Mutagenesis of high-efficiency heterotrophic nitrifying-aerobic denitrifying bacterium Rhodococcus sp. strain CPZ 24

Breeding high-efficiency heterotrophic nitrifying-aerobic denitrifying (SND) bacteria is important for the removal of biological nitrogen in wastewater treatment. In this study, a high-efficiency SND mutant strain, & UDelta;Rhodococcus sp. CPZ 24, was obtained by ultraviolet-diethyl sulfate compound mutagenesis. The maximum nitrification and denitrification rates were 3.77 and 1.37 mg.L-1.h(-1), respectively 30.30 % and 17.10 % higher than those of wild bacteria. Biolog technology and network model analysis revealed that & UDelta;CPZ 24 significantly improved the utilisation ability and metabolic activity of organic carbon sources. Furthermore, the expression levels of the nitrogen removal function genes nxrA, nosZ, amoA, and norB in strain delta CPZ 24 increased signifi-cantly. In actual sewage, mutant bacteria delta CPZ 24 have a 95.05 % ammonia-nitrogen degradation rate and a 96.67 % nitrate-nitrogen degradation rate. These results suggested that UV-DES compound mutation was a successful strategy to improve the nitrogen removal performance of SND bacteria in wastewater treatment.

Automated summary

In this study, a high-efficiency heterotrophic nitrifying-aerobic denitrifying (SND) mutant strain was obtained using ultraviolet-diethyl sulfate compound mutagenesis. The mutant strain showed significantly improved nitrogen removal performance in wastewater treatment, with higher nitrification and denitrification rates compared to wild bacteria. This study provides a successful strategy for improving the nitrogen removal efficiency of SND bacteria.