects cereal crops, including wheat, barley, and rice, worldwide. Fusarium-infected kernels not only cause reduced yields but also cause quality loss by producing mycotoxins, such as trichothecenes and zearalenone, which are toxic to animals and humans. For decades, chemical fungicides have been used to control FHB because of their convenience and high control efficacy. However, the prolonged use of chemical fungicides has caused adverse effects, including the emergence of drug resistance to pathogens and environmental pollution. Biological control is considered one of the most promising alternatives to chemicals and can be used for integrated management of FHB due to the rare possibility of environment pollution and reduced health risks. In this study, Bacillus velezensis JCK-7158 isolated from rice was selected as an ecofriendly alternative to chemical fungicides for the management of FHB. JCK-7158 produced the extracellular enzymes protease, chitinase, gelatinase, and cellulase; the plant growth hormone indole-3-acetic acid; and the 2,3-butanediol precursor acetoin. Moreover, JCK-7158 exhibited broad antagonistic activity against various phytopathogenic fungi and produced iturin A, surfactin, and volatile substances as active antifungal compounds. It also enhanced the expression of PR1, a known induced resistance marker gene, in transgenic Arabidopsis plants expressing β-glucuronidase (GUS) fused with the PR1 promoter. Under greenhouse conditions, treatments with the culture broth and suspension concentrate formulation of JCK-7158 at a 1,000-fold dilution inhibited the development of FHB by 50 and 66%, respectively. In a field experiment, treatment with the suspension concentrate formulation of JCK-7158 at a 1,000-fold dilution effectively controlled the development of FHB with a control value of 55% and reduced the production of the mycotoxin nivalenol by 40%. Interestingly, treatment with JCK-7158 enhanced the expression of plant defense-related genes in salicylic acid, jasmonic acid, ethylene, and reactive oxygen species (ROS) signaling pathways before and after FHB pathogen inoculation. Taken together, our findings support that JCK-7158 has the potential to serve as a new biocontrol agent for the management of FHB.

BACKGROUNDFusarium oxysporum f. sp. cucumerinum and Rhizoctonia solani AG-4 are the two most important fungal pathogens causing soil-borne fungal diseases of cucumber; they are difficult to control and cause serious economic losses. Given the detrimental effects of the indiscriminate use of chemical fungicides, biocontrol emerges as an efficient and ecofriendly alternative for managing soil-borne fungal diseases.RESULTSStreptomyces lydicus JCK-6019 (hereafter, JCK-6019) was isolated from rhizosphere soil. Its fermentation filtrate and volatile organic compounds exhibited broad-spectrum antifungal activity against various phytopathogenic fungi and oomycetes. JCK-6019 produced natamycin as an agar-diffusible antifungal metabolite. It also produced indole-3-acetic acid and various hydrolytic enzymes. In vivo experiments revealed that a ten-fold-diluted optimized JCK-6019 fermentation broth exhibited 100% control efficiency against cucumber damping-off disease and 62.5% control efficiency against cucumber Fusarium wilt disease. Pretreatment of cucumber seedlings with 1000-fold-diluted optimized JCK-6019 fermentation broth resulted in 68.18% and 23.91% disease control values against cucumber damping-off and Fusarium wilt disease, respectively. Moreover, peroxidase activity in cucumbers after 1 day of treatment was 1.5-fold higher than that in the control. Similarly, polyphenol oxidase activity in cucumbers after 3 days of treatment was 2.34-fold higher than that in the control, indicating that JCK-6019 can induce plant resistance.CONCLUSIONThe natamycin-producing strain JCK-6019 could effectively suppress the development of cucumber Fusarium wilt and damping-off disease by inducing plant resistance and producing antifungal metabolites, including natamycin and volatile organic compounds. Thus, JCK-6019 possesses high potential for application in the development of biocontrol agents against soil-borne fungal diseases of cucumber. (c) 2024 Society of Chemical Industry.

Building upon prior research demonstrating the excellent antifungal and nematicidal efficacy of Annona squamosa Lin. seed extracts, this study extends its scope to investigate similar properties in seed extracts from two other Annonaceae species: Annona muricata Lin. and Annona glabra Lin. The focus is on assessing their effectiveness against tomato late blight (TLB) and wheat leaf rust (WLR) diseases, as well as their broader antifungal activity against Colletotrichum sp. and Fusarium sp. The A. glabra seed extract exerted a superior control efficacy against TLB (85 % at 62.5 mu g/mL) and WLR (75 % at 125 mu g/mL) in vivo. The two Annonaceous extracts also exhibited in vitro antifungal inhibition against Colletotrichum sp. and Fusarium sp., as well as toxicology against pine wilt nematodes and Artemia salina. Besides, they showed phytotoxicity against Raphanus sativus seed germination. Squamocin G, a potent bioactive acetogenin, was isolated from A. glabara, which was found to occur at high contents in the following ascending order in A. glabra, A. muricata and A. squamosa dichloromethane extracts. To investigate the antifungal mechanism, molecular docking and molecular dynamic of squamocin G ligand were also performed for the first time at the active site of succinate dehydrogenase and beta-tubulin.

This study explores the biocontrol potential of Pediococcus sp. M21F004, a lactic acid bacteria (LAB) isolated from marine environments, against several bacterial and fungal phytopathogens. Out of 50 marine bacterial isolates, Pediococcus sp. M21F004 was selected for its exceptional antimicrobial activity. The strain, isolated from the intestine of a starry flounder, was identified as Pediococcus sp. Gas chromatography–mass spectrometry (GC-MS) analysis revealed that oleic acid (OA) is a key antimicrobial compound produced by Pediococcus sp. M21F004. In vitro assays showed that the culture broth (CB) of Pediococcus sp. M21F004, as well as OA, exhibited significant inhibitory effects against pathogens such as Fusarium oxysporum, Clarireedia homoeocarpa, and Pectobacterium carotovorum subsp. carotovorum. In vivo tests on cucumber Fusarium wilt, creeping bentgrass dollar spot, tomato bacterial wilt, and kimchi cabbage soft rot further demonstrated the strain’s efficacy in reducing disease severity. Moreover, OA had the highest control value of 74% against tomato bacterial wilt, followed by 64.1% against cucumber fusarium wilt, 42.5% against kimchi cabbage soft rot, and 16.5% against creeping bentgrass dollar spot. These findings suggest that Pediococcus sp. M21F004 and its metabolite OA offer promising alternatives to chemical pesticides, contributing to sustainable plant disease management by promoting resistance induction and providing an eco-friendly approach to agriculture.

Apple fire blight, caused by the bacterium Erwinia amylovora, is a devastating disease of apple and pear trees. Biological control methods have attracted much attention from researchers to manage plant diseases as they are eco-friendly and viable alternatives to synthetic pesticides. Herein, we isolated Streptomyces sp. JCK-8055 from the root of pepper and investigated its mechanisms of action against E. amylovora. Streptomyces sp. JCK-8055 produced aureothricin and thiolutin, which antagonistically affect E. amylovora. JCK-8055 and its two active metabolites have a broad-spectrum in vitro activity against various phytopathogenic bacteria and fungi. They also effectively suppressed tomato bacterial wilt and apple fire blight in in vivo experiments. Interestingly, JCK-8055 colonizes roots as a tomato seed coating and induces apple leaf shedding at the abscission zone, ultimately halting the growth of pathogenic bacteria. Additionally, JCK-8055 can produce the plant growth regulation hormone indole-3-acetic acid (IAA) and hydrolytic enzymes, including protease, gelatinase, and cellulase. JCK-8055 treatment also triggered the expression of salicylate (SA) and jasmonate (JA) signaling pathway marker genes, such as PR1, PR2, and PR3. Overall, our findings demonstrate that Streptomyces sp. JCK-8055 can control a wide range of plant diseases, particularly apple fire blight, through a combination of mechanisms such as antibiosis and induced resistance, highlighting its excellent potential as a biocontrol agent. • JCK-8055 produces the systemic antimicrobial metabolites, aureothricin, and thiolutin. • JCK-8055 treatment upregulates PR gene expression in apple plants against E. amylovora. • JCK-8055 controls plant diseases with antibiotics and induced resistance.

Certain Bacillus thuringiensis (Bt) strains such as Bt subsp. kurstaki and Bt subsp. aizawai have been widely used for pest management in agricultural practices. However, each strain only shows high specificity for pest control against a narrow range of lepidopteran species, and numerous lepidopteran pests have developed resistance to commercialized Bt strains. Therefore, there is a need for the development of novel Bt bioinsecticides which allow for potent and broad-spectrum insecticidal activity against lepidopteran species, including Spodoptera spp. (Noctuidae) and Plutella xylostealla (Plutellidae). In order to develop a novel bioinsecticide using Bt subsp. kurstaki IMBL-B9 (Btk IMBL-B9) that exhibits excellent insecticidal activity against three different lepidopteran species, we have developed a viable microencapsulation-based spray drying Btk IMBL-B9 formulation. The spore-crystal complex of Btk IMBL-B9 was microencapsulated using coating materials such as gum arabic, maltodextrin, and corn starch via spray drying. The encapsulated formulation of Btk IMBL-B9 presented an increased survival rate and storage stability at 54 ± 2°C for up to 6 weeks. The formulation showed similar insecticidal activity as the commercial bioinsecticide XenTari® against P. xylostella. Under controlled greenhouse conditions, the Btk IMBL-B9 formulation was more effective against Lepidoptera spp. S. frugiperda and P. xylostella, than XenTari®. These results suggest that the microencapsulation-based spray drying formulation of Btk IMBL-B9 can be used effectively for the control of a wide range of moths.