Inhibitory effects of extracts from Tunisian marine species on serine-protease from a local Beauveria bassiana strain

The effect of marine biological extracts, collected from the Gabes gulf area located in Tunisia, was evaluated on the extracellular proteolytic activity of Beauveria bassiana. The majority of extracts exhibited a marked inhibitory activity against the protease. Depending on extract origin, the inhibition percentages differed when the extracts were dissolved either in ethanol or in water. The ethanol extract from Caulerpa prolifera, Posidonia oceanica algae and from the internal organs of both Holothuria polii and Paracentrotus lividus exhibited inhibition greater than 50%. However, when dissolved in water, only C. prolifera, Hippospongia communis and P. oceanicaextracts led to an inhibition greater than 50%. Interestingly, only C. prolifera extract displayed a very important activity against the proteolytic enzyme and a total inhibition was obtained in the crude extract dissolved in water, in a dose dependent manner. This inhibitory activity was destroyed by boiling. The fractionation of inhibitor compounds from C. prolifera extract by C18 reversed-phase followed by gel-filtration chromatography allowed the isolation of fraction with 62% of inhibition. C. proliferaextract may therefore, be useful in developing new molecules with interesting potential of utilization in several biotechnological applications.   Key words:  Marine species, extraction, inhibitors, protease, high performance liquid chromatography (HPLC).