The growth pattern of the Bacillus cereus HY-1 and the enzymatic degradation characteristics of insecticide chlorpyrifos

Abstract:

The growth pattern of the bacteria and degradation characteristics of the crude enzyme extracted from an isolated strain Bacillus cereus HY-1 were approached in the paper. The results showed that the adaptation period of the bacteria was prolonged by addition of chlorpyrifos and the logarithmic phase and stationary phase were also extended against the control. Moreover, the pH of the culture medium increased with the growth of the strain. The results also indicated that the soluble protein of the crude enzyme was determined with Albumin (bovine serum) as standard protein and the soluble protein content of the crude enzyme was 2.21 g/L. The Km value and the maximal enzymatic degradation rate for chlorpyrifos were 1.235 6 mmol/L and 0.022 6 μmol/(mg·min), respectively. The appropriate incubation time for the enzymatic degradation was 1 h. The highest specific activity of the crude enzyme was gained when the adding volume of the crude enzyme was 1 mL. The crude enzyme activity had optimal temperature of 28 °C for the enzymatic degradation of chlorpyrifos, which was still over 78% of the maximal activity within temperature ranged from 20 °C to 44 °C. The crude enzyme showed comparatively greatest enzymatic activity at pH 6, high activity pH ranged from 5 to 9. Furthermore, additional experimental evidence revealed that the crude enzyme had some extent stability for temperature and pH. The crude enzyme also degraded chlorpyrifos efficiently while it was dealt with sodium chloride from 10 g/L to 70 g/L for 1 h.