I am an associate research scholar in François Morel's trace metal research group in the Geosciences department at Princeton University. Here, I use interdisciplinary tools to study the principles guiding the structure, function, and evolution of microbes important for biogeochemical cycles. I obtained a B.S. in Biological & Environmental Engineering from Cornell University in 2004 and a Ph.D. in Environmental Science & Engineering from the California Institute of Technology in 2010.
My specific scientific pursuits have evolved over time but at a broad scale they are all motivated by my fascination how the physical environment interacts with microbiology on both short (transcriptional) and long (evolutionary) timescales.
Ongoing Research Projects:
- Trace metals in biological N2 fixation (BNF): BNF, a key reaction controlling the fertility of natural and managed ecosystems, is catalyzed by nitrogenase. This enzyme exists in the canonical form containing Mo and alternative isozymic forms containing V or only Fe in the active site. The controls on BNF in its different metalloenzyme forms are not well understood, in part due to a lack of methods. I have developed a method that distinguishes the activity of Mo, V, and Fe-only nitrogenases and am now applying the method to BNF in the field and in the laboratory to better constrain how the cycles of nitrogen and catalytic trace metals are coupled.
Zhang X., Sigman, D.M., Morel F.M.M., and Kraepiel A.M.L. (2014) Nitrogen isotope fractionation by alternative nitrogenases and past ocean anoxia. PNAS 111(13):4782-4787.
Bellenger J.P., Xu Y., Zhang X., Morel F.M.M., and Kraepiel A.M.L. (2014) Possible contribution of alternative nitrogenases to nitrogen fixation by asymbiotic N2-fixing bacteria in soils. Soil Biology and Biochemistry 69(0):413-420.
- Chemistry, ecology, and evolution of agriculturally important N2 fixers such as Azotobacter spp.
Previous Research Projects:
- Metabolic impacts on the hydrogen stable isotope content of bacterial lipids.
Zhang X., Gillespie A. L., and Sessions A.L. (2009) Large D/H variations in bacterial lipids reflect central metabolic pathways. PNAS 106:12580-12586.
- Trace element influences on gene diversity in the symbiotic gut microbial communities of lignocellulose-feeding insects
Rosenthal A.Z.*, Zhang, X.*, et al. (2013) Localizing transcripts to single cells suggests an important role of uncultured deltaproteobacteria in the termite gut hydrogen economy. PNAS *equal contributors
Matson E.G., Rosenthal A.Z., Zhang X., and Leadbetter J.R. (2013) Genome-wide effects of selenium and translational uncoupling on transcription in the termite gut symbiont Treponema primitia. mBio 4(6).
Zhang X., and Leadbetter J.R. (2012) Evidence for cascades of perturbation and adaptation in the metabolic genes of higher termite gut symbionts. mBIO 3(4): e00223-12.
Zhang X., Matson E.G., and Leadbetter J.R. (2011) Genes for selenium dependent and independent formate dehydrogenase in the gut microbial communities of 3 lower, wood-feeding termites and a wood-feeding roach. Environmental Microbiology 13(2): 307-323.
Matson E.G., Zhang X., and Leadbetter J.R. (2010) Selenium controls transcription of paralogous formate dehydrogenase genes in the termite gut acetogen, Treponema primitia. Environmental Microbiology 12: 2245-2258.
Princeton University, Department of Geosciences, 152 Guyot Hall, Princeton NJ 08544
Phone: (609) 258-2489