Carbon isotope fractionation by anoxygenic phototrophic bacteria in euxinic Lake Cadagno

Autor:	Raymond P. Cox, Mauro Tonolla, Niels-Ulrik Frigaard, Donald E. Canfield, Nicole R. Posth, Francesco Danza, Laura A. Bristow, Kirsten Silvia Habicht
Rok vydání:	2017
Předmět:	0301 basic medicine Geologic Sediments 030106 microbiology Chemocline Bacteria Anaerobic 03 medical and health sciences Purple sulfur bacteria Botany Dissolved organic carbon Organic Chemicals Ecology Evolution Behavior and Systematics General Environmental Science Carbon Isotopes biology Phototroph Sulfur cycle biology.organism_classification Anoxygenic photosynthesis Lakes Phototrophic Processes 030104 developmental biology Environmental chemistry General Earth and Planetary Sciences Photosynthetic bacteria Switzerland Geology
Zdroj:	Posth, N R, Bristow, L A, Cox, R P, Habicht, K S, Danza, F, Tonolla, M, Frigaard, N U & Canfield, D E 2017, ' Carbon isotope fractionation by anoxygenic phototrophic bacteria in euxinic Lake Cadagno ', Geobiology, vol. 15, no. 6, pp. 798-816 . https://doi.org/10.1111/gbi.12254
ISSN:	1472-4669 1472-4677
DOI:	10.1111/gbi.12254
Popis:	Anoxygenic phototrophic bacteria utilize ancient metabolic pathways to link sulfur and iron metabolism to the reduction of CO2. In meromictic Lake Cadagno, Switzerland, both purple sulfur (PSB) and green sulfur anoxygenic phototrophic bacteria (GSB) dominate the chemocline community and drive the sulfur cycle. PSB and GSB fix carbon utilizing different enzymatic pathways and these fractionate C-isotopes to different extents. Here, these differences in C-isotope fractionation are used to constrain the relative input of various anoxygenic phototrophs to the bulk community C-isotope signal in the chemocline. We sought to determine whether a distinct isotopic signature of GSB and PSB in the chemocline persists in the settling fraction and in the sediment. To answer these questions, we also sought investigated C-isotope fractionation in the water column, settling material, and sediment of Lake Cadagno, compared these values to C-isotope fractionation of isolated anoxygenic phototroph cultures, and took a mass balance approach to investigate relative contributions to the bulk fractionation signature. We found a large C-isotope fractionation between dissolved inorganic carbon (DIC) and particulate organic carbon (POC) in the Lake Cadagno chemocline. This large fractionation between the DIC and POC was also found in culture experiments carried out with anoxygenic phototrophic bacteria isolated from the lake. In the Lake Cadagno chemocline, anoxygenic phototrophic bacteria controlled the bulk C-isotope fractionation, but the influence of GSB and PSB differed with season. Furthermore, the contribution of PSB and GSB to bulk C-isotope fractionation in the chemocline could be traced in the settling fraction and in the sediment. Taken together with other studies, such as lipid biomarker analyzes and investigations of other stratified lakes, these results offer a firmer understanding of diagenetic influences on bacterial biomass.
Databáze:	OpenAIRE
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