RESUMO
A strain bacterium that is thermophilic, heterotrophic nitrifying, and aerobic denitrifying was isolated and identified as Anoxybacillus contaminans HA for the first time. The identification was based on morphological and physiological characterizations, together with phylogenetic analysis of 16S rDNA sequence. The strain possessed excellent tolerance to high temperatures, with 55 °C as its optimum and 60 °C as viable. Moreover, NH4 (+)-N and NO3 (-)-N could be efficiently removed under thermophilic and solely aerobic conditions, with little intermediate accumulation. Average removal efficiencies of NH4 (+)-N and NO3 (-)-N at 55 °C reached 71.0 and 74.7 %, respectively, with removal rates of 5.83 and 32.08 mg l(-1) h(-1), respectively. Single-factor experiments suggested that the optimal conditions for both heterotrophic nitrification and aerobic denitrification were glucose as carbon source, NH4 (+)-N range of 50-200 mg l(-1), and wide NO3 (-)-N range of 200-1000 mg l(-1). These results indicated that strain HA had heterotrophic nitrification and aerobic denitrification abilities, as well as the notable ability to remove ammonium under thermophilic condition. Thus, this strain has potential application in waste-gas treatment.
Assuntos
Anoxybacillus/metabolismo , Desnitrificação , Nitrificação , Aerobiose , Anoxybacillus/classificação , Anoxybacillus/genética , Anoxybacillus/isolamento & purificação , Técnicas de Tipagem Bacteriana , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Temperatura Alta , Microscopia Eletrônica de Transmissão , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , TemperaturaRESUMO
The reduction of Fe(II)EDTA-NO is one of the core processes in BioDeNOx, an integrated physicochemical and biological technique for NOx removal from industrial flue gases. A newly isolated thermophilic Anoxybacillus sp. HA, identified by 16S rRNA sequence analysis, could simultaneously reduce Fe(II)EDTA-NO and Fe(III)EDTA. A maximum NO removal efficiency of 98.7% was achieved when 3mM Fe(II)EDTA-NO was used in the nutrient solution at 55°C. Results of this study strongly indicated that the biological oxidation of Fe(II)EDTA played an important role in the formation of Fe(III)EDTA in the anaerobic system. Fe(II)EDTA-NO was more competitive than Fe(III)EDTA as an electron acceptor, and the presence of Fe(III)EDTA slightly affected the reduction rate of Fe(II)EDTA-NO. At 55°C, the maximum microbial specific growth rate µmax reached the peak value of 0.022h(-1). The maximum NO removal efficiency was also measured (95.4%) under this temperature. Anoxybacillus sp. HA, which grew well at 50°C-60°C, is a potential microbial resource for Fe(II)EDTA-NO reduction at thermophilic temperatures.
