Studies on the screening of denitrifying and phosphorus removal bacteria and its characteristics

Abstract:

[Objective] In order to study on the characteristics of denitrifying and phosphorus removal bacteria. [Methods] Many strains with denitrification and phosphorus removal characteristics under aerobic condition were isolated by screening of microorganism and methods of biological characteristics from the water and sediment samples of shrimp culture ponds. [Results] Among them strain LY-1 could remove nitrite nitrogen from 10 mg/L to 0.04 mg/L, and the PO43?-P from 10 mg/L to 0.05 mg/L in 18 h, respectively; and approximately to 100% of denitrifying and phosphorus removal rate were reached at the DO concentration of 5.0?5.9 mg/L. Furthermore, in comparison with a denitrifying and phosphorus removal bacterium, Ba-cillus subtilis selected as the positive control and Escherichia coli as the negative control, strain LY-1 was tested under different pH, temperature, salty, PO43?-P and nitrite concentra-tion, its denitrifying removal rate was reached approximately 99%, and phosphorus removal rate reached 86% at the pH of 5?9; the denitrifying and phosphorus removal rate of strain YX-6 reached proximately 100% at 30 °C; The rate almost reached 99% when salty ranged between 5 and 15, phosphorus concentration was 10 mg/L and nitrite nitrogen concentration was 20 mg/L. [Conclusion] The results showed that the denitrifying and phosphorus removal of LY-1 was significantly higher than that of the two controls (P<0.05). According to the mor-phological, physiological and biochemical properties, and the analysis of its 16S rRNA gene sequence, strain LY-1 was identified as Bacillus cereus primarily.