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Separation and concentration of living dinoflagellate resting cysts from marine sediments via density‐gradient centrifugation

1991; Wiley; Volume: 36; Issue: 3 Linguagem: Inglês

10.4319/lo.1991.36.3.0588

1939-5604

Peter Schwinghamer, Donald M. Anderson, D. M. Kulis,

Algal biology and biofuel production

A method for separating and concentrating resting cysts of dinoflagellates from marine sediments via centrifugation in a nontoxic, isosmotic density gradient has been developed and tested. The density‐gradient medium is an aqueous suspension of colloidal silica (Nalco 1060) made isosmotic with seawater of salinity 32‰ using sucrose. The density of the medium, which is isosmotic throughout a density range of 1.086–1.405 g cm −3 , may be adjusted by varying the proportion of sucrose solution mixed with the colloidal silica. Unlike other methods, there is no problem with jelling of the silica in seawater with this method, and Nalco 1060 is not highly toxic to aquatic organisms as are some other commonly used formulations. Cysts of Scrippsiella trochoidea and Alexandrium fun dyense were extracted quantitatively from a muddy silt marine sediment and showed no sign of differential mortality related to the centrifugation procedure. Cultures of S. trochoidea were successfully initiated with centrifuged cysts.