This proposal seeks to characterize the microbes recovered from sub ocean floor sediments cored during IODP leg 339 and compare them to the well-characterized microbial suite found in similar sediments off the Peru margin. Metatranscriptomic analysis enables the recognition of the active biome by targeting the whole sample messenger RNA and relating the RNA to known gene function. Thus the metabolic behavior and taxonomy of the entire microbial community can be assessed and the relative proportion of active vs. inactive biota (paleome vs. biome) determined. The samples for metatranscriptomic analysis are selected from portions of the core taken from 1.) sulfate-rich areas in the shallow subsurface; 2.) methane-rich samples from the deeper subsurface, and 3.) samples taken from near the sulfate-methane transition. The hypothesis to be tested is that these chemical variations are directly related to sample biology. This work is needed in order for the objectives of expedition 339 to be fully met. Broader impacts include graduate and early career investigator involvement, community outreach, and an IODP lectureship. Scientific impacts include characterization of part of the world?s largest and most poorly understood ecosystem, the sub-seafloor deep biosphere. The potential for discovering new species and metabolic pathways is significant.
