Baltic TRANSCOAST Seminar - Ass. Prof. Dr. Martyna Glodowska (Radboud University, The Netherlands)

Abstract
Methane (CH4) is a potent greenhouse gas significantly contributing to the climate warming we
are currently facing. Microorganisms play a crucial role in the global CH4 cycle that is controlled
by the balance between anaerobic production via methanogenesis and CH4 removal via
methanotrophic oxidation. Research in recent decades advanced our understanding of
CH4 oxidation, which until 1976 was believed to be a strictly aerobic process. Anaerobic oxidation
of methane (AOM) coupled with sulfate reduction is now known to be a major sink of CH4 in
marine ecosystems. Furthermore, in 2006 it was discovered that anaerobic CH4 oxidation can
also be coupled to nitrate reduction (N-DAMO). The N-DAMO process attracted a lot of attention
due to its biotechnological potential to efficiently remove nitrate (NO3-) while decreasing CH4
emission. Moreover, it further demonstrated that AOM may be much more versatile than
previously thought and linked to other electron acceptors. In consequence, an increasing number
of studies in recent years showed or suggested that alternative electron acceptors can be used
in the AOM process including FeIII, MnIV, AsV, CrVI, SeV, SbV, VV, and BrV. Anaerobic methanotrophic
archaea, the so-called ANME archaea, are key players in the AOM process, yet we still lack a
deeper understanding of their metabolism, electron acceptor preferences, and their interaction
with other microbial community members. It is still not clear whether ANME archaea can oxidize
CH4 and reduce metallic electron acceptors independently or via electron transfers to syntrophic
partners, interspecies electron transfer, nanowires, or conductive pili. In this lecture, I will
present our current knowledge about the AOM process and bring some examples of how relevant
it is in various ecosystems base on our recent research.