25th International Meeting on Organic Geochemistry IMOG 2011

P-231
Bacteriohopanepolyol content of pasture soils in NE England
Martin Cooke, Helen Talbot
Newcastle University, Newcastle Upon Tyne, United Kingdom (corresponding author:M.P.Cooke@ncl.ac.uk)
Bacteriohopanpolyols (BHPs) are a group of
membrane lipids synthesized by a wide range of
prokaryotes with a high degree of structural specificity
relative to bacterial source. BHPs are pentacyclic
triterpenoids with a 5-carbon side chain which can
contain 4, 5 or 6 functional groups (Tetra-, Penta- and
Hexa-functionalisation), predominantly hydroxyls,
amine or composite groups such as amino sugars. In
addition to the functional groups BHPs can be
methylated at either C-2, C-3 or C-12 and unsaturated
at C-6 or C-11.
Recent investigations into the BHP content
of soils have shown a high number of BHP structures
(e.g. Cooke et al., 2008). This observation opens up
the possibility that variations in BHP content of soils
may be used as proxies for a variety of bacterially
driven processes in soils.
The Palace Leas experimental pasture plots
(Cockle Park Farm, Northumbria), consist of 14 plots
that have received consistent fertilizer treatments
since 1896. The plots studied here have received: no
fertilizer, manure, potassium, nitrogen or phosphorous
fertilizer only. In this study we investigated the semiquantitative
BHP concentration (indicated as [BHP])
of pasture soils in Northern England. BHPs were
extracted from freeze dried soils and analysed by
HPLC-MS n (Cooke et al., 2008).
Investigation into the [BHP] of the plots
during 2006 and 2007 identified 38 different BHPs
with the distribution being dominated by 5 compounds
(Fig.1):, bacteriohopanetetrol (m/z 655), aminotriol
(m/z 714), adenosylhopane (m/z 746),
adenosylhopane type-1 (m/z 761) and
bacteriohopanetetrol cyclitol ether (m/z 1002 ce).
Principle component analysis identified a
separation based upon their BHP profile indicating
that the different fertilizer treatments had influenced
the BHP producing bacterial population of the plots.
An apparent annual cycle to the BHP concentration
with peaks during the summer and autumn months
and significant reduction in BHP concentration during
the winter was observed at all depths (Fig. 2).
Analysis of the variation in [BHPs] during this
time indicated that there was a rise in the
concentrations of most BHPs during this time implying
a rise in total BHP producing bacterial population or
an increase in BHP production by the existing
bacterial population.
These observations suggest that analysis of
the [BHP] in soils could reflect active BHP-producing
populations and therefore provide insight into current
population dynamics and environmental factors.
µg BHP/gTOC
350
300
250
200
150
100
50
0
655
2Me 669
712
714
2Me 728
Palace Leas Plot 2 May 2006
3Me 728
772
830
844
746
760
m/z
761
775
0-5 cm 5-10 cm 10-15 cm
1002 ce
1002 glu
2Me 1016
3Me 1016
1060
2Me 1060
3Me 1060
1086
1118
2Me 1132
Fig. 1. Plot 2, May 2006 [BHP]. Manure treatment.
BHPs are identified by the m/z value of the acetylated
form with amine containing BHPs being [M+H] and
other forms being [M+H-CH3COOH] (Talbot et al.,
2003).
µg BHP/gTOC
2500
2000
1500
1000
500
0
Jan 06, 0-5 cm
May 06, 0-5 cm
Oct 06, 0-5 cm
Jan 07, 0-5 cm
Palace Leas Plot 2, Total [BHP]
Jan 06, 5-10
cm
Fig. 2 Annual variation in [BHP], Plot 2 May 2006.
May 06, 5-10
cm
Cooke, M.P., Talbot, H.M., Farrimond, P., 2008.
Organic Geochemistry 39, 1347-1358.
Talbot, H.M., Squier, A.H., Keely, B.J., Farrimond, P.,
2003. Rapid Communications in Mass Spectrometry
17, 728-737.
Oct 06, 5-10
cm
Jan 07, 5-10cm
Jan 06, 10-15
cm
May 06, 10-15
cm
Oct 06, 10-15
cm
Jan 07, 10-15
cm
368