DISCOVRE 2008

Pre-Cruise Log: 10/02/2008

Microbial Ecology of Deep-Sea Corals

Christina Kellogg, Ph.D.

Coral-microbial ecology is the study of the relationship of coral-associated microorganisms to each other, the coral host, and to their environment. Just as we humans have bacteria living on our skin and in our intestines that keep us healthy, corals also have co-habitating microbes.

Why is coral microbial ecology important? Understanding the coral's bacterial component contributes a critical missing piece to the study of overall coral biology. It has been speculated that coral-associated bacteria help the coral by fixing nitrogen, breaking down waste products, and cycling basic nutrients. Bacteria may also ward off other potentially harmful microbes by producing antibiotics or by occupying the available space.

Deep-sea or cold-water corals live in dark, cold, high-pressure environments. The microbial communities of these corals are adapted to this extreme environment and so are likely to contain novel bacteria. Identifying and characterizing those bacteria will not only increase our understanding of microbial diversity, but could also uncover a new source of enzymes or pharmaceuticals.

How do we study the coral-associated bacteria? One way is to grow them on nutrient agar so we can identify them and test their metabolic and biochemical capabilities. The other way we can study bacteria (especially the ones that don't like to grow on agar) is to extract the bacterial DNA directly from the coral and then use molecular techniques to identify the bacterial types in the community. Molecular work requires specialized sampling gear that is too complex for the size ROV we are using, so on this cruise we will be focusing on growing bacteria using a variety of different 'flavors' of nutrient agar. Preparation for the cruise includes making up these different agars: carefully following recipes to mix them, sterilizing the components, and pouring the hot liquid into Petri dishes (like jello) to solidify before packing.

On this cruise we will also be screening mobile fauna (like crabs and fish) to see if they are transporting bacterial species between coral mounds. That is, if we can catch any!