Bacillus subtilis RB14 was used as an antagonist against fungal pathogen Rhizoctonia solani K1 to control damping-off diseases in tomato plants. Tomato seeds were treated with B. subtilis RB14 culture. The concentrati...Bacillus subtilis RB14 was used as an antagonist against fungal pathogen Rhizoctonia solani K1 to control damping-off diseases in tomato plants. Tomato seeds were treated with B. subtilis RB14 culture. The concentration of bacterial cells for the treatment was about 10<sup>8</sup> cfu/ml. Treated tomato seeds showed 99% germination index similar to the untreated seeds. Scanning Electron Microscopic observations showed a clear evidence of the presence of B. subtilis RB14 on tomato seed surface. Clear inhibition zone was observed using treated seed in dual plate assay against R. solani K1. B. subtilis RB14 treated seed showed 80% reduction in disease incidence during in vivo plant experiments. B. subtilis RB14 produces lipopeptide antifungal antibiotic iturin A which could suppress R. solani K1. The phenomenon was supported by our observation where we found significant amount of iturin A from the root zone soil of the seed treated plants.展开更多
The present study was conducted with an aim to scale up the production of iturin A using soybean curd residue (okara). Iturin A was produced by indigenous bacterial strain Bacillus subtilis RB14-CS through glass colum...The present study was conducted with an aim to scale up the production of iturin A using soybean curd residue (okara). Iturin A was produced by indigenous bacterial strain Bacillus subtilis RB14-CS through glass column reactor (GCR) under solid state fermentation (SSF) was characterized. The enhanced iturin A production was observed with respect to enhanced substrate bed height when SSF was conducted in Erlenmeyer flask. To check the effect of substrate bed height on iturin A production under SSF of okara, GCR was introduced. Substrate bed height of 15 cm was suitable for iturin A production which was about 2700 mg/kg wet substrate. The observed iturin A production by the aerobic bacteria Bacillus subtilis in nearly anaerobic condition in such high substrate bed for SSF is a wonderful finding for development of SSF system in future.展开更多
This study examined the inhibitory effects of Iturin A on food spoilage yeasts and tried to elucidate the underlying mechanisms of its action.Four yeast strains—Saccharomyces cerevisiae,Pichia kluyveri,Debaryomyces h...This study examined the inhibitory effects of Iturin A on food spoilage yeasts and tried to elucidate the underlying mechanisms of its action.Four yeast strains—Saccharomyces cerevisiae,Pichia kluyveri,Debaryomyces hansenii,and Cyberlindnera fabianii—were evaluated through inhibition zone diameters,minimum inhibitory concentration,and minimum fungicidal concentration.Iturin A effectively inhibited all four strains,with minimum inhibitory concentration,and minimum fungicidal concentration of 0.03 and 0.06 g/L,0.06 and 0.125 g/L,0.125 and 0.50 g/L,and 0.125 and 0.25 g/L,respectively.Cell permeability assays demonstrated that Iturin A increased membrane permeability,resulting in nucleic acid and protein leakage.Scanning electron microscopy altered cell morphology,suggesting membrane damage following Iturin A treatment.Non-targeted metabolomic analysis indicated that Iturin A exerts its antifungal effects through multiple mechanisms,including disruption of fatty acid and phospholipid profiles in the cell membrane,impairment of ion channels,and cell wall disruption via inhibition of glycosylphosphatidylinositol-anchored molecule synthesis.Additionally,Iturin A induced DNA damage,which prompted S.cerevisiae cells to enhance uridine 5′-diphosphate synthesis,promote cell wall and DNA synthesis,elevate DNA methylation,activate purine salvage pathway,promote DNA repair,and strengthen the tricarboxylic acid cycle to enhance energy production.These findings offer novel insights into the antifungal mechanisms of Iturin A and underscore its potential for controlling food spoilage.展开更多
The antimicrobial efficacy of silver nanoparticles(AgNPs)in food safety applications is increasingly compromised by rapid bacterial resistance evolution through virulence upregulation.A biofunctionalized nanohybrid(It...The antimicrobial efficacy of silver nanoparticles(AgNPs)in food safety applications is increasingly compromised by rapid bacterial resistance evolution through virulence upregulation.A biofunctionalized nanohybrid(Iturin A-AgNPs)was engineered to synergistically combine the amphiphilic lipopeptide iturin A with AgNPs to counteract resistance mechanisms in Escherichia coli(E.coli).Transcriptomic and phenotypic analyses revealed that PVP-AgNPs triggered bacterial adaptation via overexpression of outer membrane vesicle(OMV)biogenesis genes(e.g.,MlaA/C/E),flagellar assembly proteins(FliC/D/F/G/I),and suppression of energy metabolism(atpC/G/H).In contrast,Iturin A-AgNPs suppressed these resistance-driving pathways by(1)downregulating flagellar assembly proteins to impair bacterial motility,(2)breaking the“dormant mode”of reduced energy metabolism,and(3)overriding the PVP-AgNPs resistance phenotype mediated by Mla system upregulation.This multi-target mechanism effectively prevented the emergence of resistant phenotypes,as evidenced by a reduction in the minimum inhibitory concentration(MIC)against AgNPs-resistant E.coli.These findings highlight the potential of biofunctionalized nanohybrids to combat antimicrobial resistance through coordinated genetic and metabolic interference,offering a template for engineering next-generation antibacterial agents.展开更多
Biocontrol microorganisms and their derived metabolites with antagonistic activity represent promising alternatives to chemical fungicides in managing plant pathogens.The lipopeptides(LPs)iturin and fengycin derived f...Biocontrol microorganisms and their derived metabolites with antagonistic activity represent promising alternatives to chemical fungicides in managing plant pathogens.The lipopeptides(LPs)iturin and fengycin derived from Bacillus amyloliquefaciens S76-3 exhibit highly inhibitory effects against pathogenic fungi,especially Fusarium graminearum(Fg),the primary pathogen causing Fusarium head blight(FHB)in cereals.However,the specific target of iturin and fengycin in Fg and the underlying mechanism of antagonistic activity remain unclear.Here,global transcriptome sequencing,combined with both genetic and chemical approaches,demonstrates that the LPs exhibit antagonism toward Fg by binding to multiple components in the cell membrane of Fg cells,including ergosterol,phospholipids,glycosylphosphatidylinositol,and ankyrin.Lipopeptides result in cell swelling by inducing cell wall remodeling and osmotic substance glycerol synthesis mediated by cell wall integrity and high-osmolarity glycerol signaling pathways.Furthermore,we found that LPs can activate the induced systemic resistance in wheat against FHB and deoxynivalenol accumulation.Additionally,LPs were able to promote wheat growth by regulating auxin,cytokinin,and gibberellin signaling pathways while also delaying seed germination through the stimulation of abscisic acid and ethylene signaling pathways.These findings advance knowledge on the underlying mechanism of iturin and fengycin antagonistic activity and provide a new avenue for developing agricultural and clinical broad-spectrum antifungal agents and identifying plant growth regulators in the future.展开更多
文摘Bacillus subtilis RB14 was used as an antagonist against fungal pathogen Rhizoctonia solani K1 to control damping-off diseases in tomato plants. Tomato seeds were treated with B. subtilis RB14 culture. The concentration of bacterial cells for the treatment was about 10<sup>8</sup> cfu/ml. Treated tomato seeds showed 99% germination index similar to the untreated seeds. Scanning Electron Microscopic observations showed a clear evidence of the presence of B. subtilis RB14 on tomato seed surface. Clear inhibition zone was observed using treated seed in dual plate assay against R. solani K1. B. subtilis RB14 treated seed showed 80% reduction in disease incidence during in vivo plant experiments. B. subtilis RB14 produces lipopeptide antifungal antibiotic iturin A which could suppress R. solani K1. The phenomenon was supported by our observation where we found significant amount of iturin A from the root zone soil of the seed treated plants.
文摘The present study was conducted with an aim to scale up the production of iturin A using soybean curd residue (okara). Iturin A was produced by indigenous bacterial strain Bacillus subtilis RB14-CS through glass column reactor (GCR) under solid state fermentation (SSF) was characterized. The enhanced iturin A production was observed with respect to enhanced substrate bed height when SSF was conducted in Erlenmeyer flask. To check the effect of substrate bed height on iturin A production under SSF of okara, GCR was introduced. Substrate bed height of 15 cm was suitable for iturin A production which was about 2700 mg/kg wet substrate. The observed iturin A production by the aerobic bacteria Bacillus subtilis in nearly anaerobic condition in such high substrate bed for SSF is a wonderful finding for development of SSF system in future.
基金supported by the Natural Science Foundation of Sichuan Province(2022NSFSC1634)the Key Projects of Chengdu Institute of Biology,Chinese Academy of Sciences(QYJC2024-3)The Science and Technology Program of Sichuan Province(2022JDTD0027).
文摘This study examined the inhibitory effects of Iturin A on food spoilage yeasts and tried to elucidate the underlying mechanisms of its action.Four yeast strains—Saccharomyces cerevisiae,Pichia kluyveri,Debaryomyces hansenii,and Cyberlindnera fabianii—were evaluated through inhibition zone diameters,minimum inhibitory concentration,and minimum fungicidal concentration.Iturin A effectively inhibited all four strains,with minimum inhibitory concentration,and minimum fungicidal concentration of 0.03 and 0.06 g/L,0.06 and 0.125 g/L,0.125 and 0.50 g/L,and 0.125 and 0.25 g/L,respectively.Cell permeability assays demonstrated that Iturin A increased membrane permeability,resulting in nucleic acid and protein leakage.Scanning electron microscopy altered cell morphology,suggesting membrane damage following Iturin A treatment.Non-targeted metabolomic analysis indicated that Iturin A exerts its antifungal effects through multiple mechanisms,including disruption of fatty acid and phospholipid profiles in the cell membrane,impairment of ion channels,and cell wall disruption via inhibition of glycosylphosphatidylinositol-anchored molecule synthesis.Additionally,Iturin A induced DNA damage,which prompted S.cerevisiae cells to enhance uridine 5′-diphosphate synthesis,promote cell wall and DNA synthesis,elevate DNA methylation,activate purine salvage pathway,promote DNA repair,and strengthen the tricarboxylic acid cycle to enhance energy production.These findings offer novel insights into the antifungal mechanisms of Iturin A and underscore its potential for controlling food spoilage.
基金supported by National Natural Science Foundation of China(32172183,32302254).
文摘The antimicrobial efficacy of silver nanoparticles(AgNPs)in food safety applications is increasingly compromised by rapid bacterial resistance evolution through virulence upregulation.A biofunctionalized nanohybrid(Iturin A-AgNPs)was engineered to synergistically combine the amphiphilic lipopeptide iturin A with AgNPs to counteract resistance mechanisms in Escherichia coli(E.coli).Transcriptomic and phenotypic analyses revealed that PVP-AgNPs triggered bacterial adaptation via overexpression of outer membrane vesicle(OMV)biogenesis genes(e.g.,MlaA/C/E),flagellar assembly proteins(FliC/D/F/G/I),and suppression of energy metabolism(atpC/G/H).In contrast,Iturin A-AgNPs suppressed these resistance-driving pathways by(1)downregulating flagellar assembly proteins to impair bacterial motility,(2)breaking the“dormant mode”of reduced energy metabolism,and(3)overriding the PVP-AgNPs resistance phenotype mediated by Mla system upregulation.This multi-target mechanism effectively prevented the emergence of resistant phenotypes,as evidenced by a reduction in the minimum inhibitory concentration(MIC)against AgNPs-resistant E.coli.These findings highlight the potential of biofunctionalized nanohybrids to combat antimicrobial resistance through coordinated genetic and metabolic interference,offering a template for engineering next-generation antibacterial agents.
基金supported by grants from the National Key R&D Program of China(2022YFD1400102and 2018YFD02005)the National Natural Science Foundation of China(32272170 and 31271717)+1 种基金China Postdoctoral Science Foundation(2021M701348)Hubei Hongshan Laboratory(2022hspy010).
文摘Biocontrol microorganisms and their derived metabolites with antagonistic activity represent promising alternatives to chemical fungicides in managing plant pathogens.The lipopeptides(LPs)iturin and fengycin derived from Bacillus amyloliquefaciens S76-3 exhibit highly inhibitory effects against pathogenic fungi,especially Fusarium graminearum(Fg),the primary pathogen causing Fusarium head blight(FHB)in cereals.However,the specific target of iturin and fengycin in Fg and the underlying mechanism of antagonistic activity remain unclear.Here,global transcriptome sequencing,combined with both genetic and chemical approaches,demonstrates that the LPs exhibit antagonism toward Fg by binding to multiple components in the cell membrane of Fg cells,including ergosterol,phospholipids,glycosylphosphatidylinositol,and ankyrin.Lipopeptides result in cell swelling by inducing cell wall remodeling and osmotic substance glycerol synthesis mediated by cell wall integrity and high-osmolarity glycerol signaling pathways.Furthermore,we found that LPs can activate the induced systemic resistance in wheat against FHB and deoxynivalenol accumulation.Additionally,LPs were able to promote wheat growth by regulating auxin,cytokinin,and gibberellin signaling pathways while also delaying seed germination through the stimulation of abscisic acid and ethylene signaling pathways.These findings advance knowledge on the underlying mechanism of iturin and fengycin antagonistic activity and provide a new avenue for developing agricultural and clinical broad-spectrum antifungal agents and identifying plant growth regulators in the future.
