Ironing out the potential barriers of characterizing obligate iron metabolizing bacteria

Abstract

Iron metabolizing bacteria have far reaching impacts on not only the geochemical cycling of iron, but also on the cycling of bioavailable sulfur, nitrogen, and carbon. To understand the biotic factors that affect these cycles, the characterization of the metabolic capabilities of environmentally relevant Fe(III)-reducing and Fe(II)-oxidizing bacteria is required. The following thesis showcases the isolation and characterization of a novel Fe(III)-reducing microorganism from an underground iron mine and the implementation of a new strategy to study an uncooperative Fe(II)-oxidizing bacteria while also elucidating its full genomic context. The identification of the Soudan Underground Mine isolate “Metallumcola ferriviriculae” MK1 gives more insights into the understudied Gram-positive Fe(III)-reducing bacteria that are rich in multiheme cytochromes. Additionally, evaluation of the multiheme cytochromes within the “M. ferriviriculae” MK1 genome predicts homologs of Geobacter and Thermincola cytochromes in their proposed Fe(III)-reduction pathways. On the other hand, the analysis of the transposon mutagenesis of the Fe(III)-oxidizing Mariprofundus ferrooxydans PV-1 investigated gene essentiality within a non-colony-forming metabolic specialist. Additionally, the M. ferrooxydans PV-1 genome was resequenced to completion, which allows for full genomic context for future bioinformatic studies. While these studies expand both our knowledge of iron-metabolizing bacteria and the ways to study them, it has become apparent that there is still much to learn about the microbial players that impact the biogeochemical cycling of iron.