Influences of cell growth rate and cellular structures on molecular stable carbon isotopic composition of planktonic fatty acids
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In order to explore the influence of intracellular structures and cell growth rates on the stable carbon isotopic compositions of cellular fatty acids in marine phytoplankton, two series of culturing experiments of a typical diatom, Thalassiosira pseudonana, were conducted: (1) batch culturing through exponential and stationary growth stages to study the influence of cellular structures on molecular carbon isotopic compositions; and (2) culturing in continuous culture environments with four growth rates to examine the influence of cell growth rate on molecular carbon isotopic compositions of fatty acids bound in cellular components. The results from all experiments showed that δ13C values of unsaturated fatty acids in intracellular energy storage component were enriched (1 2‰) than those in membrane associated component. With the decrease in growth rate, the δ13C values of unsaturated fatty acids were generally enriched (1-5‰). The result of this research can potentially influence the applications of fatty acid biomarkers to study sources of organic matters and food webs.