B13C-0632
Using metatranscriptomics to understand the roles of Fe(II)-oxidizing microbes in marine hydrothermal vents

Monday, 14 December 2015
Poster Hall (Moscone South)
Sean Mcallister1, Shawn W Polson1, Brian T Glazer2 and Clara Sze-Yue Chan3, (1)University of Delaware, Newark, DE, United States, (2)University of Hawaii at Manoa, Department of Oceanography, Honolulu, HI, United States, (3)University of Delaware, Geological Sciences, Newark, DE, United States
Abstract:
 Fe(II)-oxidizing microbes (FeOM) are thought to be key players in marine Fe cycling, particularly at hydrothermal vents. However, we do not have tools to track their activity, largely because we do not know the genes involved in neutrophilic chemolithotrophic Fe oxidation. Researchers have used gene homology between FeOM isolates to suggest several genes that may be involved in Fe(II) oxidation, including the Fe oxidase cyc2 found in the Zetaproteobacteria type strain Mariprofundus ferrooxydans, as well as all other known neutrophilic microaerophilic FeOM. Although many Zetaproteobacteria are found within natural Fe mats, close relatives of Fe(II)-oxidizing isolates are rarely present. Therefore, one goal of this study was to determine the activity of putative Fe(II) oxidation genes in dominant OTUs found in natural environments. We collected Fe mats from hydrothermal vents at Loihi Seamount, Hawaii, preserving RNA in situ. By analyzing metatranscriptomes of different Fe mat niches, we were able to determine the OTUs involved and the gene expression patterns associated with Fe(II) oxidation in the marine environment.

  Analysis of metatranscriptomic data confirms that the Zetaproteobacteria express the various genes necessary to support the Fe mat community through chemoautotrophic growth. Globally ubiquitous and even some rare species of the Zetaproteobacteria were active, with different relative abundances depending on Fe mat niches defined by fluid flow and geochemistry. Initial results show that genes thought to be involved in the electron transport pathway from Fe(II) to O2, including cyc2, are some of the most highly expressed genes in marine Fe microbial mats. Species-specific variants of these genes suggest that many of the Zetaproteobacteria species, spanning the breadth of the diversity of the class, are expressing genes necessary for Fe(II) oxidation within natural Fe mat niches. Understanding the differential expression of these genes in different niches will enable us to quantify the activity of marine FeOM and their effect on Fe and associated element cycling within deep and coastal marine systems.