Continued investigation of the marine alga Laurencia claviformis has led to the isolation of pacifenol, a halogenated sesquiterpene as the major metabolite. The microbial transformation of pacifenol is reported. It was cultivated with a marine strain of Penicillium brevicompactum yielding a new compound. The structure was elucidated on the basis of spectroscopic data. The anti-microbial activit...