暹罗芽孢杆菌DY3123的分离、鉴定及其降解黄曲霉毒素B1的效果研究

Isolation, Identification of Bacillus siamensis DY3123 and Its Degradation Effect on Aflatoxin B1

摘要:

【目的】筛选能够降解黄曲霉毒素B₁（AFB₁）的微生物菌株，并分析其降解AFB₁的机理。【方法】以香豆素为唯一碳源，从松墨天牛（鞘翅目天牛科）幼虫肠道中分离、筛选对AFB₁具有降解能力的菌株，同时对其降解AFB₁的机理进行研究。【结果】通过初筛和复筛，成功获得一株对AFB₁的降解率高达94.71%的菌株，鉴定为暹罗芽孢杆菌（Bacillus siamensis，B. siamensis）DY3123。不同细胞组分降解AFB₁的试验结果表明，降解AFB₁的主要活性物质来自暹罗芽孢杆菌DY3123无细胞培养基上清液；上清液降解AFB₁的最适温度为80 ℃，最适初始pH为8.0，最适反应时间为36 h；Cu²⁺可以提高上清液的降解活性，Zn²⁺、Mg²⁺和Fe³⁺会抑制其降解活性。此外，采用3-（4，5-二甲基噻唑-2）-2，5-二苯基四氮唑溴盐（methyl thiazolyl tetrazolium，MTT）法测定了降解产物对淋巴细胞存活率的影响，结果表明降解产物对细胞存活率无显著影响。【结论】该研究为暹罗芽孢杆菌DY3123在食品和动物饲料行业中的应用提供了参考。

Abstract:

[Objective] This study aimed to screen out a microbial strain capable of degrading aflatoxin B₁ (AFB₁) and decipher the degradation mechanism. [Method] With coumarin as the sole carbon source, AFB₁-degrading strains were isolated and screened from the larval gut of Monochamus alternatus (Coleoptera: Cerambycidae), and the degradation mechanism for AFB₁ was investigated. [Result] After primary screening and re-screening, a strain with the degradation rate reaching 94.71% for AFB₁ was obtained, and this strain was identified as Bacillus siamensis (B. siamensis) DY3123. The results of experiments on the degradation of AFB₁ by different cellular components indicated that the main active substances responsible for degrading AFB₁ were from the cell-free culture supernatant of B. siamensis DY3123, which showed the optimum degradation performance at 80 ℃ and pH 8.0 after 36 h. Cu²⁺ improved the degradation activity of the cell-free supernatant, while Zn²⁺, Mg²⁺, and Fe³⁺ exerted inhibitory effects. In addition, the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (methyl thiazolyl tetrazolium, MTT) assay was employed to examine the effects of the degradation products on the viability of lymphocytes, which indicated that the degradation products had no significant impact on cell viability. [Conclusion] The findings lay a foundation for the application of B. siamensis DY3123 in the food and animal feed industry.