Stable Carbon Isotope Ratios of Lipid Biomarkers of Sulfate-Reducing Bacteria

AUTOR(ES)
FONTE

American Society for Microbiology

RESUMO

We examined the potential use of natural-abundance stable carbon isotope ratios of lipids for determining substrate usage by sulfate-reducing bacteria (SRB). Four SRB were grown under autotrophic, mixotrophic, or heterotrophic growth conditions, and the δ13C values of their individual fatty acids (FA) were determined. The FA were usually 13C depleted in relation to biomass, with Δδ13C(FA − biomass) of −4 to −17‰; the greatest depletion occurred during heterotrophic growth. The exception was Desulfotomaculum acetoxidans, for which substrate limitation resulted in biomass and FA becoming isotopically heavier than the acetate substrate. The δ13C values of FA in Desulfotomaculum acetoxidans varied with the position of the double bond in the monounsaturated C16 and C18 FA, with FA becoming progressively more 13C depleted as the double bond approached the methyl end. Mixotrophic growth of Desulfovibrio desulfuricans resulted in little depletion of the i17:1 biomarker relative to biomass or acetate, whereas growth with lactate resulted in a higher proportion of i17:1 with a greater depletion in 13C. The relative abundances of 10Me16:0 in Desulfobacter hydrogenophilus and Desulfobacterium autotrophicum were not affected by growth conditions, yet the Δδ13C(FA − substrate) values of 10Me16:0 were considerably greater during autotrophic growth. These experiments indicate that FA δ13C values can be useful for interpreting carbon utilization by SRB in natural environments.

ACESSO AO ARTIGO

Documentos Relacionados