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Xu Z, d'Ippolito G. Thermotoga neapolitana. Trends Microbiol 2023; 31:107-108. [PMID: 36244922 DOI: 10.1016/j.tim.2022.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/29/2022] [Accepted: 09/12/2022] [Indexed: 11/05/2022]
Affiliation(s)
- Zhaohui Xu
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, USA.
| | - Giuliana d'Ippolito
- Institute of Biomolecular Chemistry (ICB), National Research Council (CNR), Via Campi Flegrei 34, 80078 Pozzuoli, Naples, Italy
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Occurrence of Capnophilic Lactic Fermentation in the Hyperthermophilic Anaerobic Bacterium Thermotoga sp. Strain RQ7. Int J Mol Sci 2022; 23:ijms231912049. [PMID: 36233345 PMCID: PMC9570489 DOI: 10.3390/ijms231912049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/03/2022] [Accepted: 10/06/2022] [Indexed: 11/17/2022] Open
Abstract
Capnophilic lactic fermentation (CLF) is an anaplerotic pathway exclusively identified in the anaerobic hyperthermophilic bacterium Thermotoga neapolitana, a member of the order Thermotogales. The CO2-activated pathway enables non-competitive synthesis of hydrogen and L-lactic acid at high yields, making it an economically attractive process for bioenergy production. In this work, we discovered and characterized CLF in Thermotoga sp. strain RQ7, a naturally competent strain, opening a new avenue for molecular investigation of the pathway. Evaluation of the fermentation products and expression analyses of key CLF-genes by RT-PCR revealed similar CLF-phenotypes between T. neapolitana and T. sp. strain RQ7, which were absent in the non-CLF-performing strain T. maritima. Key CLF enzymes, such as PFOR, HYD, LDH, RNF, and NFN, are up-regulated in the two CLF strains. Another important finding is the up-regulation of V-ATPase, which couples ATP hydrolysis to proton transport across the membranes, in the two CLF-performing strains. The fact that V-ATPase is absent in T. maritima suggested that this enzyme plays a key role in maintaining the necessary proton gradient to support high demand of reducing equivalents for simultaneous hydrogen and lactic acid synthesis in CLF.
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Sha C, Wang Q, Wang H, Duan Y, Xu C, Wu L, Ma K, Shao W, Jiang Y. Characterization of Thermotoga neapolitana Alcohol Dehydrogenases in the Ethanol Fermentation Pathway. BIOLOGY 2022; 11:biology11091318. [PMID: 36138797 PMCID: PMC9495900 DOI: 10.3390/biology11091318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/26/2022] [Accepted: 09/01/2022] [Indexed: 11/16/2022]
Abstract
Hyperthermophilic Thermotoga spp. are candidates for cellulosic ethanol fermentation. A bifunctional iron-acetaldehyde/alcohol dehydrogenase (Fe-AAdh) has been revealed to catalyze the acetyl-CoA (Ac-CoA) reduction to form ethanol via an acetaldehyde intermediate in Thermotoga neapolitana (T. neapolitana). In this organism, there are three additional alcohol dehydrogenases, Zn-Adh, Fe-Adh1, and Fe-Adh2, encoded by genes CTN_0257, CTN_1655, and CTN_1756, respectively. This paper reports the properties and functions of these enzymes in the fermentation pathway from Ac-CoA to ethanol. It was determined that Zn-Adh only exhibited activity when oxidizing ethanol to acetaldehyde, and no detectable activity for the reaction from acetaldehyde to ethanol. Fe-Adh1 had specific activities of approximately 0.7 and 0.4 U/mg for the forward and reverse reactions between acetaldehyde and ethanol at a pHopt of 8.5 and Topt of 95 °C. Catalyzing the reduction of acetaldehyde to produce ethanol, Fe-Adh2 exhibited the highest activity of approximately 3 U/mg at a pHopt of 7.0 and Topt of 85 °C, which were close to the optimal growth conditions. These results indicate that Fe-Adh2 and Zn-Adh are the main enzymes that catalyze ethanol formation and consumption in the hyperthermophilic bacterium, respectively.
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Affiliation(s)
- Chong Sha
- Biofuels Institute, School of the Environment, Jiangsu University, Zhenjiang 212013, China
| | - Qiang Wang
- Biofuels Institute, School of the Environment, Jiangsu University, Zhenjiang 212013, China
- School of Biological and Food Engineering, Suzhou University, Bianhe Middle Road 49, Suzhou 234000, China
| | - Hongcheng Wang
- Biofuels Institute, School of the Environment, Jiangsu University, Zhenjiang 212013, China
| | - Yilan Duan
- School of Biological and Food Engineering, Suzhou University, Bianhe Middle Road 49, Suzhou 234000, China
| | - Chongmao Xu
- Huzhou Research Center of Industrial Biotechnology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Huzhou 313000, China
| | - Lian Wu
- Huzhou Research Center of Industrial Biotechnology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Huzhou 313000, China
| | - Kesen Ma
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Weilan Shao
- Shine E BioTech (Nanjing) Company, Nanjing 210023, China
- Correspondence: (W.S.); (Y.J.)
| | - Yu Jiang
- Huzhou Research Center of Industrial Biotechnology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Huzhou 313000, China
- Correspondence: (W.S.); (Y.J.)
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