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Research at
Gallaudet University
2005 - 2006

Who Are the Primary Consumers of Urea in Estuarine Waters?

Status: Ongoing Begin date: May, 2005 End date: No set date

Description

Urea, an organic substrate, supplies needed carbon and nitrogen for marine phytoplankton and bacteria metabolism. Urea was originally believed to contribute only a small percentage of total nitrogen requirements of marine microbes as compared to other nitrogen sources. Recently, urea has been found to contribute a large percentage of total nitrogen metabolic requirements in estuaries with a large diversity of microbes. In this study, the investigator is using a modification of a novel technique (DNA-SIP) to determine the eukaryotic consumers of urea in the Chesapeake Bay. The DNA-SIP method has been successful with investigators using 13C tracers to find methanotrophs in soil environments. Only one study to date has used 15N tracers to determine bacterial consumers of nitrogenous substrates. Furthermore, no studies have investigated the use of nitrogenous substrates by eukaryotic organisms such as phytoplankton. For those reasons, progress on this project has largely focused on making sure the method works for phytoplankton. The dinoflagellate, Prorocentrum minimum, is serving as the test organism. Dinoflagellates are generally difficult organisms to extract DNA from due to their tough cell membranes and complex chromosome structures. DNA extraction from P. minimum has been successful, but obtaining a visual band after cesium chloride centrifugation (another step in the DNA-SIP method) has proved difficult. The researcher is currently working with a scientist from the Center of Marine Biotechnology in Baltimore, Maryland to overcome this methodological hurdle.

Investigators