Marine organisms habitats

The underlying assumption driving marine natural products chemistry research is that secondary metabolites produced by marine plants, animals, and microorganisms will be substantially different from those found in traditional terrestrial sources simply because marine life forms are very different from terrestrial life forms and the habitats which they occupy present very different physiological and ecological challenges. The expectation is that marine organisms will utilize completely unique biosynthetic pathways or exploit unique variations on well established pathways. The marine natural products chemistry research conducted to date has provided many examples that support these expectations. 

Wurl, O., Obbard, J.P., 2004. A review of pollutants in the sea-surface microlayer (SML) A unique habitat for marine organisms. Mar. Pollut. Bull. 48, 1016-1030. 

S. Baldwin, W. A. Maher, E. Kleber, F. Krikowa, Selenium in marine organisms of seagrass habitats (Posidonia australis) of Jervis Bay Australia, Mar. Pollut. Bull., 32 (1996), 310-316. 

In summary, the marine environment contains a wealth of plants, animals and microorganisms. Due to their unique adaptations to their ocean habitat, they contain a wide diversity of natural products. These compounds have shown activity in a variety of assays which have relevance to human diseases. As our understanding of the molecular basis of disease expands, these compounds and ones yet to be discovered will provide lead compounds for human therapeutic treatment. Innovations in synthesis, fermentation of symbionts as well as in manipulation of biosynthetic genes will allow us to produce sufficient material for clinical use of the compounds. Marine organisms provide a unique opportunity for access to chemical diversity. 

Because of the diversity of marine organisms and habitats, marine natural products encompass a wide variety of chemical classes, including terpenes, shikimates, polyketides, acetogenins, peptides, alkaloids of varying structures, and a multitude of compounds of mixed biosynthesis. In the past decade alone, the structures of over 5000 marine natural products have been published (3-10). 

Table 1 General types of responses to PCB contamination for marine organisms. (PCB concentrations in tissues or habitat types eliciting a given intensity of response varies with species and ecosystem)...

Dissimilatory sulfate reducers such as Desul-fovibrio derive their energy from the anaerobic oxidation of organic compounds such as lactic acid and acetic acid. Sulfate is reduced and large amounts of hydrogen sulfide are generated in this process. The black sediments of aquatic habitats that smell of sulfide are due to the activities of these bacteria. The black coloration is caused by the formation of metal sulfides, primarily iron sulfide. These bacteria are especially important in marine habitats because of the high concentrations of sulfate that exists there. 

Organisms in natural ecosystems may not be actively dividing but may, nonetheless, be metabolically active. This may be particularly important for ultramicro marine bacteria in their natural habitat. 

---