Pyoluteorin production byPseudomonas fluorescens strain CHA0 is involved in the suppression ofPythium damping-off of cress but not of cucumber

Pseudomonas fluorescens strain CHA0 is an effective biocontrol agent of various soilborne pathogens. It controls damping-off or root rot caused byPythium ultimum on cucumber, wheat and cress. Strain CHA0 synthesizes several antibiotic metabolites such as hydrogen cyanide, 2,4-diacetylphloroglucinol, and pyoluteorin. The role of pyoluteorin in the suppression of damping-off was investigated. Two Tn5 mutants (CHA660 and CHA661) of strain CHA0 were isolated which had lost the capacity to produce pyoluteorin but still produced 2,4-diacteylphloroglucinol and HCN. These mutants still inhibitedP. ultimum on malt agar (which favours the production of 2,4-diacetylphloroglucinol) but had partially lost the ability to inhibit this pathogen on King's B agar (which favours the production of pyoluteorin). The two pyoluteorin-negative mutants showed a reduced capacity to suppress damping-off of cress caused byP. ultimum but were as effective in the protection of cucumber against this pathogen as the wild-type strain.These results indicate that, depending on the plant, pyoluteorin production plays a role in the suppression of damping-off by strain CHA0 without being a major mechanism in disease suppression. We suggest that the contribution of pyoluteorin to the biocontrol activity of strain CHA0 is determined by the quantity of this antibiotic produced in the rhizosphere, which might depend on the root exudates of the host plant.     

The global regulator GacA of Pseudomonas fluorescens CHA0 is required for suppression of root diseases in dicotyledons but not in Gramineae

Pseudomonas fluorescens strain CHA0 suppresses various plant diseases caused by soil-borne fungi. The pseudomonad produces the antimicrobial metabolites 2,4-diacetylphloroglucinol (Phl), pyoluteorin (Plt) and hydrogen cyanide, which are important for disease suppression, as well as the siderophores pyoverdine (Pvd), salicylic acid (Sal) and pyochelin (Pch). In the current work, a derivative of CHA0 with a mutation in the global regulator gene gacA (GacA⁻), which is unable to produce Phl, Plt and HCN, failed to protect the dicotyledonous plants cress and cucumber against damping-off caused by Pythium ultimum . In contrast, the GacA⁻ mutant could still protect the Gramineae wheat and maize against damping-off mediated by the same strain of P. ultimum , and wheat against take-all caused by Gaeumannomyces graminis . However, the GacA⁻ mutant overproduced Pch and Pvd. To gain more insight into disease protection afforded by the GacA⁻ mutant, a GacA⁻ Pvd⁻ double mutant (strain CHA496) was constructed by gene replacement. Strain CHA496 overproduced Pch and Sal compared with CHA0 and protected wheat against P. ultimum and G. graminis , whereas cress and cucumber were not protected. Addition of FeCl₃ repressed Pch and Sal production by strain CHA496 in vitro and impaired the protection of wheat in soil microcosms. In conclusion, a functional gacA gene was necessary for the protection of dicotyledons against root diseases, but not for that of Gramineae. Results indicated also that Pch and/or Sal were involved in the ability of the GacA⁻ Pvd⁻ mutant of CHA0 to suppress root diseases in Gramineae.     

Biotic Factors Affecting Expression of the 2,4-Diacetylphloroglucinol Biosynthesis Gene phlA in Pseudomonas fluorescens Biocontrol Strain CHA0 in the Rhizosphere

ABSTRACT Production of the polyketide antimicrobial metabolite 2,4-diacetyl-phloroglucinol (DAPG) is a key factor in the biocontrol activity of Pseudomonas fluorescens CHA0. Strain CHA0 carrying a translational phlA'-'lacZ fusion was used to monitor expression of the phl biosynthetic genes in vitro and in the rhizosphere. Expression of the reporter gene accurately reflected actual production of DAPG in vitro and in planta as determined by direct extraction of the antimicrobial compound. In a gnotobiotic system containing a clay and sand-based artificial soil, reporter gene expression was significantly greater in the rhizospheres of two monocots (maize and wheat) compared with gene expression in the rhizospheres of two dicots (bean and cucumber). We observed this host genotype effect on bacterial gene expression also at the level of cultivars. Significant differences were found among six additional maize cultivars tested under gnotobiotic conditions. There was no difference between transgenic maize expressing the Bacillus thuringiensis insecticidal gene cry1Ab and the near-isogenic parent line. Plant age had a significant impact on gene expression. Using maize as a model, expression of the phlA'-'lacZ reporter gene peaked at 24 h after planting of pregerminated seedlings, and dropped to a fourth of that value within 48 h, remaining at that level throughout 22 days of plant growth. Root infection by Pythium ultimum stimulated bacterial gene expression on both cucumber and maize, and this was independent of differences in rhizosphere colonization on these host plants. To our knowledge, this is the first comprehensive evaluation of how biotic factors that commonly confront bacterial inoculants in agricultural systems (host genotype, host age, and pathogen infection) modulate the expression of key biocontrol genes for disease suppression.     

Salicylic Acid Biosynthetic Genes Expressed in Pseudomonas fluorescens Strain P3 Improve the Induction of Systemic Resistance in Tobacco Against Tobacco Necrosis Virus

ABSTRACT Application of salicylic acid induces systemic acquired resistance in tobacco. pchA and pchB, which encode for the biosynthesis of salicylic acid in Pseudomonas aeruginosa, were cloned into two expression vectors, and these constructs were introduced into two root-colonizing strains of P. fluorescens. Introduction of pchBA into strain P3, which does not produce salicylic acid, rendered this strain capable of salicylic acid production in vitro and significantly improved its ability to induce systemic resistance in tobacco against tobacco necrosis virus. Strain CHA0 is a well-described biocontrol agent that naturally produces salicylic acid under conditions of iron limitation. Introduction of pchBA into CHA0 increased the production of salicylic acid in vitro and in the rhizosphere of tobacco, but did not improve the ability of CHA0 to induce systemic resistance in tobacco. In addition, these genes did not improve significantly the capacity of strains P3 and CHA0 to suppress black root rot of tobacco in a gnotobiotic system.     

Interactions between the biocontrol agent Pseudomonas fluorescens CHA0 and Thielaviopsis basicola in tobacco roots observed by immunofluorescence microscopy

Pseudomonas fluorescens CHA0 protects plants from damage caused by several soilborne fungi. In this work, immunofluorescence microscopy was used to investigate the colonization of tobacco roots by CHA0 and its physical relationship with the black root rot fungus Thielaviopsis basicola . The pseudomonad colonized the rhizoplane shortly after planting of tobacco seedlings in sterile soil microcosms, in which it had been introduced as soil inoculant. CHA0 was found between and inside cells in the epidermis and the cortex, as well as in the xylem vessels, within 4–7 days after planting of seedlings. The presence of CHA0 delayed the colonization of the interior of tobacco roots by T. basicola compared with the treatment in which only the fungus had been inoculated. Likewise, the pseudomonad reduced the extent of black root rot from 82% to 28%. However, CHA0 was seldom found in contact with the mycelium of T. basicola or in its vicinity, indicating that direct colonization of the mycelium of T. basicola by CHA0 was not required for protection of tobacco against black root rot. Overall, the results suggest that the interior of the root is a key site for implementation of the strain's biocontrol activity against soilborne plant-pathogenic fungi.     

Transformants of Trichoderma longibrachiatum Overexpressing the beta-1,4-Endoglucanase Gene egl1 Show Enhanced Biocontrol of Pythium ultimum on Cucumber

ABSTRACT Nine transformants of Trichoderma longibrachiatum with extra copies of the egl1 gene were studied for mitotic stability, endoglucanase production, and biocontrol activity against Pythium ultimum on cucumber seedlings. The transformants showed a significantly higher level of expression of the egl1 gene in comparison to the wild type under both inducing and noninducing growth conditions. Transformants with the egl1 gene under the control of a constitutive promoter had the highest enzymatic activity. Both the endoglucanase activity and the transforming sequences were stable under nonselective conditions. When applied to cucumber seeds sown in P. ultimum-infested soil, T. longibrachiatum transformants with increased inducible or constitutive egl1 expression generally were more suppressive than the wild-type strain.     

Zinc Improves Biocontrol of Fusarium Crown and Root Rot of Tomato by Pseudomonas fluorescens and Represses the Production of Pathogen Metabolites Inhibitory to Bacterial Antibiotic Biosynthesis

ABSTRACT Crown and root rot of tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici is an increasing problem in Europe, Israel, Japan, and North America. The biocontrol agent Pseudomonas fluorescens strain CHA0 provides only moderate control of this disease. A one-time amendment of zinc EDTA at 33 mug of Zn(2+)/ml to hydroponic nutrient solution in soilless rockwool culture did not reduce disease when used alone, but did reduce disease by 25% in the presence of CHA0. In in vitro studies with the pathogen, zinc at concentrations as low as 10 mug/ml abolished production of the phytotoxin fusaric acid, a Fusarium pathogenicity factor, and increased production of microconidia over 100-fold, but reduced total biomass. Copper EDTA at 33 mug of Cu(2+)/ml had a similar effect as zinc on the pathogen in vitro; it reduced disease when used alone, and increased the biocontrol activity of CHA0 in soilless culture. Ammonium-molybdate neither improved the biocontrol activity of CHA0 nor affected production of fusaric acid or microconidia. Strain CHA0 did not degrade fusaric acid. Fusaric acid at concentrations as low as 0.12 mug/ml repressed production by CHA0 of the antibiotic 2,4-diacetylphloroglucinol, a key factor in the biocontrol activity of this strain. Production of pyoluteorin by CHA0 was also reduced, but production of hydrogen cyanide and protease was not affected, suggesting that fusaric acid affects biosynthesis at a regulatory level downstream of gacA and apdA genes. Fusaric acid did not affect the recovery of preformed antibiotics nor did it affect bacterial growth even at concentrations as high as 200 mug/ml. When microbial meta-bolite production was measured in the rockwool bioassay, zinc amendments reduced fusaric acid production and enhanced 2,4-diacetylphloro-glucinol production. We suggest that zinc, which did not alleviate the repression of antibiotic biosynthesis by fusaric acid, improved biocontrol activity by reducing fusaric acid production by the pathogen, which resulted in increased antibiotic production by the biocontrol agent. This demonstrates that pathogens can have a direct negative impact on the mechanism(s) of biocontrol agents.     

Mutation of a degS homologue in Enterobacter cloacae decreases colonization and biological control of damping-off on cucumber

We have been using mutagenesis to determine how biocontrol bacteria such as Enterobacter cloacae 501R3 deal with complex nutritional environments found in association with plants. E. cloacae C10, a mutant of 501R3 with a transposon insertion in degS, was diminished in growth on synthetic cucumber root exudate (SRE), colonization of cucumber seed and roots, and control of damping-off of cucumber caused by Pythium ultimum. DegS, a periplasmic serine protease in the closely related bacterium Escherichia coli K12, is required for the RpoE-mediated stress response. C10 containing wild-type degS from 501R3 or from E. coli K12 on pBeloBAC11 was significantly increased in growth on SRE, colonization of cucumber roots, and control of P. ultimum relative to C10 containing pBeloBAC11 alone. C10 and 501R3 were similar in sensitivity to acidic conditions, plant-derived phenolic compounds, oxidative stress caused by hydrogen peroxide, dessication, and high osmoticum; stress conditions potentially associated with plants. This study demonstrates a role for degS in the spermosphere and rhizosphere during colonization and disease control by Enterobacter cloacae. This study implicates, for the first time, the involvement of DegS and, by extension, the RpoE-mediated stress response, in reducing stress on E. cloacae resulting from the complex nutritional environments in the spermosphere and rhizosphere.     

生防菌EN5的定殖能力及其对根际土壤微生物类群的影响

［目的］ 明确生防菌EN5菌株在番茄根、茎及根际土壤中和在黄瓜、烟草体内的定殖情况,及对根际土壤微生态的影响,为细菌性青枯病的生态治理提供理论依据。［方法］ 采用抗生素抗性标记法测定生防芽胞杆菌EN5的定殖能力;以平板培养及ERIC PCR法分析菌株EN5对番茄根际土壤微生物种群的影响。［结果］ 菌株EN5在番茄根、茎及根际土壤中均能稳定定殖,当菌株EN5处理植株15 d时,其在番茄茎内的定殖量可达5.6×104 cfu/g;此外,菌株EN5在烟草和黄瓜体内亦可定殖,其在烟草体内的定殖量较大。菌株EN5处理使根际土壤中细菌、真菌和放线菌的数量明显高于对照土壤,对氨化细菌、固氮菌、纤维素降解菌等微生物群体有促进作用,对反硫化细菌群体有抑制作用。同时,菌株EN5处理还改善了根际土壤中细菌群体的多样性。［结论］ 菌株EN5可以在其自然寄主番茄的根、茎及根际土壤中稳定定殖。同时,菌株EN5处理有助于改善根际土壤微生态环境,抑制病菌繁殖。     

调控基因gacA在荧光假单胞菌2P24防治土传病害中的作用

 Pseudomonas fluorescens 2P24分离自山东小麦全蚀病自然衰退土壤,该菌株能产生抗生素2,4-二乙酰基藤黄酚(2,4-diacetylphloroglucinol,2,4-DAPG)、氢氰酸,嗜铁素和蛋白酶,且抑菌谱广,可防治多种作物土传病害。本研究应用Tn5转座突变技术,获得1株产嗜铁素过量,同时不产生2,4-DAPG、HCN、蛋白酶、不能形成生物膜(biofilm)的突变菌株PM3390,其表现型与调控基因gacA的突变体表型相似。通过PCR介导的文库筛选方法,从2P24基因组文库中获得2个含有gacA基因的阳性克隆,进一步亚克隆,得到只含有完整gacA开放阅读框的1.2 kb片段,互补实验表明其能恢复突变菌株的多种缺失表型。生测结果表明,gacA-突变菌株与野生型2P24相比,对不同土传病害的生防效果均显著降低。以上结果证实gacA在2P24中具有整体水平的调控功能,并在2P24防治土传病害中起到重要的作用。     

Cyclic Lipopeptide Surfactant Production by Pseudomonas fluorescens SS101 Is Not Required for Suppression of Complex Pythium spp. Populations

ABSTRACT Previously, the zoosporicidal activity and control of Pythium root rot of flower bulbs by Pseudomonas fluorescens SS101 was attributed, in part, to the production of the cyclic lipopeptide surfactant massetolide A. The capacity of strain SS101 and its surfactant-deficient massA mutant 10.24 to suppress populations and root infection by complex Pythium spp. communities resident in orchard soils was assessed on apple and wheat seedlings and on apple rootstocks. Both strains initially became established in soil and persisted in the rhizosphere at similar population densities; however, massA mutant 10.24 typically was detected at higher populations in the wheat rhizosphere and soil at the end of each experiment. Both strains effectively suppressed resident Pythium populations to an equivalent level in the presence or absence of plant roots, and ultimately suppressed Pythium root infection to the same degree on all host plants. When split-root plant assays were employed, neither strain suppressed Pythium spp. infection of the component of the root system physically separated from the bacterium, suggesting that induced systemic resistance did not play a role in Pythium control. Strain SS101 only marginally suppressed in vitro growth of Pythium spp. and growth was not inhibited in the presence of mutant 10.24. When incorporated into the growth medium, the cyclic lipopeptide massetolide A significantly slowed the rate of hyphal expansion for all Pythium spp. examined. Differences in sensitivity were observed among species, with Pythium heterothallicum, P. rostratum, and P. ultimum var. ultimum exhibiting significantly greater tolerance. Pythium spp. populations indigenous to the two soils employed were composed primarily of P. irregulare, P. sylvaticum, and P. ultimum var. ultimum. These Pythium spp. either do not or rarely produce zoospores, which could account for the observation that both SS101 and mutant 10.24 were equally effective in disease control. Collectively, the results showed that (i) Pseudomonas fluorescens SS101 is very effective in controlling diverse Pythium populations on different crops grown in different soils and (ii) production of the cyclic lipopeptide massetolide A does not play a significant role in disease suppression. Other, as yet undefined mechanisms appear to play a significant role in the interaction between P. fluorescens SS101 and soilborne Pythium spp. communities.     

烟草赤星病菌拮抗菌解淀粉芽胞杆菌YW-2-6鉴定及生防效果

为获得有效拮抗烟草赤星病菌的生防资源,采用稀释分离法和平板对峙法从烟草根际土壤中分离筛选烟草赤星病菌拮抗菌株。通过形态学观察、生理生化特征和16S rDNA序列分析进行鉴定,并测定其对烟株的促生作用,验证菌株的产IAA能力,评价生防菌发酵液对烟草赤星病的田间防效。结果表明,从分离的65株细菌菌株中筛选到5株烟草赤星病拮抗细菌,其中菌株YW-2-6对烟草赤星病菌拮抗效果最好,抑制率为71.32%,初步鉴定菌株YW-2-6为解淀粉芽胞杆菌Bacillus amyloliquefaciens。菌株YW-2-6对小麦赤霉病菌、辣椒疫霉病菌、烟草靶斑病菌等病原菌具有显著的拮抗作用。YW-2-6发酵液对烟草赤星病防效为56.93%,且菌株YW-2-6对烟株有明显的促生作用。菌株YW-2-6具有良好的生防潜力和开发前景。     

Biological control of fusarium seedling blight disease of wheat and barley

ABSTRACT Fusarium fungi, including F. culmorum, cause seedling blight, foot rot, and head blight diseases of cereals, resulting in yield loss. In a screen for potential disease control organisms and agents, Pseudomonas fluorescens strains MKB 100 and MKB 249, P. frederiksbergensis strain 202, Pseudomonas sp. strain MKB 158, and chitosan all significantly reduced the extent of both wheat coleoptile growth retardation and wheat and barley seedling blight caused by F. culmorum (by 53 to 91%). Trichodiene synthase is a Fusarium enzyme necessary for trichothecene mycotoxin biosynthesis; expression of the gene encoding this enzyme in wheat was 33% lower in stem base tissue coinoculated with Pseudomonas sp. strain MKB 158 and F. culmorum than in wheat treated with bacterial culture medium and F. culmorum. When wheat and barley were grown in soil amended with either chitosan, P. fluorescens strain MKB 249, Pseudomonas sp. strain MKB 158, or culture filtrates of these bacteria, the level of disease symptoms on F. culmorum-inoculated stem base tissue (at 12 days post- F. culmorum inoculation) was >/=31% less than the level on F. culmorum-inoculated plants grown in culture medium-amended soil. It seems likely that at least part of the biocontrol activity of these bacteria and chitosan may be due to the induction of systemic disease resistance in host plants. Also, in coinoculation studies, Pseudomonas sp. strain MKB 158 induced the expression of a wheat class III plant peroxidase gene (a pathogenesis-related gene).     

Evaluation of Bacterial Antagonists for Biological Control of Broccoli Head Rot Caused by Pseudomonas fluorescens

ABSTRACT Pectolytic strains of Pseudomonas fluorescens are opportunistic pathogens of broccoli, causing head rot in temperate regions of the world. In this study, we investigated the potential of two bacterial isolates, P. fluorescens m6418 and Bacillus sp. A24, for biological control of broccoli head rot caused by P. fluorescens 5064, isolated from diseased broccoli in Scotland, UK. P. fluorescens m6418, a Tn5 mutant of wild-type 5064, is nonpathogenic and overproduces an extracellular metabolite with strong antimicrobial activity. In this study, we identified the anti-microbial metabolite produced by strain m6418 as pyrrolnitrin. P. fluorescens m6418 had significant inhibitory effects against strain 5064 both in culture and on broccoli leaves. In an excised broccoli head pathogenicity test, strain m6418, when coinoculated with P. fluorescens 5064, reduced disease by 41%. Bacillus sp. A24 produces an enzyme that can degrade N-acyl homoserine lactones, signaling molecules employed by bacteria for quorum sensing. Bacillus sp. A24 was capable of out-competing P. fluorescens 5064 when grown together in culture, and could degrade the quorum sensing signal of P. fluorescens 5064 (and thereby attenuate its virulence gene production). However, Bacillus sp. A24 had only a limited biocontrol effect on P. fluorescens 5064 in the excised broccoli head assay.     

荧光假单胞菌拮抗菌株对烟草疫霉的抑菌机制及控病效果

为探讨烟草根际生防细菌对烟草疫霉Phytophthora nicotianae的抑菌机制,从重庆地区连作烟田健康烟株根际土壤分离获得5株荧光假单胞菌Pseudomonas fluorescens拮抗菌株。通过平板对峙及代谢产物抑菌试验筛选对烟草疫霉具有高效拮抗作用的菌株,其中,P-72-10菌株抑菌效果最强,抑菌带半径达13.0 mm,相对抑制率为68.57%,且该菌株代谢产物对烟草疫霉菌丝生长有明显的抑制作用,相对抑制率达25.39%～46.03%;显微观察发现该菌株可引起烟草疫霉菌丝的分支增多,菌丝顶端膨大呈畸形,多数菌丝中间或顶端细胞的细胞壁加厚、原生质浓缩和产生类似厚壁孢子的细胞。在温室盆栽条件下P-72-10菌株对烟草黑胫病也表现出良好的控病效果,对抗病和感病品种的相对防效分别为53.57%和66.37%。     

Application of formulated rhizobacteria against root rot of field pea

Formulations of bacterial biocontrol agents were evaluated for the control of pea root-rot caused primarily by Pythium ultimum and Rhizoctonia solani, at different levels of disease severity in field trials. Pseudomonas fluorescens (strain PRA25) in a peat-based formulation increased yield by 17% over the untreated, in a trial with light disease infection, and by 120% in another with moderate infection. Other bacteria including P . cepacia (strain AMMD) and fluorescent pseudomonads increased seedling emergence, and decreased disease incidence and severity, but with variable effects on yield when disease level was light to moderate. Biocontrol agents resulted in only limited control when disease was severe. Control with Captan did not differ significantly from that obtained with bacterial biocontrol agents. The application of Rhizobium granular inoculum together with PRA25 granules did not differ from other treatments in disease control, indicating that Rhizobium is compatible with biocontrol agents. The population dynamics of a fluorescent pseudomonad introduced into the rhizosphere in peat or granular formulation was monitored using an antibiotic-resistant mutant marker strain. The bacterium in peat formulation established a considerably higher population than that in granular formulation in 1993 trials, and a slightly higher population in 1994 trials. The higher population may have been responsible for the efficiency of root colonization and the effectiveness of disease control.     

荧光假单胞菌2P24中phlF基因对抗生素2,4-二乙酰基间苯三酚产生的影响

Pseudomonas fluorescens2P24是分离自山东小麦全蚀病自然衰退土的1株生物防治菌株,产生抗生素2,4-二乙酰基间苯三酚(2,4-diacetylphloroglucinol;2,4-DAPG)是其主要防病机制。2,4-DAPG是由phlACBD基因簇合成,受多种调控因子调控。本研究用Tn5转座子插入技术,获得1株phlA基因转录增强的突变体,其突变基因为抗生素合成的负调控基因phlF。与野生菌相比,phlF基因的缺失突变体中phlA的转录增强约100倍,抗生素产量提高492倍。同时,菌株2P24的phlF缺失突变体对病原真菌的拮抗作用明显增强。但2,4-DAPG过量表达菌株对多种作物种子根生长有抑制作用。     

Seed-colonizing microbes from municipal biosolids compost suppress Pythium ultimum damping-off on different plant species

Composts are known for their suppressive properties toward many different seed- and root-infecting pathogens and diseases. Although disease and pathogen suppression induced by composts is believed to be mediated by microbial activities, the nature of the microbial species and processes responsible for suppressiveness remain unknown. We demonstrated previously that seed-colonizing microbial consortia from leaf compost could explain the observed levels of Pythium ultimum-induced damping-off suppression on cotton. The aim of the present work was to determine whether seed-colonizing microbial consortia could explain Pythium damping-off suppression in municipal biosolids compost on three different plant species. Significant levels of disease suppression were observed on cucumber, wheat, and pea at water potentials of -2 kPa. The suppression of damping-off on cucumber and wheat could be eliminated by autoclaving the compost prior to sowing. High levels of suppressiveness were expressed both on cucumber and on wheat seed surfaces within 8 h of sowing. However, the expression of damping-off suppression on the surface of pea seeds was inconsistent and highly variable. Our results demonstrate that compost-induced suppression of P. ultimum damping-off of cucumber and wheat can be explained by the microbial consortia colonizing seeds within 8 h of sowing. These results further suggest that disease suppression in composts is related to microbial species that interact with the pathogen in its infection court and not in the bulk compost.     

皮尔瑞俄类芽胞杆菌ZF390对黄瓜细菌性软腐病的防治效果

针对黄瓜细菌性软腐病发生严重且难以防治的问题,本研究以活体防治效果为指标,筛选更加有利于田间应用的高效生防菌株。采用梯度稀释法分离纯化病害发生严重地块的健康黄瓜植株根际中的细菌菌株,再利用双层培养法筛选到6株黄瓜细菌性软腐病菌拮抗菌株,最终通过喷雾接种法筛选得到能够有效防治黄瓜细菌性软腐病的生防菌株ZF390,其防效可达77.94%,且该菌株能够有效抑制8种病原细菌的生长,抑菌谱广。结合形态学特征、生理生化特性和多位点序列分型分析,鉴定菌株ZF390为皮尔瑞俄类芽胞杆菌Paenibacillus peoriae。采用单因素试验对菌株ZF390摇瓶发酵工艺进行优化,最终发酵液菌体浓度提高了4个数量级,可达2.94×10⁹ CFU/mL。菌株ZF390是一株能够有效防治黄瓜细菌性软腐病的生防菌株,具有进一步开发成生防制剂的应用潜力。