Production of antibacterial activities by two Bacillariophyceae grown in dialysis culture

Using a dialysis culture system for marine algae which allows for the recovery of high cell yield, we detected in the aqueous phase of the algal extracts an active component which inhibited gram-negative bacteria. Results show a direct relation between cell growth phase at time of harvest and the activity observed. It was possible to confirm previous results whereby Bacillariophyceae produce lipophilic substances inhibiting gram-positive terrestrial and marine bacteria. These findings corroborate the observation that Skeletonema costatum is more active man Phaeodactylum tricornutum against Staphyloccoci.