Nitrate reduction in Haloferax alexandrinus: the case of assimilatory nitrate reductase

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Title: Nitrate reduction in Haloferax alexandrinus: the case of assimilatory nitrate reductase
Authors: Kilic, Volkan | Kilic, Gözde Aydoğan | Kutlu, Hatice Mehtap | Martínez-Espinosa, Rosa María
Research Group/s: Biotecnología de Extremófilos (BIOTECEXTREM)
Center, Department or Service: Universidad de Alicante. Departamento de Agroquímica y Bioquímica
Keywords: N-cycle | Halophiles | Archaea | Nitrate reductase | Assimilatory nitrate pathway | Denitrification
Knowledge Area: Bioquímica y Biología Molecular
Issue Date: 21-Mar-2017
Publisher: Springer Japan
Citation: Extremophiles. 2017. doi:10.1007/s00792-017-0924-4
Abstract: Haloferax alexandrinus Strain TM JCM 10717T = IFO 16590T is an extreme halophilic archaeon able to produce significant amounts of canthaxanthin. Its genome sequence has been analysed in this work using bioinformatics tools available at Expasy in order to look for genes encoding nitrate reductase-like proteins: respiratory nitrate reductase (Nar) and/or assimilatory nitrate reductase (Nas). The ability of the cells to reduce nitrate under aerobic conditions was tested. The enzyme in charge of nitrate reduction under aerobic conditions (Nas) has been purified and characterised. It is a monomeric enzyme (72 ± 1.8 kDa) that requires high salt concentration for stability and activity. The optimum pH value for activity was 9.5. Effectiveness of different substrates, electron donors, cofactors and inhibitors was also reported. High nitrite concentrations were detected within the culture media during aerobic/microaerobic cells growth. The main conclusion from the results is that this haloarchaeon reduces nitrate aerobically thanks to Nas and may induce denitrification under anaerobic/microaerobic conditions using nitrate as electron acceptor. The study sheds light on the role played by haloarchaea in the biogeochemical cycle of nitrogen, paying special attention to nitrate reduction processes. Besides, it provides useful information for future attempts on microecological and biotechnological implications of haloarchaeal nitrate reductases.
Sponsor: This work was funded by research grant from the MINECO Spain (CTM2013-43147-R) and by funds from the Department of Biology, Faculty of Science, Anadolu University (Turkey).
ISSN: 1431-0651 (Print) | 1433-4909 (Online)
DOI: 10.1007/s00792-017-0924-4
Language: eng
Type: info:eu-repo/semantics/article
Rights: © Springer Japan 2017. The final publication is available at Springer via
Peer Review: si
Publisher version:
Appears in Collections:INV - BIOTECEXTREM - Artículos de Revistas
INV - AppBiochem - Artículos de Revistas

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