To survive and thrive in cold conditions, Gram-negative bacteria have evolved structurally distinct lipopolysaccharide (endotoxin) molecules.  This molecule is the "bacterial skin" - the outermost layer of the cellular envelope of these bacteria - and as such is critically important in reaction to and interaction with the environment.  We use cutting-edge mass spectrometry and MS/MS techniques to determine the structure of these molecules in organisms isolated from the planktonic environmental microbiome of the Chesapeake Bay watershed, the rivers of North Slope Borough, Alaska (for example unusual doubly aminoarabinosylated lipid A structures from the beta-proteobacterial oxalobacteraceae family including Massilia rubra, seen at left), and others.  

We investigate the structure of riverine and estuarine microbial communities (including those of the Chesapeake Bay watershed and Arctic rivers), their relationships to other communities and to geochemical and hydrological conditions, and their potential changes over time in response to climatic and anthropogenic impacts.  This work leverages both classical culture-based characterization techniques and modern metagenomic and bioinformatic approaches to better define and compare the structure and origin of these microbiomes.