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Update submitted by Jason Sylvan, September 2015
The goal of this project is to determine if microbial mats, which are the dominant feature at the summit of Loihi Seamount near active venting, are seeded by microbial populations from the subsurface hydrothermal fluids or from background seawater. To determine that, we sampled microbial mats, hydrothermal fluids nearest to those mats, and background seawater during a cruise to Loihi in spring 2013. Sequencing of bacterial and archaeal 16S rRNA from these samples is supported by the CoDL. To date, all DNA has been extracted and several of the samples have been PCR amplified and sequenced, but there are more samples to analyze by MBL.Related to this project, one paper by co-investigator Moyer was published in 2015. In it, Jesser et al. analyzed functional genes in the microbial mats to be sequenced by CoDL and found that the percentage of Zetaproteobacteria, the numerically dominant group of bacteria at Loihi, is significantly related to the presence of genes for nitrate reduction, arsenic reduction and carbon fixation, and that morphology of the microbial mats is correlated to vent chemistry. Sylvan is lead author on a paper in prep, to be submitted fall 2015, studying nitrogen cycling in the Loihi fluids. The chemistry of several of the samples to be sequenced by CoDL is presented in this initial manuscript, as well as isotopic analysis of inorganic nitrogen species and bioenergetic calculations.