Performance Assessment and Enrichment of Anaerobic Methane Oxidizing Microbial Communities from Marine Sediments in Bioreactors

This study is broadly divided into three sections: a) understanding and knowledge development on anaerobic oxidation of methane (AOM), anaerobic methanotrophs and their physiology and distribution; b) characterisation of AOM hosting sediment, basically in the coastal sediment from marine lake Grevelingen; and c) enrichment based study of ANME in different bioreactors configurations which includes membrane bioreactor, biotrickling filter and high pressure bioreactor. This research experimentally demonstrates that biomass retention and the continuous supply of methane can favour the growth of the slow growing anaerobic methane oxidizing community in bioreactors even under ambient conditions.

Anaerobic oxidation of methane (AOM) coupled to sulfate reduction (AOM-SR) is a biological process mediated by anaerobic methanotrophs (ANME) and sulfate reducing bacteria. It has scientifi c and societal relevance in regulating the global carbon cycle and biotechnological application for treating sulfate-rich wastewater. This research aimed to enhance the recent knowledge on ANME distribution and its enrichment in different bioreactor confi gurations, i.e. membrane bioreactor (MBR), biotrickling fi lter (BTF) and high pressure bioreactor (HPB). Marine sediment from Ginsburg mud volcano, Gulf of Cadiz was used as inoculum in the BTF and MBR. The BTF operation showed the enrichment of ANME in the biofi lm, especially ANME-1 (40%) and ANME-2 (10%). Whereas, the dominancy of ANME-2 and Desulfosarcina aggregates was observed in the MBR. Moreover, HPB study was performed by using highly enriched ANME-2 community from Captain Arutyunov mud volcano. During the study of HPB at different temperature and pressure conditions, the incubation at 10 MPa pressure and 15°C was observed to be the most suitable condition for the studied AOM-SR community. Furthermore, AOM-SR activity in the coastal sediments from marine Lake Grevelingen (the Netherlands) was explored and the microbial community was characterised which was dominated by ANME-3 among known ANME types.