Flux of organic matter from phytoplankton to bacteria

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1.Estimation of ^<13>C isotopic ratio of fatty acid by gas chromatography-mass spectrometry(GC-MS): The accuracy of the estimation of ^<13>C isotopic ratio of fatty acid was ascertained by using ^<13>C enriched palmitic acid. The results indicated the applicability of ^<13>C-GC-MS method to estimate the carbon flow from phytoplankton to bacteria.2.Production of fatty acid at subarctic and subtropical area of Northern Pacific: ^<13>C tracer experiments were carried out at subarctic and subtropical area of Northern Pacific. Fatty acid composition of photosynthetic products of phytoplankton was determined by ^<13>C-GC-MS method. Polyunsaturated fatty acids constituted major part of products at subarctic area, whereas saturated fatty acids were main product at subtropical region. This defference was mainly due to the difference in the water temperature of these region. High contribution of polyunsaturated fatty acids at subarctic region can keep the fluid condition of membrane of phytoplankton.3.Carbon flux to the bacterial specific fatty acids: The ^<13>C atomic ratio of bacterial specific fatty acids were estimated by GC-MS to elucidate carbon flow from phytoplankton to bacteria. Samples obtained from subarctic and subtropical region were analyzed. The ^<13>C atom % of bacterial specific fatty acids were much lower than phytoplankton fatty acids, indication that carbon flow form phytoplankton to bacteria was not high which has been suggested by ^<14>C tracer studies. However, the effects of same factors such as incubation length and ^<13>C atom% of phytoplankton carbon must be considered to estimate carbon flux.