Sulfur-oxidizing bacteria in full-scale biogas cleanup system of ethanol industry

Biogas from distillery anaerobic digesters in the ethanol industry consist of hydrogen sulfide (H2S) at concentrations up to 12,000 ppm. Before being used as a feed for an electrical generator H2S levels need to be reduced to concentrations below 100 ppm. H2S removal performance depends on the activity of sulfur-oxidizing bacteria (SOB). Next Generation Sequencing (NGS) analysis of samples collected from the bioscrubber with 3 different samples including starting seed (TRE1), recirculating liquid (TRE2), bioscrubber plastic media (TRE3) were taken. Genera Fastidiosipila belonging to the phylum Firmicutes was dominant in the starting seed, while genera Pseudomonas, MWH UniP1_aquatic_group, Hydrogenophaga belonging to phyla Proteobacteria were dominant in the bioscrubber. Pseudomonas anguilliseptica (33%) and Pseudomonas alcaligenes (18%) were the major members of facultative chemoautotrophic SOB in the bioscrubber. Two species of SOB were isolated using a selective culture medium technique including Sphingobium yanoikuyae and Enhydrobacter aerosaccus. (C) 2019 Elsevier Ltd. All rights reserved.