[Objective] Pseudomonas as one of the dominant spoilage bacteria highly form biofilms in chilled meat products and processing environment when contaminating single or mixed with other species.This study aims to invest...[Objective] Pseudomonas as one of the dominant spoilage bacteria highly form biofilms in chilled meat products and processing environment when contaminating single or mixed with other species.This study aims to investigate the antibiofilm properties of the cell-free supernatants(CFSs) of three Bacillus species isolated from fermented food and rice seeds on Pseudomonas lundensis(PL) or and Acinetobacter johnsonii(AJ) as mono-or dual-species.[Methods] Biofilm biomass,extracellular polymeric substances(EPSs),and biofilm structure were measured by crystal violet staining,spectrophotometry,confocal laser scanning microscopy(CLSM),respectively,as well as transcription of biofilm-related genes determined by qPCR.[Results] The CFSs of Bacillus amyloliquefaciens ZG08,B.velezensis B5,and B.subtilis YB11 inhibited the biofilm formation of PL and AJ without affecting their growth.The treatment with 50% CFSs of ZG08 and B5 decreased the cell viability of two biofilms by 12.73%–21.04%,which was higher than that of YB11(0.15%–4.38%).The inhibition rates of 50% CFSs of the three strains were 59.75%–79.59% against the PL biofilm and 63.62%–78.57% against the biofilm of PL+AJ,in which the CFS of YB11 had weaker activity.The content of exopolysaccharides and exoprotein in the two biofilms treated with these CFSs were reduced by 53.77%–73.30% and 54.84%–62.38%,respectively.The treatment with the three CFSs also reduced the adhesive cells,loosened biofilm structures,and thinned their thickness by 57.63%–74.49% and 60.43%–64.64%,respectively.Moreover,the CFSs of ZG08 and B5 effectively eradicated by 41.77%–69.79% against the mature biofilms of PL and PL+AJ,compared to weak activity of YB11.In addition,the antibiofilm activities of the three CFSs were stable under four enzyme digestion and heating conditions.Compared with the control,the CFSs of ZG08 and B5 significantly down-regulated the expression of six biofilm-related genes,lapA,alg44,pelG,luxR,wspR,and rpoS.[Conclusion] The CFSs of ZG08 and B5 have strong antibi展开更多
In this research,an atmospheric-pressure air plasma is used to inactivate the multidrug-resistant Acinetobacter baumannii in liquid.The efficacy of the air plasma on bacterial deactivation and the cytobiological varia...In this research,an atmospheric-pressure air plasma is used to inactivate the multidrug-resistant Acinetobacter baumannii in liquid.The efficacy of the air plasma on bacterial deactivation and the cytobiological variations after the plasma treatment are investigated.According to colony forming units,nearly all the bacteria（6-log） are inactivated after 10 min of air plasma treatment.However,7% of the bacteria enter a viable but non-culturable state detected by the resazurin based assay during the same period of plasma exposure.Meanwhile,86% of the bacteria lose their membrane integrity in the light of SYTO 9/PI staining assay.The morphological changes in the cells are examined by scanning electron microscopy and bacteria with morphological changes are rare after plasma exposure in the liquid.The concentrations of the long-living RS,such as H2O2,NO3^- and O3,in liquid induced by plasma treatment are measured,and they increase with plasma treatment time.The changes of the intracellular ROS may be related to cell death,which may be attributed to oxidative stress and other damage effects induced by RS plasma generated in liquid.The rapid and effective bacteria inactivation may stem from the RS in the liquid generated by plasma and air plasmas may become a valuable therapy in the treatment of infected wounds.展开更多
文摘[Objective] Pseudomonas as one of the dominant spoilage bacteria highly form biofilms in chilled meat products and processing environment when contaminating single or mixed with other species.This study aims to investigate the antibiofilm properties of the cell-free supernatants(CFSs) of three Bacillus species isolated from fermented food and rice seeds on Pseudomonas lundensis(PL) or and Acinetobacter johnsonii(AJ) as mono-or dual-species.[Methods] Biofilm biomass,extracellular polymeric substances(EPSs),and biofilm structure were measured by crystal violet staining,spectrophotometry,confocal laser scanning microscopy(CLSM),respectively,as well as transcription of biofilm-related genes determined by qPCR.[Results] The CFSs of Bacillus amyloliquefaciens ZG08,B.velezensis B5,and B.subtilis YB11 inhibited the biofilm formation of PL and AJ without affecting their growth.The treatment with 50% CFSs of ZG08 and B5 decreased the cell viability of two biofilms by 12.73%–21.04%,which was higher than that of YB11(0.15%–4.38%).The inhibition rates of 50% CFSs of the three strains were 59.75%–79.59% against the PL biofilm and 63.62%–78.57% against the biofilm of PL+AJ,in which the CFS of YB11 had weaker activity.The content of exopolysaccharides and exoprotein in the two biofilms treated with these CFSs were reduced by 53.77%–73.30% and 54.84%–62.38%,respectively.The treatment with the three CFSs also reduced the adhesive cells,loosened biofilm structures,and thinned their thickness by 57.63%–74.49% and 60.43%–64.64%,respectively.Moreover,the CFSs of ZG08 and B5 effectively eradicated by 41.77%–69.79% against the mature biofilms of PL and PL+AJ,compared to weak activity of YB11.In addition,the antibiofilm activities of the three CFSs were stable under four enzyme digestion and heating conditions.Compared with the control,the CFSs of ZG08 and B5 significantly down-regulated the expression of six biofilm-related genes,lapA,alg44,pelG,luxR,wspR,and rpoS.[Conclusion] The CFSs of ZG08 and B5 have strong antibi
基金supported by the Spark Program of the second Affiliated Hospital of Anhui Medical University (Grant No.2015hhjh04)National Natural Science Foundation of China under Grant No.51777206+6 种基金Natural Science Foundation of Anhui Province (Grant No.1708085MA13 and No.1708085MB47)Science Foundation of Institute of Plasma Physics,Chinese Academy of Sciences under Grant (No.DSJJ-14-YY02)City University of Hong Kong Applied Research Grant (ARG) (No.9667144)Hong Kong Research Grants Council (RGC) General Research Funds (GRF) (No.City U 11301215)Doctoral Fund of Ministry of Education of China (No.2017M612058)Specialized Research Fund for the Doctoral Program of Hefei University of Technology (No.JZ2016HGBZ0768)Foundation of Anhui Province Key Laboratory of Medical Physics and Technology (Grant No.LMPT2017Y7BP0U1581)
文摘In this research,an atmospheric-pressure air plasma is used to inactivate the multidrug-resistant Acinetobacter baumannii in liquid.The efficacy of the air plasma on bacterial deactivation and the cytobiological variations after the plasma treatment are investigated.According to colony forming units,nearly all the bacteria（6-log） are inactivated after 10 min of air plasma treatment.However,7% of the bacteria enter a viable but non-culturable state detected by the resazurin based assay during the same period of plasma exposure.Meanwhile,86% of the bacteria lose their membrane integrity in the light of SYTO 9/PI staining assay.The morphological changes in the cells are examined by scanning electron microscopy and bacteria with morphological changes are rare after plasma exposure in the liquid.The concentrations of the long-living RS,such as H2O2,NO3^- and O3,in liquid induced by plasma treatment are measured,and they increase with plasma treatment time.The changes of the intracellular ROS may be related to cell death,which may be attributed to oxidative stress and other damage effects induced by RS plasma generated in liquid.The rapid and effective bacteria inactivation may stem from the RS in the liquid generated by plasma and air plasmas may become a valuable therapy in the treatment of infected wounds.
