Estimates of the number of microbes such as bacteria, algae, and fungi living in the marine environment range into the millions. Many of these are free-living however marine invertebrates provide unique habitats for microorganisms that differ from the adjacent sediment or water column. Numerous studies over the past 20 years have documented the diversity of marine microorganisms associated with sponges. This has led to the designation of sponges as “microbial fermenters” where sponges can provide modified nutrient and oxygen levels from those in the surrounding sediment and water column. Invertebrate tissues can also provide varied surface characteristics and possible exposure to secondary metabolites that may affect the growth and metabolic activity of associated microorganisms.
With the development of methods to isolate and culture these uniquely evolved microorganisms, their immense and untapped resource of chemical diversity is being released. Significant challenges remain in defining suitable media for both the isolation of the invertebrate-derived strains as well as in the fermentation of these organisms. Our group has an on-going program in the development and evaluation of novel media for the isolation of the organisms and has demonstrated success in improving recoverability from environmental samples by over 300% (Olson 2000). This has led to the development of the Harbor Branch Marine Microbial Culture Collection which is used in our drug discovery program and also as a resource for biotechnological applications.
