This proposal aims to gain a better understanding of sponge-bacterial associations and, in particular, to determine which bacteria are involved and how stable these associations are. Understanding such symbioses is predicted to yield new approaches for the aquaculture of pharmacologically-active sponges or the cultivation of the producing bacterial strains. Such methods would have enormous potential to solve the supply problem of pharmaceutically-active marine natural products. We intend to use molecular techniques such as Denaturing Gradient Gel Electrophoresis (DGGE) to monitor the microbial communities in sponges as well as to apply state-of-the-art chemical analysis in order to determine the corresponding secondary metabolite profiles. Furthermore, we propose to adopt the innovative technique of Diffusion Growth Chambers (DGCs) to the cultivation of previously "unculturable" sponge bacteria. DGCs are essentially semi-permeable membranes filled with homogenized sponge tissue and agar. This immobilizes bacteria inside the polymer membranes, while simultaneously exposing bacteria to the "sponge chemistry". These techniques will allow us to examine whether: 1) changes in sponge secondary metabolites correlate with changes in sponge-associated microbial communities; 2) DGCs allow culturing of previously "unculturable" sponge bacteria; and 3) symbiotic sponge bacteria or sponges themselves yield new, interesting, pharmacologically-active compounds. In addition to new insights on sponge-bacterial symbiosis (e.g. are ; sponge bacteria generalists or specialists?), we will create a library of potentially unique bacterial strains isolated from sponges with the new DGC technique. Isolated sponge bacteria will be grown out and extracted, and extracts screened for possible new anticancer or antiinfectant metabolites. Activity in either screen will be followed by the isolation and structure elucidation of the active secondary metabolites. To effectively treat diseases such as cancer or tuberculosis (caused by multi-drug-resistant bacteria), it is important to develop new drugs. Although several potential drug candidates have been isolated from marine organisms, further development is often hampered by a supply problem. Our research aims to identify new drug candidates from microbial sources and simultaneously develop new culturing techniques to address the supply problem