What's in an ANME?: Investigating the Evolution, Ecology, and Spatial Structure of Anaerobic Methane Oxidizing Archaea

Author: Woods, Philip Hanley

Year: 2027

Degree: Dissertation (Ph.D.)

Advisor: Orphan, Victoria J

Committee Members: Fischer, Woodward W.; Leadbetter, Jared R.; Parker, Joseph; Orphan, Victoria J.

Option: Geobiology

Abstract

Anaerobic oxidation of methane (AOM) is an important component of the marine methane cycle carried out by a syntrophic partnership between anaerobic methane-oxidizing archaea (ANME) and syntrophic sulfate-reducing bacteria (SRB). This thesis investigates the key factors underpinning anaerobic methane oxidation across spatial and temporal scales. Chapter I describes the importance of AOM in the Earth system and reviews major advances in the study of the ecology and physiology of ANME and syntrophic SRB. Chapter II investigates the development of methanotrophic metabolism from a methanogenic ancestral state over evolutionary timescales. Chapter III investigates the ecological driving factors that govern microbial communities at marine methane seeps over multiple years and multiple levels of methane seep activity. Chapter IV uses enrichment cultures established in situ at methane seeps to probe ecological differences between ANME taxa more directly. Finally, chapter V uses high-resolution imaging techniques to characterize the fine structure within ANME-SRB aggregates. Together, this work highlights key genomic, ecological, and structural determinants of ANME-SRB physiology.