Marine macroalgae and their associated microbiomes as a source of antimicrobial chemical diversity

Figures & data

Figs 1–6. Molecular structures of acyl homoserine lactones and quorum sensing inhibitors isolated from marine algae. Fig. 1. General structure of acyl homoserine lactones. Fig. 2. Halogenated furanones. Fig. 3. Floridoside. Fig. 4. Betonicine. Fig. 5. Isethionic acid. Fig. 6. 2-dodecanoyloxyethanesulfonate. Figure adapted from Saurav et al. (2017).

Figs 7–10. The red algae Bonnemaisonia hamifera and Bonnemaisonia asparagoides display strong antimicrobial activity against AHL quorum sensing bioreporter strain Chromobacterium violaceum. Algal samples were overlaid with C. violaceum in 0.5% agar prior to incubation. Fig. 7. B. hamifera washed in ddH₂O. Fig. 8. B. hamifera pre-washed in 70% ethanol; QSI activity not altered by ethanol wash. Fig. 9. B. asparagoides washed in ddH₂O. Fig. 10. B. asparagoides washed in 70% ethanol, exhibiting significant loss of QSI activity which has been extracted by the ethanol wash.

Fig. 11. Structure of 1,1,3,3-tetrabromo-2-heptanone, a poly-brominated 2-heptanone produced by Bonnemaisonia hamifera displaying antifouling properties.

Figs 12–13. SEM of the epiphytic microbial colonization of Halidrys siliquosa algal fronds. Fig. 12. Diatom embedded amongst diverse prokaryotes. Fig. 13. Three-dimensional structure of microbial biofilm.

Saurav, K., Costantino, V., Venturi, V., Steindler, L. (2017). Quorum sensing inhibitors from the sea discovered using bacterial N-acyl-homoserine lactone-based biosensors. Marine Drugs, 15: 53.

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