Isolation and characterization of low molecular weight carbohydrates dissolved in seawater

Chemical characterization and quantitative determination of dissolved low molecular weight carbohydrates in Mikawa Bay near Nagoya, Japan were conducted. The water samples were collected during the period of algal bloom of the dinoflagellate Prorocentrum minimum on 31 May 1980.Low molecular weight carbohydrates in seawater samples from depths of 1 and 6 m were first retained on a charcoal column and then eluted with aqueous ethanol. The carbohydrates obtained were permethylated and then isolated into each of the components by thin layer chromatography. The sugars isolated were characterized by gas chromatography (GC), combined gas chromatography and mass spectrometry (GC-MS), proton nuclear magnetic resonance spectroscopy (¹H-NMR) and some chemical analyses. Laminaribiose, laminaritriose, sucrose, raffinose,

Full-size image

,

Full-size image

Full-size image

were fully characterized and quantified with ranges from 2.3 to 27.7 μg l⁻¹ and from 0.5 to 17.8 μg l⁻¹.These low molecular weight carbohydrates were also identified, with some difference in their relative abundance, in particulate matter consisting mainly of dinoflagellate cells collected on the same occasion from this bay. These results indicate that low molecular weight carbohydrates dissolved in seawater are directly derived from those of phytoplankton through extracellular release or cell lysis.