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Industrial Prospects of Bacterial Microcompartment Technologies
Published in Deepak Kumar Verma, Ami R. Patel, Sudhanshu Billoria, Geetanjali Kaushik, Maninder Kaur, Microbial Biotechnology in Food Processing and Health, 2023
Shagun Rastogi, Chiranjit Chowdhury
Several enteric bacteria degrade rhamnose and fucose, the common plant sugars under an anaerobic environment, and produce 1,2-PD; which is then taken up as carbon and energy source by these bacteria (Obradors et al., 1988). During 1,2-PD degradation, the substrate gets converted to propionaldehyde by diol dehydratase, a coenzyme B12-dependent enzyme (Bobik et al., 1997; Chowdhury et al., 2014) (Figure 10.3). Propionaldehyde dehydrogenase converts propionaldehyde to propionyl-CoA. In aerobic respiration, propionyl-CoA feeds into TCA (tricarboxylic acid cycle) cycle via the methyl citrate pathway (Horswill and Escalante-Semerena, 1999; Chowdhury et al., 2014). Therefore, 1,2-PD serves as both carbon and energy source in aerobic conditions (Jeter, 1990). However, an earlier study reveals that Salmo- nella can respire 1,2-PD anaerobically in the presence of tetrathionate. In anaerobic conditions, tetrathionate serves as the terminal electron acceptor (Price-Carter et al., 2001). It has been shown that breakdown of 1,2-PD occurs inside MCP (Bobik et al., 1997; Chowdhury et al., 2014) (Figure 10.3). The function of the Pdu MCP is to isolate propionaldehyde to mitigate cytotoxicity and DNA damage caused by toxic aldehyde intermediate. It was shown that propionaldehyde is built up to a toxic level in the mutants that disrupt shell formation during growth on 1,2-PD (Havemann et al., 2002; Sampson and Bobik, 2008).
Metabolic Engineering of Methanogenic Archaea for Biomethane Production from Renewable Biomass
Published in Sonil Nanda, Prakash K. Sarangi, Biomethane, 2022
Rajesh Kanna Gopal, Preethy P. Raj, Ajinath Dukare, Roshan Kumar
In biomethane production, CO2 is first reduced to form activated formylmethanofuran (Wagner et al., 2016) by reduced ferredoxin as an electron donor. Next, the formyl group is transferred to tetrahydromethanopterin in the second reaction. Dehydration and reduction take place in the formyl group to form methylene-tetrahydromethanopterin with reduced F420 as an electron donor (Liu and Whitman, 2008). Coenzyme M acts as a transferase and transfers methyl group from the methylene-tetrahydromethanopterin. Lastly, coenzyme B (CoB) as an electron donor reduces methyl-CoM to generate methane. Then the reduction of residual heterodisulfide (CoM-S-S-CoB) took place by the action of H2 to recycle coenzymes (Thauer et al., 2008; Liu and Whitman, 2008). In contrast to this, Methanothermobacter thermautotrophicus and Methanosarcina barkeri oxidize four molecules of CO to form CO2 by CO dehydrogenase enzyme and subjected to reduce into one molecule of CO2 to synthesize CH4 with H2 molecule as an electron donor (O’Brien et al., 1984; Daniels et al., 1977).
Biomethanization in Anaerobic Systems
Published in Akinola Rasheed Popoola, Emeka Godfrey Nwoba, James Chukwuma Ogbonna, Charles Oluwaseun Adetunji, Nwadiuto (Diuto) Esiobu, Abdulrazak B. Ibrahim, Benjamin Ewa Ubi, Bioenergy and Environmental Biotechnology for Sustainable Development, 2022
N. C. Ezebuiro, C. O. Onyia, I. Körner
MCR is only found in methanogens and catalyzes the final stage of CH4 production from the reduction of –CH3. This involves the reaction between methyl-coenzyme-M (CH3-S-CoM) and coenzyme-B (SH-CoB) in the presence of MCR to form CH4, SH-CoM and SH-CoB. Two forms of MCR known as MCR-I and MCR-II exist: MCR-I functions optimally in the pH range between 7.0 and 7.5 and has a maximum reaction rate of approximately 6 µmol/min/mg. The maximum reaction rate for MCR-II is approximately 21 µmol/min/mg and the optimum pH range is 7.5–8.0. Notwithstanding the form of existence, the general feature of MCR includes a reactive co-factor known as F430, which is dependent on its active Ni-complex for catalysis. Ni-complex in MCR is similar to the Co-complex in MeTr, and the active form of Ni in MCR is the Ni+ state, which forms CH3-Ni3+ when it receives CH3 group from MeTr (Caspi et al., 2008).
Microbial and functional characterization of granulated sludge from full-scale UASB thermophilic reactor applied to sugarcane vinasse treatment
Published in Environmental Technology, 2022
Franciele Pereira Camargo, Isabel Kimiko Sakamoto, Tiago Palladino Delforno, Cédric Midoux, Iolanda Cristina Silveira Duarte, Edson Luiz Silva, Ariane Bize, Maria Bernadete Amâncio Varesche
The K03388 was the second most abundant KO related with methanogenesis (0.0034%). It is a heterodisulfide reductase (subunit A2), which can be found in most methanogenic organisms and catalyzes the regeneration of the Coenzyme B and Coenzyme M heterodisulfide (Equation (19)), using two molecules of ferredoxin (oxidized, [4Fe-4S] cluster). In Methanosarcina, it can also catalyze the reactions involving the coenzyme F420:CoB-CoM heterodisulfide and ferredoxin reductase (reduced, [4Fe-4S] cluster) (Equation (20)). Also, this enzyme can be found in formate-oxidizing CO2-reducing methanogenic archaea, such as Methanococcus, reducing both ferredoxin and CoB-CoM heterodisulfide to formate (Equation (21)) [15]. Being that, it is possible to state that this enzyme is involved in the three types of methanogenesis: acetoclastic, hydrogenotrophic and methylotrophic. In this study, the genera Methanosarcina (29.6%), Methanothermobacter (20.9%) and Methanoculleus (20.7%) were related to this KO.