Verticillium wilt of cotton, caused by Verticillium dahliae, is one of the most devastating soilborne fungal diseases in cotton production, urgently demanding the development of effective control measures. Myxobacteria, a group of higher prokaryotes exhibiting multicellular social behaviors, possess predatory activity against plant pathogenic fungi and bacteria, giving them unique potential for application in plant disease biocontrol. In this study, based on a previously myxobacterial strain collection, a myxobacterial strain, HM-E, exhibiting broad-spectrum antifungal activity was screened. Through morphological observation, physiological and biochemical characterization, and multi-locus sequence analysis, this strain was identified as Cystobacter fuscus HM-E. C. fuscus HM-E not only significantly lysed V. dahliae hyphae but also inhibited its spore germination. Both its cell-free fermentation filtrate and volatile metabolites exhibited certain antifungal activity. Greenhouse pot assays showed that the fermentation broth of C. fuscus HM-E had a control efficacy of only 23.01% against cotton Verticillium wilt, whereas the solid agent formulated with white star flower chafer (Protaetia brevitarsis) frass achieved a significantly higher control efficacy of 70.90%, and the myxobacterial solid agent also significantly promoted cotton seedling growth. Furthermore, the crude extracts concentrated using macroporous resin and acid precipitation showed no antifungal activity against V. dahliae, whereas the crude protein obtained by ammonium sulfate precipitation disrupted not only the cell wall and cell membrane of V. dahliae hyphae, induced intracellular reactive oxygen species (ROS) burst but also lysed spores and inhibited spore germ tube elongation. Enzyme substrate profile assays indicated that several peptidases, lipases, and glycoside hydrolases secreted by C. fuscus HM-E might play important roles in its antifungal process and are potential biocontrol factors. This study suggests C. fuscus HM-E, as a novel biocontrol agent, has great potential for application in the combating of cotton Verticillium wilt.

Fire blight, caused by the Gram-negative bacterium Erwinia amylovora, poses a substantial threat to pome fruit production worldwide. Despite existing control strategies, a pressing need remains for sustainable and environmentally friendly fire blight management. Myxobacteria, renowned for their predatory behavior and potent enzymes, emerge as a groundbreaking biocontrol approach with significant potential. Here, we report the biocontrol potential of a novel Myxococcus fulvus WCH05, against E. amylovora. Using various in vitro and planta assays, we demonstrated the multifaceted biocontrol abilities of strain WCH05. In plate predation assays, strain WCH05 exhibited not only strong predation against E. amylovora but also broad-spectrum activities against other plant pathogenic bacteria. Pre-treatment with strain WCH05 significantly decreased pear blossom blight incidence in detached inflorescence assays, achieving a controlled efficacy of 76.02% that rivaled the antibiotic streptomycin (79.79%). In greenhouse trials, strain WCH05 effectively reduced the wilting rate and disease index in young pear seedlings, exhibiting both protective (73.68%) and curative (68.66%) control. Further investigation revealed that the biocontrol activity of strain WCH05 relies on both direct contact and extracellular enzyme secretion. While cell extracts lacked inhibitory activity, ammonium sulfate-precipitated secreted proteins displayed potent lytic activity against E. amylovora. Substrate spectrum analysis identified peptidases, lipases, and glycosidases among the secreted enzymes, suggesting their potential roles in pathogen degradation and biocontrol efficacy. This study presents the first evidence of Myxococcus fulvus WCH05 as a biocontrol agent against fire blight. Its potent predatory abilities and enzymatic arsenal highlight its potential for sustainable disease management in pome fruit production. Future research will focus on identifying and characterizing specific lytic enzymes and optimizing strain WCH05 application strategies for field efficacy.

Fire blight, a devastating bacterial disease caused by Erwinia amylovora, has posed significant challenges to apple and pear production for over a century. This study introduces a gliding filamentous bacterium, the strain NSD29, isolated from natural forest soil in Xinjiang, China, as a biological control agent for managing this disease. Comprehensive characterization based on morphological, physiological, biochemical, 16S rRNA gene, and whole-genome analyses identified the strain NSD29 as Herpetosiphon llansteffanensis. The train NSD29 demonstrated potent predatory activity against E. amylovora in vitro. Its biocontrol efficacy was subsequently evaluated on detached leaves, inflorescences, young fruit, and shoots of fragrant pear under controlled greenhouse conditions. Results indicated that applying H. llansteffanensis NSD29 significantly inhibited lesion expansion on pear leaves and young fruit, achieving protective efficacies of 75.2% and 72.0%, respectively. Furthermore, pre-treatment spraying with NSD29 effectively reduced the incidence of blossom blight, with a control efficacy of 61.2%. On detached pear shoots, the application of NSD29 fermentation broth suppressed lesion expansion, demonstrating substantial protective (86.8%) and curative (75.6%) efficacies. This research provides the first evidence for the potential of Herpetosiphon species in the biological control of plant diseases, highlighting H. llansteffanensis NSD29 as a promising candidate for developing strategies to combat fire blight.

Myxococcus fulvus WCH05, isolated from desert soil in Manas County, Xinjiang, China, exhibits strong predatory activity against Erwinia amylovora and has p

Fusarium Crown Rot (FCR), primarily caused by Fusarium species, is a significant soil-borne disease that severely threatens global wheat production and food security. To identify myxobacterial resources with biocontrol potential against FCR, we screened 81 myxobacterial strains using dual-culture assays and evaluated their efficacy through greenhouse and field experiments. Three strains—HM-E, KT23, and KE15—were identified for their potent broad-spectrum activity against the dominant pathogens F. pseudograminearum , F. graminearum , and F. culmorum , achieving mycelial inhibition rates ranging from 82.01 to 94.84%. Their cell-free filtrates significantly inhibited hyphal growth while inducing spore lysis and suppressing germination. These strains employed a range of inhibitory mechanisms complementary to their conventional predatory activity. Greenhouse trials demonstrated that both fermentation broths and solid agents provided control efficacies of 52.94–88.24% against single and complex infections, consistently outperforming the chemical fungicide Tebuconazole (40.75–59.15%). Furthermore, myxobacterial treatments significantly promoted wheat growth, as evidenced by increased plant height, primary root length, and fresh weight. In field trials, the biocontrol efficacy reached 61.60–74.67% at the flowering stage and 57.95–71.53% at the grain-filling stage. Compared to the pathogen-only control (5,860.00 kg/ha), myxobacterial treatments increased grain yield by 13.71–27.82%. Based on morphological and multigene phylogenetic analyses, strains KT23 and KE15 were identified as Myxococcus fulvus , while HM-E was identified as Cystobacter fuscus . This study identifies C. fuscus HM-E and M. fulvus KT23 and KE15 as robust biocontrol resources with dual functions in disease suppression and growth promotion, providing a novel technical framework and microbial candidates for the sustainable management of wheat Fusarium Crown Rot.

Cotton Verticillium wilt, caused by Verticillium dahliae , is one of the most destructive soil-borne fungal diseases threatening cotton production worldwide, necessitating the development of effective and sustainable control strategies. Myxobacteria are higher-order prokaryotes characterized by multicellular social behavior and predatory activity against diverse microorganisms, conferring significant potential for plant disease management. Based on a previously established myxobacterial mini-resource library, a strain designated KS01 with broad-spectrum antifungal activity was screened and characterized. Morphological, conservative genes (16S rRNA and gyrB ) and genomic core genes phylogenetic tree identified the strain as Myxococcus fulvus KS01. In vitro assays demonstrated that M. fulvus KS01 lysed hyphae and spores of V. dahliae and significantly inhibited spore germination. Both sterile fermentation filtrates and volatile organic compounds (VOCs) exhibited antifungal activity. While crude secondary metabolite extracts (via macroporous resin adsorption) and crude lipopeptide extracts (via acid precipitation) exhibited no inhibitory activity, the ammonium sulfate–precipitated extracellular crude protein fraction displayed pronounced antifungal activity. This fraction disrupted fungal cell wall and membrane integrity, induced intracellular reactive oxygen species (ROS) accumulation, lysed spores, and suppressed germ tube elongation. Substrate spectrum analysis further revealed that KS01 produces peptidases, lipases, and glycoside hydrolases, which are likely key biocontrol determinants. Greenhouse pot experiments showed that a solid formulation of M. fulvus KS01, prepared using white star flower chafer ( Protaetia brevitarsis ) frass as the fermentation substrate, achieved a control efficacy of 63.01% against cotton Verticillium wilt and significantly promoted cotton seedling growth. Collectively, M. fulvus KS01 represents a promising predatory biocontrol agent with substantial potential for the sustainable management of cotton Verticillium wilt.