Gaining insights into the physiology of neutrophilic, iron-oxidizing chemolithoautotrophs.

Barco Roman A, North Hollywood CA

Investigators

Abstract

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2015, Broadening Participation. The fellowship supports a research and training plan in a host laboratory for the Fellow and a plan to broaden participation of groups under-represented in science. The title of the research plan for this fellowship to Dr. Roman A. Barco is "Gaining insights into the physiology of autotrophic, iron-oxidizing microorganisms." The host institutions for this fellowship are Bigelow Laboratory for Ocean Sciences (BLOS) and the University of Southern California (USC). The sponsoring scientists are Dr. David Emerson (lead sponsor at BLOS) and Dr. Kenneth Nealson (co-sponsor at USC). The phylum Proteobacteria comprises a large and varied group of bacteria, including many pathogens but also many of benefit to humans, e.g., nitrogen-fixing bacteria crucial to agriculture. A class within the Proteobacteria phylum, the Zetaproteobacteria, plays a key role in the global iron cycle. All the Zetaproteobacteria that have been isolated to date obtain energy by oxidizing iron. They are both abundant and very active in marine environments with low concentrations of oxygen and with conditions that fall between acid and basic pH, known as circumneutral pH (pH 6 to 8). In addition to oxidizing iron, they also fix carbon, making them primary producers (autotrophs) in marine habitats associated with high iron content, such as hydrothermal vents, the oceanic crust and the deep marine subsurface. Yet despite these important environmental roles, their physiology has not been elucidated and requires further study. Conveniently, a Zetaproteobacteria relative has been isolated that does not require iron for its growth and, by comparison with the wild type, allows for identification of the proteins that carry out iron oxidation. A group of bacteria from the Gammaproteobacteria class, Thiomicrospira, obtains energy by oxidizing sulfur. Its genome has been sequenced, making it possible to compare the physiology of iron and sulfur oxidizers at the most basic level. Such analysis conducted during this fellowship promises useful insights into the mechanisms of iron-oxidation across different classes of the Proteobacteria phylum. Both of these types of bacteria are potentially useful in a number of biotechnology applications, including bioremediation. Training goals for the fellowship include acquiring programming skills for bioinformatics, especially for analyzing next-generation sequencing data and learning techniques in electromicrobiology, the use of electrodes to enrich and isolate microorganisms. The Fellow serves as a role model and mentor to undergraduate students at both host institutions and collaborates with the Center for Dark Energy Biosphere Investigations via the Community College Connections (CCC) program. The CCC program targets community colleges in Los Angeles, CA and surrounding areas, to disseminate information about environmental microbiology and how it links to other scientific fields such as geology, chemistry, and oceanography.