A method of isolating clean and viable zooxanthellae by density gradient centrifugation

Abstract

Attempts to prepare viable suspensions of zooxanthellae isolated from coelenterate hosts have been hampered by the large amounts of mucus secreted by the host tissues. A method is described which overcomes this by density gradient ultracentrifugation of the isolate, using the silica sol Percoll which forms its own density gradient during ultracentrifugation. Between 106 and 107 zooxanthellae can be isolated per gradient. Contamination is reduced to the occasional nematocyst or piece of animal cell debris. The zooxanthellae thus isolated are viable and appear to show normal respiration and photosynthesis.