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Multi-Disciplinary Nature of Microbes in Agricultural Research
Published in Gustavo Molina, Zeba Usmani, Minaxi Sharma, Abdelaziz Yasri, Vijai Kumar Gupta, Microbes in Agri-Forestry Biotechnology, 2023
Zengwei Feng, Honghui Zhu, Qing Yao
Nitrogen fixation is the most prominent feature of N-fixing microbes and also the core mechanism for them to promote growth of host plants. It is catalyzed by one of the nitrogenase metalloenzymes, including iron-iron (FeFe), vanadium-iron (VFe), and molybdenum-iron (MoFe) nitrogenases, which are cooperatively regulated by the electron transfer protein (known as nitrogenase reductase or iron protein and encoded by nifH) and the α-subunit (encoded by nifD) and β-subunit (encoded by nifK) of the catalytic enzyme in the root and/or stem nodules (Eady 1996; Kuypers et al. 2018). BNF can effectively offset N limitation, especially in N-depleted soil, resulting in a release of plant growth potential. For instance, inoculation with Klebsiella variicola strain DX120E significantly increased the dry weight, N, P, and K contents of sugarcane plants at 52%, 80%, 69%, and 67%, respectively (Wei et al. 2014). A field experiments using 15N natural abundance or 15N-enrichment assessments over five years indicated that atmospheric N fixation contributed 29–82% of the N nutrition of maize (van Deynze et al. 2018).
Biofuel Production
Published in Nitin Kumar Singh, Siddhartha Pandey, Himanshu Sharma, Sunkulp Goel, Green Innovation, Sustainable Development, and Circular Economy, 2020
Prabuddha Gupta, Tejas Oza, Mahendrapalsingh Rajput, Ujwalkumar Trivedi, Gaurav Sanghvi
The first observation of hydrogen production using algae was by Gaffron and Rubrin in 1942 when they reported for the first time that algae species Scenedesmus obliquus produces hydrogen at low rates in the dark and hydrogen production was enhanced in presence of light. The simpler structure of algae allows them to easily adapt to the environmental conditions and to prosper in the long term (Rathore and Singh, 2013). Currently, three main approaches are followed for the production of hydrogen. The first approach involves hydrogen production using Cyanobacteria and green algae (Elshahed, 2010). During hydrogen generation, the water is split to produce electrons. These electrons are used for energy production via an electron transport chain followed by anabolic reaction (biomass and sugar production). Further, these products are converted to hydrogen using hydrogenase enzymes (Elshahed, 2010; Prince and Kheshgi, 2005). The second approach involves the use of nitrogenase enzymes for hydrogen production using photoheterotrophic microorganisms. The nitrogenase enzyme fixes atmospheric nitrogen to ammonia and fixes it into cell biomass. This enables the microorganism to grow in the absence of both organic and inorganic nitrogen, leading to hydrogen production during the growth process. The third approach involves the production of hydrogen using anaerobic bacteria and substrates like lignocellulosic waste, industrial and residential waste. Many bacteria like Enterobacteria and Clostridium sp. are known for hydrogen production as an end product in fermentation pathways (Elshahed, 2010).
The Chemical Work of Biosynthesis
Published in Jean-Louis Burgot, Thermodynamics in Bioenergetics, 2019
This brief summary calls for the following comments: – The fixation of N2 as NH3 is carried out enzymatically with the aid of the nitrogenate complex. This system is constituted of two kinds of proteic components: one reductase of strong reducing potential, and a nitrogenase which reduces N2 in NH4+. Each component is a protein iron-sulfur. The nitrogenase also contains a molybdenum atom. The reduction of N2 in NH4+ requires the occurrence of ATP and of a powerful reductant. The reduction reaction is: N2 + 6e− + 12ATP + 12H2O→2NH4+ + 12ADP + 12P + 4H+
Oxovanadium and dioxomolybdenum complexes: synthesis, crystal structure, spectroscopic characterization and applications as homogeneous catalysts in sulfoxidation
Published in Journal of Coordination Chemistry, 2021
Hadi Kargar, Azar Kaka-Naeini, Mehdi Fallah-Mehrjardi, Reza Behjatmanesh-Ardakani, Hadi Amiri Rudbari, Khurram Shahzad Munawar
Molybdenum is an essential element, present in more than 40 different naturally occurring enzymes involved in redox reactions. It is important for the fixation and assimilation of atmospheric nitrogen with the help of bacterial nitrogenase and nitrate reductase [24]. Moreover, molybdoenzymes, sulfite oxidase and aldehyde oxidase are used for oxidation of sulfite and aldehyde, respectively [25]. In addition to the importance of molybdenum complexes in biological process, they have potential to be used as effective catalyst in epoxidation of olefins (styrene and cyclohexane), olefin metathesis, isomerization of allylic alcohol, oxidation of sulfides to sulfoxides and oxidation of amines [26–28]. Coordination of molybdenum with the aroylhydrazones usually generates MoO2L or MoOL complexes which bear one or two open sites that can be used to enhance the coordination number by binding with substrate molecules. Due to the presence of these vacant sites molybdenum complexes can be regarded as template for numerous enzymatic and catalytic sites [29, 30].
Prediction models for evaluating heavy metal uptake by Pisum sativum L. in soil amended with sewage sludge
Published in Journal of Environmental Science and Health, Part A, 2020
Ebrahem M. Eid, Kamal H. Shaltout, Saad A. M. Alamri, Nasser A. Sewelam, Tarek M. Galal, Eid I. Brima
The top three HM concentrations in P. sativum tissues and the soil amended with SS were Fe > Mn > Zn, suggesting ease of uptake of these HMs due to their presence in higher concentrations in the soil and their essential roles in plant growth.[41,43] For example, Fe is capable of acting as an electron carrier in enzyme systems that bring about oxidation-reduction reactions in plants; such reactions are essential steps in photosynthesis and many other metabolic processes. Fe and Mn are components of the enzyme nitrogenase, which is essential for the processes of symbiotic and non-symbiotic nitrogen fixation.[4] Mn and Zn function as bridges to connect enzymes with their substrates, while Mn is essential for certain nitrogen transformations in plants and microorganisms. In addition, Zn plays a role in protein synthesis, the formation of some growth hormones, and the productive process of certain plants. However, Cd, Pb, Mo, Co and Ni tend to accumulate poorly in the tissues of investigated plants, and their uptake occurs mainly in the root system. Similar findings have been reported in many studies, such as Latare et al.,[44] Eid et al.[10] and Ahmed and Slima.[42] Some toxic HMs, such as Cd and Pb, have been recognized by the World Health Organization (WHO) to cause cancer, livestock health problems, and human nerve damage, among other severe health problems.[45] Additionally, both elements were suggested to reduce the total chlorophyll content by inhibiting chlorophyll biosynthetic enzymes.[46]
Green hydrogen production by Rhodobacter sphaeroides
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Dahbia Akroum-Amrouche, Hamza Akroum, Hakim Lounici
Nitrogenase is an enzyme that catalyzes N2 fixation and it is essential for maintaining the nitrogen cycle on the earth. A wide range of microorganisms possesses this enzyme, including R. sphaeroides. Nitrogenase is metalloenzyme complex converting nitrogen to ammonia with the hydrolysis of ATP. The nitrogen reduction to ammonium, catalyzed by nitrogenase, is a strongly endergonic reaction requiring ATP. Two ATPs are required for each electron transfer, and therefore, a total of 16 ATPs are required to fix one mole of N2, as indicated in the equation (1). In the absence of N2 and oxygen, the nitrogenase produces exclusively H2 (Eq. 2) (Kim and Kim 2011).