ENTICKNAP, J.J.; PERAUD, O.; LOHR, J.E.; HAMANN, M.T.; HILL, R.T.*; Center of Marine Biotechology, University of Maryland Biotechnology Institute: The Diversity of Microbes Associated with Sponges: New Approaches to an Old Mystery

It has long been known that sponges contain microbial symbionts and was demonstrated four decades ago that microbes can comprise 50% of the weight of a sponge. Early culture-based and microscopic analysis suggested that there was a diverse assemblage of microbes associated with sponges. It is only in the last three years that the application of molecular techniques has revealed the amazing extent of this diversity and indicated that sponges harbor groups of bacteria such as actinomycetes that have an excellent track-record as sources of novel bioactive compounds. Microbes associated with nine different species of sponges from three different locations (Indonesia, Jamaica and the Florida Keys) were studied by molecular techniques. Culturable isolates were collected from the sponges and total DNA was extracted for molecular analysis. Microbial community analysis was conducted on PCR amplified 16S rDNA by clone library construction and by denaturing gradient gel electrophoresis. This combination of molecular techniques is useful in identifying predominant groups of sponge-associated bacteria that are targeted in on-going attempts to culture novel microbes. Fluorescent in situ hybridization can be applied to visualize spatial arrangements of individual bacterial species within the sponge matrix. General findings are that the sponge associated microbial communities are more diverse than communities in the surrounding water, contain many novel microbes (on the basis of 16S rDNA sequence analysis) and some microbes (e.g. alpha-proteobacteria) appear to be ubiquitous in many sponges. Sponges generally contain diverse communities of novel actinomycetes that may be a valuable resource for drug discovery.