DrAlessandro N Garritano

Role of fluctuating and imbalanced resource supply in shaping microbial populations and function:

Resource variation over time has a large influence on the species composition and performance of biological systems. Current understanding is largely based on top-down models of processes such as rainfall, fire, or food availability. We aim to improve capacity to manage biological systems through developing understanding of bottom-up processes, based on the assumption that all life has an essential requirement for a limited number of elements. We test the idea that flexibility in elemental stoichiometry due to intracellular carbon, nitrogen or phosphorus storage is a key physiological adaptation to fluctuating resource availability.

Novel microbial processes that support life in the deep ocean:

The proposed project aims to explore sponge-associated microbiomes and their metabolic activities in the deep-sea. Coral reefs and sponge gardens appear to survive and grow very well in this deep-sea site and we postulate that the microbiomes can utilize "unusual" carbon and energy sources to convert those into useful nutrients and energy for the coral and sponge hosts. Specifically, it is likely that various hydrocarbons will leak from the petrol extraction site and, while these constitute carbon and energy sources, they can not be directly used by corals or sponges. Bacteria are however known to be able to convert hydrocarbons into other forms of carbon (such as carbohydrates or fatty acids) that could act as potential food and energy sources for corals and sponges. In addition, deep-sea sites often leak reduced inorganic compounds such as hydrogen, from the seafloor and these compounds can be used by bacteria as energy sources do drive the fixation of CO2. This fixed carbon can then be potentially used by corals and sponges and would represent a long-term sequestration of CO2. Finally, bacteria are also likely to produce essential vitamins and nutrients that can not be synthesized by coral and sponges. As such bacterial symbionts are expected to underpin the growth of coral reefs and sponge gardens in the deep-seas environment.