【目的】研究不同温度条件下的石油烃降解产甲烷菌系中是否存在乙酸互营氧化产甲烷代谢途径。【方法】以3个不同温度条件的正十六烷烃降解产甲烷菌系Y15(15℃)、M82(35℃)和SK(55℃)作为接种物,通过乙酸喂养实验、并添加乙酸营养型产甲...【目的】研究不同温度条件下的石油烃降解产甲烷菌系中是否存在乙酸互营氧化产甲烷代谢途径。【方法】以3个不同温度条件的正十六烷烃降解产甲烷菌系Y15(15℃)、M82(35℃)和SK(55℃)作为接种物,通过乙酸喂养实验、并添加乙酸营养型产甲烷古菌的选择性抑制剂NH4Cl和CH3F,结合末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)和克隆文库技术,分析乙酸产甲烷潜力及产甲烷古菌群落的演替趋势,推测产甲烷代谢途径的变化趋势。【结果】无论是否添加NH4Cl和CH3F,这3个菌系都可以利用乙酸生长并产生甲烷,但是添加NH4Cl和CH3F后产甲烷延滞期增加,最大比甲烷增长速率降低;只添加乙酸后,3个不同温度的菌系的古菌群落主要由乙酸营养型产甲烷古菌甲烷鬃毛菌属(Methanosaeta)组成,其丰度分别为92.8±1.4%、97.3±2.4%和82.8±9.0%;当添加选择性抑制剂NH4Cl,3个菌系中的Methanosaeta的丰度分别变为98.5±0.7%、87.4±4.8%和6.1±8.6%,中温菌系M82中氢营养型产甲烷古菌甲烷袋装菌属(Methanoculleus)的相对丰度增加到12.6±4.0%,高温菌系SK中另一类氢营养型产甲烷古菌甲烷热杆菌属(Methanothermobacter)增至84.3±1.5%;当添加选择性抑制剂CH3F,Methanosaeta丰度分别降至77.1±14.5%,86.4±6.1%和35.8±7.8%,低温菌系Y15中的甲烷八叠球菌属(Methanosarcina)增高(15.7±21%),这类产甲烷古菌具有多种产甲烷代谢途径,M82中Methanoculleus丰度上升到13.6±13.1%,SK中Methanothermobacter丰度增大到48.5±11.2%。【结论】在低温条件下,菌系Y15可能主要通过乙酸裂解完成产甲烷代谢,在中高温条件下,菌系M82和SK中可能存在乙酸互营氧化产甲烷代谢途径,并且甲烷的产生分别通过不同种群的氢营养型产甲烷古菌来完成。展开更多
CuY zeolite is a promising catalyst in the field of manufacturing dimethyl carbonate(DMC) through oxidative carbonylation of methanol. Cu^+ exchanged with Br?nsted acid sites are supposed to be active for this reactio...CuY zeolite is a promising catalyst in the field of manufacturing dimethyl carbonate(DMC) through oxidative carbonylation of methanol. Cu^+ exchanged with Br?nsted acid sites are supposed to be active for this reaction. However, the location of Cu^+ in small cages can not interact with reactants because of steric hindrance, which lead to a waste of Cu species. In this work, NH_4F solution was used to modify the pore structure of zeolite Y by etching the framework T atoms. Physical and chemical adsorption of probe molecules with different size are used to determine the changes of porosity as well as the accessibility of Cu^+ sites. At an optimized etching time, the small cages were opened with maintained zeolitic framework. As a result, more Cu^+ species located in small cages become accessible to reactants, which contributes to the enhanced activity in this reaction.展开更多
文摘【目的】研究不同温度条件下的石油烃降解产甲烷菌系中是否存在乙酸互营氧化产甲烷代谢途径。【方法】以3个不同温度条件的正十六烷烃降解产甲烷菌系Y15(15℃)、M82(35℃)和SK(55℃)作为接种物,通过乙酸喂养实验、并添加乙酸营养型产甲烷古菌的选择性抑制剂NH4Cl和CH3F,结合末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)和克隆文库技术,分析乙酸产甲烷潜力及产甲烷古菌群落的演替趋势,推测产甲烷代谢途径的变化趋势。【结果】无论是否添加NH4Cl和CH3F,这3个菌系都可以利用乙酸生长并产生甲烷,但是添加NH4Cl和CH3F后产甲烷延滞期增加,最大比甲烷增长速率降低;只添加乙酸后,3个不同温度的菌系的古菌群落主要由乙酸营养型产甲烷古菌甲烷鬃毛菌属(Methanosaeta)组成,其丰度分别为92.8±1.4%、97.3±2.4%和82.8±9.0%;当添加选择性抑制剂NH4Cl,3个菌系中的Methanosaeta的丰度分别变为98.5±0.7%、87.4±4.8%和6.1±8.6%,中温菌系M82中氢营养型产甲烷古菌甲烷袋装菌属(Methanoculleus)的相对丰度增加到12.6±4.0%,高温菌系SK中另一类氢营养型产甲烷古菌甲烷热杆菌属(Methanothermobacter)增至84.3±1.5%;当添加选择性抑制剂CH3F,Methanosaeta丰度分别降至77.1±14.5%,86.4±6.1%和35.8±7.8%,低温菌系Y15中的甲烷八叠球菌属(Methanosarcina)增高(15.7±21%),这类产甲烷古菌具有多种产甲烷代谢途径,M82中Methanoculleus丰度上升到13.6±13.1%,SK中Methanothermobacter丰度增大到48.5±11.2%。【结论】在低温条件下,菌系Y15可能主要通过乙酸裂解完成产甲烷代谢,在中高温条件下,菌系M82和SK中可能存在乙酸互营氧化产甲烷代谢途径,并且甲烷的产生分别通过不同种群的氢营养型产甲烷古菌来完成。
基金financial supports from the National Natural Science Foundation of China NSFC, Nos. U1510203, 21406120, 21325626
文摘CuY zeolite is a promising catalyst in the field of manufacturing dimethyl carbonate(DMC) through oxidative carbonylation of methanol. Cu^+ exchanged with Br?nsted acid sites are supposed to be active for this reaction. However, the location of Cu^+ in small cages can not interact with reactants because of steric hindrance, which lead to a waste of Cu species. In this work, NH_4F solution was used to modify the pore structure of zeolite Y by etching the framework T atoms. Physical and chemical adsorption of probe molecules with different size are used to determine the changes of porosity as well as the accessibility of Cu^+ sites. At an optimized etching time, the small cages were opened with maintained zeolitic framework. As a result, more Cu^+ species located in small cages become accessible to reactants, which contributes to the enhanced activity in this reaction.
