ANTIBACTERIAL ACTIVITY OF 2 SPECIES OF BRYOZOANS FROM NORTHERN PUGET-SOUND

For the first time, bryozoan species from northern Puget Sound have be en shown to contain antibacterial compounds. The antibacterial activit y of two local marine cheilostome species was tested against six strai ns of local marine bacteria and against stock cultures of Vibrio angui llarium, Bacillus subtilis, Staphylococcus aureus, and Escherichia col i. The filter paper disc method was used to test for antibacterial act ivity. A crude extract made from the bryozoan Bugula pacifica inhibite d the growth of two marine isolates, as well as B. subtilis, S. aureus , and E. coli. A crude extract made from the bryozoan Tricellaria occi dentalis inhibited the growth of B. subtilis. Preliminary scanning ele ctron microscopy data indicate that Tricellaria occidentalis had highe r densities of surface bacteria than Bugula pacifica. This inverse rel ationship between antibacterial activity and surface fouling may indic ate an antifouling role for these bryozoan secondary metabolites. The presence of antibacterial compounds may allow bryozoans to manipulate the microbial film growing on them, and may influence the types of org anisms that are able to settle near or on them. The ability to manipul ate microbial films may also enable bryozoans to make the substrate ne arby more suitable for the settlement of their own larvae.