Gray, Isabel Del Carmen. Sponge-associated dehalogenating microorganisms and isotope analysis of their dehalogenation of brominated phenols. Retrieved from https://doi.org/doi:10.7282/T3WD42JT
DescriptionSponges are filter feeders, ancient animals that have been extremely successful in surviving for over 600 million years almost unchanged. These metazoa can harbor microbes comprising almost 35% of their bodies at densities of 109 cells/g. Sponges are also rich in organohalides, usually with bioactive cytostatic and/or cytotoxic characteristics. Some of these organohalides resemble anthropogenic pollutants, such as halogenated dioxins and flame retardants. Thus, in nature some sponges contain both a high number of microbes as well as a high concentration of organohalides. This includes the sponge Aplysina aerophoba, from where Desulfoluna spongiiphila was isolated, a sulfate reducing Deltaproteobacteria that can reductively dehalogenate bromophenols. This observation led to the interest of enriching for sponge-associated microbes capable of dehalogenation from different ecoregions of the temperate and tropical oceans. The hypothesis is that dehalogenating bacteria are widespread among sponge species regardless of geographical location and form stable populations within the sponge animal that function in the cycling of organohalide compounds. Anaerobic dehalogenating activity was found to be widespread among sponges. In addition, new isolates obtained were closely related to D. spongiiphila. Compound Specific Isotope Analysis (CSIA) of 2,6-dibromophenol and its dehalogenation products revealed that carbon isotopic enrichment factors for sponge-associated bacterial dehalogenation are identical, probably due to a high similarity in the dehalogenating mechanism. The results support the hypothesis that dehalogenating microorganisms are widely distributed within marine sponges. The association between host sponge and associated microbiota is probably driven by the unique organohalide chemistry. At the same time the research of dehalogenating sponge-associated microorganism provided a unique setting for a deeper understanding into microbe-animal associations that could potentially be an ancient symbiosis