ZnO nanorods, with the c-axis orientation used for transparent conductors, solar cells, sensors especially the functionalized ZnO nanorods with some kinds of enzymes have been used for biosensor. In this work, we desc...ZnO nanorods, with the c-axis orientation used for transparent conductors, solar cells, sensors especially the functionalized ZnO nanorods with some kinds of enzymes have been used for biosensor. In this work, we describe the process immobilization of galactose oxidase on ZnO nanorods surface with glutaraldehyde as a cross-linker molecule to make the working electrode in electrochemical biosensor. ZnO nanorods were grown on FTO （Fluorine-doped tin oxide） substrate by solution method at low temperature. The crystalline phase and orientation of ZnO nanorods were identified using X-ray diffraction. The efficiency of the immobilization was calculated by Braford method showed that about 36% enzyme content was immobilized on ZnO nanorods surface. The working electrode based on the immobilized ZnO nanorods was tested in galactose solution by CV （cyclic voltammetry） method indicated the value of current intensity is about 0.14 μA. These results clearly demonstrate the potential of galactose sensor based on ZnO nanorod.展开更多
The term ＂extreme environments＂ describes the conditions that deviate from what mesophilic cells can tolerate. These condi- tions are ＂extreme＂ in the eye of mankind, but they may be suitable or even essential liv...The term ＂extreme environments＂ describes the conditions that deviate from what mesophilic cells can tolerate. These condi- tions are ＂extreme＂ in the eye of mankind, but they may be suitable or even essential living conditions for most microorgan- isms. Hypertherrnophilic microorganisms form a branch at the root of the phylogenetic tree, indicating that early life originated from extreme environments similar to that of modern deep-sea hydrothermal vents, which are characterized by high-tempera- ture and oxygen-limiting conditions. During the inevitable cooling and gradual oxidation process on Earth, microorganisms developed similar mechanisms of adaptation. By studying modem extremophiles, we may be able to decode the mysterious history of their genomic evolution and to reconstruct e~,rly life. Because life itself is a process of energy uptake to maintain a dissipative structure that is not in thermodynamic equilibrium, the energy metabolism of microorganisms determines the path- way of evolution, the structure of an ecosystem, and the physiology of cells. ＂Following energy＂ is an essential approach to understand the boundaries of life and to search for life beyond Earth.展开更多
Anaerobic ammonium oxidation(anammox) is a relatively new pathway within the N cycle discovered in the late 1990 s. This eminent discovery not only modified the classical theory of biological metabolism and matter cyc...Anaerobic ammonium oxidation(anammox) is a relatively new pathway within the N cycle discovered in the late 1990 s. This eminent discovery not only modified the classical theory of biological metabolism and matter cycling, but also profoundly influenced our understanding of the energy sources for life. A new member of chemolithoautotrophic microorganisms capable of carbon fixation was found in the vast deep dark ocean. If the discovery of the chemosynthetic ecosystems in the deep-sea hydrothermal vent environments once challenged the old dogma "all living things depend on the sun for growth," the discovery of anammox bacteria that are widespread in anoxic environments fortifies the victory over this dogma. Anammox bacteria catalyze the oxidization of NH_4^+ by using NO_2^- as the terminal electron acceptor to produce N_2. Similar to the denitrifying microorganisms, anammox bacteria play a biogeochemical role of inorganic N removal from the environment. However, unlike heterotrophic denitrifying bacteria, anammox bacteria are chemolithoautotrophs that can generate transmembrane proton motive force, synthesize ATP molecules and further carry out CO_2 fixation through metabolic energy harvested from the anammox process. Although anammox bacteria and the subsequently found ammonia-oxidizing archaea(AOA), another very important group of N cycling microorganisms are both chemolithoautotrophs, AOA use ammonia rather than ammonium as the electron donor and O_2 as the terminal electron acceptor in their energy metabolism. Therefore, the ecological process of AOA mainly takes place in oxic seawater and sediments, while anammox bacteria are widely distributed in anoxic water and sediments, and even in some typical extreme marine environments such as the deep-sea hydrothermal vents and methane seeps. Studies have shown that the anammox process may be responsible for 30%–70% N_2 production in the ocean. In environmental engineering related to nitrogenous wastewater treatment, anammox provides a new technology with low energy consumption, low cost, and high efficiency that can achieve energy saving and emission reduction. However, the discovery of anammox bacteria is actually a hard-won achievement. Early in the 1960 s, the possibility of the anammox biogeochemical process was predicted to exist according to some marine geochemical data. Then in the 1970 s, the existence of anammox bacteria was further predicted via chemical reaction thermodynamic calculations. However, these microorganisms were not found in subsequent decades. What hindered the discovery of anammox bacteria, an important N cycling microbial group widespread in hypoxic and anoxic environments? What are the factors that finally led to their discovery? What are the inspirations that the analyses of these questions can bring to scientific research? This review article will analyze and elucidate the above questions by presenting the fundamental physiological and ecological characteristics of the marine anammox bacteria and the principles of scientific research.展开更多
文摘ZnO nanorods, with the c-axis orientation used for transparent conductors, solar cells, sensors especially the functionalized ZnO nanorods with some kinds of enzymes have been used for biosensor. In this work, we describe the process immobilization of galactose oxidase on ZnO nanorods surface with glutaraldehyde as a cross-linker molecule to make the working electrode in electrochemical biosensor. ZnO nanorods were grown on FTO （Fluorine-doped tin oxide） substrate by solution method at low temperature. The crystalline phase and orientation of ZnO nanorods were identified using X-ray diffraction. The efficiency of the immobilization was calculated by Braford method showed that about 36% enzyme content was immobilized on ZnO nanorods surface. The working electrode based on the immobilized ZnO nanorods was tested in galactose solution by CV （cyclic voltammetry） method indicated the value of current intensity is about 0.14 μA. These results clearly demonstrate the potential of galactose sensor based on ZnO nanorod.
基金supported by National Natural Science Foundation of China (Grant No. 31290232)National High-Tech Program (Grant No. 2012AA092103-2)National Basic Research Program of China (Grant No. 2011CB808800)
文摘The term ＂extreme environments＂ describes the conditions that deviate from what mesophilic cells can tolerate. These condi- tions are ＂extreme＂ in the eye of mankind, but they may be suitable or even essential living conditions for most microorgan- isms. Hypertherrnophilic microorganisms form a branch at the root of the phylogenetic tree, indicating that early life originated from extreme environments similar to that of modern deep-sea hydrothermal vents, which are characterized by high-tempera- ture and oxygen-limiting conditions. During the inevitable cooling and gradual oxidation process on Earth, microorganisms developed similar mechanisms of adaptation. By studying modem extremophiles, we may be able to decode the mysterious history of their genomic evolution and to reconstruct e~,rly life. Because life itself is a process of energy uptake to maintain a dissipative structure that is not in thermodynamic equilibrium, the energy metabolism of microorganisms determines the path- way of evolution, the structure of an ecosystem, and the physiology of cells. ＂Following energy＂ is an essential approach to understand the boundaries of life and to search for life beyond Earth.
基金the National Natural Science Foundation of China (Grant Nos. 91328209, 91428308)the National Key Basic Research Program of China (Grant No. 2013CB955700)+2 种基金the State Oceanic Administration of China Program (Grant No. GASI-03-01-02-05)the Program of China National Offshore Oil Corporation (Grant Nos. CNOOC-KJ 125 FZDXM 00TJ 001-2014, CNOOC-KJ 125 FZDXM 00ZJ 001-2014)the Ministry of Science and Technology of the People’s Republic of China Program (Grant No. 2011IM010700)
文摘Anaerobic ammonium oxidation(anammox) is a relatively new pathway within the N cycle discovered in the late 1990 s. This eminent discovery not only modified the classical theory of biological metabolism and matter cycling, but also profoundly influenced our understanding of the energy sources for life. A new member of chemolithoautotrophic microorganisms capable of carbon fixation was found in the vast deep dark ocean. If the discovery of the chemosynthetic ecosystems in the deep-sea hydrothermal vent environments once challenged the old dogma "all living things depend on the sun for growth," the discovery of anammox bacteria that are widespread in anoxic environments fortifies the victory over this dogma. Anammox bacteria catalyze the oxidization of NH_4^+ by using NO_2^- as the terminal electron acceptor to produce N_2. Similar to the denitrifying microorganisms, anammox bacteria play a biogeochemical role of inorganic N removal from the environment. However, unlike heterotrophic denitrifying bacteria, anammox bacteria are chemolithoautotrophs that can generate transmembrane proton motive force, synthesize ATP molecules and further carry out CO_2 fixation through metabolic energy harvested from the anammox process. Although anammox bacteria and the subsequently found ammonia-oxidizing archaea(AOA), another very important group of N cycling microorganisms are both chemolithoautotrophs, AOA use ammonia rather than ammonium as the electron donor and O_2 as the terminal electron acceptor in their energy metabolism. Therefore, the ecological process of AOA mainly takes place in oxic seawater and sediments, while anammox bacteria are widely distributed in anoxic water and sediments, and even in some typical extreme marine environments such as the deep-sea hydrothermal vents and methane seeps. Studies have shown that the anammox process may be responsible for 30%–70% N_2 production in the ocean. In environmental engineering related to nitrogenous wastewater treatment, anammox provides a new technology with low energy consumption, low cost, and high efficiency that can achieve energy saving and emission reduction. However, the discovery of anammox bacteria is actually a hard-won achievement. Early in the 1960 s, the possibility of the anammox biogeochemical process was predicted to exist according to some marine geochemical data. Then in the 1970 s, the existence of anammox bacteria was further predicted via chemical reaction thermodynamic calculations. However, these microorganisms were not found in subsequent decades. What hindered the discovery of anammox bacteria, an important N cycling microbial group widespread in hypoxic and anoxic environments? What are the factors that finally led to their discovery? What are the inspirations that the analyses of these questions can bring to scientific research? This review article will analyze and elucidate the above questions by presenting the fundamental physiological and ecological characteristics of the marine anammox bacteria and the principles of scientific research.
