25th International Meeting on Organic Geochemistry IMOG 2011

P-156
A detailed study of the intact polar lipids in Dutch coastal waters
and microbial mats using multistage liquid chromatography
mass spectrometry
Nicole Bale, Ellen Hopmans, Laura Villanueva, Stefan Schouten, Jaap Sinninghe
Damste
Royal Netherlands Institute for Sea Research, Texel, Netherlands (corresponding
author:nicole.bale@nioz.nl)
Nitrogen is a key nutrient in marine waters and can be
a limiting factor for primary production. The marine
nitrogen cycle involves many complex and
interrelated process driven by microbial activity. As
part of the NICYCLE project (The nitrogen cycle and
changes in the carrying capacity of coastal waters) we
have been analysing Intact Polar Lipids (IPLs) in
order to examine the abundance, distribution and
activity of microorganisms involved in marine nitrogen
cycling, specifically in coastal environments. A
principle focus of this study was to examine the
spatial and temporal variability of the nitrogen cycling
microorganisms and we have, with this aim, collected
samples from three different time series in the Dutch
Coastal environment, both from the North Sea and
Wadden Sea.
For the first time series we collected North Sea water,
from a fixed station in the Marsdiep Tidal inlet, every
two weeks for 1.5 years. Secondly we collected
microbial mats from the beaches of a Wadden Sea/
North Sea barrier island bimonthly for a year. The
third time series is made up of four seasonally-distinct
research cruises in one year, carried out along a 235
km transect from the barrier islands into the North
Sea. On these cruises we have collected particulate
matter in the water column as well as sediment.
We have used two analytical approaches in the study
of the microbial IPLs. We worked firstly with a
‗lipidomic‘-style method using liquid chromatography-
multistage mass spectrometry (LC-MS/MS),
whereby we looked at the ‗fingerprint‘ of IPLs in each
sample and examined how this changes, spatially and
temporally between seasons and geographical
settings. The second approach will concentrate on
changes in specific ‗target‘ IPLs which are indicative
of nitrogen-cycling microorganisms, e.g. the IPLs of
crenarchaeol (for ammonia-oxidizing
Thaumarchaeota), heterocyst glycolipids (for nitrogenfixing
cyanobacteria) and ladderanes (for anaerobic
ammonia-oxidizing anammox bacteria). This will be
done using specific LC-MS/MS essays such as
selective reaction monitoring (SRM).
Using the first approach we have identified a range of
IPLs in the samples examined, including
phospholipids such as phosphatidylglycerols (PGs),
phosphatidylethanolamines (PEs) and
phosphatidylcholines (PCs) as well as phosphorousfree
IPLs such as the nitrogen-containing betaine
lipids, the sulphur-containing sulfoquinovosyl
diacylglycerols (SQDGs) and galacto lipids (Fig. 1).
The presence, abundance and range of these IPLs
vary between the sampling sites (spatially) as well as
during the time series (temporally).
Using the second, SRM-based approach we can
monitor whether there are observable changes in our
target lipids over annual timescales. The data will be
compared with those obtained using molecular
ecological techniques on complimentary samples.
Our results will shed light on the utility of IPLs as
markers for general microbial community
composition as well as the presence and abundance
of microbes involved in the marine nitrogen cycle.
Figure 1. A Base peak LC/MS
chromatogram of a Bligh Dyer
Extract from a microbial mat
sample collected from
Schiermonnikoog, a North
Sea/Wadden Sea barrier
island, in February 2010.
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