RESEARCH WITH THE MOREL GROUP GEOSCIENCES DEPARTMENT • Also called the “Trace Metals Group” • Studies the biological and chemical processes that control the cycling of trace metals in the environment • Lab Supervisor: Francois Morel • My supervisor: Xinning Zhang OBJECTIVE • I studied the purple nonsulfur bacterium Rhodopseudomonas palustris this summer. • The purple bug bacteria has a certain Fe requirement for growth. The project I worked on involved analyzing how the purple bug adapts to Fe-deplete growing conditions. • In particular, I was searching for the presence of a siderophore, which is an Fe-binding compound that certain microorganisms excrete. WHY STUDY PURPLE BUG? • It is one of the most metabolically versatile organisms out there. • It can undergo four different types of metabolisms (photoautotrophic, photoheterotrophic, chemoautotrophic, and chemoheterotrophic) • Thus, it can grow under light and dark conditions and use organic and inorganic compounds for growth. MY CULTURES Cultures on the left (darker ones, bottle 5 &6) are the Fe-replete cells Cultures on the right (lighter ones, bottle 2,3, 4) are the Fe-deplete cells PIGMENT CONTENT PER CELL A) bcha per cell bcha or chl cell ( fg/cell) 3.0 2.5 2.0 1.5 1.0 0.5 0.0 bot 6 (2.5 uM Fet) bot 5 (2.5 uM Fet) bot 3 (no Fe added) bot 3 (no Fe added) bot 2 (no Fe added) rep TOTAL PROTEIN PER CELL A) 4.5E-07 4.0E-07 total protein (ug/cell) 3.5E-07 3.0E-07 2.5E-07 2.0E-07 1.5E-07 1.0E-07 5.0E-08 0.0E+00 6 (+FE) 5(+Fe) 3 (-Fe) 2( -Fe) SIDEROPHORES PER CELL 2.00E-10 1.80E-10 DFOB equivalents/cell 1.60E-10 1.40E-10 1.20E-10 1.00E-10 8.00E-11 6.00E-11 4.00E-11 2.00E-11 0.00E+00 Bottle 6 (+2.5 uM Fe) Bottle 5 (+2.5 uM Fe) Bottle 3 (no Fe added) Bottle 2 (no Fe added) FUTURE COURSE • Although I was not able to detect a significant difference in the amount of siderophores between the Fe-replete and Fe-deplete cells, I learned a lot of skills as a result of this internship, such as how to analyze and troubleshoot data. • This project has encouraged me to continue pursuing research with the purple bug bacteria. • Currently, I am studying the H2 producing capacity of various strains of the purple bug and exploring its potential as a source of biofuel.