Samples of Spirulina platensis were collected from Lake Foum Elouad, Laayoune (South of Morocco) and cultivated using Zarrouk¿s synthetic medium in the laboratory. The essential oil was isolated by hydrodistillation and analysed by GC/FID and GC/MS. The average yield oil obtained was 0.9%. A total of 66 compounds, amounting 96.7 % of the essential oils, were identified. The major components of S. platensis essential oils were heptadecane (41.7 %), tetradecane (25.3 %), ethyl benzene (5.5 %) and 6-methyl-5-hepten-2- one (3.7 %). Interestingly, it has been reported for the first time in the Moroccan Spirulina, the presence of geosmin, which is a very important component of odour in cyanobacteria. To our knowledge, the geosmin was not found in any S. platensis essential oils before. The antibacterial activity of the essential oil was evaluated against six strains. The most potent effect of the essential oil was obtained against two Gram (+) bacteria: B. antharcis, S. epidermidis and the Gram (-) bacteria E. coli (with the higher inhibition zone as 28 mm). The MICs were respectively 16.37, 19.13 and 17.81 ¿L/mL. A total inhibition was shown for S. aureus. Thus the essential oil of S. platensis possess effective antimicrobial properties.

The authors thank the Moroccan Foundation forAdvanced Science Innovation and Research(MAScIR) for the characterization and theidentification of the strain.