Chapter 9
Mutagens, Radicals, Rocket Fuel,
and Laughing Gas: Stringing Metabolic
Modules to Survive on Nitrogenous Poisons
Martin G. Klotz and Lisa Y. Stein
Abstract Nitrogen is a key element, enabling life on planet Earth as we know it. In
addition to being essential as a major component of biomass, its unsurpassed redox
reactivity and versatility makes it an exceptional actor in abiotic nutrient cycling and
cellular metabolism. While nitrogen compounds have been essential parts in the
processes that led to the incredible diversity of life, from humble molecular beginnings throughout its evolution before and after the oxygenation of planet Earth, their
impact has emerged and will persist into the future as instruments to the metabolic
creativity of microorganisms. Whether this plays out in natural harmony, providing
support for extant diversity, or eventually leads to abyss and an inhabitable planet to
multicellular creatures is in the hands of humankind.
Nitrogen is a peculiar element. Like carbon and boron, nitrogen can form a triple
bond with itself, one of the strongest covalent bonds known; however, dinitrogen
(N 2 ) is the only triple-bonded molecule that exists as an inert gas. Its high molecular
stability is the reason why N 2 gas is virtually unreactive and permits life to exist in an
atmosphere that consists of about 78% dinitrogen. In contrast to the nonpolar N 2
molecule, triple-bonded carbons, the alkynes, are reduced hydrocarbons and thus
polar and reactive gases, liquids, or even solids. Uniquely, nitrogen can also form a
triple bond with carbon giving rise to the salt-forming (iso)cyanides, R-CN, which
are rapidly interactive, inhibitory to many metabolic reactions and thus highly toxic
to cells. Nevertheless, a sizeable number of microbes utilize cyanide derivatives such
as cyanate as a source of energy and reductant (Fig. 9.1) while being able to protect
sensitive intracellular targets from cyanide activity.
M. G. Klotz (*)
School of Molecular Biosciences, College of Veterinary Medicine, Washington State
University, Richland, WA, USA
L. Y. Stein
Department of Biological Sciences, Faculty of Science, University of Alberta, Edmonton, AB,
Canada
© Springer Nature Switzerland AG 2021
C. J. Hurst (ed.), Microbes: The Foundation Stone of the Biosphere, Advances in
Environmental Microbiology 8, https://doi.org/10.1007/978-3-030-63512-1_9
151
Mutagens, Radicals, Rocket Fuel,
and Laughing Gas: Stringing Metabolic
Modules to Survive on Nitrogenous Poisons
Martin G. Klotz and Lisa Y. Stein
Abstract Nitrogen is a key element, enabling life on planet Earth as we know it. In
addition to being essential as a major component of biomass, its unsurpassed redox
reactivity and versatility makes it an exceptional actor in abiotic nutrient cycling and
cellular metabolism. While nitrogen compounds have been essential parts in the
processes that led to the incredible diversity of life, from humble molecular beginnings throughout its evolution before and after the oxygenation of planet Earth, their
impact has emerged and will persist into the future as instruments to the metabolic
creativity of microorganisms. Whether this plays out in natural harmony, providing
support for extant diversity, or eventually leads to abyss and an inhabitable planet to
multicellular creatures is in the hands of humankind.
Nitrogen is a peculiar element. Like carbon and boron, nitrogen can form a triple
bond with itself, one of the strongest covalent bonds known; however, dinitrogen
(N 2 ) is the only triple-bonded molecule that exists as an inert gas. Its high molecular
stability is the reason why N 2 gas is virtually unreactive and permits life to exist in an
atmosphere that consists of about 78% dinitrogen. In contrast to the nonpolar N 2
molecule, triple-bonded carbons, the alkynes, are reduced hydrocarbons and thus
polar and reactive gases, liquids, or even solids. Uniquely, nitrogen can also form a
triple bond with carbon giving rise to the salt-forming (iso)cyanides, R-CN, which
are rapidly interactive, inhibitory to many metabolic reactions and thus highly toxic
to cells. Nevertheless, a sizeable number of microbes utilize cyanide derivatives such
as cyanate as a source of energy and reductant (Fig. 9.1) while being able to protect
sensitive intracellular targets from cyanide activity.
M. G. Klotz (*)
School of Molecular Biosciences, College of Veterinary Medicine, Washington State
University, Richland, WA, USA
L. Y. Stein
Department of Biological Sciences, Faculty of Science, University of Alberta, Edmonton, AB,
Canada
© Springer Nature Switzerland AG 2021
C. J. Hurst (ed.), Microbes: The Foundation Stone of the Biosphere, Advances in
Environmental Microbiology 8, https://doi.org/10.1007/978-3-030-63512-1_9
151