以冷藏大黄鱼特定腐败菌腐败希瓦氏菌(Shewanella putrefaciens)为研究对象,采用修正Gompertz、修正Logistic和Baranyi方程拟合5、8、15℃和25℃条件下其在胰蛋白胨大豆肉汤中的生长动力学模型,采用Belehradek方程建立二级模型,探讨温...以冷藏大黄鱼特定腐败菌腐败希瓦氏菌(Shewanella putrefaciens)为研究对象,采用修正Gompertz、修正Logistic和Baranyi方程拟合5、8、15℃和25℃条件下其在胰蛋白胨大豆肉汤中的生长动力学模型,采用Belehradek方程建立二级模型,探讨温度对腐败希瓦氏菌生长动力学的影响,并对模型的拟合优度及适用性进行评价。结果表明:温度对腐败希瓦氏菌生长动力学影响显著,其在5℃环境中延滞期较长,生长趋势得到明显抑制,当温度上升到25℃时,腐败希瓦氏菌的延滞期显著缩短,比生长速率随着温度的升高而增大,温度与延滞期及比生长速率均存在线性关系。采用均方根误差(root mean square error,RMSE)、残差平方和(residual sum of squares,RSS)、偏差度(bias factor,BF)、准确度(accuracy factor,AF)、R2对修正的Gompertz、修正的Logistic和Baranyi方程的拟合优度进行评价,修正的Logistic方程的RSS和RMSE均最小,BF和AF均最接近1,修正的Logistic模型的拟合优度最佳,适用性最强,水产品中腐败希瓦氏菌的生长情况能通过修正的Logistic模型得到较好地预测。展开更多
In Northwest Florida, the soil is mainly covered by poorly drained sandy soil of Myakka, which is characterized by a subsurface accumulation of humus and AI and Fe oxides. When organic rich landfill leachate is leaked...In Northwest Florida, the soil is mainly covered by poorly drained sandy soil of Myakka, which is characterized by a subsurface accumulation of humus and AI and Fe oxides. When organic rich landfill leachate is leaked to the iron rich soils, ferrous iron is released with the oxidation of organic compounds in the leachate. In this research, we investigated the activities of S. putrefaciens in reducing iron oxide in the iron rich soil of Northwest Florida with landfill leachate serving as the carbon source. S. putrefaciens had similar maximum specific growth rate and half saturation coefficients for all the leachate and soil samples. The average maximum specific growth rate was 0.008 hr^-1 and the average half saturation coefficient was 243.8 mg/L. Averagely, 2.2 mg ferrous iron was generated per mg COD consumed. In addition, adsorption of reduced ferrous iron on S. putrefaciens was further characterized. Ferrous iron adsorption on S. putrefaciens was a kinetic process, which increased with the increase of the reaction time. Equilibrium ferrous iron adsorption on S. putrefaciens can be reached after three hours. Ferrous iron had linear adsorption isotherms on S. putrefaciens for the pH range of 5 to 9.展开更多
In this study, Pb(Ⅱ) was used as a target heavy metal pollutant, and the metabolism of Shewanella putrefaciens(S. putrefaciens) was applied to achieve reducing conditions to study the effect of microbial reduction on...In this study, Pb(Ⅱ) was used as a target heavy metal pollutant, and the metabolism of Shewanella putrefaciens(S. putrefaciens) was applied to achieve reducing conditions to study the effect of microbial reduction on lead that was preadsorbed on graphene oxide(GO) surfaces.The results showed that GO was transformed to its reduced form(r-GO) by bacteria, and this process induced the release of Pb(Ⅱ) adsorbed on the GO surfaces. After 72 hr of exposure in an S. putrefaciens system, 5.76% of the total adsorbed Pb(Ⅱ) was stably dispersed in solution in the form of a Pb(Ⅱ)-extracellular polymer substance(EPS) complex, while another portion of Pb(Ⅱ) released from GO-Pb(Ⅱ) was observed as lead phosphate hydroxide(Pb_(10)(PO_(4))_(6)(OH)_(2))precipitates or adsorbed species on the surface of the cell. Additionally, increasing pH induced the stripping of oxidative debris(OD) and elevated the content of dispersible Pb(Ⅱ)in aqueous solution under the conditions of S. putrefaciens metabolism. These research results provide valuable information regarding the migration of heavy metals adsorbed on GO under reducing conditions due to microbial metabolism.展开更多
目的:分析没食子酸(GA)和咖啡酸(CA)对腐败希瓦氏菌生物被膜形成及致腐性的影响,并探究其协同作用特点。方法:测定亚抑菌浓度的GA和CA对腐败希瓦氏菌生长曲线、生物被膜形成(形成量、微观结构、黏附性、胞外聚合物含量)、运动能力、胞...目的:分析没食子酸(GA)和咖啡酸(CA)对腐败希瓦氏菌生物被膜形成及致腐性的影响,并探究其协同作用特点。方法:测定亚抑菌浓度的GA和CA对腐败希瓦氏菌生长曲线、生物被膜形成(形成量、微观结构、黏附性、胞外聚合物含量)、运动能力、胞外酶活性、产硫能力及致腐性的影响。结果:1/4最小抑菌浓度(MIC)GA、1/4 MIC CA和1/8 MIC GA+1/8MIC CA等亚抑菌浓度的GA和CA虽未影响细菌生长,但显著抑制了生物被膜形成量。1/8 MIC GA+1/8 MIC CA组生物被膜形成量、黏附性以及胞外多糖的产量较对照组分别降低了68%,64%,49%,且显著低于单一处理组,导致腐败希瓦氏菌不能形成致密完整的生物被膜结构。此外,GA和CA显著抑制了腐败希瓦氏菌的运动、产胞外酶和产硫能力。接种腐败希瓦氏菌后,GA和CA联用组鱼肉的菌落总数在贮藏8 d后达到7 lg(CFU/g),相较于对照组延迟2 d以上。结果表明,GA和CA联用可有效延缓腐败希瓦氏菌引发的鱼肉腐败进程。结论:GA与CA对腐败希瓦氏菌生物被膜及致腐特性具有不同程度的协同抑制作用,可在水产品保鲜中联合使用。展开更多
文摘以冷藏大黄鱼特定腐败菌腐败希瓦氏菌(Shewanella putrefaciens)为研究对象,采用修正Gompertz、修正Logistic和Baranyi方程拟合5、8、15℃和25℃条件下其在胰蛋白胨大豆肉汤中的生长动力学模型,采用Belehradek方程建立二级模型,探讨温度对腐败希瓦氏菌生长动力学的影响,并对模型的拟合优度及适用性进行评价。结果表明:温度对腐败希瓦氏菌生长动力学影响显著,其在5℃环境中延滞期较长,生长趋势得到明显抑制,当温度上升到25℃时,腐败希瓦氏菌的延滞期显著缩短,比生长速率随着温度的升高而增大,温度与延滞期及比生长速率均存在线性关系。采用均方根误差(root mean square error,RMSE)、残差平方和(residual sum of squares,RSS)、偏差度(bias factor,BF)、准确度(accuracy factor,AF)、R2对修正的Gompertz、修正的Logistic和Baranyi方程的拟合优度进行评价,修正的Logistic方程的RSS和RMSE均最小,BF和AF均最接近1,修正的Logistic模型的拟合优度最佳,适用性最强,水产品中腐败希瓦氏菌的生长情况能通过修正的Logistic模型得到较好地预测。
文摘In Northwest Florida, the soil is mainly covered by poorly drained sandy soil of Myakka, which is characterized by a subsurface accumulation of humus and AI and Fe oxides. When organic rich landfill leachate is leaked to the iron rich soils, ferrous iron is released with the oxidation of organic compounds in the leachate. In this research, we investigated the activities of S. putrefaciens in reducing iron oxide in the iron rich soil of Northwest Florida with landfill leachate serving as the carbon source. S. putrefaciens had similar maximum specific growth rate and half saturation coefficients for all the leachate and soil samples. The average maximum specific growth rate was 0.008 hr^-1 and the average half saturation coefficient was 243.8 mg/L. Averagely, 2.2 mg ferrous iron was generated per mg COD consumed. In addition, adsorption of reduced ferrous iron on S. putrefaciens was further characterized. Ferrous iron adsorption on S. putrefaciens was a kinetic process, which increased with the increase of the reaction time. Equilibrium ferrous iron adsorption on S. putrefaciens can be reached after three hours. Ferrous iron had linear adsorption isotherms on S. putrefaciens for the pH range of 5 to 9.
基金supported by the National Key Project of Research and Development Plan of China (No. 2017YFC04034033)the Shanxi National Science Foundation (No. 2020JQ-664)the Key Laboratory of Education Department of Shanxi Province, China (No. 20JS085)。
文摘In this study, Pb(Ⅱ) was used as a target heavy metal pollutant, and the metabolism of Shewanella putrefaciens(S. putrefaciens) was applied to achieve reducing conditions to study the effect of microbial reduction on lead that was preadsorbed on graphene oxide(GO) surfaces.The results showed that GO was transformed to its reduced form(r-GO) by bacteria, and this process induced the release of Pb(Ⅱ) adsorbed on the GO surfaces. After 72 hr of exposure in an S. putrefaciens system, 5.76% of the total adsorbed Pb(Ⅱ) was stably dispersed in solution in the form of a Pb(Ⅱ)-extracellular polymer substance(EPS) complex, while another portion of Pb(Ⅱ) released from GO-Pb(Ⅱ) was observed as lead phosphate hydroxide(Pb_(10)(PO_(4))_(6)(OH)_(2))precipitates or adsorbed species on the surface of the cell. Additionally, increasing pH induced the stripping of oxidative debris(OD) and elevated the content of dispersible Pb(Ⅱ)in aqueous solution under the conditions of S. putrefaciens metabolism. These research results provide valuable information regarding the migration of heavy metals adsorbed on GO under reducing conditions due to microbial metabolism.
文摘目的:分析没食子酸(GA)和咖啡酸(CA)对腐败希瓦氏菌生物被膜形成及致腐性的影响,并探究其协同作用特点。方法:测定亚抑菌浓度的GA和CA对腐败希瓦氏菌生长曲线、生物被膜形成(形成量、微观结构、黏附性、胞外聚合物含量)、运动能力、胞外酶活性、产硫能力及致腐性的影响。结果:1/4最小抑菌浓度(MIC)GA、1/4 MIC CA和1/8 MIC GA+1/8MIC CA等亚抑菌浓度的GA和CA虽未影响细菌生长,但显著抑制了生物被膜形成量。1/8 MIC GA+1/8 MIC CA组生物被膜形成量、黏附性以及胞外多糖的产量较对照组分别降低了68%,64%,49%,且显著低于单一处理组,导致腐败希瓦氏菌不能形成致密完整的生物被膜结构。此外,GA和CA显著抑制了腐败希瓦氏菌的运动、产胞外酶和产硫能力。接种腐败希瓦氏菌后,GA和CA联用组鱼肉的菌落总数在贮藏8 d后达到7 lg(CFU/g),相较于对照组延迟2 d以上。结果表明,GA和CA联用可有效延缓腐败希瓦氏菌引发的鱼肉腐败进程。结论:GA与CA对腐败希瓦氏菌生物被膜及致腐特性具有不同程度的协同抑制作用,可在水产品保鲜中联合使用。
