Abstract

Chemolithoautotrophic Fe(II) oxidizers belonging to Zetaproteobacteria play an important role in multiple biogeochemical cycles in the deep-sea biosphere. However, molecular and mechanistic understanding of Zetaproteobacteria physiology and metabolism remains speculative in the absence of a genetic system. These bacteria are considered recalcitrant to classical genetic techniques owing to their inability to form colonies on a solid medium, and production of copious amounts of iron oxyhydroxides with very few cells during liquid cultivation. Another challenge is their singular life style of Fe(II) dependent autotrophy, which prohibits comparative studies under different metabolic conditions. During my C-DEBI postdoctoral tenure, I successfully developed the first genetic tools and techniques to transform and express foreign genes in Mariprofundus ferrooxydans PV-1 as a model Zetaproteobacteria for genetic studies. I designed, constructed and transformed several different plasmids expressing foreign genes to provide M. ferrooxydans an ability to grow using an alternate metabolism. I successfully modified M. ferrooxydans genetically to grow using glucose as the sole carbon source, instead of carbon dioxide, while using Fe(II) as the energy source. The alternate metabolic ability thus provided to M. ferrooxydans can be leveraged to perform comparative studies in the future to decipher its physiology and metabolism. Furthermore, I developed an undergraduate teaching module for incoming freshmen students, focused on principles of chemolithoautotrophy in Fe(II) oxidizing bacteria.