AUTOHYDROGENOTROPHIC DENITRIFYING MICROBIAL COMMUNITY IN A GLASS BEAD BIOFILM REACTOR

Glass bead biofilm reactor was operated by using hydrogen as an electron donor to reduce 150 mg NO3−-N l-1 to below detection level. The microbial community in the glass bead biofilm reactor was investigated by using DGGE and FISH. In DGGE analysis, five bands were shown at the same position in all cases including seed sludge and enriched sludge in suspended and biofilm. Two bands were shown from the samples in suspended culture and biofilm grown on glass beads. In the biofilm, 5 bands were found to be dominant. The majority was consisted of eight β-proteobacteria, one γ-proteobacteria and twelve clostridia in phylogenetic trees. Especially, Uncultured hydrogenophaga sp. is a new genus of hydrogen-oxidizing bacteria (An8, BF9). This microorganism was revealed not only in all cases including seed sludge and enriched sludge in suspended culture and biofilm but also dominated in microbial community. In FISH using EUB338 probe, it was proved that β-proteobacteria was dominant group in anaerobic sludge and biofilm.