The biogeochemistry and ecology of anaerobic sponge microbes, and their role in spongemicrobe associations

• Applicant: Dr. Friederike Hoffmann
• Subject Area: Palaeontology
• Term: from 2005 to 2008
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5445843

Sponges are evolutionary ancient marine organisms, which may host high amounts of associated microbes ("bacteriosponges"). In this project, sponges are viewed as specialized microbial habitats. The aim is to understand the impact of anaerobic processes on the metabolic capacities of the sponge animal as a whole, including its microbial assemblages. An important result of the current project period is that tissue anoxia is rather the exception than the rule in many sponge species, but occurs frequently enough to make them attractive habitats for anaerobic microbes. The frequent switch between oxic and anoxic situations greatly influences physiological variety and community diversity of the sponge-microbesystem. Some microbial key processes and the phylogeny and spatial distribution of the involved microbes were already successfully determined. Based on these results, we have means to presume complete microbial sulphur and nitrogen cycles in sponges, and that coupling of aerobic and anaerobic processes enables extra carbon uptake and efficient nutrient recycling in the sponge-microbe system. This will be examined in the proposed project period. Understanding the impact of these processes on the metabolic capacities of the sponge animal as a whole may help to overcome persistent difficulties in the biotechnological production of pharmacologically potent sponge metabolites.

• DFG Programme: Research Grants