蜡状芽孢杆菌HY-1的生长及对毒死蜱的酶促降解特性

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

摘要:

为明确毒死蜱降解菌——蜡状芽孢杆菌Bacillus cereus HY-1的生长和粗酶液对毒死蜱的降解特性, 采用种子液中定量添加毒死蜱和测定粗酶比活力的方法, 研究含毒死蜱的种子液培养基中菌株的生长规律和环境因素对粗酶液降解毒死蜱的影响。结果表明: 含毒死蜱的培养液和空白对照相比, 菌株生长的适应期延长, 对数期、稳定期顺序后延。随着培养液中菌体数量的增长, 培养液的pH也随之升高。粗酶液中可溶性蛋白的含量为2.21 g/L, 测得粗提酶中其米氏常数Km为1.235 6 mmol/L, 最大降解速率Vm

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.