Antagonistic antimicrobial activity of marine fungi and bacteria isolated from marine biofilm and seawaters of Hong Kong

The antagonistic interaction between marine fungi and marine bacteria was investigated using 19 bacterial species isolated from marine biofilm and 46 waterborne fungal isolates obtained from Hong Kong waters. Of the 46 fungal isolates, 70% inhibited the growth of at least 1 target bacterial species. Active fungal strains belonged mainly to the genera Cladosporium, Paraphaeosphaeria, Trichoderma, Alternaria, Phoma, and Arthrinium. Eight fungal isolates (17% of all fungal isolates tested) were sensitive to at least 1 target bacterial species. Eleven of the 19 bacterial species showed antifungal activity. Two Staphylococcus strains inhibited the growth of all of the sensitive fungal strains. The results indicated that marine fungi could provide an important source of natural antimicrofouling compounds and that the interaction between marine fungi and marine bacteria in biofilms cannot easily be generalized.