206 Marine Microbiology 



work to be followed by more detailed identification of molecular 

 components of the extracts. 



EXPERIMENTAL METHODS 



The sediments were sampled immediately after collection 

 (usually by piston-coring equipment) or were taken from cores 

 which had been frozen. A few analyses were made on cores 

 preserved by sealing (without air) in a plastic bag and stored 

 in metal tubes. 



Protein was detennined by an adaptation of the method of 

 Krey (2) for protein in marine plankton. The sediment samples 

 were treated for twenty-four hours at room temperature with 8 

 per cent sodium hydroxide, filtered and diluted. Color was de- 

 veloped in the filtrate with the Folin reagent and measured by a 

 spectrophotometer. 



Carbohydrates were extracted with hot 80 per cent ethanol 

 (approximately 3 ml per gm of sample). After evaporation 

 of solvent, the extract was taken up in water. Determination of 

 reducing sugars was by the method of Folin and Malmros ( 1 ) . 



Lipids were extracted with ether from ground, air-dried 

 samples in a standard Soxhlet apparatus. 



"Bound" lipid was determined by a second ether extraction 

 after treatment with O.IN HCl, drying, and re-grinding. 



RESULTS 



Recently, we reported (3) some of our preliminary data 

 from these studies. Analysis of sediments from the Orinoco Delta 

 (Venezuela) showed that proteins and carbohydi'ates decrease 

 rapidly with depth to about ten feet, from which point the de- 

 crease is much slower. Protein decreases by 22.8 /xg per gm of dry 

 sediment per foot as detennined by the slope of a regression line 

 through the points. The correlation coefficient (r) of -0.435 is 

 significant at the 99.9 per cent level. The carbohydrate decrease 

 is 0.648 Mg/gm/ft (r = -0.468, p = 0.001). 



Ether-extractable lipids, on the other hand, show a slight 

 increase below ten feet, after the initial rapid decrease. The 

 increase of 1.224 ppm/ft is independent of lithology and is sig- 

 nificant at the 99 per cent level (r = +0.434). When the sedi- 



