R L Hettich has completed his PhD from Purdue University and joined the Oak Ridge National Laboratory in 1986. He is a distinguished Research Scientist in the Chemical Sciences
Division at ORNL and a joint Faculty Member in the Microbiology Division/ Genome Science and Technology (GST) Graduate Schools at the University of Tennessee. His research
interests involve the development and demonstration of advanced mass spectrometry technology for characterizing biological samples ranging from purifi ed proteins to environmental
microbial proteomes. He has over 230 peer-reviewed publications, and is active in teaching and mentoring graduate students.


Details about microbial species population structure and functional dynamics during microbiome establishment are poorly
understood in the human infant gut. Th e objective of this work is to exploit a high performance LC-MS/MS based metaproteomic
approach to explore host and microbiome temporal functional shift s during microbial colonization of the pre-term infant gut. Fecal
metaproteomes of nine pre-term infants were measured at discrete time-points over several months. Approximately 10,000 human
and microbial protein groups were identifi ed in each infant. In early time points, human proteins were more abundant than microbial
proteins, and comprised pathways involving epithelial barrier establishment and immune response. Intriguingly, comparison of
genomic and proteomic patterns identifi ed some microbial species that were both active and in low abundance. Most functional
core metabolic processes were conserved in the microbiome; however, temporal and inter-individual variations were identifi ed. For
example, lipid metabolism (specifi cally glycerol degradation) was dominant early in one infant, and progressed to predominantly
amino acid metabolism over time, in stark contrast to other pre-term infants. Th ese diff erences are likely related to microbiome or
environmental factors that distinguished the infants. In response to bacterial colonization, the human hosts expressed proteins that
play pivotal roles in the integrity and barrier properties of mucosal epithelial layers. Th e time-course metaproteomics measurements
revealed core metabolic pathways in both human and microbial proteins, revealing the establishment of the mutualistic relationship
between the microbiome and human host early in infancy. In total, these results reveal functional stability and inter-individual
signatures of the preterm infant gut microbiome.