TY - JOUR
T1 - Environmental indications and controls of bacterial membrane lipids in a tropical peatland from Panama
AU - Schneider, Vivien
AU - Antoszkiewicz, Joanna M. W.
AU - Vreeken, Mike
AU - Cheung, Man Kit
AU - Zeng, Z.
AU - Atencio, D.
AU - Gallego-Sala, Angela V
AU - Blewett, Jerome
AU - Pancost, Rich D
AU - Naafs, B D A
N1 - Publisher Copyright:
© 2025 The Author(s). Published by Elsevier Ltd.
PY - 2025/12/1
Y1 - 2025/12/1
N2 - Lipid biomarkers are widely used to trace microbial activity and environmental changes, yet gaps remain in our understanding of their environmental occurrence, including in tropical peatlands. We analyzed the bacterial lipid abundance in a series of 2 m long peat cores from the Republic of Panama, focusing on the diether glycerol with C15:0 n-alkyl chains (C15:0 DEG), 13,16-dimethyl octacosanedioic acid (iso-diabolic acid: iso-DA), and branched Glycerol Dialkyl Glycerol Tetraethers (brGDGTs) and combined these with novel genomic data from the same cores. In addition to understanding these compounds’ environmental occurrence, we present the first environmental insights into the co-occurrence of brGDGT-Ia with its potential precursors C15:0 DEGs and iso-DA. Our results show that iso-DA is found only in the occasionally dry top peat layer and is absent in water-saturated peat horizons. We suggest that the production of iso-DA in this peatland dependents on oxygen availability, likely due to the metabolism of the source organisms and consistent with limited available culture data of acidobacteria. In contrast, C15:0 DEGs and brGDGTs (mainly in the form of brGDGT-Ia) persist across all depths with increasing concentrations at greater depths. Although these contrasting trends in abundance could reflect the greater persistence of ether lipids relative to acyl/acid lipids due to differences in preservation rates, they could also suggest that iso-DA is not a major precursor in the biosynthetic pathway of brGDGTs in these settings. When combined with novel genomic data, we show that acidobacteria, one of the few known iso-DA and brGDGT producers, were detected at all sites and depths, forming a stable proportion of the prokaryotic community. Their consistent presence aligns more with the brGDGT and C15:0 DEG distribution than iso-DA. Combining the results from our study with experimental evidence, it appears that multiple pathways for brGDGT biosynthesis exist in tropical peats, with the phylogenetic and environmental control on their expression yet to be elucidated.
AB - Lipid biomarkers are widely used to trace microbial activity and environmental changes, yet gaps remain in our understanding of their environmental occurrence, including in tropical peatlands. We analyzed the bacterial lipid abundance in a series of 2 m long peat cores from the Republic of Panama, focusing on the diether glycerol with C15:0 n-alkyl chains (C15:0 DEG), 13,16-dimethyl octacosanedioic acid (iso-diabolic acid: iso-DA), and branched Glycerol Dialkyl Glycerol Tetraethers (brGDGTs) and combined these with novel genomic data from the same cores. In addition to understanding these compounds’ environmental occurrence, we present the first environmental insights into the co-occurrence of brGDGT-Ia with its potential precursors C15:0 DEGs and iso-DA. Our results show that iso-DA is found only in the occasionally dry top peat layer and is absent in water-saturated peat horizons. We suggest that the production of iso-DA in this peatland dependents on oxygen availability, likely due to the metabolism of the source organisms and consistent with limited available culture data of acidobacteria. In contrast, C15:0 DEGs and brGDGTs (mainly in the form of brGDGT-Ia) persist across all depths with increasing concentrations at greater depths. Although these contrasting trends in abundance could reflect the greater persistence of ether lipids relative to acyl/acid lipids due to differences in preservation rates, they could also suggest that iso-DA is not a major precursor in the biosynthetic pathway of brGDGTs in these settings. When combined with novel genomic data, we show that acidobacteria, one of the few known iso-DA and brGDGT producers, were detected at all sites and depths, forming a stable proportion of the prokaryotic community. Their consistent presence aligns more with the brGDGT and C15:0 DEG distribution than iso-DA. Combining the results from our study with experimental evidence, it appears that multiple pathways for brGDGT biosynthesis exist in tropical peats, with the phylogenetic and environmental control on their expression yet to be elucidated.
U2 - 10.1016/j.orggeochem.2025.105094
DO - 10.1016/j.orggeochem.2025.105094
M3 - Article (Academic Journal)
SN - 0146-6380
VL - 210
JO - Organic Geochemistry
JF - Organic Geochemistry
M1 - 105094
ER -