title: Reactivation of aerobic and anaerobic ammonium oxidizers in OLAND biomass after long-term storage.
abstract: The biomass of an oxygen-limited autotrophic nitrification/denitrification (OLAND) biofilm reactor was preserved in various ways to find a storage method for both aerobic and anaerobic ammonium-oxidizing bacteria (AerAOB and AnAOB). Storage occurred at -20 degrees C with and without glycerol as cryoprotectant and at 4 and 20 degrees C with and without nitrate as redox buffer. After 2 and 5 months, reactivation of AerAOB and AnAOB was achieved with the biomass stored at 4 degrees C with and without nitrate and at 20 degrees C with nitrate. Moreover, the presence of the AerAOB and AnAOB was confirmed with fluorescent in situ hybridization (FISH). Preservation in a nitrate environment resulted in a lag phase for the AnAOB reactivation. The supplied nitrate was denitrified during storage, and a real-time polymerase chain reaction with nitrifying and denitrifying genes allowed to estimate that at least 1.0 to 6.0% of the OLAND biofilm consisted of denitrifiers. It was concluded that reactivation after long-term storage is possible and that preservation at 4 degrees C without nitrate addition is the recommended storage technique. The possibility to store OLAND biomass will facilitate research on AnAOB and can overcome larger-scale start-up and inhibition problems of novel nitrogen processes involving AnAOB.
authors.affiliation: Laboratory of Microbial Ecology and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Siegfried E
authors.initials: SE
authors.lastname: Vlaeminck
authors.forename: Joke
authors.initials: J
authors.lastname: Geets
authors.forename: Han
authors.initials: H
authors.lastname: Vervaeren
authors.forename: Nico
authors.initials: N
authors.lastname: Boon
authors.forename: Willy
authors.initials: W
authors.lastname: Verstraete
mesh_terms: D001420:Bacteria, Aerobic / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018441:Biofilms; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D017404:In Situ Hybridization, Fluorescence; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry / Q000378:metabolism; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D000644:Quaternary Ammonium Compounds / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature
chemical_list: D009566:Nitrates; D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D009584:Nitrogen