Abstract: The mycelial and broth extracts of a marine-derived strain of the fungus Penicillium herquei FS83 were tested for theirantibacterial activities against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli by filter paper method, andinvestigated for their antifungal activities against Trichoderma viride, Aspergillus niger, Aspergillus flavus, Alternaria alternate and Colletotrichumgloeosporioides by growth rate method. Minimum inhibitory concentrations(MICs)of the culture extracts were determined by serial dilutionmethod. Furthermore, the extracts were evaluated for their cytotoxic activities against NCI-H460, MCF-7, and SF-268 tumor cell lines by theMTT method. The results showed that the mycelial extract displayed significant inhibitory effect on S. aureus and B. subtilis with inhibition zonediameters of 18.1 and 17.3 mm respectively, and the same MIC of 1.56 mg/mL, and also exhibited satisfactorg antifungal activities against allthe test fungi with inhibitory rates of over 50% and MICs in the range of 0.78-3.12 mg/mL. The broth extract showed a remarkable antibacterialeffect on B. subtilis with an inhibition zone diameter of 16.4 mm and an MIC of 1.56 mg/mL, and also displayed antifungal activities on all thetest fungi with MICs in the range of 1.56-6.25 mg/mL. The mycelial extract had a strong cytotoxic activity against the three tumor cell lines withIC50 values between 55.9-63.5 μg/mL, and the broth extract showed a strong cytotoxic activity against MCF-7 cell line with an inhibition rate of84.3% at a concentration of 200 μg/mL.

Key words: Marine fungus , Penicillium herquei , Extract , Antimicrobial activity , Bacteria , Fungi , Cytotoxic activity