ISSN:
1432-1793
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Production of extracellular dissolved organic substances by cultures of the marine coccolithophorid Hymenomonas carterae SMBA 254 was investigated by the 14C-tracer technique. In 4 h incubations, extracellular 14C production represented 20 to 64% of 14C incorporation into cell material for cultures nearing, or during stationary growth; for rapidly growing cultures with relatively low cell densities the 14C-production was only 4 to 10% of incorporation. Intra-and extra-cellular material was fractionated by ion-exchange membrane electrodialysis. Ionic compounds accounted for 40 to 60% of extracellular material; in contrast only 16 to 27% of intracelular metabolites were in this category. Of a range of methods which were investigated, separation of compounds by gel-filtration in conjunction with two-dimensional thin-layer chromatography proved most effective. Up to 80% of extracellular material was of less than 1 800 mol. wt and included carbohydrates and amino acids, with glutamic acid predominating. The intracellular material was more heterogeneous, with a substantially greater proportion of high molecular weight material. The quite distinct compositions show clearly that extracellular production observed in these experiments arose through excretion and was not attributable to cell lysis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00391154
