DIVERSITY OF CRENARCHAEOTA ASSOCIATED WITH GAS HYDRATES AND HYDROCARBON SEEPS IN THE GULF OF MEXICO

The deep-sea represents a significant long-term sink in the global carbon budget and can effectively remove carbon for hundreds to millions of years. Planktonic non-thermophilic Crenarchaeota are recently recognized as a major group of metabolically active pelagic microorganisms in the deep sea. The goal of this research was to understand the distribution and abundance of Crenarchaeota in the subsurface ocean in the Gulf of Mexico where gas hydrates and hydrocarbon seeps are widespread. We hypothesize that production of Crenarchaeota is enhanced in gas hydrates and hydrocarbon seeps, which provide carbon and other essential nutrients for microbial growth. Environmental samples were taken from a gas hydrate mound (GC 234) and near a hydrocarbon seep in a brine pool (GC 233) using a research submersible. Normal marine sediments (NBP) were collected using box cores to serve as background control. Environmental DNA was extracted using commercially available test kits and amplified using the specific primers for Archaea (Arch 21F/ Arch 958R) and Crenarchaeota (Cren 28F/ Cren 457R). PCR products showed the presence of Archaea and Crenarchaeota from GC 234 and the NBP but not from GC 233. A microbial mat (Beggiatoa) at GC 234 also showed the presence of Archaea and Crenarchaeota. These results suggest Crenarchaeota may be heterogeneously distributed in the hydrate or seep environments. The presence of Crenarchaeota in the surface Beggiatoa mat suggest that the community structure in the mat may be more complex than previously recognized.