Control Of Bacterial Wilt Research Articles

Exposure to Umbelliferone Reduces Ralstonia solanacearum Biofilm Formation, Transcription of Type III Secretion System Regulators and Effectors and Virulence on Tobacco.

Ralstonia solanacearum is one of the most devastating phytopathogens and causes bacterial wilt, which leads to severe economic loss due to its worldwide distribution and broad host range. Certain plant-derived compounds (PDCs) can impair bacterial virulence by suppressing pathogenic factors of R. solanacearum. However, the inhibitory mechanisms of PDCs in bacterial virulence remain largely unknown. In this study, we screened a library of coumarins and derivatives, natural PDCs with fused benzene and α-pyrone rings, for their effects on expression of the type III secretion system (T3SS) of R. solanacearum. Here, we show that umbelliferone (UM), a 7-hydroxycoumarin, suppressed T3SS regulator gene expression through HrpG–HrpB and PrhG–HrpB pathways. UM decreased gene expression of six type III effectors (RipX, RipD, RipP1, RipR, RipTAL, and RipW) of 10 representative effector genes but did not alter T2SS expression. In addition, biofilm formation of R. solanacearum was significantly reduced by UM, though swimming activity was not affected. We then observed that UM suppressed the wilting disease process by reducing colonization and proliferation in tobacco roots and stems. In summary, the findings reveal that UM may serve as a plant-derived inhibitor to manipulate R. solanacearum T3SS and biofilm formation, providing proof of concept that these key virulence factors are potential targets for the integrated control of bacterial wilt.

トマト青枯病に対する拮抗菌Pseudomonas putida FP-16株のトマト根への定着性

トマト青枯病に対する拮抗菌Pseudomonas putida FP-16株のトマト根への定着性

Combined use of Bacillus subtilis strain B‐001 and bactericide for the control of tomato bacterial wilt

Tomato bacterial wilt caused by Ralstonia solanacearum poses a serious threat to tomato production. However, no effective control measures are available. In this study, the bactericide Saisentong was combined with an effective biological control agent, Bacillus subtilis B-001, to control tomato bacterial wilt under greenhouse and field conditions. Growth of B-001 in vitro was unaffected by Saisentong. In greenhouse experiments, the combined application of B-001 and Saisentong via root irrigation or spray resulted in better disease control compared with either agent alone. In two field trials, at a Saisentong concentration of 400 or 500 mg kg-1 , the combined treatment was more effective than expected and showed a synergistic effect. A lower concentration of Saisentong (200 or 300 mg kg-1 ) in combination with B-001 resulted in an antagonistic effect. However, disease control was significantly greater compared with either treatment alone. The combination of Saisentong and B-001 effectively controls tomato bacterial wilt. The integrated strategy represents a promising new tool to control this disease. © 2016 Society of Chemical Industry.

Evaluation of Phytophthora root rot- and bacterial wilt-resistant inbred lines and their crosses for use as rootstocks in pepper (Capsicum annuum L.)

Breeding lines and their crosses with genic male sterile (GMS) and cytoplasmic male sterile (CMS) lines, developed for use as rootstocks with resistance to Phytophthora root rot and bacterial wilt, were evaluated for their resistance against these diseases and for supporting the growth of scions. Five inbred lines of the Yanggang (YG) series of breeding lines and 10 crosses between these lines and the male sterile lines, the commercial rootstock Tantan, and the susceptible scion cultivar Gilsang were tested for resistance to infection by Ralstonia solanacearum and Phytophthora capsici at the seedling stage. YG4, YG5, GMS x YG5, and CMS x YG3 remained disease-free, whereas Gilsang succumbed to both diseases. The grafted plants, corresponding not-grated rootstocks, auto-grafted (Gilsang/Gilsang) and non-grafted Gilsang seedlings (controls) were inoculated with R. solanacearum, planted side-by-side in a greenhouse, and evaluated for incidence of bacterial wilt under hot greenhouse conditions during summer. Gilsang scions grafted to the rootstocks YG2, YG3, YG4, YG5, GMS x YG5, and CMS x YG6 remained healthy through the end of the experiment, without any symptoms of bacterial wilt, whereas Gilsang scions grafted to rootstocks CMS x YG2 and Tantan, as well as the auto-grafted and non-grafted Gilsang seedlings failed to survive the disease, with 100% death observed. The survival rate of the rootstocks to bacterial wilt was higher than that of the grafted plants, except for Tantan, in which all plants died. Thus, the resistant rootstocks developed and selected in this study were effective in the control of bacterial wilt under high temperature conditions. The rootstocks were found to have a minimal effect on the growth and fruit size of the scion.

Studies on biological control of bacterial wilt caused by Ralstonia solanacearum using endophytic bacteria

Studies on biological control of bacterial wilt caused by Ralstonia solanacearum using endophytic bacteria

In vitro screening of plant growth promoting rhizobacteria to control bacterial wilt (Ralstonia solanacearum) of tomato (Lycopersicon esculentum)

Ralstonia solanacearum is the causative agent of bacterial wilt that causes considerable damages in the yield of various crop plants. The intent of the study was to evaluate potential of bacterial antagonists to suppress bacterial wilt disease development and evaluate the role of the strains as plant growth-promoting rhizobacteria (PGPR) in tomato. One hundred rhizosphere bacterial isolates were screened against virulent strain of Ralstonia solanacearum . After in vitro screening 10 antagonistic strains designated PR3, PR17, PR26, 1NAB15, 1NAB20, 3NAA1, 3NAA2, 2CBA2, 2CBA4, 2CBA18 showed antagonistic effect by producing inhibition zone supressing the growth of R. Solanacearum . The isolate PR3 showed the highest inhibition zone measuring 33.3mm whereas 1NAB15 showed the lowest zone measuring 10mm. The present study, therefore, suggests that the use of PGPR isolates which showed the antagonistic activity can be used as inoculants/ bioantagonists might be beneficial for the control of bacterial wilt of tomato in field studies.

The secondary compost products enhances soil suppressive capacity against bacterial wilt of tomato caused by Ralstonia solanacearum

Composting crop residues and animal manures for CO2 fertilization of vegetable crops is popular in China, but its rapid adoption in greenhouses faces a roadblock: the public concern over the disposition of much large amounts of compost products. In the present study, we used a secondary compost process to re-use the compost products, and evaluated the effect of secondary compost products (SCP) on tomato bacterial wilt in three field trials. The results showed that SCP application had great potential for the control of tomato bacterial wilt. Compared with the control (local conventional cultivation), SCP application decreased the disease incidence by 32–81% and increased fruit yields by 59–95% across the three trials. Irrespective of treatment, significant correlations were found between Ralstonia solanacearum populations and total nitrogen, soil organic carbon and NO3−-N contents. Moreover, the severity of bacterial wilt negatively associated with the activity of phosphomonoesterase and β-d-glucosidase, FDA hydrolysis, soil respiration, microbial biomass carbon and bacterial community diversity, whereas positively related with fungal community diversity. The results indicate that the enhancement of soil suppressiveness against R. solanacearum by SCP application was likely due to the alteration of microbial community structure and increased competitive ability of beneficial microorganisms with pathogens. We concluded that SCP application, as a way of re-utilization of compost products have the ability to increase soil suppressive capacity against bacterial wilt.

Potential of Chitosan for the Control of Tomato Bacterial Wilt Caused by Ralstonia solanacearum (Smith) Yabuuchi et al

Bacterial wilt is an important constraint to tomato production. The search for an effective and safe method of managing bacterial wilt is imperative. Chitosan, adeactylated chitin was reported to possess direct antimicrobial property against certain pathogens and is a plant resistance booster. This study was conducted to: evaluate the effectiveness of varying chitosan concentrations and sources against bacterial wilt in vitro and in vivo and compare different application methods in bacterial wilt control. Varying chitosan concentrations (100, 200, 300, 400 and 500 ppm) immersed/dissolved in water, 1% acetic acid, and streptomycin were evaluated against R. solanacearum in laboratory and pot experiments. Three chitosan sources were also evaluated against the pathogen. Different methods of application were compared. Regardless of source, chitosan in water has no direct antimicrobial activity against R.solanacearum but when dissolved 1% acetic acid, it was able to inhibit the bacteria. Inhibition of chitosan/acetic acid was best at 300 ppm and significantly higher than 1% acetic acid alone indicating that its antimicrobial property was enhanced by the acid. Two hundred ppm chitosan/acetic acid-treated plants delayed the onset of disease and produced the lowest percentage infection, lowest disease severity rating, and highest percentage survival in inoculated tomato. The action of 200 ppm chitosan/acetic acid treatment was due to a dual effect, i.e., antimicrobial and as an elicitor of resistance. All application methods were effective in controlling bacterial wilt but one time root dipping to 200 ppm chitosan/acetic acid before transplanting was enough to protect the plants against the disease.

Control of tomato bacterial wilt and root-knot diseases by Bacillus thuringiensis CR-371 and Streptomyces avermectinius NBRC14893

Ralstonia solanacearum and Meloidogyne incognita are two soilborne pathogens that cause serious damage and great losses in the production of tomato. For this purpose, a bacterial isolate, Bacillus thuringiensis CR-371, and an actinomyces isolate, Streptomyces avermectinius NBRC14893, were examined for their ability to protect tomato from root-knot nematode and bacterial wilt diseases under glasshouse conditions. Treatment of tomato roots with B. thuringiensis CR-371 and S. avermectinius NBRC14893 followed by challenge inoculation with R. solanacearum and M. incognita significantly decreased disease severity of bacterial wilt alone, root-knot nematode alone, or mixed infection by both pathogens compared to the control. Furthermore, pretreatment of tomato roots with B. thuringiensis CR-371 and S. avermectinius NBRC14893 significantly reduced bacterial proliferation of R. solanacearum both in pathogen alone inoculated plants and in plants co-inoculated with R. solanacearum and M. incognita. In conclusion, our results suggest that the treatment of tomato roots with B. thuringiensis CR-371 and S. avermectinius NBRC14893 simultaneously suppresses bacterial wilt and root-knot nematode diseases. Therefore, B. thuringiensis CR-371 and S. avermectinius NBRC14893 could provide new options for integrated pest management strategies against plant diseases, especially against bacterial-nematode disease complexes that cause synergistic yield losses.

Suppression of bacterial wilt of tomato by bioorganic fertilizer made from the antibacterial compound producing strain Bacillus amyloliquefaciens HR62.

Ralstonia solanacearum (Smith) is an important soil-borne pathogen worldwide. We investigated the effects of a new bioorganic fertilizer, BIO62, which was made from organic fertilizer and antagonist Bacillus amyloliquefaciens HR62, on the control of bacterial wilt of tomato in greenhouse condition. The results showed that the application of BIO62 significantly decreased disease incidence by 65% and strongly reduced R. solanacearum populations both in the rhizosphere soil (8.04 log cfu g(-1) dry soil) and crown sections (5.63 log cfu g(-1) fresh plant section) at 28 days after pathogen challenge. Antibacterial compounds produced by HR62 were purified by silica gel, Sephadex LH-20, and HPLC and then identified using HPLC/electrospray ionization mass spectrometry analysis. Macrolactin A and 7-O-malonyl macrolactin A (molecular weights of 402 and 488 Da, respectively), along with surfactin B (molecular weights of 994, 1008, 1022, and 1036 Da), were observed to inhibit the growth of R. solanacearum.

Crotalaria spectabilis and Raphanus sativus as Previous Crops Show Promise for the Control of Bacterial Wilt of Tomato Without Reducing Bacterial Populations

AbstractRalstonia solanacearum is responsible for bacterial wilt affecting many crops worldwide. The emergent population of R. solanacearum (phylotype IIB/4NPB) wilts previously resistant varieties and has rapidly spread throughout Martinique. No conventional method is known to control it. In this study, previous crops used as sanitizing crops were investigated as an environmentally safe alternative method of control. The ability of the emergent population of R. solanacearum to persist in planta and in the rhizosphere of Brassicaceae, Asteraceae and Fabaceae grown as previous crops was evaluated in controlled conditions, and the incidence of bacterial wilt was assessed in the following tomato crop. Results showed that all species carried R. solanacearum latently. Among Brassicaceae and Asteraceae, the highest density of R. solanacearum was found in planta and in the rhizosphere of Tagetes erecta. The density of the R. solanacearum population in the rhizosphere of Raphanus sativus cv. Karacter was significantly higher than that in Raphanus sativus cv. Melody. In Fabaceae, the density of R. solanacearum population in planta was statistically similar in all species. The density of the R. solanacearum population in the rhizosphere of Crotalaria juncea was significantly higher than that in Crotalaria spectabilis. This study showed for the first time that Crotalaria spectabilis and Raphanus sativus cv. Melody grown as previous crops improve the performance of the following tomato with similar effects on R. solanacearum populations in the soil as bare soil. The incidence of the disease in tomato decreased by 86% and 60%, after R. sativus cv. Melody and C. spectabilis, respectively, and the proportion of infected plants also decreased. These results suggest that C. spectabilis and R. sativus cv. Melody can be used as previous crops to help bacterial wilt control in ecological management strategies without drastic suppression of R. solanacearum population in stem tissues and in the rhizosphere.

Biological control of eucalyptus bacterial wilt with rhizobacteria

The antagonistic potential of 298 rhizobacteria obtained from the rhizosphere and rhizoplane of tomato and eucalyptus plants was assessed for the control of bacterial wilt of eucalyptus caused by Ralstonia solanacearum. Several tests were performed using tomato plants as a screening system to select efficient rhizobacteria. Different methods for antagonist delivery and pathogen inoculation were evaluated: (1) seeds were microbiolized (soaked for 12h in a suspension of the antagonist propagules) and germinated seedlings had their roots immersed in the pathogen inoculum suspension; (2) seedlings originated from microbiolized seeds were transplanted to soil infested with R. solanacearum and (3) roots of seedlings were immersed in a suspension of propagules of the antagonist and subsequently in a suspension of R. solanacearum. Nine isolates (UFV-11, 32, 40, 56, 62, 101, 170, 229, and 270) were selected as potential antagonists to R. solanacearum as they suppressed bacterial wilt in at least one of the methods assessed. The selected antagonists were evaluated against two isolates of R. solanacearum using in vitro and in vivo (inoculated eucalyptus) tests. Isolates UFV-56 (Bacillus thuringiensis), UFV-62 (Bacillus cereus) and a commercial formulation of several rhizobacteria (Rizolyptus®) suppressed bacterial wilt in eucalyptus protecting the plants during the early stages of development.

A plant growth-promoting rhizobacteria (PGPR) mixture does not display synergistic effects, likely by biofilm but not growth inhibition

Combination of different PGPR strains with complementary characteristics as a mixture to reduce possible instability under fluctuating environment has been considered practical. However, PGPR mixtures do not always play synergistic roles in growth promotion or biological control as reflected in our previous findings and other publications. In this work, we accidentally discovered that a mixture containing two well compatible PGPR strains, Bacillus pumilus WP8 and Erwinia persicinus RA2, did not synergize in growth promotion or biological control of tomato bacterial wilt under field conditions. Considering the importance of PGPR biofilm formation in growth promotion and biocontrol activities, we hypothesized that this phenomenon may be related to inhibition of biofilm formation. In vitro experiments showed that biofilm-formation ability of WP8 was inhibited by both RA2 cells and filtered supernatants collected from RA2 cultures at 12 h (RA2-12) rather than 48 h (RA2-48), even at high-temperatures (within 100°C). An in vivo experiment derived from crystal violet staining yielded similar results. Using liquid chromatography-mass spectrometry (LC-MS), we compared primary and secondary metabolites of RA2 (namely RA2-12 and RA2-48) and found D-glutamine, abundant in RA2-12, as the putative inhibitory factor. Trace amounts of jasmonic acid together with viscous extracellular polysaccharides in RA2-48 likely promoted the rescue of robust biofilm formation. This work suggests that inhibition of biofilm formation should be considered in PGPR mixture development.

Effects of calcium carbonate on the survival of Ralstonia solanacearum in soil and control of tobacco bacterial wilt

The effects of Calcium carbonate (CaCO3) on the survival of Ralstonia solanacearum in the laboratory and on the control of bacterial wilt in the field were investigated. In the laboratory, the influences of pH and Ca2+ on bacteria were studied as well. The laboratory results showed that soils treated with CaCO3 particles (0 ~ 1 mm) significantly inhibited the survival of R. solanacearum and increased the pH by approximately 1.5 units as compared to the control. For the growth of R. solanacearum, the suitable pH range was 6.0 ~ 7.0 with pH = 6.5 being the optimal. The results of CaCl2 and NaCl showed that the growth of R. solanacearum was significantly inhibited by Ca2+ instead of Cl−. With increase of Ca2+ concentration, the pectinase activity decreased pronouncedly, while there were no obvious effects on the production of extracellular polysaccharide. The field results indicated that CaCO3 reduced disease incidence. Treatment with organic fertilizer and CaCO3 increased soil pH and lowered the R. solanacearum population nearly 100 times and increased the Ca2+ content in tobacco significantly compared to treatments without CaCO3. It is suggested that CaCO3 could serve as a potential soil amendment for the control of bacterial wilt caused by R. solanacearum.

Effect of selected essential oil plants on bacterial wilt disease development in potatoes

Objective: Bacterial wilt disease caused by Ralstonia solanacearum is a major constrain to production of potatoes (Solanum tuberosum). Control of bacterial wilt is very difficult as there are no effective curative chemicals. This study was aimed at investigating the potential roles of essential oil plants in control of the disease. Methodology and Result: The plants used included: Lippie javanica (Sage brush), Ocimum suave (Cambodia) and Tarchonanthus camphorates (Camphor brush).Experiments were conducted with potatoes grown in greenhouse condition. Freshly harvested leaves, stems and flowers from L. javanica, O. suave and T. camphorates were chopped into small portions that were soaked in water for one hour then applied in the inoculated experimental plots. Each plot was planted with disease-free potato tubers and disease development observed and recorded for a period of two months. Plots treated with T. camphorates had significantly low bacterial wilt incidence (P< 0.05) having been reduced by more than 90%.Treatment with the other two plants, O. suave and L. javanica reduced the disease by 38% and 21% respectively and were not significantly different from untreated plots. Conclusion and Application of Results: This finding shows that use of essential oils isa potential approach to bacterial wilt disease management. It can be concluded that essential oils plants possess antibacterial activity that is effective in control of R. solanacearum. Application of these essential oils can volatilize with increase of temperature. The application can be done by burying chopped essential oil plant parts in the soil during the time of land preparation just before planting. Further studies on the mode of action of these essential oils particularly those of T. comphrates in the control of R. solanacearum are suggested.Keywords: Essential oil plants; Potatoes; Ralstonia solanacearum; Wilt incidence

Effect of selected essential oil plants on bacterial wilt disease development in potatoes

Objective: Bacterial wilt disease caused by Ralstonia solanacearum is a major constrain to production of potatoes (Solanum tuberosum). Control of bacterial wilt is very difficult as there are no effective curative chemicals. This study was aimed at investigating the potential roles of essential oil plants in control of the disease. Methodology and Result: The plants used included: Lippie javanica (Sage brush), Ocimum suave (Cambodia) and Tarchonanthus camphorates (Camphor brush).Experiments were conducted with potatoes grown in greenhouse condition. Freshly harvested leaves, stems and flowers from L. javanica, O. suave and T. camphorates were chopped into small portions that were soaked in water for one hour then applied in the inoculated experimental plots. Each plot was planted with disease-free potato tubers and disease development observed and recorded for a period of two months. Plots treated with T. camphorates had significantly low bacterial wilt incidence (P< 0.05) having been reduced by more than 90%.Treatment with the other two plants, O. suave and L. javanica reduced the disease by 38% and 21% respectively and were not significantly different from untreated plots. Conclusion and Application of Results: This finding shows that use of essential oils isa potential approach to bacterial wilt disease management. It can be concluded that essential oils plants possess antibacterial activity that is effective in control of R. solanacearum. Application of these essential oils can volatilize with increase of temperature. The application can be done by burying chopped essential oil plant parts in the soil during the time of land preparation just before planting. Further studies on the mode of action of these essential oils particularly those of T. comphrates in the control of R. solanacearum are suggested.Keywords: Essential oil plants; Potatoes; Ralstonia solanacearum; Wilt incidence

Ácidos orgânicos no controle da murcha bacteriana do pimentão

The effect of disinfectant organic acids on the control of bacterial wilt of sweet pepper (Capsicum annuum L.) caused by Ralstonia solanacearum (Smith) Yabuuchi et al. was evaluated. The in vitro sensitivity of bacteria to the ascorbic, citric and lactic (0.25, 0.5, 1, 2.5, 5 and 10%) acids and the stable mixture of the ascorbic (1%), citric (0.475%) and lactic (0.475%) acids (0.4, 0.8, 2.5, 5, 10 and 100%) (v/v) was evaluated. After the phytotoxicity test the 0.8% stable mixture and ascorbic, citric and lactic acids 1% were selected and tested for bacterial wilt severity reduction, by root immersion or shoot spraying. The pathogen was inoculated by wounding roots and deposition of the inoculum. In vitro, R. solanacearum showed high sensitivity to lactic acid 10% and medium sensitivity to lactic acid (5 and 2.5%), ascorbic and citric acids 10% and stable mixture 100%. All treatments applied by root immersion significantly increased the incubation period (IP) and reduced the area under the disease progress curve (AUDPC), mainly lactic acid 1% (100%). The citric and lactic acids 1% and stable mixture 0.8% also increased IP and reduced AUDPC until 46.1% when applied by shoot spraying.

Tomato plant growth promotion and antibacterial related-mechanisms of four rhizobacterial Bacillus strains against Ralstonia solanacearum

Bacillus strains are extensively studied for their beneficial role in plant growth and biological control of tomato bacterial wilt (TBW), however their underlying mechanisms remained unexplored. In this study, four rhizobacterial strains, Bacillus amyloliquefaciens D29, B. amyloliquefaciens Am1, B. subtilis D16 and B. methylotrophicus H8 were investigated for their antibacterial activity against (TBW) pathogen and their ability to stimulate Tomato growth. Results revealed that all four strains were able to form robust biofilm, produce Indole acetic acid (IAA) and siderophores, while only D29, Am1 and H8 have capability to solubilize phosphate. The culture filtrate of each strain significantly suppressed the growth and biofilm of Ralstonia solanacearum, where, the cell wall was severely disrupted, which resulted into cell lysis and subsequent leakage of intracellular cytosolic contents. PCR analysis revealed that all four strains are harboring the antimicrobial associated genes for biosynthesis of Bacyllomicin, Fengycin, Iturin, Surfactin and Bacylisin. Subsequent real-time qPCR analysis revealed that the expression of ituC and srfAA genes in Am1 and D16 was remarkably up-regulated during in vitro interaction with R. solanacearum. This suggest that the potential antibacterial and anti-biofilm related mechanisms are associated to their ability to secret the corresponding lipopeptides in surrounding niche. In greenhouse, a positive correlation (0.777 and 0.686) was noted between the IAA amount produced by Bacillus strains and fresh/dry weight of bacterized tomato plants. This the first report demonstrated the mode of antibacterial effect of Bacillus strains against R. solanacearum, moreover this study will help in understanding the mode of action of Bacillus strains during biological management of TBW and promoting the growth of tomato plants.

Effects of bio-organic fertilizer plus soil amendment on the control of tobacco bacterial wilt and composition of soil bacterial communities

Tobacco bacterial wilt (TBW) is caused by Ralstonia solanacearum (R. solanacearum), a severe pathogenic agent with a wide host range. In this study, lime + ammonium bicarbonate (L + AB), organic fertilizer (OF), bio-organic fertilizer (BOF), and integrated treatment (L + AB + BOF) were assessed for the ability to control TBW and to influence the composition of native soil bacterial communities. The results showed that disease incidence of L + AB + BOF for two growth seasons in pot experiment was the lowest, with only 15.56 and 11.11 % at seasons 1 and 2, respectively. The integrated treatment could also significantly suppress TBW in the field, with a disease incidence of only 14.27 % compared with 35.41, 50.03, and 31.32 % in L + AB, OF, and BOF treatments, respectively. With application of the integrated treatment in pot and field experiments, the abundances of R. solanacearum were both significantly lower than those with other treatments. Denaturing gradient gel electrophoresis (DGGE) patterns showed that application of BOF significantly affected composition of bacterial communities of rhizosphere. The analysis of 454 sequencing data showed that application of integrated treatment recruited more beneficial bacteria than other treatments, such as Bacillus, Paenibacillus, Arthrobacter, and Streptomyces, while the abundance of Ralstonia with the integrated treatment was decreased. Overall, these results suggested that application of integrated agricultural management could effectively suppress bacterial wilt by affecting the composition of bacterial community and reducing the population of R. solanacearum.

Isolation of Bacillus amyloliquefaciens S20 and its application in control of eggplant bacterial wilt

Bacterial strain S20 was isolated and identified as Bacillus amyloliquefaciens based on physiological and biochemical characteristics and a 16S rRNA gene sequence analysis. Strain S20 inhibits the growth of Fusarium oxysporum and Ralstonia solanacearum. Some genes associated with the synthesis of some lipopeptides were detected in strain S20 by PCR. Iturins A were identified as the main antagonistic substrates by analysis with electrospray ionization mass spectrometry/collision-induced dissociation (ESI-MS/CID). Four homologues of iturin A (C13–C16) were identified. Pot experiments showed that the application of strain S20 alone could control eggplant wilt with an efficacy of 25.3% during a 40 day experiment. If strain S20 was used with organic fertilizer, the control efficacy against eggplant wilt reached as high as 70.7%. The application of organic fertilizer alone promotes the growth of R. solanacearum, resulting in a higher wilt incidence than that observed in control plants. The application of strain S20 effectively inhibits R. solanacearum in the rhizosphere soil of eggplant. The combined use of strain S20 and organic fertilizer more effectively controlled R. solanacearum in soil than the use of strain S20 alone. The soil count of strain S20 decreased gradually during the course of the experiment after inoculation. Organic fertilizer was beneficial for the survival of the antagonistic bacterial strain S20; a higher level of these bacteria could be maintained. The application of organic fertilizer with strain S20 increased bacterial diversity in rhizosphere soil.