Continuing a study of the secondary metabolites of microorganisms associated with marine invertebrates [i], we have investigated two strains (D-7 and D-12) from the sponge Dendrilla sp. collected in November, 1986, off the coast of Madagascar. We have shown that during their development the strains D-7 and D-12 synthesize substances with an antimicrobial activity. From their morphological characteristics and physiological tests, the microorganisms were identified as Bacillus pumilus [2].