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| Titel |
D/H Ratios in Lipids as a Tool to Elucidate Microbial Metabolism |
| VerfasserIn |
Reto S. Wijker, Alex L. Sessions |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250125442
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| Publikation (Nr.) |
 EGU/EGU2016-5023.pdf |
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| Zusammenfassung |
| Large D/H fractionations have been observed in the lipids and growth water of
most organisms studied today. These fractionations have generally been assumed to
be constant across most biota because they originate solely from isotope effects
imposed by the highly conserved lipid biosynthetic pathway. Recent data is illustrating
this conclusion as incomplete. Lipids from field and laboratory samples exhibit
huge variations in D/H fractionation. In environmental samples, lipids vary in δD
by up to 300 ‰ and in laboratory cultures the documented variation is up to 500
‰ within the same organism. Remarkably, the isotope fractionation appears to be
correlated with the type of metabolism employed by the host organism. However, the
underlying biochemical mechanisms leading to these isotopic variations are not yet fully
understood.
Because the largest proportion of H-bound C in fatty acids is derived directly from
NADPH during biosynthesis, the original hypothesis was that large differences in the isotopic
composition of NADPH, generated by different central metabolic pathways, were the primary
source of D/H variation in lipids. However, recent observations indicate that this
cannot be the whole story and lead us to the conclusion that additional processes
must affect the isotope composition of NADPH. These processes may include the
isotopic exchange of NADPH with water as well as fractionation of NADPH by
transhydrogenases, interconverting NADH to NADPH by exhibiting large isotope
effects.
In this project, our objective is to ascertain whether D/H fractionation and these
biochemical processes are correlated. We investigate correlations between cellular
NADPH/NADP+ as well as NADH/NAD+ pool sizes and the D/H fractionation in a set of
different microorganisms and will present the trends here. Our results will contribute to a
more comprehensive understanding of the basic biological regulations over D/H fractionation
and potentially enables their use as tracers and proxies across earth and biological sciences. |
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