کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5783592 1637954 2017 44 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Production rates of bacterial tetraether lipids and fatty acids in peatland under varying oxygen concentrations
ترجمه فارسی عنوان
میزان تولید لیپید های تتراتر باکتری ها و اسیدهای چرب در سرزمین های زیرزمینی تحت تنش های مختلف اکسیژن
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
چکیده انگلیسی
Interpretations of the abundance and distribution of branched glycerol dialkyl glycerol tetraether (brGDGT) lipids have been increasingly applied to infer changes in paleoenvironment and to estimate terrigenous organic matter inputs into estuarine and marine sediments. However, only preliminary information is known regarding the ecology and physiology of the source organisms of these biomarkers. We assessed the production rates of brGDGTs under different redox conditions in peat, where these lipids are found in high concentrations, particularly at greater depths below the fluctuating water table. The incorporation of hydrogen relative to carbon into lipids observed in our dual stable isotope probing assay indicates that brGDGTs were produced by heterotrophic bacteria. Unexpectedly, incubations with stable isotope tracers of the surface horizon (5-20 cm) initiated under oxic conditions before turning suboxic and eventually anoxic exhibited up to one order of magnitude higher rates of brGDGT production (16-87 ng cm−3 y−1) relative to the deeper, anoxic zone (20-35 cm; ca. 7 ng cm−3 y−1), and anoxic incubations of the surface horizon (<3 ng cm−3 y−1). Turnover times of brGDGTs in the surface horizon ranged between 8 and 41 years in the incubations initiated under oxic conditions, in contrast to 123-742 years in anoxic incubations. As brGDGTs were actively produced during both anoxic incubations and those exposed to oxygen, we conclude that their source organisms are likely facultative aerobic heterotrophs that are particularly active in the peat acrotelm. Production rates of bacterial fatty acids (ca. 2 μg cm−3 y−1) were roughly two orders of magnitude higher than those of brGDGTs, suggesting that brGDGT producers are a minor constituent of the microbial community or that brGDGTs are a small component of the microbial cell membrane in comparison to fatty acids, despite the typically high brGDGT concentrations observed in peat. Multivariate analysis identified two branched fatty acids that shared a similar production pattern as brGDGTs among the experimental treatments and may be associated with brGDGT biosynthesis.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geochimica et Cosmochimica Acta - Volume 203, 15 April 2017, Pages 103-116
نویسندگان
, , , , , , ,