Physiological and molecular biological characteristics of heterotrophic ammonia oxidation by Bacillus sp. LY
2010
Lin, Yan | Kong, Hainan | Wu, Deyi | Li, Chunjie | Wang, Rongying | Tanaka, Shuzo
This work concerned the study of ammonia oxidation by a heterotrophic bacterium, Bacillus sp. LY, isolated from a membrane bioreactor (MBR) treating a synthetic domestic wastewater with 15-l working volume. During the batch test 74.8% of ammonium and 61.0% of CODCr were removed, and the maximum nitrification rate was 173.6 mgN/(g dry weight day). The ammonia oxidation ability was inhibited by high organic substrate concentrations and was highest in the poorest medium. The isolate oxidized ammonia to NH₂OH, and the presence of ammonia monooxygenase (AMO) in Bacillus sp. LY was further confirmed by a specific 491-bp fragment of the amoA gene, but the results of PCR amplification suggest that amoB may not be a member of the amo operon in this isolate. Moreover, from the nitrogen balance, the percentage of nitrogen lost in a batch test was estimated to be 61.9%, which was presumed to have been removed via aerobic denitrification.
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