The production of antimicrobial compounds by British marine algae. IV. Variation of antimicrobial activity with algal generation

Abstract

Using Staphylococcus aureus and Escherichia coli as test organisms, various life-cycle phases of 22 species of British marine algae were screened for antimicrobial activity. The species examined were members of the three major seaweed groups: Rhodophyta, Phaeophyta and Chlorophyta. The growth forms of the two species of Chlorophyta investigated exhibited no variation in activity and of the 10 species of Phaeophyta examined, only the growth forms of Alaria esculenta showed a significant variation in the levels of antimicrobial activity—the sterile parts of the thallus being active whilst the reproductive sporophylls were inactive. the different growth phases of seven of the 10 species of Rhodophyta screened showed no significant differences in their antibiotic content. However, Plocamium cartilagineum and Gracilaria verrucosa produced cystocarpic plants with enhanced antibacterial properties, whilst the tetrasporic phase of Bonnemaisonia hamifera possessed considerably more activity than the gametophytic generations.