Effect of Post-Collection Storage Time and Season on the Antibacterial Activity of Selected Southern African Marine Macroalgae

Abstract

The effect of post-collection storage time and season of 5 selected southern African seaweeds on the antibacterial activity was investigated. Seaweeds were collected at different times during the period of 1994 followed by air-drying and cleaning (by the manual removal of sand, crustaceans and salt) and stored at 18+/-2degreesC until May, 1998. At this time each seaweed sample was milled and extracted by boiling 10 g of the milled seaweed material in 80% ethanol (in water) for 4 hours. Antibacterial activity was determined by pipetting extracts into wells in overlay agar seeded with test bacteria. The antibacterial activity of Zonaria subarticulata increased with increasing post-collection storage time, whilst that of Sargassum incisifolium decreased. Extracts of Osmundaria serrata, Galaxaura diessingiana and Codium duthieae showed no changes in antibacterial activity over a period of 3 years under the storage conditions of this study. Seasonal variation in antibacterial activity of Galaxaura diessingiana and Codium duthieae was not found. However, the antibacterial activity of Osmundaria serrata peaked in the winter season.