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Using combined gas chromatography and mass spectrometry a growth-promoting, organic component of sea water has been quantitatively estimated and identified as the cytokinin 6-(3 methyl-2-butenylamino) purine. Additions of this cytokinin, kinetin or sea water from the Fucus-Ascophyllum zone increased the growth of Ectocarpus confervoides and Pylaiella litoralis in artificial sea water. Additions of kinetin to bacteria-free cultures of Ectocarpus fasciculatus also initiated the production of upright ectocarpoid filaments. [ABSTRACT FROM AUTHOR]

The brown algae Lithosiphon pusillus, Ectocarpus fasciculatus and Pylaiella litoralis were cultivated in bacteria-free cultures in artificial sea water, ASP 6F. The growth was tested with different additions of vitamins and other metabolites. Lithosiphon pusillus and Ectocarpus fasciculatus were found to require vitamin B12 for optimal growth. The Zoospores of Pylaiella litoralis, when cultured in medium Asp 6F with kinetin added, had an absolute requirement for vitamin B12. [ABSTRACT FROM AUTHOR]

Three marine brown algae have been cultivated with different additions of iodine and bromine in bacteria-free cultures. Ectocarpus fasciculatus appeared to have an absolute demand for iodine and was inhibited by a concentration of 64 μmol of KJ per 1. Lithosiphon pusillus had the best growth in the highest concentration tested (64 μmol/l) but there was always some growth in the series without iodine. Additions could be made either as inorganic iodine or as organically bound iodine. Additions of KJ to a culture medium consisting of vitamin-free Asp 6 F with B12 (1 μg/l) and kinetin (20 μmol/l) remarkably increased the growth of the zoospores of Pylaiella litoralis. Lithosiphon pusillus proved to be indifferent to bromide additions in media containing KJ. In media lacking KJ addition of 1 μmol of KBr per 1 is stimulating but higher concentrations of KBr are inhibiting. The inhibiting effect is overcome by iodide addition. [ABSTRACT FROM AUTHOR]

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