New bacteria Bacillus nitroreducens PLC9 with hydrogen peroxide-degrading activity with high survival rate in hydrogen peroxide

Abstract

Bacteria were isolated from wastewater containing highly concentrated hydrogen peroxide that had been used to clean the pure water delivery system in a semiconductor plant. One bacterium was selected for its high hydrogen peroxide degradation activity. In the presence of 1% hydrogen peroxide, it degraded 72.5% in 5 min. It showed 100% viability after 6 h at 1% hydrogen peroxide. Even at 3% hydrogen peroxide, it survived for more than 6 h. This bacterium was named as Bacillus nitroreducens PLC9 since its 16S rRNA showed 100% similarity with the recently reported new species B. nitroreducens. Purified catalase from B. nitroreducens PLC9 was characterized as a thermo-alkali-stable hydroperoxidase type II catalase, and it is suggested as a new type of catalase based on following: (1) it is stable over a broad pH range (pH 4-11); (2) it is consisted of homodimers with a molecular weight of 66 kDa (total molecular weight, 134 kDa); (3) its activity was not inhibited by 3-amino-1,2,4-triazole; and (4) its N-terminal sequence has never been reported before. Both B. nitroreducens PLC9 and the isolated catalase can be used for efficient degradation of hydrogen peroxide at high concentrations.