Lipid class and carbohydrate concentrations in marine colloids

Liu, Qingjun. 1962- (1994) Lipid class and carbohydrate concentrations in marine colloids. Masters thesis, Memorial University of Newfoundland.

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Abstract

Cross-flow filtration (CFF) was used to concentrate marine colloids from microalgal cultures and surface seawater. Lipid classes in different size fractions were determined using the Chromarod-Iatroscan thin-layer chromatography with the flame ionization detection method. Total carbohydrate concentrations were determined colorimetrically using methyl benzothiazolinone hydrazone reagent. Extensive determinations of CFF blanks and recoveries were conducted for each lipid class to optimize CFF operating procedures. The total lipid blank in the CFF system was approximately 6-7 μg (~0.5 μM C). Recoveries for the major lipid classes in marine samples varied from 80% to 120%. -- Both colloidal lipid and carbohydrate concentrations in microalgal cultures were found to be 120-140 μg/L. Triacylglycerol (TAG) and polar lipids were the major lipid classes in colloids from microalgal cultures. Concentrations of colloidal (> 10,000 dalton) lipids and carbohydrates in Newfoundland seawater ranged from 0.9 μg/L to 8.7 μg/L and from 21 μg/L to 30 μg/L, respectively. The major lipid classes present in coastal seawater colloids were TAG, free fatty acids, and phospholipids. -- Data from both algal cultures and actual seawater samples showed that marine colloids are characterized by having high proportions of free fatty acids, phospholipids and hydrocarbons by comparison with truly dissolved material. The free fatty acids may be produced by microbial degradation, the phospholipids are probably derived from biological membranes, and the hydrocarbons are likely preferentially adsorbed from the surrounding water onto the colloids.

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