Aim The purpose of this study was to develop a mathe-matical model to quantitatively describe the passive trans-port of macromolecules within dental biofilms. Methodology Fluorescently labeled dextrans with different ...Aim The purpose of this study was to develop a mathe-matical model to quantitatively describe the passive trans-port of macromolecules within dental biofilms. Methodology Fluorescently labeled dextrans with different molecular mass （3 kD,10 kD,40 kD,70 kD,2 000 kD） were used as a series of diffusion probes. Streptococcus mutans,Streptococcus sanguinis,Actinomyces naeslundii and Fusobacterium nucleatum were used as inocula for biofilm formation. The diffusion processes of different probes through the in vitro biofilm were recorded with a confocal laser microscope. Results Mathematical function of biofilm penetration was constructed on the basis of the inverse problem method. Based on this function,not only the relationship between average concentration of steady-state and molecule weights can be analyzed,but also that between penetrative time and molecule weights. Conclusion This can be used to predict the effective concentration and the penetrative time of anti-biofilm medicines that can diffuse through oral biofilm. Further-more,an improved model for large molecule is proposed by considering the exchange time at the upper boundary of the dental biofilm.展开更多
This Staphylococcus epidermidis has been discovered as the most frequent germ detected during indwelling medical devices infection. This fact is well attached with the ability of this bacterium to form structured laye...This Staphylococcus epidermidis has been discovered as the most frequent germ detected during indwelling medical devices infection. This fact is well attached with the ability of this bacterium to form structured layered population known as biofilm. Inside S. epidermidis biofilm, bacterial cells present more different behavior than in their planktonic counterpart. This paper describes the thriving application of Petri net theory for modeling of interaction between different regulations actors leading S. epidermidis to switch from Planctonik to Biofilm. Indeed this biologic system is very sensible and has dangerous effect. We propose Agent Petri Nets model to describe and analyze the process of formation of Biofilm molecule. This model presents a formal framework based on Multi Agents system characteristics.展开更多
Objective To develop a new antimicrobial sensitivity test model for oral products in vitro.Methods A biofilm artificial mouth model for antimicrobial sensitivity tests was established by modifying the LKB chromatograp...Objective To develop a new antimicrobial sensitivity test model for oral products in vitro.Methods A biofilm artificial mouth model for antimicrobial sensitivity tests was established by modifying the LKB chromatography chamber. Using sodium fluoride and Tea polyphenol as antimicrobial agent and Streptococcus mu-tans as target, sensitivity tests were studied. Results The modeling biofilm assay resulted in a MIC of 1. 28mg/ ml for fluoride against S. mutans, which was 32 times the MIC for broth maco-dilution method. The differential resistance of bacteria bioflim to antimicrobial agent relative to planktonic cells was also demonstrated. Conclusion The biofilm artificial mouth model may be useful in oral products test.展开更多
A laboratory scale aerobic fixed film bioreactor packed with glass beads for biofilm growth was used to evaluate the removal efficiencies of COD and phenol for a carbohydrate—phenol mixture in wastewater. It was done...A laboratory scale aerobic fixed film bioreactor packed with glass beads for biofilm growth was used to evaluate the removal efficiencies of COD and phenol for a carbohydrate—phenol mixture in wastewater. It was done by an indigenous mixed culture inoculums developed after collecting sludge from a return line of an activated sludge plant. The test result on continuous flow in the above biofilm reactor indicated an optimum hydraulic loading range of 4-6.4 m3day-1m-2 for attainment of reasonable amount of COD removal in case of carbohydrate substrate only. The COD removal efficiency, however, gradually depleted from 100% to 54% by gradual increase in organic loading (OLR) from 0.72-4.32 kgday-1m-3, beyond which removal was not significant. For the identical loading conditions, in presence of phenol in the substrate along with carbohydrate, the COD removal was observed varying from 100-40% in the above organic loading range. The COD removal kinetics in presence of phenol also shows a decreasing trend compared to data obtained without the presence of phenol in wastewater that reveals biological inhibition. The experimental data were fitted in a simple plug flow model for evaluating the zero order, first order and Monod form of rate equations to evaluate the kinetics. It was found that Monod type rate equations combining a zero and first order rate expression is the best fit for the above hydraulic and organic loading that gives a best fit half velocity constant value of 35 mgL-1 (R2 = 0.9612).展开更多
目的探讨纳米银离子对细菌生物被膜(biofilm,BF)的细菌死亡率的影响。方法采用摇床法,以纳米银离子含量不同的乙烯-醋酸乙烯酯(Ethylene-Vinyl acetate,EVA)塑料为细菌粘附载体,模拟体内铜绿假单胞菌(P.aerugi-nosa,PA)BF形成的微环境,...目的探讨纳米银离子对细菌生物被膜(biofilm,BF)的细菌死亡率的影响。方法采用摇床法,以纳米银离子含量不同的乙烯-醋酸乙烯酯(Ethylene-Vinyl acetate,EVA)塑料为细菌粘附载体,模拟体内铜绿假单胞菌(P.aerugi-nosa,PA)BF形成的微环境,建立体外BF模型;将培养3 d的空白标本分别在扫描电子显微镜(SEM)下及用FITC-ConA染色后荧光显微镜下观察不含纳米银离子EVA中BF的形成情况;将生长0.5、1、2、3、5 d的BF模型行SYTO9/PI染色,激光共聚焦扫描电镜(CLSM)下摄取不同层面的图像,然后采用Image Pro Plus 6.0分析软件分析不同干预条件下BF的细菌的死亡率。结果运用SEM及荧光显微镜的方法,在以不含纳米银离子EVA塑料的细菌粘附载体上培养3 d的标本中均观察到流线状的BF形成;纳米银离子含量、作用时间对BF的细菌死亡率均有明显影响(F值分别为84.62,85.67,P<0.01);不同时间点含有纳米银离子材料的BF细菌死亡率均显著高于空白对照组(P<0.05),但纳米银离子含量不同的2种材料上BF的细菌死亡率无明显影响(P>0.05);纳米银离子含量不同的(0、0.05%、0.1%)材料上的BF,其第1、2、3天细菌死亡率均分别显著高于第0.5、5天的细菌死亡率(P<0.05);含纳米银离子0.1%的材料上BF在作用的第2天其细菌死亡率最高[(88.53±1.88)%]。结论运用摇床法成功建立了体外BF模型,纳米银离子对BF内的细菌有明显杀灭作用。展开更多
基金supported by a grant from the National Natural Science Foundation of China (NSFC) No. 81070826/30872886/30400497Sponsored by Shanghai Rising-Star Program No. 09QA1403700+1 种基金funded by Shanghai Leading Academic Discipline Project (Project Number: S30206)the Science and Technology Commission of Shanghai (08DZ2271100)
文摘Aim The purpose of this study was to develop a mathe-matical model to quantitatively describe the passive trans-port of macromolecules within dental biofilms. Methodology Fluorescently labeled dextrans with different molecular mass （3 kD,10 kD,40 kD,70 kD,2 000 kD） were used as a series of diffusion probes. Streptococcus mutans,Streptococcus sanguinis,Actinomyces naeslundii and Fusobacterium nucleatum were used as inocula for biofilm formation. The diffusion processes of different probes through the in vitro biofilm were recorded with a confocal laser microscope. Results Mathematical function of biofilm penetration was constructed on the basis of the inverse problem method. Based on this function,not only the relationship between average concentration of steady-state and molecule weights can be analyzed,but also that between penetrative time and molecule weights. Conclusion This can be used to predict the effective concentration and the penetrative time of anti-biofilm medicines that can diffuse through oral biofilm. Further-more,an improved model for large molecule is proposed by considering the exchange time at the upper boundary of the dental biofilm.
文摘This Staphylococcus epidermidis has been discovered as the most frequent germ detected during indwelling medical devices infection. This fact is well attached with the ability of this bacterium to form structured layered population known as biofilm. Inside S. epidermidis biofilm, bacterial cells present more different behavior than in their planktonic counterpart. This paper describes the thriving application of Petri net theory for modeling of interaction between different regulations actors leading S. epidermidis to switch from Planctonik to Biofilm. Indeed this biologic system is very sensible and has dangerous effect. We propose Agent Petri Nets model to describe and analyze the process of formation of Biofilm molecule. This model presents a formal framework based on Multi Agents system characteristics.
文摘Objective To develop a new antimicrobial sensitivity test model for oral products in vitro.Methods A biofilm artificial mouth model for antimicrobial sensitivity tests was established by modifying the LKB chromatography chamber. Using sodium fluoride and Tea polyphenol as antimicrobial agent and Streptococcus mu-tans as target, sensitivity tests were studied. Results The modeling biofilm assay resulted in a MIC of 1. 28mg/ ml for fluoride against S. mutans, which was 32 times the MIC for broth maco-dilution method. The differential resistance of bacteria bioflim to antimicrobial agent relative to planktonic cells was also demonstrated. Conclusion The biofilm artificial mouth model may be useful in oral products test.
文摘A laboratory scale aerobic fixed film bioreactor packed with glass beads for biofilm growth was used to evaluate the removal efficiencies of COD and phenol for a carbohydrate—phenol mixture in wastewater. It was done by an indigenous mixed culture inoculums developed after collecting sludge from a return line of an activated sludge plant. The test result on continuous flow in the above biofilm reactor indicated an optimum hydraulic loading range of 4-6.4 m3day-1m-2 for attainment of reasonable amount of COD removal in case of carbohydrate substrate only. The COD removal efficiency, however, gradually depleted from 100% to 54% by gradual increase in organic loading (OLR) from 0.72-4.32 kgday-1m-3, beyond which removal was not significant. For the identical loading conditions, in presence of phenol in the substrate along with carbohydrate, the COD removal was observed varying from 100-40% in the above organic loading range. The COD removal kinetics in presence of phenol also shows a decreasing trend compared to data obtained without the presence of phenol in wastewater that reveals biological inhibition. The experimental data were fitted in a simple plug flow model for evaluating the zero order, first order and Monod form of rate equations to evaluate the kinetics. It was found that Monod type rate equations combining a zero and first order rate expression is the best fit for the above hydraulic and organic loading that gives a best fit half velocity constant value of 35 mgL-1 (R2 = 0.9612).
文摘目的探讨纳米银离子对细菌生物被膜(biofilm,BF)的细菌死亡率的影响。方法采用摇床法,以纳米银离子含量不同的乙烯-醋酸乙烯酯(Ethylene-Vinyl acetate,EVA)塑料为细菌粘附载体,模拟体内铜绿假单胞菌(P.aerugi-nosa,PA)BF形成的微环境,建立体外BF模型;将培养3 d的空白标本分别在扫描电子显微镜(SEM)下及用FITC-ConA染色后荧光显微镜下观察不含纳米银离子EVA中BF的形成情况;将生长0.5、1、2、3、5 d的BF模型行SYTO9/PI染色,激光共聚焦扫描电镜(CLSM)下摄取不同层面的图像,然后采用Image Pro Plus 6.0分析软件分析不同干预条件下BF的细菌的死亡率。结果运用SEM及荧光显微镜的方法,在以不含纳米银离子EVA塑料的细菌粘附载体上培养3 d的标本中均观察到流线状的BF形成;纳米银离子含量、作用时间对BF的细菌死亡率均有明显影响(F值分别为84.62,85.67,P<0.01);不同时间点含有纳米银离子材料的BF细菌死亡率均显著高于空白对照组(P<0.05),但纳米银离子含量不同的2种材料上BF的细菌死亡率无明显影响(P>0.05);纳米银离子含量不同的(0、0.05%、0.1%)材料上的BF,其第1、2、3天细菌死亡率均分别显著高于第0.5、5天的细菌死亡率(P<0.05);含纳米银离子0.1%的材料上BF在作用的第2天其细菌死亡率最高[(88.53±1.88)%]。结论运用摇床法成功建立了体外BF模型,纳米银离子对BF内的细菌有明显杀灭作用。
