Changes in bacterial communities inhabiting massive sulfide deposits on the Juan de Fuca Ridge across a ~10 My transects.

Hydrothermal vent depositsprovide inorganic compounds that anerobic bacteria use through chemolithoautotrophic primary productivity for survival in the extreme conditions of the ocean floor. Active chimney structures have been studied to understand the distribution of primary productivity pathways (Olins et al., 2013). However, metabolic processes supported by the massive sulfides away from the active venting has not been adequately addressed. Here we describe the sampling of massive sulfides ranging in ages up to ~10 Myr, from the Juan de Fuca ridge. Metabolic processes are investigated using two approaches, enrichment of active cultures and quantification of metabolic genes in the eDNA extracted from these massive sulfides. All massive sulfides collected from each site were broken down into sizable portions and placed in mason jars with ocean water. Bacteria were enriched from the massive sulfide deposits by inoculation cultures from each sample to establish the aerobic and anerobic tendencies of the bacteria amongst the varying aged sulfides. Furthermore, goals for the cultures included determining phenotypic qualities and species differentiation along aerobic and anaerobic column, as well as ferrous sulfide and inorganic metabolisms. These inoculation cultures consisted of an iron-sulfide layer followed by low-melt agarose- and 1% agarose. Samples for DNA analysis were frozen onboard the R/V Kilo Moana for later extraction. DNA was extracted from the samples via bead beating technique and qPCR was used to quantify bacterial 16S rRNA, aclB, sox and dsrA genes.