Lysozyme possesses unique biological properties and finds wide-ranging applications,but the adaptive responses of microorganisms under lysozyme stress remain poorly understood.In this study,we investigated the respons...Lysozyme possesses unique biological properties and finds wide-ranging applications,but the adaptive responses of microorganisms under lysozyme stress remain poorly understood.In this study,we investigated the response mechanisms of Dermacoccus abyssi HZAU 226 and Kocuria rhizophila H9,which with different lysozyme resistance.The results revealed similar regulatory mechanisms in two strains.D.abyssi demonstrated resistance to cationic activity and displayed typical growth curves,membrane permeability was concentration-dependent.Under 5 mg/mL lysozyme stress,the isoelectric point increased and the negative zeta potential decreased.The hydrophobicity and adhesion with a concomitant increase in the surface N/C and P/C element ratios,cells stretched in length and increased adhesion to limit lysozyme diffusion,and peptidoglycan modification and two-component regulatory genes were significantly up-regulated.The findings help to understand the relationship between adaptive stress responses and lysozyme resistance,provided a theoretical basis for the development of new food antibacterial agents.展开更多
Aflatoxin,a harmful secondary metabolite produced by Aspergillus flavus and Aspergillus parasiticus,poses a significant risk to human health and food safety.Therefore,the development of safe and environmentally friend...Aflatoxin,a harmful secondary metabolite produced by Aspergillus flavus and Aspergillus parasiticus,poses a significant risk to human health and food safety.Therefore,the development of safe and environmentally friendly techniques for controlling A.flavus and its aflatoxin production is imperative.In this study,Bacillus velezensis 906 cell-free fermentation supernatant(CFS)inhibited the germination of A.flavus spores and myce-lium growth.Scanning electron microscopy and fluorescence microscopy revealed that CFS altered cell morphology and damaged the cell membrane of A.flavus leading to cell death.Fourier transform infrared spectroscopy indicated changes in the functional groups of A.flavus filaments treated with CFS.The trend in ergosterol content demonstrated that CFS effectively inhibited the normal growth of A.flavus cell membranes.The CFS exhibited remarkable efficacy in degrading aflatoxin B1(AFB1),achieving a degradation rate of up to 60%after 48 h of interaction.The addition of 0.2 mg/mL Cu^(2+)or Fe^(3+)metal ions to CFS significantly increased the degradation rate of AFB1 up to 90%.Furthermore,the analysis indicated that the active components responsible for AFB1 degradation might be heat-resistance and exhibit resistance to protease K.These findings underscore the potential of CFS as a green,safe,and economically viable strategy for controlling aflatoxin production by A.flavus,offering promising prospects for mitigating mold contamination in food and feed applications.展开更多
Films with excellent mechanical properties and antimicrobial activity have potential applications in food pres-ervation.The antimicrobial film was prepared by blending probiotic Bacillus velezensis 906 metabolites(906...Films with excellent mechanical properties and antimicrobial activity have potential applications in food pres-ervation.The antimicrobial film was prepared by blending probiotic Bacillus velezensis 906 metabolites(906),potassium sorbate(PS),and polyvinyl alcohol(PVA).The film was characterized using scanning electron mi-croscopy(SEM),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),and thermal stability analysis.The mechanical,barrier,and antimicrobial properties of the film were tested.The results of the physicochemical analysis indicated that,compared to the pure PVA film,the film’s mechanical properties decreased,while its barrier properties and hydrophobicity increased with the addition of PS and 906,respec-tively.The results of the antimicrobial tests revealed that the blend film exhibited significant antimicrobial activity against Vibrio parahaemolyticus,Psychrobacter maritimus,Oceanobacillus kimchii,Pseudomonas aeruginosa,and Listeria monocytogenes.SEM demonstrated good fusion between the components of the PVA/PS/906 film,resulting in a dense and crack-free structure.FTIR suggested that PS and 906 enhance molecular interactions within the film matrix.XRD revealed that the film was crystallized,with 906 increasing the crystallinity of the bonds between the film components.Thermal analysis indicated the thermal stability of the films was enhanced.Consequently,the PVA/PS/906 blend film shows significant potential for application in the preservation of aquatic products.展开更多
基金supported by grants from the Major Science and Technology Fund of Guangxi Province(AB23026035)the Hubei Province Health and Family Planning Scientific Research Project(No.WJ 2023M168).
文摘Lysozyme possesses unique biological properties and finds wide-ranging applications,but the adaptive responses of microorganisms under lysozyme stress remain poorly understood.In this study,we investigated the response mechanisms of Dermacoccus abyssi HZAU 226 and Kocuria rhizophila H9,which with different lysozyme resistance.The results revealed similar regulatory mechanisms in two strains.D.abyssi demonstrated resistance to cationic activity and displayed typical growth curves,membrane permeability was concentration-dependent.Under 5 mg/mL lysozyme stress,the isoelectric point increased and the negative zeta potential decreased.The hydrophobicity and adhesion with a concomitant increase in the surface N/C and P/C element ratios,cells stretched in length and increased adhesion to limit lysozyme diffusion,and peptidoglycan modification and two-component regulatory genes were significantly up-regulated.The findings help to understand the relationship between adaptive stress responses and lysozyme resistance,provided a theoretical basis for the development of new food antibacterial agents.
基金supported by grants from the Major Science and Technology Fund of Guangxi Province(AB23026035)the Hubei Province Health and Family Planning Scientific Research Project(No.WJ2023M168).
文摘Aflatoxin,a harmful secondary metabolite produced by Aspergillus flavus and Aspergillus parasiticus,poses a significant risk to human health and food safety.Therefore,the development of safe and environmentally friendly techniques for controlling A.flavus and its aflatoxin production is imperative.In this study,Bacillus velezensis 906 cell-free fermentation supernatant(CFS)inhibited the germination of A.flavus spores and myce-lium growth.Scanning electron microscopy and fluorescence microscopy revealed that CFS altered cell morphology and damaged the cell membrane of A.flavus leading to cell death.Fourier transform infrared spectroscopy indicated changes in the functional groups of A.flavus filaments treated with CFS.The trend in ergosterol content demonstrated that CFS effectively inhibited the normal growth of A.flavus cell membranes.The CFS exhibited remarkable efficacy in degrading aflatoxin B1(AFB1),achieving a degradation rate of up to 60%after 48 h of interaction.The addition of 0.2 mg/mL Cu^(2+)or Fe^(3+)metal ions to CFS significantly increased the degradation rate of AFB1 up to 90%.Furthermore,the analysis indicated that the active components responsible for AFB1 degradation might be heat-resistance and exhibit resistance to protease K.These findings underscore the potential of CFS as a green,safe,and economically viable strategy for controlling aflatoxin production by A.flavus,offering promising prospects for mitigating mold contamination in food and feed applications.
基金supported by grants from the Major Science and Technology Fund of Guangxi Province[AB23026035].
文摘Films with excellent mechanical properties and antimicrobial activity have potential applications in food pres-ervation.The antimicrobial film was prepared by blending probiotic Bacillus velezensis 906 metabolites(906),potassium sorbate(PS),and polyvinyl alcohol(PVA).The film was characterized using scanning electron mi-croscopy(SEM),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),and thermal stability analysis.The mechanical,barrier,and antimicrobial properties of the film were tested.The results of the physicochemical analysis indicated that,compared to the pure PVA film,the film’s mechanical properties decreased,while its barrier properties and hydrophobicity increased with the addition of PS and 906,respec-tively.The results of the antimicrobial tests revealed that the blend film exhibited significant antimicrobial activity against Vibrio parahaemolyticus,Psychrobacter maritimus,Oceanobacillus kimchii,Pseudomonas aeruginosa,and Listeria monocytogenes.SEM demonstrated good fusion between the components of the PVA/PS/906 film,resulting in a dense and crack-free structure.FTIR suggested that PS and 906 enhance molecular interactions within the film matrix.XRD revealed that the film was crystallized,with 906 increasing the crystallinity of the bonds between the film components.Thermal analysis indicated the thermal stability of the films was enhanced.Consequently,the PVA/PS/906 blend film shows significant potential for application in the preservation of aquatic products.
