ABSTRACT
In marine environments, which cover almost 70% of the earth's total surface, the methane cycle is exclusively controlled by microbial activities with an estimated annual rate of methanogenesis of 85–300 Tg methane years. Out of the total amount of methane produced in sea sediments, ca. 90% is consumed by microbially mediated anaerobic oxidation of methane (AOM). The AOM coupled to sulfate reduction (AOM-SR) process involves methane oxidation by anaerobic methanotrophic archaea, while sulfate in the subsurface of the marine sediment is reduced by sulfate reducing bacteria. AOM-SR has mainly two relevances, one is ecological, prevention of methane emission to the atmosphere and another potential biotechnological applications. AOM is restricting a large amount of methane to the sea floor with a significant effect in global warming. Moreover, AOM-SR is a biological process with potential application for the desulfurization of wastewater. The chapter also presents an overview of the key concepts discussed in this book.
