ABSTRACT
This study aimed to enrich anaerobic methane oxidizers (ANME) present in sediment from the Ginsburg Mud Volcano (Gulf of Cadiz) in a polyurethane foam packed biotrickling filter (BTF). The inoculated sediment was stored for 4 years at 4°C under methane atmosphere prior to inoculation in BTF. The BTF was operated in continuous supply of methane and/or nitrogen for 380 days. Under the methane-rich environment in the BTF, methane and sulfate consumption were coupled to total dissolved sulfide production at approximately equimolar ratios. Sulfate reduction with simultaneous sulfide production accumulating up to 7 mM after 200 days, indicates the development of anaerobic oxidation of methane (AOM) coupled to sulfate reduction. Illumina high-throughput sequence analysis of 16S rRNA genes showed that after 248 days of bioreactor operation, nearly 50% of the archaeal sequences belonged to the anaerobic methanotrophs (ANME) clades, including ANME-1 (42%) and ANME-2 (8%). Other major archaeal clades in the bioreactor enrichment were the Miscellaneous Crenarchaeotic Group (33%). A relatively shorter BTF start-up period in comparison to other AOM enriching bioreactors and high rate of AOM induced sulfate reduction were achieved in this study. The proliferation of ANME was supported by the packing material of the BTF.
