Oceanography Seminar-Dr. Victoria Orphan

“Life electric: ecophysiology, adaptations, and inter-organismal interactions of methanotrophic consortia and viruses in the deep sea”

Multicellular assemblages of microorganisms are ubiquitous in nature, and the proximity afforded by aggregation is thought to permit intercellular metabolic coupling that can accommodate otherwise unfavorable metabolic reactions. Consortia of methane-oxidizing archaea and sulphate-reducing bacteria are well-known examples of microbial co-aggregation in marine methane seep environments. The coupling mechanisms that occurs in these symbioses however is only beginning to be understood, despite the global significance of the process of anaerobic methane oxidation. To further our understanding of microscale processes that help regulate global scale carbon fluxes, we are examining interspecies spatial positioning and biosynthetic activities in methane-oxidizing consortia.  Our primary approach tracks the stable isotope incorporation into individual archaeal and bacterial cells under in situ conditions, to constrain their potential metabolic interactions.  A generalized model of electric conductivity between co-associated archaea and bacteria best fit the empirical data. Combined with the detection of large multi-haem cytochromes in the genomes of methanotrophic archaea and the demonstration of redox-dependent staining of the matrix between cells in consortia, our results provide evidence for syntrophic coupling through direct electron transfer. 

VICTORIA ORPHAN

PROFESSOR

JAMES IRVINE PROFESSOR OF ENVIRONMENTAL SCIENCE AND GEOBIOLOGY AND DIRECTOR

CENTER FOR ENVIRONMENTAL MICROBIAL INTERACTIONS

CALIFORNIA INSTITUTE OF TECHNOLOGY