Mak Saito, Ph.D.

Interactions between metals and microbes using analytical chemistry and proteomics


Focusing on the nutritional requirements of microbes, particularly for biologically required metals and vitamins such as iron, zinc, cobalt, and B12.

Mak Saito, Ph.D.

Research Description

Marine microbes exert a tremendous influence on the cycling of chemical elements in the marine environment. Both microbes and ocean chemistry are largely invisible to the human eye, yet their complex and intertwined relationship sets the foundations for Earth’s habitable conditions. Our research group focuses on the nutritional requirements of microbes, particularly for biologically required metals and vitamins such as iron, zinc, cobalt, and B12. We study the functions those metals have within metal-containing enzymes used by microbes, and how scarcities of those metals and vitamins affect marine ecology and biogeochemistry. To conduct our research we develop and adapt new methods, such as using proteomics, which is the study of all of proteins within a cell, and deploy them in oceanic field expeditions. Such approaches can provide new information about what marine microbes are experiencing in the environment as that environment changes.

Research Impact

Our research group has been applying emerging proteomic techniques to microbial culture experiments and directly to the ocean environments. These approaches enable a variety of scientific findings, including the discover novel indicators for nutrient stress, the examination of cellular responses to environmental changes, the estimation of stoichiometric and metabolic costs of those responses, and most recently to directly examine microbial metabolisms and biomarkers in the complex ocean environments. For examples measurement of proteins in natural populations has demonstrated the microbial responses to the extreme nutrient scarcity through increased production of nutrient transporters and through sparing strategies to conserve nutrient use. It is our hope that the emergence of proteomic methods will allow a powerful metabolic diagnosis capability for natural populations of marine microbes that can be deployed throughout the ocean basins. These methods, coupled with other traditional and emerging technologies, could provide a deeper understand of how the oceans function as well as allowing us to observe how microbial biogeochemistry is responding to changes in the environment.

Media Press

Oceanus Magazine - Proteomics Reveals Ocean's Inner Workings

WHOI News - Scientists Apply Biomedical Technique to Reveal Ocean Changes Within the Body of the Ocean


related links

Marine Microbiology Initiative Science California Institute of Technology, Division of Geology and Planetary Sciences Back


Ph.D., Chemical Oceanography 
Massachusetts Institute of Technology and Woods Hole Oceanographic Institution Join Program, 2001

B.A., Biology and Environmental Studies
Oberlin College, 1994


National Academy of Sciences Kavli Fellow, 2012


Saito, M. A., M. R. McIlvin, D. M. Moran, T. J. Goepfert, G. R. DiTullio, A. F. Post, & C. H. Lamborg. (2014). Multiple nutrient stresses at intersecting Pacific Ocean biomes detected by protein biomarkers. Science, 345(6201), 1173-1177. doi: 10.1126/science.1256450

Lamborg, C. H., C. R. Hammerschmidt, K. L. Bowman, G. J. Swarr, K. M. Munson, D. C. Ohnemus, P. J. Lam, L. E. Heimburger, M. J. Rijkenberg, & M. A. Saito. (2014). A global ocean inventory of anthropogenic mercury based on water column measurements. Nature, 512(7512), 65-68. doi: 10.1038/nature13563

Swanner, E. D., N. J. Planavsky, S. V. Lalonde, L. J. Robbins, A. Bekker, O. J. Rouxel, M. A. Saito, A. Kappler, S. J. Mojzsis, & K. O. Konhauser. (2014). Cobalt and marine redox evolution. Earth and Planetary Science Letters, 390, 253-263. doi: 10.1016/j.epsl.2014.01.001

Cox, A. D., & M. A. Saito. (2013). Proteomic responses of oceanic Synechococcus WH8102 to phosphate and zinc scarcity and cadmium additions. Front Microbiol, 4, 387.doi: 10.3389/fmicb.2013.00387

Saito, M.A., A. E. Noble, A. Tagliabue, T.J. Geopfert, C. H. Lamborg, & W.J. Jenkins. (2013). Slow-spreading submarine ridges in the South Atlantic as a significant oceanic iron source. Nature Geosci, 3, 775-779. doi: 10.1038/ngeo1893 

Affiliated Investigators