耐盐性毒死蜱降解菌HY-1 的产酶培养基及发酵条件优化

Optimized culture medium and fermentation conditions for enzyme production by the salt-tolerant chlorpyrifos-degrading bacterium HY-1

摘要:

为了明确生化处理和微生物降解的关系, 通过增加耐盐菌的比例可以提高农药废水生化处理效果。本研究从农药厂废水中分离到1 株耐盐性毒死蜱降解菌——蜡状芽孢杆菌(Bacillus cereus HY-1), 以从该菌中提取到的降解酶比活力为指标, 进行产酶培养基和发酵条件的优化研究。通过单一因素试验和正交试验, 对细菌HY-1 的产酸培养基和发酵条件进行了优化。运用SPSS 软件进行结果分析, 所获优化培养基配方为: 葡萄糖6.0 g/L, 胰蛋白胨2.2 g/L, K₂HPO₄ 2.0 g/L,KH₂PO₄ 0.2 g/L, MgSO₄·7H₂O 0.1 g/L, NaCl 0.1 g/L 和微量元素溶液2 mL/L。得到菌株发酵培养的最佳优化条件为: 种子液培养时间为16 h, 发酵培养时间为18 h, 接种量为1% (V/V), 发酵培养基初始pH 值为7.0。氯化钠浓度为0?30 g/L 时降解酶比活力不受影响, 这是已报道的耐盐性最强的一株毒死蜱降解菌。

关键词:毒死蜱, 降解酶, 培养基, 发酵条件优化, 耐盐菌

Abstract:

In order to improve the treatment effect of wastewater from pesticide enterprise, it is necessary to study the salt-tolerant characteristics and fermentation conditions of the degrading bacterium. A chlorpyrifos-degrading bacterium Bacillus cereus HY-1 was isolated in laboratory from pesticide wastewater. The optimal fermentation medium and fermentation conditions of HY-1 were selected by single factor and orthogonal test, and the amount of enzyme produced by HY-1 was estimated based on the specific activity of the enzyme. The experimental results were analyzed by the SPSS system. The optimal composition of the culture medium included glucose 6.0 g/L, tryptone 2.2 g/L, K₂HPO₄ 2.0 g/L, K₂HPO₄ 0.2 g/L, MgSO₄·7H₂O 0.1 g/L, NaCl 0.1 g/L, trace elements solution 2 mL/L. The optimal fermentation conditions of HY-1 were: incubation time of the seed culture 16 h, fermentation time 18 h, inoculum size 1% (V/V), initial pH 7.0. The specific activity of the degrading enzyme was not affected while the sodium chloride concentration of the fermentation medium increased from 0 g/L to 30 g/L. To the best of our knowledge, this is the most extremely salt-tolerant bacterium reported that could degrade chlorpyrifos.

Key words:Chlorpyrifos, Degrading enzyme, Culture medium, Fermentation condition optimization, Salt-tolerant bacterium