Characterization of fungal antagonistic bacilli isolated from aerial roots of banyan (Ficus benghalensis ) using intact-cell MALDI-TOF mass spectrometry (ICMS)

Isolation and identification of endophytic bacteria and associated compound from Gloriosa superba and their antibacterial activities

Gloriosa superba L., which belongs to the genus Gloriosa and family Colchicaceae, is a climbing annual herb and tuberous poisonous tropical medicinal plant. This study was aimed to isolate possible endophytic bacteria from leaves, stems and tubers of Gloriosa superba. Thirty pure endophytic bacteria were isolated and subjected to biochemical characterization. Bacterial identification was conducted by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The structure of the isolated compound was characterized. The antibacterial activity was also evaluated. Majority (21, 70 %) of the isolates were Gram-positive. Certain of them are spore formers. Based on MALDI-TOF MS, 26 of the isolates were identified as Bacillus spp. (65.4 %), Escherichia spp. (30.8 %) and Providencia spp. (3.9 %). A 1-undecene was isolated from culture filtrate of E. coli (GST-5). The ethyl acetate extracts (1000 μg/mL) of GSL-5 and GST-2 culture filtrates recorded maximum inhibition zone against E. coli (9.4 ± 0.6 mm) and S. aurous ATCC 25923T (8.4 ± 0.8 mm), respectively. The Pseudomonas aeruginosa ATCC 27853T was prone to all ethyl acetate extracts. A 1-undecene showed a moderate activity against E. coli ATCC 25922Tand P. aeruginosa ATCC 27853T at 50 μg/mL. The present finding would be a breakthrough to studies of similar works in Ethiopia since it may be for the first time.

Mustard seed–associated endophytes suppress Sclerotinia sclerotiorum causing Sclerotinia rot in mustard crop

Mustard-rapeseed cultivation is affected by Sclerotinia sclerotiorum resulting in loss of oil yield and degradation of crop quality. This study adopted an environment friendly biocontrol approach of screening mustard endophytes against the pathogen. Two bacterial isolates, Bacillus safensis (TS46 bac4) and Bacillus australimaris (SM2) showed potential biocontrol activity under both in vitro and in vivo conditions. Dual culture assay reported 90% inhibition of fungal growth. The bacterial cell free supernatant of isolate SM2 showed 52.89% inhibition and the other isolate TS46 bac4 showed 57.97% inhibition. The crude (10 mg/ml) and purified (10 mg/ml) metabolite extract of SM2 showed 100% and 97% inhibition respectively. Both crude (10 mg/ml) and purified (7.5 mg/ml) metabolite extract of TS46 bac4 exhibited 99% inhibition of the pathogen. Antifungal lipopeptides: surfactin, iturin and fengycin were identified in bacterial metabolite extract of the isolates. Both strains promoted healthy germination and prevented the formation of any disease symptoms in seedling. The selected Bacillus strains applied by spray method showed better results against fungal infection on mustard leaf and stem. Microscopic studies revealed degradation of fungal mycelial growth by both isolates. These findings support the employment of the bacterial strains as potential biocontrol agents to reduce the effects of S. sclerotiorum in mustard-rapeseed.

Bacillus spp.-Mediated Growth Promotion of Rice Seedlings and Suppression of Bacterial Blight Disease under Greenhouse Conditions

Rice (Oryza sativa L.) is a major cereal and staple food crop worldwide, and its growth and production are affected by several fungal and bacterial phytopathogens. Bacterial blight (BB) is one of the world's most devastating rice diseases, caused by Xanthomonas oryzae pv. oryzae (Xoo). In the current study, Bacillus atrophaeus FA12 and B. cabrialesii FA26 were isolated from the rice rhizosphere and characterized as having broad-range antifungal and antibacterial activities against various phytopathogens, including Xoo. In addition, the selected strains were further evaluated for their potent rice growth promotion and suppression efficacy against BB under greenhouse conditions. The result shows that FA12 and FA26, applied as seed inoculants, significantly enhanced the vigor index of rice seedlings by 78.89% and 108.70%, respectively. Suppression efficacy against BB disease by FA12 and FA26 reached up to 59.74% and 54.70%, respectively, in pot experiments. Furthermore, MALDI-TOF MS analysis of selected strains revealed the masses ranged from m/z 1040 to 1540, representing that iturins and fengycin are the major antimicrobial compounds in the crude extracts, which might have beneficial roles in rice defence responses against BB. In conclusion, FA12 and FA26 possess broad-range antagonistic activity and have the capability to promote plant growth traits. More importantly, applying these strains has a high potential for implementing eco-friendly, cost-effective, and sustainable management practices for BB disease.

Investigating plant-microbe interactions within the root

A diverse lineage of microorganisms inhabits plant roots and interacts with plants in various ways. Further, these microbes communicate and interact with each other within the root microbial community. These symbioses add an array of influences, such as plant growth promotion or indirect protection to the host plant. Omics technology and genetic manipulation have been applied to unravel these interactions. Recent studies probed plants' control over microbes. However, the activity of the root microbial community under host influence has not been elucidated enough. In this mini-review, we discussed the recent advances and limits of omics technology and genetics for dissecting the activity of the root-associated microbial community. These materials may help us formulate the correct experimental plans to capture the entire molecular mechanisms of the plant-microbe interaction.

Genome analysis uncovers the prolific antagonistic and plant growth-promoting potential of endophyte Bacillus velezensis K1

Insights into the application of endophytic bacilli in sustainable agricultural practices have opened up new avenues for the inhibition of soil-borne pathogens and the improvement of plant health. Bacillus subtilis K1, an endophytic bacterium originally isolated from aerial roots of Ficus benghalensis is a potential biocontrol agent secreting a mixture of surfactins, iturins and fengycins. The current study extends the characterization of this bacterium through genomic and comparative genomics approaches. The sequencing of the bacterial genome at Illumina MiSeq platform revealed that it possessed a 4,103,502-bp circular chromosome with 45.98% GC content and 4325 predicted protein-coding sequences. Based on phylogenomics and whole-genome average nucleotide identity, the B. subtilis K1 was taxonomically classified as Bacillus velezensis. The formerly evaluated phenotypic traits viz. C-source utilization and lipopeptide-mediated fungal antagonism were correlated to their molecular determinants. The genome also harbored several genes associated with induced systemic resistance and plant growth promotion i.e, phytohormone production, nitrogen assimilation and reduction, siderophore production, phosphate solubilization, biofilm formation, swarming motility, acetoin and butanediol synthesis. The production of antifungal volatile organic compounds and plant growth promotion was experimentally demonstrated by volatile compound assay and seed germination assay on cumin and groundnut. The isolate also holds great prospects for application as a soil inoculant as indicated by enhancement in the growth of groundnut via in planta pot studies. Bacterial pan-genome analysis based on a comparison of whole genomes with eighteen other Bacillus strains was also conducted. Comparative examination of biosynthetic gene clusters across all genomes indicated that the largest number of gene clusters were harbored by the K1 genome. Based on the findings, we propose K1 as a model for scrutinizing non-ribosomally synthesized peptide synthetase and polyketide synthetase derived molecules.

Metabolomics as an emerging tool to study plant-microbe interactions

In natural environments, interaction between plant roots and microorganisms are common. These interactions between microbial species and plants inhabited by them are being studied using various techniques. Metabolomics research based on mass spectrometric techniques is one of the crucial approaches that underpins system biology and relies on precision instrument analysis. In the last decade, this emerging field has received extensive attention. It provides a qualitative and quantitative approach for determining the mechanisms of symbiosis of bacteria and fungi with plants and also helps to elucidate the tolerance mechanisms of host plants against various abiotic stresses. However, this -omics application and its tools in plant-microbe interaction studies is still underutilized compared with genomic and transcriptomic methods. Therefore, it is crucial to bring this field forward to bear on the study of plant resistance and susceptibility. This review describes the current status of methods and progress in metabolomics applications for plant-microbe interaction studies discussing current challenges and future prospects.

Biosynthesis of Silver Chloride Nanoparticles by Rhizospheric Bacteria and Their Antibacterial Activity against Phytopathogenic Bacterium Ralstonia solanacearum

Ralstonia solanacearum is the most destructive pathogen, causing bacterial wilt disease of eggplant. The present study aimed to develop green synthesis and characterization of silver chloride nanoparticles (AgCl-NPs) by using a native bacterial strain and subsequent evaluation of their antibacterial activity against R. solanacearum. Here, a total of 10 bacterial strains were selected for the biosynthesis of AgCl-NPs. Among them, the highest yield occurred in the synthesis of AgCl-NPs using a cell-free aqueous filtrate of strain IMA13. Ultrastructural observation revealed that the AgCl-NPs were spherical and oval with smooth surfaces and 5-35 nm sizes. XRD analysis studies revealed that these particles contained face-centered cubic crystallites of metallic Ag and AgCl. Moreover, FTIR analysis showed the presence of capping proteins, carbohydrates, lipids, and lipopeptide compounds and crystalline structure of AgCl-NPs. On the basis of phylogenetic analysis using a combination of six gene sequences (16S, gyrA, rpoB, purH, polC, and groEL), we identified strain IMA13 as Bacillus mojavensis. Three kinds of lipopeptide compounds, namely, bacillomycin D, iturin, and fengycin, forming cell-free supernatant produced by strain IAM13, were identified by MALDI-TOF mass spectrometry. Biogenic AgCl-NPs showed substantial antibacterial activity against R. solanacearum at a concentration of 20 µg/mL-1. Motility assays showed that the AgCl-NPs significantly inhibited the swarming and swimming motility (61.4 and 55.8%) against R. solanacearum. Moreover, SEM and TEM analysis showed that direct interaction of AgCl-NPs with bacterial cells caused rupture of cell wall and cytoplasmic membranes, as well as leakage of nucleic acid materials, which ultimately resulted in the death of R. solanacearum. Overall, these findings will help in developing a promising nanopesticide against phytopathogen plant disease management.

Genomic characterization and production of antimicrobial lipopeptides by Bacillus velezensis P45 growing on feather by-products

AIMS

To investigate the potential of novel Bacillus velezensis P45 as an eco-friendly alternative for bioprocessing poultry by-products into valuable antimicrobial products.

METHODS AND RESULTS

The complete genome of B. velezensis P45 was sequenced using the Illumina MiSeq platform, showing 4455 protein and 98 RNA coding sequences according to the annotation on the RAST server. Moreover, the genome contains eight gene clusters for the production of antimicrobial secondary metabolites and 25 putative protease-related genes, which can be related to feather-degrading activity. Then, in vitro tests were performed to determine the production of antimicrobial compounds using feather, feather meal and brain-heart infusion (BHI) cultures. Antimicrobial activity was observed in feather meal and BHI media, reaching 800 and 3200 AU ml^-1 against Listeria monocytogenes respectively. Mass spectrometry analysis indicates the production of antimicrobial lipopeptides surfactin, fengycin and iturin.

CONCLUSIONS

The biotechnological potential of B. velezensis P45 was deciphered through genome analysis and in vitro studies. This strain produced antimicrobial lipopeptides growing on feather meal, a low-cost substrate.

SIGNIFICANCE AND IMPACT OF STUDY

The production of antimicrobial peptides by this keratinolytic strain may represent a sustainable alternative for recycling by-products from poultry industry. Furthermore, whole B. velezensis P45 genome sequence was obtained and deposited.

Unravel the Local Complexity of Biological Environments by MALDI Mass Spectrometry Imaging

Classic metabolomic methods have proven to be very useful to study functional biology and variation in the chemical composition of different tissues. However, they do not provide any information in terms of spatial localization within fine structures. Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) does and reaches at best a spatial resolution of 0.25 μm depending on the laser setup, making it a very powerful tool to analyze the local complexity of biological samples at the cellular level. Here, we intend to give an overview of the diversity of the molecules and localizations analyzed using this method as well as to update on the latest adaptations made to circumvent the complexity of samples. MALDI MSI has been widely used in medical sciences and is now developing in research areas as diverse as entomology, microbiology, plant biology, and plant–microbe interactions, the rhizobia symbiosis being the most exhaustively described so far. Those are the fields of interest on which we will focus to demonstrate MALDI MSI strengths in characterizing the spatial distributions of metabolites, lipids, and peptides in relation to biological questions.

Efficacy of bioinoculants to control of bacterial and fungal diseases of rice (Oryza sativa L.) in northwestern Himalaya

INTRODUCTION

Biological control holds great promise for environmentally friendly and sustainable management of the phytopathogens. The multi-function features of plant growth-promoting rhizobacteria (PGPR) enable to protect the plants from disease infections by replacing the chemical inputs. The interaction between the plant root exudates and the microbes stimulates the production of secondary metabolism and enzymes and induces systemic resistance in the plants.

AIM

The aim was to identify the potential PGPR which would show an antagonistic effect against basmati rice fungal and bacterial diseases.

METHODS

In the study, native originating microbes have been isolated, characterized using 16S rRNA sequencing, and used as potential antagonistic microbial isolates against diseases of rice plants.

RESULTS

Rhizobacteria isolated from rhizosphere, endo-rhizosphere, and bulk soil samples of Basmati 370 exhibited promising inhibitory activity against rice pathogens. Molecular characterization of bacterial isolates based on 16S rRNA sequencing classified the bacterial isolates into different genera such as Bacillus, Pseudomonas, Streptomyces, Exiguobacterium, Aeromonas, Chryseobacterium, Enterobacter, and Stenotrophomonas. PGPRs exhibited biocontrol activities against various rice diseases like bacterial leaf blight, leaf blast, brown spot, and sheath blight and boost the plant growth traits.

CONCLUSION

In the study, the potentially identified PGPRs isolates could be used as efficient bioinoculants as bio-fertilizers and biocontrol agents for sustainable rice crop production.

Detection of simultaneous production of kurstakin, fengycin and surfactin lipopeptides in Bacillus mojavensis using a novel gel-based method and MALDI-TOF spectrometry

Bacterial lipopeptides have become a research focus of many studies owing to their industrial and pharmaceutical importance. Although such studies focused on researching purification procedures and qualitative analysis, much remains to be explored and developed to improve the current methods. To enable thorough studies of lipopeptides, this paper describes a new method for purification and characterization of in-gel anionic lipopeptides. Specifically, lipopeptides attributed to the anti-staphylococcal activity of Bacillus mojavensis HF were separated using SDS-PAGE (sodium dodecyl sulphate-polyacrylamide gel electrophoresis) and subsequently characterized using mass spectrometry. Lipopeptide band obtained by gel electrophoresis was first visualized using three different staining methods. Next, the lipopeptide isomers were efficiently recovered from the gel band and structural characterization of the extracted lipopeptides was carried out by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). MS analysis revealed that Bacillus mojavensis HF produced three types of lipopeptides including surfactin, fengycin, and kurstakin. 14 clusters of ion peaks were identified as fengycin A with fatty acid of C15-C17, fengycin B (C16, C17), surfactin (C13-C16), and kurstakin (C9-C12). Moreover, tandem mass spectrometric analysis (MS/MS) revealed the sequences of fengycin A and surfactin. In this study, we identified a high variety and number of surfactin and fengycin isomers, which previous reports lacked. To the best of our knowledge, we are the first to report the presence of kurstakin in Bacillus mojavensis species. Finally, we demonstrated that our gel-based study of lipopeptides allowed for a precise and reproducible investigation of these molecules.

Antifungal potential against Sclerotinia sclerotiorum (Lib.) de Bary and plant growth promoting abilities of Bacillus isolates from canola (Brassica napus L.) roots

Endophytic bacteria show important abilities in promoting plant growth and suppressing phytopathogens, being largely explored in agriculture as biofertilizers or biocontrol agents. Bacteria from canola roots were isolated and screened for different plant growth promotion (PGP) traits and biocontrol of Sclerotinia sclerotiorum. Thirty isolates belonging to Bacillus, Paenibacillus, Lysinibacillus, and Microbacterium genera were obtained. Several isolates produced auxin, siderophores, hydrolytic enzymes, fixed nitrogen and solubilized phosphate. Five isolates presented antifungal activity against S. sclerotiorum by the dual culture assay and four of them also inhibited fungal growth by volatile organic compounds production. All antagonistic isolates belonged to the Bacillus genus, and had their genomes sequenced for the search of biosynthetic gene clusters (BGC) related to antimicrobial metabolites. These isolates were identified as Bacillus safensis (3), Bacillus pumilus (1), and Bacillus megaterium (1), using the genomic metrics ANI and dDDH. Most strains showed several common BGCs, including bacteriocin, polyketide synthase (PKS), and non-ribosomal peptide synthetase (NRPS), related to pumilacidin, bacillibactin, bacilysin, and other antimicrobial compounds. Pumilacidin-related mass peaks were detected in acid precipitation extracts through MALDI-TOF analysis. The genomic features demonstrated the potential of these isolates in the suppression of plant pathogens; however, some aspects of plant-bacterial interactions remain to be elucidated.

Multifarious allelochemicals exhibiting antifungal activity from Bacillus subtilis MBCU5

A potential antagonist, designated strain Bacillus subtilis MBCU5 was previously isolated from vermicompost-amended soils of Gandhinagar, Gujarat, India. Crude allelochemicals from strain MBCU5 displayed strong antifungal activity against Macrophomina phaseolina as well as Rhizoctonia solani. These crude allelochemicals were tentatively identified as iturin, fengycin and surfactin through TLC and HPTLC analysis. Lipopeptides produced by MBCU5 were identified by MALDI-TOF-MS and LC-ESI-MS/MS analysis showed that iturin homologues (m/z 1020-1120), surfactin (m/z 1008.7 and m/z 1022.7), fengycin A and fengycin B (m/z 1400-1550) types of allelochemicals which are responsible for antifungal activity against pathogens. PCR analysis showed presence of genes (i.e. Iturin A synthetase KJ531680 and Surfactin synthetase KJ601726) involved in the biosynthesis of allelochemicals. Many reports showed lipopeptides from Bacillus species; this is the first report executed of multifarious allelochemicals from vermicompost-amended soil due to the presence of predominant Bacillus species.

Effect of root-extracts of Ficus benghalensis (Banyan) in memory, anxiety, muscle co-ordination and seizure in animal models

Background

Ficus benghalensis L. (Banyan) is a commonly found tree in Eastern Nepal. Its different plant parts are used for various neurological ailments. This study was performed in mice to see its effects in various neuropharmacological parameters.

Methods

Passive-avoidance (memory), Open-field (anxiety), Pentobarbital-induced Sleep potentiation (sleep), Rota-rod (muscle-co-ordination), Pentylenetetrazol-Induced and Maximal Electroshock Seizure Tests were performed. Sample size was calculated using G*Power 3.1.9.2. Aqueous root extracts (Soxhlet method) of Ficus benghalensis 100 mg/kg and 200 mg/kg with negative and positive controls were used. The experimental results were represented as Mean ± SD. P-value was set at <0.05. Oneway analysis of variance (ANOVA) or Mann-Whitney U test was appropriately used.

Results

Passive-avoidance test showed 200 mg/kg group spent significantly less. Time (0.00s + 0.00s) in shock-zone than Normal Saline-group (9.67 s + 14.36 s, P = 0.000) or Diazepam-group (41.07 s + 88.24 s, P = 0.000).

Open-field test showed 200 mg/kg group spent significantly longer Time (24.77 s + 12.23 s) in central-square than either Normal Saline group (15.08 s + 6.81 s, P = 0.000) or Diazepam-group (15.32 s + 5.12 s, P = 0.000).

In Rota-rod test, 200 mg/kg group fell off the rod significantly (P = 0.000) earlier (33.01 s + 43.61 s) than both Normal Saline (>120 s) and Diazepam (62.07 s + 43.83 s) PTZ model showed that 100 mg/kg significantly (P = 0.004) delayed seizure-onset (184.40s + 36.36 s) compared to Normal Saline (101.79 s + 22.81 s), however, in MES model 200 mg/kg significantly (P = 0.000) prolonged tonic hind-limb extension (17.57 s + 2.15 s) compared to Normal Saline (13.55 s + 2.75 s) or Phenytoin (00.00s + 00.00s).

Conclusion

Aerial roots of Ficus benghalensis have memory-enhancing, anxiolytic, musclerelaxant, and seizure-modifying effect.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1413-5) contains supplementary material, which is available to authorized users.

Rapid differentiation of in vitro cellular responses to toxic chemicals by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Changes in protein expression as a cellular response to chemical exposure have been well established. Current methods for monitoring cellular responses usually require the use of specific reagents and/or labor-intensive procedures. The present study demonstrates the concept of using mass spectral pattern to distinguish different cellular responses. The concept is based on the ability to acquire a unique mass spectral pattern directly from a specific cell culture by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The results demonstrate that distinguishable and reproducible spectral patterns can be obtained from different cellular responses.

Isolation and identification of allelochemicals produced by B. sonorensis for suppression of charcoal rot of Arachis hypogaea L

Bacillus sonorensis MBCU2 isolated from vermicompost-amended soil from Gujarat, India showed most antagonistic activity against Macrophomina phaseolina by dual culture screening. The culture supernatant of MBCU2 completely suppressed the mycelia growth of pathogen, indicating that suppression was due to the presence of allelochemicals in the culture filtrate. Results of scanning electron microscopy revealed that MBCU2 caused morphological alteration in mycelia of M. phaseolina as evident by hyphal lysis and perforation. Lipopeptides (iturin A and surfactin) produced by MBCU2 were detected and identified by MALDI-TOF-MS as well as liquid chromatography coupled with ESI-MS/MS. Pot trial studies conducted by seed bacterization with MBCU2 resulted in statistically significant increase in Arachis hypogaea L. vegetative growth parameters such as root length (91%), shoot length (252%), fresh weight (71%), dry weight (57%), number of pod (128%), and number of seed (290%) in M. phaseolina infested soil over control as well as decreased M. phaseolina disease severity. We suggest that allelochemicals production can be linked to the mechanism of protection of A. hypogaea L. from M. phaseolina by B. sonorensis MBCU2.

The bacterial lipopeptide iturins induce Verticillium dahliae cell death by affecting fungal signalling pathways and mediate plant defence responses involved in pathogen-associated molecular pattern-triggered immunity

Verticillium wilt in cotton caused by Verticillium dahliae is one of the most serious plant diseases worldwide. Because no known fungicides or cotton cultivars provide sufficient protection against this pathogen, V. dahliae causes major crop yield losses. Here, an isolated cotton endophytic bacterium, designated Bacillus amyloliquefaciens 41B-1, exhibited greater than 50% biocontrol efficacy against V. dahliae in cotton plants under greenhouse conditions. Through high-performance liquid chromatography and mass analysis of the filtrate, we found that the antifungal compounds present in the strain 41B-1 culture filtrate were a series of isoforms of iturins. The purified iturins suppressed V. dahliae microsclerotial germination in the absence or presence of cotton. Treatment with the iturins induced reactive oxygen species bursts, Hog1 mitogen-activated protein kinase (MAPK) activation and defects in cell wall integrity. The oxidative stress response and high-osmolarity glycerol pathway contribute to iturins resistance in V. dahliae. In contrast, the Slt2 MAPK pathway may be involved in iturins sensitivity in this fungus. In addition to antagonism, iturins could induce plant defence responses as activators and mediate pathogen-associated molecular pattern-triggered immunity. These findings suggest that iturins may affect fungal signalling pathways and mediate plant defence responses against V. dahliae.

Enhancement of Biocontrol Activities and Cyclic Lipopeptides Production by Chemical Mutagenesis of Bacillus subtilis XF-1, a Biocontrol Agent of Plasmodiophora brassicae and Fusarium solani

Bacillus subtilis XF-1 has been used as a biocontrol agent of clubroot disease of crucifers infected by Plasmodiophora brassicae, an obligate pathogen. In order to maximize the growth inhibition of the pathogen, random mutagenesis using N-methyl-N'-nitro-N-nitrosoguanidine was applied to strain XF-1. The efficacy of 226 selected mutants was assessed against the growth of an indicator fungal pathogen: Fusarium solani using agar plate assay and the disruptive effects on the resting spores of P. brassicae. Four mutants exhibited inhibition activity significantly higher than the wild type. The cell extracts of these mutants and the XF-1 were subjected to matrix-assisted laser desorption ionization-time of flight mass spectra analysis, and three families of cyclic lipopeptides (CLPs) fengycin, surfactin and iturin were identified from the parental strain and the screened mutants. However, the relative contents and compound diversity changed after mutagenesis, and there was slight variation in the surfactin and fengycin. Notably, only 5 iturin components were discovered from the wild strain XF-1, but 13 were obtained from the mutant strains, and the relative CLPs contents of all mutant strains increased substantially. The results suggested that CLPs might be one of main biocontrol mechanisms of the clubroot disease by XF-1. The 4 mutants are far more effective than the parental strain, and they would be promising biocontrol candidates not only against P. brassicae but probably other plant diseases caused by fungi.